[PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL

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* [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API
@ 2025-01-28  9:14 Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 1/6] mips: fix mips_get_syscall_arg() for o32 Dmitry V. Levin
                   ` (6 more replies)
  0 siblings, 7 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:14 UTC (permalink / raw)
  To: Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Will Deacon, Guo Ren, Brian Cain,
	Huacai Chen, WANG Xuerui, Geert Uytterhoeven, Michal Simek,
	Thomas Bogendoerfer, Dinh Nguyen, Jonas Bonn, Stefan Kristiansson,
	Stafford Horne, James E.J. Bottomley, Helge Deller,
	Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
	Madhavan Srinivasan, Paul Walmsley, Palmer Dabbelt, Albert Ou,
	Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
	Christian Borntraeger, Sven Schnelle, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, Shuah Khan,
	linux-snps-arc, linux-kernel, linux-arm-kernel, linux-csky,
	linux-hexagon, loongarch, linux-m68k, linux-mips, linux-openrisc,
	linux-parisc, linuxppc-dev, linux-riscv, linux-s390, linux-sh,
	sparclinux, linux-um, linux-arch, linux-kselftest, linux-api

PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of
system calls the tracee is blocked in.

This API allows ptracers to obtain and modify system call details
in a straightforward and architecture-agnostic way.

Current implementation supports changing only those bits of system call
information that are used by strace, namely, syscall number, syscall
arguments, and syscall return value.

Support of changing additional details returned by PTRACE_GET_SYSCALL_INFO,
such as instruction pointer and stack pointer, could be added later if
needed, by using struct ptrace_syscall_info.flags to specify the additional
details that should be set.  Currently, "flags", "reserved", and
"seccomp.reserved2" fields of struct ptrace_syscall_info must be
initialized with zeroes; "arch", "instruction_pointer", and "stack_pointer"
fields are ignored.

PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations.
Other operations could be added later if needed.

Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen.  The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure
to provide an API of changing the first system call argument on riscv
architecture [1].

ptrace(2) man page:

long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
       Modify information about the system call that caused the stop.
       The "data" argument is a pointer to struct ptrace_syscall_info
       that specifies the system call information to be set.
       The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).

[1] https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/

Notes:
    v3:
    * powerpc: Submit syscall_set_return_value fix for "sc" case separately
    * mips: Do not introduce erroneous argument truncation on mips n32,
      add a detailed description to the commit message of the
      mips_get_syscall_arg change
    * ptrace: Add explicit padding to the end of struct ptrace_syscall_info,
      simplify obtaining of user ptrace_syscall_info,
      do not introduce PTRACE_SYSCALL_INFO_SIZE_VER0
    * ptrace: Change the return type of ptrace_set_syscall_info_* functions
      from "unsigned long" to "int"
    * ptrace: Add -ERANGE check to ptrace_set_syscall_info_exit,
      add comments to -ERANGE checks
    * ptrace: Update comments about supported syscall stops
    * selftests: Extend set_syscall_info test, fix for mips n32
    * Add Tested-by and Reviewed-by

    v2:
    * Add patch to fix syscall_set_return_value() on powerpc
    * Add patch to fix mips_get_syscall_arg() on mips
    * Add syscall_set_return_value() implementation on hexagon
    * Add syscall_set_return_value() invocation to syscall_set_nr()
      on arm and arm64.
    * Fix syscall_set_nr() and mips_set_syscall_arg() on mips
    * Add a comment to syscall_set_nr() on arc, powerpc, s390, sh,
      and sparc
    * Remove redundant ptrace_syscall_info.op assignments in
      ptrace_get_syscall_info_*
    * Minor style tweaks in ptrace_get_syscall_info_op()
    * Remove syscall_set_return_value() invocation from
      ptrace_set_syscall_info_entry()
    * Skip syscall_set_arguments() invocation in case of syscall number -1
      in ptrace_set_syscall_info_entry() 
    * Split ptrace_syscall_info.reserved into ptrace_syscall_info.reserved
      and ptrace_syscall_info.flags
    * Use __kernel_ulong_t instead of unsigned long in set_syscall_info test

Dmitry V. Levin (6):
  mips: fix mips_get_syscall_arg() for o32
  syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  syscall.h: introduce syscall_set_nr()
  ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op
  ptrace: introduce PTRACE_SET_SYSCALL_INFO request
  selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO

 arch/arc/include/asm/syscall.h                |  25 +
 arch/arm/include/asm/syscall.h                |  37 ++
 arch/arm64/include/asm/syscall.h              |  29 +
 arch/csky/include/asm/syscall.h               |  13 +
 arch/hexagon/include/asm/syscall.h            |  21 +
 arch/loongarch/include/asm/syscall.h          |  15 +
 arch/m68k/include/asm/syscall.h               |   7 +
 arch/microblaze/include/asm/syscall.h         |   7 +
 arch/mips/include/asm/syscall.h               |  70 ++-
 arch/nios2/include/asm/syscall.h              |  16 +
 arch/openrisc/include/asm/syscall.h           |  13 +
 arch/parisc/include/asm/syscall.h             |  19 +
 arch/powerpc/include/asm/syscall.h            |  20 +
 arch/riscv/include/asm/syscall.h              |  16 +
 arch/s390/include/asm/syscall.h               |  24 +
 arch/sh/include/asm/syscall_32.h              |  24 +
 arch/sparc/include/asm/syscall.h              |  22 +
 arch/um/include/asm/syscall-generic.h         |  19 +
 arch/x86/include/asm/syscall.h                |  43 ++
 arch/xtensa/include/asm/syscall.h             |  18 +
 include/asm-generic/syscall.h                 |  30 +
 include/uapi/linux/ptrace.h                   |   7 +-
 kernel/ptrace.c                               | 179 +++++-
 tools/testing/selftests/ptrace/Makefile       |   2 +-
 .../selftests/ptrace/set_syscall_info.c       | 514 ++++++++++++++++++
 25 files changed, 1143 insertions(+), 47 deletions(-)
 create mode 100644 tools/testing/selftests/ptrace/set_syscall_info.c

-- 
ldv

^ permalink raw reply	[flat|nested] 17+ messages in thread

* [PATCH v3 1/6] mips: fix mips_get_syscall_arg() for o32
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value() Dmitry V. Levin
                   ` (5 subsequent siblings)
  6 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov, Maciej W. Rozycki
  Cc: Alexey Gladkov, Eugene Syromyatnikov, Mike Frysinger,
	Renzo Davoli, Davide Berardi, Thomas Bogendoerfer, strace-devel,
	linux-mips, linux-kernel

This makes ptrace/get_syscall_info selftest pass on mips o32 and
mips64 o32 by fixing the following two test assertions:

1. get_syscall_info test assertion on mips o32:
  # get_syscall_info.c:218:get_syscall_info:Expected exp_args[5] (3134521044) == info.entry.args[4] (4911432)
  # get_syscall_info.c:219:get_syscall_info:wait #1: entry stop mismatch

2. get_syscall_info test assertion on mips64 o32:
  # get_syscall_info.c:209:get_syscall_info:Expected exp_args[2] (3134324433) == info.entry.args[1] (18446744072548908753)
  # get_syscall_info.c:210:get_syscall_info:wait #1: entry stop mismatch

The first assertion is fixed for mips o32 by using struct pt_regs.pad0
instead of get_user() to obtain syscall arguments.  This approach works
due to this piece in arch/mips/kernel/scall32-o32.S:

        /*
         * Ok, copy the args from the luser stack to the kernel stack.
         */

        .set    push
        .set    noreorder
        .set    nomacro

    load_a4: user_lw(t5, 16(t0))		# argument #5 from usp
    load_a5: user_lw(t6, 20(t0))		# argument #6 from usp
    load_a6: user_lw(t7, 24(t0))		# argument #7 from usp
    load_a7: user_lw(t8, 28(t0))		# argument #8 from usp
    loads_done:

        sw	t5, 16(sp)		# argument #5 to ksp
        sw	t6, 20(sp)		# argument #6 to ksp
        sw	t7, 24(sp)		# argument #7 to ksp
        sw	t8, 28(sp)		# argument #8 to ksp
        .set	pop

        .section __ex_table,"a"
        PTR_WD	load_a4, bad_stack_a4
        PTR_WD	load_a5, bad_stack_a5
        PTR_WD	load_a6, bad_stack_a6
        PTR_WD	load_a7, bad_stack_a7
        .previous

arch/mips/kernel/scall64-o32.S has analogous code for mips64 o32 that
allows obtaining syscall arguments from struct pt_regs.regs[4..11]
instead of get_user().

The second assertion is fixed by truncating 64-bit values to 32-bit
syscall arguments.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
---
 arch/mips/include/asm/syscall.h | 32 ++++++++------------------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index ebdf4d910af2..b3f00ede8bb3 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -57,37 +57,21 @@ static inline void mips_syscall_update_nr(struct task_struct *task,
 static inline void mips_get_syscall_arg(unsigned long *arg,
 	struct task_struct *task, struct pt_regs *regs, unsigned int n)
 {
-	unsigned long usp __maybe_unused = regs->regs[29];
-
+#ifdef CONFIG_32BIT
 	switch (n) {
 	case 0: case 1: case 2: case 3:
 		*arg = regs->regs[4 + n];
-
-		return;
-
-#ifdef CONFIG_32BIT
-	case 4: case 5: case 6: case 7:
-		get_user(*arg, (int *)usp + n);
 		return;
-#endif
-
-#ifdef CONFIG_64BIT
 	case 4: case 5: case 6: case 7:
-#ifdef CONFIG_MIPS32_O32
-		if (test_tsk_thread_flag(task, TIF_32BIT_REGS))
-			get_user(*arg, (int *)usp + n);
-		else
-#endif
-			*arg = regs->regs[4 + n];
-
+		*arg = regs->pad0[n];
 		return;
-#endif
-
-	default:
-		BUG();
 	}
-
-	unreachable();
+#else
+	*arg = regs->regs[4 + n];
+	if ((IS_ENABLED(CONFIG_MIPS32_O32) &&
+	     test_tsk_thread_flag(task, TIF_32BIT_REGS)))
+		*arg = (unsigned int)*arg;
+#endif
 }
 
 static inline long syscall_get_error(struct task_struct *task,
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 1/6] mips: fix mips_get_syscall_arg() for o32 Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-28 15:04   ` Christophe Leroy
  2025-01-30  8:33   ` Sven Schnelle
  2025-01-28  9:16 ` [PATCH v3 3/6] syscall.h: introduce syscall_set_nr() Dmitry V. Levin
                   ` (4 subsequent siblings)
  6 siblings, 2 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Will Deacon, Guo Ren, Brian Cain,
	Huacai Chen, WANG Xuerui, Thomas Bogendoerfer, Dinh Nguyen,
	Jonas Bonn, Stefan Kristiansson, Stafford Horne,
	James E.J. Bottomley, Helge Deller, Madhavan Srinivasan,
	Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
	Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens,
	Vasily Gorbik, Alexander Gordeev, Christian Borntraeger,
	Sven Schnelle, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, linux-snps-arc,
	linux-kernel, linux-arm-kernel, linux-csky, linux-hexagon,
	loongarch, linux-mips, linux-openrisc, linux-parisc, linuxppc-dev,
	linux-riscv, linux-s390, linux-sh, sparclinux, linux-um,
	linux-arch

These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.

This partially reverts commit 7962c2eddbfe ("arch: remove unused
function syscall_set_arguments()") by reusing some of old
syscall_set_arguments() implementations.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
---
 arch/arc/include/asm/syscall.h        | 14 +++++++++++
 arch/arm/include/asm/syscall.h        | 13 ++++++++++
 arch/arm64/include/asm/syscall.h      | 13 ++++++++++
 arch/csky/include/asm/syscall.h       | 13 ++++++++++
 arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
 arch/loongarch/include/asm/syscall.h  |  8 ++++++
 arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
 arch/nios2/include/asm/syscall.h      | 11 ++++++++
 arch/openrisc/include/asm/syscall.h   |  7 ++++++
 arch/parisc/include/asm/syscall.h     | 12 +++++++++
 arch/powerpc/include/asm/syscall.h    | 10 ++++++++
 arch/riscv/include/asm/syscall.h      |  9 +++++++
 arch/s390/include/asm/syscall.h       | 12 +++++++++
 arch/sh/include/asm/syscall_32.h      | 12 +++++++++
 arch/sparc/include/asm/syscall.h      | 10 ++++++++
 arch/um/include/asm/syscall-generic.h | 14 +++++++++++
 arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
 arch/xtensa/include/asm/syscall.h     | 11 ++++++++
 include/asm-generic/syscall.h         | 16 ++++++++++++
 19 files changed, 267 insertions(+)

diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h
index 9709256e31c8..89c1e1736356 100644
--- a/arch/arc/include/asm/syscall.h
+++ b/arch/arc/include/asm/syscall.h
@@ -67,6 +67,20 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 	}
 }
 
+static inline void
+syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+		      unsigned long *args)
+{
+	unsigned long *inside_ptregs = &regs->r0;
+	unsigned int n = 6;
+	unsigned int i = 0;
+
+	while (n--) {
+		*inside_ptregs = args[i++];
+		inside_ptregs--;
+	}
+}
+
 static inline int
 syscall_get_arch(struct task_struct *task)
 {
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index fe4326d938c1..21927fa0ae2b 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -80,6 +80,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	memcpy(args, &regs->ARM_r0 + 1, 5 * sizeof(args[0]));
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	memcpy(&regs->ARM_r0, args, 6 * sizeof(args[0]));
+	/*
+	 * Also copy the first argument into ARM_ORIG_r0
+	 * so that syscall_get_arguments() would return it
+	 * instead of the previous value.
+	 */
+	regs->ARM_ORIG_r0 = regs->ARM_r0;
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	/* ARM tasks don't change audit architectures on the fly. */
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index ab8e14b96f68..76020b66286b 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -73,6 +73,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	memcpy(&regs->regs[0], args, 6 * sizeof(args[0]));
+	/*
+	 * Also copy the first argument into orig_x0
+	 * so that syscall_get_arguments() would return it
+	 * instead of the previous value.
+	 */
+	regs->orig_x0 = regs->regs[0];
+}
+
 /*
  * We don't care about endianness (__AUDIT_ARCH_LE bit) here because
  * AArch64 has the same system calls both on little- and big- endian.
diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
index 0de5734950bf..30403f7a0487 100644
--- a/arch/csky/include/asm/syscall.h
+++ b/arch/csky/include/asm/syscall.h
@@ -59,6 +59,19 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
 }
 
+static inline void
+syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+		      const unsigned long *args)
+{
+	memcpy(&regs->a0, args, 6 * sizeof(regs->a0));
+	/*
+	 * Also copy the first argument into orig_x0
+	 * so that syscall_get_arguments() would return it
+	 * instead of the previous value.
+	 */
+	regs->orig_a0 = regs->a0;
+}
+
 static inline int
 syscall_get_arch(struct task_struct *task)
 {
diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h
index f6e454f18038..1024a6548d78 100644
--- a/arch/hexagon/include/asm/syscall.h
+++ b/arch/hexagon/include/asm/syscall.h
@@ -33,6 +33,13 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	memcpy(args, &(&regs->r00)[0], 6 * sizeof(args[0]));
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned long *args)
+{
+	memcpy(&(&regs->r00)[0], args, 6 * sizeof(args[0]));
+}
+
 static inline long syscall_get_error(struct task_struct *task,
 				     struct pt_regs *regs)
 {
@@ -45,6 +52,13 @@ static inline long syscall_get_return_value(struct task_struct *task,
 	return regs->r00;
 }
 
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->r00 = (long) error ?: val;
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_HEXAGON;
diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
index e286dc58476e..ff415b3c0a8e 100644
--- a/arch/loongarch/include/asm/syscall.h
+++ b/arch/loongarch/include/asm/syscall.h
@@ -61,6 +61,14 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	memcpy(&args[1], &regs->regs[5], 5 * sizeof(long));
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned long *args)
+{
+	regs->orig_a0 = args[0];
+	memcpy(&regs->regs[5], &args[1], 5 * sizeof(long));
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_LOONGARCH64;
diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index b3f00ede8bb3..2dcc1d01b405 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -74,6 +74,23 @@ static inline void mips_get_syscall_arg(unsigned long *arg,
 #endif
 }
 
+static inline void mips_set_syscall_arg(unsigned long *arg,
+	struct task_struct *task, struct pt_regs *regs, unsigned int n)
+{
+#ifdef CONFIG_32BIT
+	switch (n) {
+	case 0: case 1: case 2: case 3:
+		regs->regs[4 + n] = *arg;
+		return;
+	case 4: case 5: case 6: case 7:
+		*arg = regs->pad0[n] = *arg;
+		return;
+	}
+#else
+	regs->regs[4 + n] = *arg;
+#endif
+}
+
 static inline long syscall_get_error(struct task_struct *task,
 				     struct pt_regs *regs)
 {
@@ -120,6 +137,21 @@ static inline void syscall_get_arguments(struct task_struct *task,
 		mips_get_syscall_arg(args++, task, regs, i++);
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned long *args)
+{
+	unsigned int i = 0;
+	unsigned int n = 6;
+
+	/* O32 ABI syscall() */
+	if (mips_syscall_is_indirect(task, regs))
+		i++;
+
+	while (n--)
+		mips_set_syscall_arg(args++, task, regs, i++);
+}
+
 extern const unsigned long sys_call_table[];
 extern const unsigned long sys32_call_table[];
 extern const unsigned long sysn32_call_table[];
diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
index fff52205fb65..526449edd768 100644
--- a/arch/nios2/include/asm/syscall.h
+++ b/arch/nios2/include/asm/syscall.h
@@ -58,6 +58,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	*args   = regs->r9;
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+	struct pt_regs *regs, const unsigned long *args)
+{
+	regs->r4 = *args++;
+	regs->r5 = *args++;
+	regs->r6 = *args++;
+	regs->r7 = *args++;
+	regs->r8 = *args++;
+	regs->r9 = *args;
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_NIOS2;
diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
index 903ed882bdec..e6383be2a195 100644
--- a/arch/openrisc/include/asm/syscall.h
+++ b/arch/openrisc/include/asm/syscall.h
@@ -57,6 +57,13 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 	memcpy(args, &regs->gpr[3], 6 * sizeof(args[0]));
 }
 
+static inline void
+syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+		      const unsigned long *args)
+{
+	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_OPENRISC;
diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h
index 00b127a5e09b..b146d0ae4c77 100644
--- a/arch/parisc/include/asm/syscall.h
+++ b/arch/parisc/include/asm/syscall.h
@@ -29,6 +29,18 @@ static inline void syscall_get_arguments(struct task_struct *tsk,
 	args[0] = regs->gr[26];
 }
 
+static inline void syscall_set_arguments(struct task_struct *tsk,
+					 struct pt_regs *regs,
+					 unsigned long *args)
+{
+	regs->gr[21] = args[5];
+	regs->gr[22] = args[4];
+	regs->gr[23] = args[3];
+	regs->gr[24] = args[2];
+	regs->gr[25] = args[1];
+	regs->gr[26] = args[0];
+}
+
 static inline long syscall_get_error(struct task_struct *task,
 				     struct pt_regs *regs)
 {
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index 422d7735ace6..521f279e6b33 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -114,6 +114,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	}
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
+
+	/* Also copy the first argument into orig_gpr3 */
+	regs->orig_gpr3 = args[0];
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	if (is_tsk_32bit_task(task))
diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index 121fff429dce..8d389ba995c8 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -66,6 +66,15 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	regs->orig_a0 = args[0];
+	args++;
+	memcpy(&regs->a1, args, 5 * sizeof(regs->a1));
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 #ifdef CONFIG_64BIT
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 27e3d804b311..b3dd883699e7 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	args[0] = regs->orig_gpr2 & mask;
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	unsigned int n = 6;
+
+	while (n-- > 0)
+		if (n > 0)
+			regs->gprs[2 + n] = args[n];
+	regs->orig_gpr2 = args[0];
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 #ifdef CONFIG_COMPAT
diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h
index d87738eebe30..cb51a7528384 100644
--- a/arch/sh/include/asm/syscall_32.h
+++ b/arch/sh/include/asm/syscall_32.h
@@ -57,6 +57,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	args[0] = regs->regs[4];
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	regs->regs[1] = args[5];
+	regs->regs[0] = args[4];
+	regs->regs[7] = args[3];
+	regs->regs[6] = args[2];
+	regs->regs[5] = args[1];
+	regs->regs[4] = args[0];
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	int arch = AUDIT_ARCH_SH;
diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h
index 20c109ac8cc9..62a5a78804c4 100644
--- a/arch/sparc/include/asm/syscall.h
+++ b/arch/sparc/include/asm/syscall.h
@@ -117,6 +117,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	}
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	unsigned int i;
+
+	for (i = 0; i < 6; i++)
+		regs->u_regs[UREG_I0 + i] = args[i];
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 #if defined(CONFIG_SPARC64) && defined(CONFIG_COMPAT)
diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
index 172b74143c4b..2984feb9d576 100644
--- a/arch/um/include/asm/syscall-generic.h
+++ b/arch/um/include/asm/syscall-generic.h
@@ -62,6 +62,20 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	*args   = UPT_SYSCALL_ARG6(r);
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	struct uml_pt_regs *r = &regs->regs;
+
+	UPT_SYSCALL_ARG1(r) = *args++;
+	UPT_SYSCALL_ARG2(r) = *args++;
+	UPT_SYSCALL_ARG3(r) = *args++;
+	UPT_SYSCALL_ARG4(r) = *args++;
+	UPT_SYSCALL_ARG5(r) = *args++;
+	UPT_SYSCALL_ARG6(r) = *args;
+}
+
 /* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
 
 #endif	/* __UM_SYSCALL_GENERIC_H */
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index 7c488ff0c764..b9c249dd9e3d 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -90,6 +90,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	args[5] = regs->bp;
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	regs->bx = args[0];
+	regs->cx = args[1];
+	regs->dx = args[2];
+	regs->si = args[3];
+	regs->di = args[4];
+	regs->bp = args[5];
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_I386;
@@ -121,6 +133,30 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	}
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+# ifdef CONFIG_IA32_EMULATION
+	if (task->thread_info.status & TS_COMPAT) {
+		regs->bx = *args++;
+		regs->cx = *args++;
+		regs->dx = *args++;
+		regs->si = *args++;
+		regs->di = *args++;
+		regs->bp = *args;
+	} else
+# endif
+	{
+		regs->di = *args++;
+		regs->si = *args++;
+		regs->dx = *args++;
+		regs->r10 = *args++;
+		regs->r8 = *args++;
+		regs->r9 = *args;
+	}
+}
+
 static inline int syscall_get_arch(struct task_struct *task)
 {
 	/* x32 tasks should be considered AUDIT_ARCH_X86_64. */
diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
index 5ee974bf8330..f9a671cbf933 100644
--- a/arch/xtensa/include/asm/syscall.h
+++ b/arch/xtensa/include/asm/syscall.h
@@ -68,6 +68,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
 		args[i] = regs->areg[reg[i]];
 }
 
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 const unsigned long *args)
+{
+	static const unsigned int reg[] = XTENSA_SYSCALL_ARGUMENT_REGS;
+	unsigned int i;
+
+	for (i = 0; i < 6; ++i)
+		regs->areg[reg[i]] = args[i];
+}
+
 asmlinkage long xtensa_rt_sigreturn(void);
 asmlinkage long xtensa_shmat(int, char __user *, int);
 asmlinkage long xtensa_fadvise64_64(int, int,
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 5a80fe728dc8..0f7b9a493de7 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -117,6 +117,22 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 			   unsigned long *args);
 
+/**
+ * syscall_set_arguments - change system call parameter value
+ * @task:	task of interest, must be in system call entry tracing
+ * @regs:	task_pt_regs() of @task
+ * @args:	array of argument values to store
+ *
+ * Changes 6 arguments to the system call.
+ * The first argument gets value @args[0], and so on.
+ *
+ * It's only valid to call this when @task is stopped for tracing on
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
+ */
+void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+			   const unsigned long *args);
+
 /**
  * syscall_get_arch - return the AUDIT_ARCH for the current system call
  * @task:	task of interest, must be blocked
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* [PATCH v3 3/6] syscall.h: introduce syscall_set_nr()
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 1/6] mips: fix mips_get_syscall_arg() for o32 Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value() Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-28 15:13   ` Christophe Leroy
  2025-01-28  9:16 ` [PATCH v3 4/6] ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op Dmitry V. Levin
                   ` (3 subsequent siblings)
  6 siblings, 1 reply; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Catalin Marinas, Will Deacon,
	Brian Cain, Huacai Chen, WANG Xuerui, Geert Uytterhoeven,
	Michal Simek, Thomas Bogendoerfer, Dinh Nguyen, Jonas Bonn,
	Stefan Kristiansson, Stafford Horne, James E.J. Bottomley,
	Helge Deller, Michael Ellerman, Nicholas Piggin, Christophe Leroy,
	Naveen N Rao, Madhavan Srinivasan, Paul Walmsley, Palmer Dabbelt,
	Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
	Christian Borntraeger, Sven Schnelle, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, linux-snps-arc,
	linux-kernel, linux-arm-kernel, linux-hexagon, loongarch,
	linux-m68k, linux-mips, linux-openrisc, linux-parisc,
	linuxppc-dev, linux-riscv, linux-s390, linux-sh, sparclinux,
	linux-um, linux-arch

Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr()
that complements syscall_get_nr().

syscall_set_nr() is going to be needed along with
syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
---
 arch/arc/include/asm/syscall.h        | 11 +++++++++++
 arch/arm/include/asm/syscall.h        | 24 ++++++++++++++++++++++++
 arch/arm64/include/asm/syscall.h      | 16 ++++++++++++++++
 arch/hexagon/include/asm/syscall.h    |  7 +++++++
 arch/loongarch/include/asm/syscall.h  |  7 +++++++
 arch/m68k/include/asm/syscall.h       |  7 +++++++
 arch/microblaze/include/asm/syscall.h |  7 +++++++
 arch/mips/include/asm/syscall.h       | 14 ++++++++++++++
 arch/nios2/include/asm/syscall.h      |  5 +++++
 arch/openrisc/include/asm/syscall.h   |  6 ++++++
 arch/parisc/include/asm/syscall.h     |  7 +++++++
 arch/powerpc/include/asm/syscall.h    | 10 ++++++++++
 arch/riscv/include/asm/syscall.h      |  7 +++++++
 arch/s390/include/asm/syscall.h       | 12 ++++++++++++
 arch/sh/include/asm/syscall_32.h      | 12 ++++++++++++
 arch/sparc/include/asm/syscall.h      | 12 ++++++++++++
 arch/um/include/asm/syscall-generic.h |  5 +++++
 arch/x86/include/asm/syscall.h        |  7 +++++++
 arch/xtensa/include/asm/syscall.h     |  7 +++++++
 include/asm-generic/syscall.h         | 14 ++++++++++++++
 20 files changed, 197 insertions(+)

diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h
index 89c1e1736356..728d625a10f1 100644
--- a/arch/arc/include/asm/syscall.h
+++ b/arch/arc/include/asm/syscall.h
@@ -23,6 +23,17 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 		return -1;
 }
 
+static inline void
+syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
+{
+	/*
+	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
+	 * the target task is stopped for tracing on entering syscall, so
+	 * there is no need to have the same check syscall_get_nr() has.
+	 */
+	regs->r8 = nr;
+}
+
 static inline void
 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
 {
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index 21927fa0ae2b..18b102a30741 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -68,6 +68,30 @@ static inline void syscall_set_return_value(struct task_struct *task,
 	regs->ARM_r0 = (long) error ? error : val;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	if (nr == -1) {
+		task_thread_info(task)->abi_syscall = -1;
+		/*
+		 * When the syscall number is set to -1, the syscall will be
+		 * skipped.  In this case the syscall return value has to be
+		 * set explicitly, otherwise the first syscall argument is
+		 * returned as the syscall return value.
+		 */
+		syscall_set_return_value(task, regs, -ENOSYS, 0);
+		return;
+	}
+	if ((IS_ENABLED(CONFIG_AEABI) && !IS_ENABLED(CONFIG_OABI_COMPAT))) {
+		task_thread_info(task)->abi_syscall = nr;
+		return;
+	}
+	task_thread_info(task)->abi_syscall =
+		(task_thread_info(task)->abi_syscall & ~__NR_SYSCALL_MASK) |
+		(nr & __NR_SYSCALL_MASK);
+}
+
 #define SYSCALL_MAX_ARGS 7
 
 static inline void syscall_get_arguments(struct task_struct *task,
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 76020b66286b..712daa90e643 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -61,6 +61,22 @@ static inline void syscall_set_return_value(struct task_struct *task,
 	regs->regs[0] = val;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->syscallno = nr;
+	if (nr == -1) {
+		/*
+		 * When the syscall number is set to -1, the syscall will be
+		 * skipped.  In this case the syscall return value has to be
+		 * set explicitly, otherwise the first syscall argument is
+		 * returned as the syscall return value.
+		 */
+		syscall_set_return_value(task, regs, -ENOSYS, 0);
+	}
+}
+
 #define SYSCALL_MAX_ARGS 6
 
 static inline void syscall_get_arguments(struct task_struct *task,
diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h
index 1024a6548d78..70637261817a 100644
--- a/arch/hexagon/include/asm/syscall.h
+++ b/arch/hexagon/include/asm/syscall.h
@@ -26,6 +26,13 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return regs->r06;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->r06 = nr;
+}
+
 static inline void syscall_get_arguments(struct task_struct *task,
 					 struct pt_regs *regs,
 					 unsigned long *args)
diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
index ff415b3c0a8e..81d2733f7b94 100644
--- a/arch/loongarch/include/asm/syscall.h
+++ b/arch/loongarch/include/asm/syscall.h
@@ -26,6 +26,13 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return regs->regs[11];
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->regs[11] = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/m68k/include/asm/syscall.h b/arch/m68k/include/asm/syscall.h
index d1453e850cdd..bf84b160c2eb 100644
--- a/arch/m68k/include/asm/syscall.h
+++ b/arch/m68k/include/asm/syscall.h
@@ -14,6 +14,13 @@ static inline int syscall_get_nr(struct task_struct *task,
 	return regs->orig_d0;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->orig_d0 = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/microblaze/include/asm/syscall.h b/arch/microblaze/include/asm/syscall.h
index 5eb3f624cc59..b5b6b91fae3e 100644
--- a/arch/microblaze/include/asm/syscall.h
+++ b/arch/microblaze/include/asm/syscall.h
@@ -14,6 +14,13 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return regs->r12;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->r12 = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index 2dcc1d01b405..1cd25306cc13 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -41,6 +41,20 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return task_thread_info(task)->syscall;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	/*
+	 * New syscall number has to be assigned to regs[2] because
+	 * syscall_trace_entry() loads it from there unconditionally.
+	 *
+	 * Consequently, if the syscall was indirect and nr != __NR_syscall,
+	 * then after this assignment the syscall will cease to be indirect.
+	 */
+	task_thread_info(task)->syscall = regs->regs[2] = nr;
+}
+
 static inline void mips_syscall_update_nr(struct task_struct *task,
 					  struct pt_regs *regs)
 {
diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
index 526449edd768..8e3eb1d689bb 100644
--- a/arch/nios2/include/asm/syscall.h
+++ b/arch/nios2/include/asm/syscall.h
@@ -15,6 +15,11 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 	return regs->r2;
 }
 
+static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
+{
+	regs->r2 = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				struct pt_regs *regs)
 {
diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
index e6383be2a195..5e037d9659c5 100644
--- a/arch/openrisc/include/asm/syscall.h
+++ b/arch/openrisc/include/asm/syscall.h
@@ -25,6 +25,12 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 	return regs->orig_gpr11;
 }
 
+static inline void
+syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
+{
+	regs->orig_gpr11 = nr;
+}
+
 static inline void
 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
 {
diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h
index b146d0ae4c77..c11222798ab2 100644
--- a/arch/parisc/include/asm/syscall.h
+++ b/arch/parisc/include/asm/syscall.h
@@ -17,6 +17,13 @@ static inline long syscall_get_nr(struct task_struct *tsk,
 	return regs->gr[20];
 }
 
+static inline void syscall_set_nr(struct task_struct *tsk,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->gr[20] = nr;
+}
+
 static inline void syscall_get_arguments(struct task_struct *tsk,
 					 struct pt_regs *regs,
 					 unsigned long *args)
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index 521f279e6b33..7505dcfed247 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -39,6 +39,16 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 		return -1;
 }
 
+static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
+{
+	/*
+	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
+	 * the target task is stopped for tracing on entering syscall, so
+	 * there is no need to have the same check syscall_get_nr() has.
+	 */
+	regs->gpr[0] = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index 8d389ba995c8..a5281cdf2b10 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -30,6 +30,13 @@ static inline int syscall_get_nr(struct task_struct *task,
 	return regs->a7;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->a7 = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index b3dd883699e7..12cd0c60c07b 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -24,6 +24,18 @@ static inline long syscall_get_nr(struct task_struct *task,
 		(regs->int_code & 0xffff) : -1;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	/*
+	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
+	 * the target task is stopped for tracing on entering syscall, so
+	 * there is no need to have the same check syscall_get_nr() has.
+	 */
+	regs->int_code = (regs->int_code & ~0xffff) | (nr & 0xffff);
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h
index cb51a7528384..7027d87d901d 100644
--- a/arch/sh/include/asm/syscall_32.h
+++ b/arch/sh/include/asm/syscall_32.h
@@ -15,6 +15,18 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return (regs->tra >= 0) ? regs->regs[3] : -1L;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	/*
+	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
+	 * the target task is stopped for tracing on entering syscall, so
+	 * there is no need to have the same check syscall_get_nr() has.
+	 */
+	regs->regs[3] = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h
index 62a5a78804c4..b0233924d323 100644
--- a/arch/sparc/include/asm/syscall.h
+++ b/arch/sparc/include/asm/syscall.h
@@ -25,6 +25,18 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return (syscall_p ? regs->u_regs[UREG_G1] : -1L);
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	/*
+	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
+	 * the target task is stopped for tracing on entering syscall, so
+	 * there is no need to have the same check syscall_get_nr() has.
+	 */
+	regs->u_regs[UREG_G1] = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
index 2984feb9d576..bcd73bcfe577 100644
--- a/arch/um/include/asm/syscall-generic.h
+++ b/arch/um/include/asm/syscall-generic.h
@@ -21,6 +21,11 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 	return PT_REGS_SYSCALL_NR(regs);
 }
 
+static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
+{
+	PT_REGS_SYSCALL_NR(regs) = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index b9c249dd9e3d..c10dbb74cd00 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -38,6 +38,13 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 	return regs->orig_ax;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->orig_ax = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
index f9a671cbf933..7db3b489c8ad 100644
--- a/arch/xtensa/include/asm/syscall.h
+++ b/arch/xtensa/include/asm/syscall.h
@@ -28,6 +28,13 @@ static inline long syscall_get_nr(struct task_struct *task,
 	return regs->syscall;
 }
 
+static inline void syscall_set_nr(struct task_struct *task,
+				  struct pt_regs *regs,
+				  int nr)
+{
+	regs->syscall = nr;
+}
+
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 0f7b9a493de7..e33fd4e783c1 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -37,6 +37,20 @@ struct pt_regs;
  */
 int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
 
+/**
+ * syscall_set_nr - change the system call a task is executing
+ * @task:	task of interest, must be blocked
+ * @regs:	task_pt_regs() of @task
+ * @nr:		system call number
+ *
+ * Changes the system call number @task is about to execute.
+ *
+ * It's only valid to call this when @task is stopped for tracing on
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
+ */
+void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr);
+
 /**
  * syscall_rollback - roll back registers after an aborted system call
  * @task:	task of interest, must be in system call exit tracing
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* [PATCH v3 4/6] ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
                   ` (2 preceding siblings ...)
  2025-01-28  9:16 ` [PATCH v3 3/6] syscall.h: introduce syscall_set_nr() Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-28  9:16 ` [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request Dmitry V. Levin
                   ` (2 subsequent siblings)
  6 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov
  Cc: Alexey Gladkov, Eugene Syromyatnikov, Mike Frysinger,
	Renzo Davoli, Davide Berardi, strace-devel, linux-kernel

Move the code that calculates the type of the system call stop
out of ptrace_get_syscall_info() into a separate function
ptrace_get_syscall_info_op() which is going to be used later
to implement PTRACE_SET_SYSCALL_INFO API.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
---
 kernel/ptrace.c | 58 +++++++++++++++++++++++++++++--------------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d5f89f9ef29f..22e7d74cf4cd 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -921,7 +921,6 @@ ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
 	unsigned long args[ARRAY_SIZE(info->entry.args)];
 	int i;
 
-	info->op = PTRACE_SYSCALL_INFO_ENTRY;
 	info->entry.nr = syscall_get_nr(child, regs);
 	syscall_get_arguments(child, regs, args);
 	for (i = 0; i < ARRAY_SIZE(args); i++)
@@ -943,7 +942,6 @@ ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
 	 * diverge significantly enough.
 	 */
 	ptrace_get_syscall_info_entry(child, regs, info);
-	info->op = PTRACE_SYSCALL_INFO_SECCOMP;
 	info->seccomp.ret_data = child->ptrace_message;
 
 	/* ret_data is the last field in struct ptrace_syscall_info.seccomp */
@@ -954,7 +952,6 @@ static unsigned long
 ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
 			     struct ptrace_syscall_info *info)
 {
-	info->op = PTRACE_SYSCALL_INFO_EXIT;
 	info->exit.rval = syscall_get_error(child, regs);
 	info->exit.is_error = !!info->exit.rval;
 	if (!info->exit.is_error)
@@ -965,19 +962,8 @@ ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
 }
 
 static int
-ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
-			void __user *datavp)
+ptrace_get_syscall_info_op(struct task_struct *child)
 {
-	struct pt_regs *regs = task_pt_regs(child);
-	struct ptrace_syscall_info info = {
-		.op = PTRACE_SYSCALL_INFO_NONE,
-		.arch = syscall_get_arch(child),
-		.instruction_pointer = instruction_pointer(regs),
-		.stack_pointer = user_stack_pointer(regs),
-	};
-	unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
-	unsigned long write_size;
-
 	/*
 	 * This does not need lock_task_sighand() to access
 	 * child->last_siginfo because ptrace_freeze_traced()
@@ -988,18 +974,42 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
 	case SIGTRAP | 0x80:
 		switch (child->ptrace_message) {
 		case PTRACE_EVENTMSG_SYSCALL_ENTRY:
-			actual_size = ptrace_get_syscall_info_entry(child, regs,
-								    &info);
-			break;
+			return PTRACE_SYSCALL_INFO_ENTRY;
 		case PTRACE_EVENTMSG_SYSCALL_EXIT:
-			actual_size = ptrace_get_syscall_info_exit(child, regs,
-								   &info);
-			break;
+			return PTRACE_SYSCALL_INFO_EXIT;
+		default:
+			return PTRACE_SYSCALL_INFO_NONE;
 		}
-		break;
 	case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
-		actual_size = ptrace_get_syscall_info_seccomp(child, regs,
-							      &info);
+		return PTRACE_SYSCALL_INFO_SECCOMP;
+	default:
+		return PTRACE_SYSCALL_INFO_NONE;
+	}
+}
+
+static int
+ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
+			void __user *datavp)
+{
+	struct pt_regs *regs = task_pt_regs(child);
+	struct ptrace_syscall_info info = {
+		.op = ptrace_get_syscall_info_op(child),
+		.arch = syscall_get_arch(child),
+		.instruction_pointer = instruction_pointer(regs),
+		.stack_pointer = user_stack_pointer(regs),
+	};
+	unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
+	unsigned long write_size;
+
+	switch (info.op) {
+	case PTRACE_SYSCALL_INFO_ENTRY:
+		actual_size = ptrace_get_syscall_info_entry(child, regs, &info);
+		break;
+	case PTRACE_SYSCALL_INFO_EXIT:
+		actual_size = ptrace_get_syscall_info_exit(child, regs, &info);
+		break;
+	case PTRACE_SYSCALL_INFO_SECCOMP:
+		actual_size = ptrace_get_syscall_info_seccomp(child, regs, &info);
 		break;
 	}
 
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
                   ` (3 preceding siblings ...)
  2025-01-28  9:16 ` [PATCH v3 4/6] ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-28 15:21   ` Christophe Leroy
  2025-01-28  9:16 ` [PATCH v3 6/6] selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO Dmitry V. Levin
  2025-01-29 18:51 ` [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Oleg Nesterov
  6 siblings, 1 reply; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	linux-kernel, linux-api

PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of
system calls the tracee is blocked in.

This API allows ptracers to obtain and modify system call details
in a straightforward and architecture-agnostic way.

Current implementation supports changing only those bits of system call
information that are used by strace, namely, syscall number, syscall
arguments, and syscall return value.

Support of changing additional details returned by PTRACE_GET_SYSCALL_INFO,
such as instruction pointer and stack pointer, could be added later if
needed, by using struct ptrace_syscall_info.flags to specify the additional
details that should be set.  Currently, "flags", "reserved", and
"seccomp.reserved2" fields of struct ptrace_syscall_info must be
initialized with zeroes; "arch", "instruction_pointer", and "stack_pointer"
fields are ignored.

PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations.
Other operations could be added later if needed.

Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen.  The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure
to provide an API of changing the first system call argument on riscv
architecture.

ptrace(2) man page:

long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
       Modify information about the system call that caused the stop.
       The "data" argument is a pointer to struct ptrace_syscall_info
       that specifies the system call information to be set.
       The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).

Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
---
 include/uapi/linux/ptrace.h |   7 ++-
 kernel/ptrace.c             | 121 +++++++++++++++++++++++++++++++++++-
 2 files changed, 126 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 72c038fc71d0..5f8ef6156752 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -74,6 +74,7 @@ struct seccomp_metadata {
 };
 
 #define PTRACE_GET_SYSCALL_INFO		0x420e
+#define PTRACE_SET_SYSCALL_INFO		0x4212
 #define PTRACE_SYSCALL_INFO_NONE	0
 #define PTRACE_SYSCALL_INFO_ENTRY	1
 #define PTRACE_SYSCALL_INFO_EXIT	2
@@ -81,7 +82,8 @@ struct seccomp_metadata {
 
 struct ptrace_syscall_info {
 	__u8 op;	/* PTRACE_SYSCALL_INFO_* */
-	__u8 pad[3];
+	__u8 reserved;
+	__u16 flags;
 	__u32 arch;
 	__u64 instruction_pointer;
 	__u64 stack_pointer;
@@ -98,6 +100,7 @@ struct ptrace_syscall_info {
 			__u64 nr;
 			__u64 args[6];
 			__u32 ret_data;
+			__u32 reserved2;
 		} seccomp;
 	};
 };
@@ -142,6 +145,8 @@ struct ptrace_sud_config {
 	__u64 len;
 };
 
+/* 0x4212 is PTRACE_SET_SYSCALL_INFO */
+
 /*
  * These values are stored in task->ptrace_message
  * by ptrace_stop to describe the current syscall-stop.
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 22e7d74cf4cd..b9c1949186bf 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -944,7 +944,10 @@ ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
 	ptrace_get_syscall_info_entry(child, regs, info);
 	info->seccomp.ret_data = child->ptrace_message;
 
-	/* ret_data is the last field in struct ptrace_syscall_info.seccomp */
+	/*
+	 * ret_data is the last non-reserved field
+	 * in struct ptrace_syscall_info.seccomp
+	 */
 	return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
 }
 
@@ -1016,6 +1019,118 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
 	write_size = min(actual_size, user_size);
 	return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size;
 }
+
+static int
+ptrace_set_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
+			      struct ptrace_syscall_info *info)
+{
+	unsigned long args[ARRAY_SIZE(info->entry.args)];
+	int nr = info->entry.nr;
+	int i;
+
+	/*
+	 * Check that the syscall number specified in info->entry.nr
+	 * is either a value of type "int" or a sign-extended value
+	 * of type "int".
+	 */
+	if (nr != info->entry.nr)
+		return -ERANGE;
+
+	for (i = 0; i < ARRAY_SIZE(args); i++) {
+		args[i] = info->entry.args[i];
+		/*
+		 * Check that the syscall argument specified in
+		 * info->entry.args[i] is either a value of type
+		 * "unsigned long" or a sign-extended value of type "long".
+		 */
+		if (args[i] != info->entry.args[i])
+			return -ERANGE;
+	}
+
+	syscall_set_nr(child, regs, nr);
+	/*
+	 * If the syscall number is set to -1, setting syscall arguments is not
+	 * just pointless, it would also clobber the syscall return value on
+	 * those architectures that share the same register both for the first
+	 * argument of syscall and its return value.
+	 */
+	if (nr != -1)
+		syscall_set_arguments(child, regs, args);
+
+	return 0;
+}
+
+static int
+ptrace_set_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
+				struct ptrace_syscall_info *info)
+{
+	/*
+	 * info->entry is currently a subset of info->seccomp,
+	 * info->seccomp.ret_data is currently ignored.
+	 */
+	return ptrace_set_syscall_info_entry(child, regs, info);
+}
+
+static int
+ptrace_set_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
+			     struct ptrace_syscall_info *info)
+{
+	long rval = info->exit.rval;
+
+	/*
+	 * Check that the return value specified in info->exit.rval
+	 * is either a value of type "long" or a sign-extended value
+	 * of type "long".
+	 */
+	if (rval != info->exit.rval)
+		return -ERANGE;
+
+	if (info->exit.is_error)
+		syscall_set_return_value(child, regs, rval, 0);
+	else
+		syscall_set_return_value(child, regs, 0, rval);
+
+	return 0;
+}
+
+static int
+ptrace_set_syscall_info(struct task_struct *child, unsigned long user_size,
+			const void __user *datavp)
+{
+	struct pt_regs *regs = task_pt_regs(child);
+	struct ptrace_syscall_info info;
+
+	if (user_size < sizeof(info))
+		return -EINVAL;
+
+	/*
+	 * The compatibility is tracked by info.op and info.flags: if user-space
+	 * does not instruct us to use unknown extra bits from future versions
+	 * of ptrace_syscall_info, we are not going to read them either.
+	 */
+	if (copy_from_user(&info, datavp, sizeof(info)))
+		return -EFAULT;
+
+	/* Reserved for future use. */
+	if (info.flags || info.reserved || info.seccomp.reserved2)
+		return -EINVAL;
+
+	/* Changing the type of the system call stop is not supported yet. */
+	if (ptrace_get_syscall_info_op(child) != info.op)
+		return -EINVAL;
+
+	switch (info.op) {
+	case PTRACE_SYSCALL_INFO_ENTRY:
+		return ptrace_set_syscall_info_entry(child, regs, &info);
+	case PTRACE_SYSCALL_INFO_EXIT:
+		return ptrace_set_syscall_info_exit(child, regs, &info);
+	case PTRACE_SYSCALL_INFO_SECCOMP:
+		return ptrace_set_syscall_info_seccomp(child, regs, &info);
+	default:
+		/* Other types of system call stops are not supported yet. */
+		return -EINVAL;
+	}
+}
 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 
 int ptrace_request(struct task_struct *child, long request,
@@ -1234,6 +1349,10 @@ int ptrace_request(struct task_struct *child, long request,
 	case PTRACE_GET_SYSCALL_INFO:
 		ret = ptrace_get_syscall_info(child, addr, datavp);
 		break;
+
+	case PTRACE_SET_SYSCALL_INFO:
+		ret = ptrace_set_syscall_info(child, addr, datavp);
+		break;
 #endif
 
 	case PTRACE_SECCOMP_GET_FILTER:
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* [PATCH v3 6/6] selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
                   ` (4 preceding siblings ...)
  2025-01-28  9:16 ` [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request Dmitry V. Levin
@ 2025-01-28  9:16 ` Dmitry V. Levin
  2025-01-29 18:51 ` [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Oleg Nesterov
  6 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28  9:16 UTC (permalink / raw)
  To: Oleg Nesterov, Shuah Khan
  Cc: Alexey Gladkov, Eugene Syromyatnikov, Mike Frysinger,
	Renzo Davoli, Davide Berardi, strace-devel, linux-kernel,
	linux-kselftest

Check whether PTRACE_SET_SYSCALL_INFO semantics implemented in the
kernel matches userspace expectations.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
---
 tools/testing/selftests/ptrace/Makefile       |   2 +-
 .../selftests/ptrace/set_syscall_info.c       | 514 ++++++++++++++++++
 2 files changed, 515 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/ptrace/set_syscall_info.c

diff --git a/tools/testing/selftests/ptrace/Makefile b/tools/testing/selftests/ptrace/Makefile
index 1c631740a730..c5e0b76ba6ac 100644
--- a/tools/testing/selftests/ptrace/Makefile
+++ b/tools/testing/selftests/ptrace/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 CFLAGS += -std=c99 -pthread -Wall $(KHDR_INCLUDES)
 
-TEST_GEN_PROGS := get_syscall_info peeksiginfo vmaccess get_set_sud
+TEST_GEN_PROGS := get_syscall_info set_syscall_info peeksiginfo vmaccess get_set_sud
 
 include ../lib.mk
diff --git a/tools/testing/selftests/ptrace/set_syscall_info.c b/tools/testing/selftests/ptrace/set_syscall_info.c
new file mode 100644
index 000000000000..0ec69401c008
--- /dev/null
+++ b/tools/testing/selftests/ptrace/set_syscall_info.c
@@ -0,0 +1,514 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2018-2025 Dmitry V. Levin <ldv@strace.io>
+ * All rights reserved.
+ *
+ * Check whether PTRACE_SET_SYSCALL_INFO semantics implemented in the kernel
+ * matches userspace expectations.
+ */
+
+#include "../kselftest_harness.h"
+#include <err.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <asm/unistd.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+
+#if defined(_MIPS_SIM) && _MIPS_SIM == _MIPS_SIM_NABI32
+/*
+ * MIPS N32 is the only architecture where __kernel_ulong_t
+ * does not match the bitness of syscall arguments.
+ */
+typedef unsigned long long kernel_ulong_t;
+#else
+typedef __kernel_ulong_t kernel_ulong_t;
+#endif
+
+struct si_entry {
+	int nr;
+	kernel_ulong_t args[6];
+};
+struct si_exit {
+	unsigned int is_error;
+	int rval;
+};
+
+static unsigned int ptrace_stop;
+static pid_t tracee_pid;
+
+static int
+kill_tracee(pid_t pid)
+{
+	if (!pid)
+		return 0;
+
+	int saved_errno = errno;
+
+	int rc = kill(pid, SIGKILL);
+
+	errno = saved_errno;
+	return rc;
+}
+
+static long
+sys_ptrace(int request, pid_t pid, unsigned long addr, unsigned long data)
+{
+	return syscall(__NR_ptrace, request, pid, addr, data);
+}
+
+#define LOG_KILL_TRACEE(fmt, ...)				\
+	do {							\
+		kill_tracee(tracee_pid);			\
+		TH_LOG("wait #%d: " fmt,			\
+		       ptrace_stop, ##__VA_ARGS__);		\
+	} while (0)
+
+static void
+check_psi_entry(struct __test_metadata *_metadata,
+		const struct ptrace_syscall_info *info,
+		const struct si_entry *exp_entry,
+		const char *text)
+{
+	unsigned int i;
+
+	ASSERT_EQ(PTRACE_SYSCALL_INFO_ENTRY, info->op) {
+		LOG_KILL_TRACEE("%s: entry stop mismatch", text);
+	}
+	ASSERT_TRUE(info->arch) {
+		LOG_KILL_TRACEE("%s: entry stop mismatch", text);
+	}
+	ASSERT_TRUE(info->instruction_pointer) {
+		LOG_KILL_TRACEE("%s: entry stop mismatch", text);
+	}
+	ASSERT_TRUE(info->stack_pointer) {
+		LOG_KILL_TRACEE("%s: entry stop mismatch", text);
+	}
+	ASSERT_EQ(exp_entry->nr, info->entry.nr) {
+		LOG_KILL_TRACEE("%s: syscall nr mismatch", text);
+	}
+	for (i = 0; i < ARRAY_SIZE(exp_entry->args); ++i) {
+		ASSERT_EQ(exp_entry->args[i], info->entry.args[i]) {
+			LOG_KILL_TRACEE("%s: syscall arg #%u mismatch",
+					text, i);
+		}
+	}
+}
+
+static void
+check_psi_exit(struct __test_metadata *_metadata,
+	       const struct ptrace_syscall_info *info,
+	       const struct si_exit *exp_exit,
+	       const char *text)
+{
+	ASSERT_EQ(PTRACE_SYSCALL_INFO_EXIT, info->op) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+	ASSERT_TRUE(info->arch) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+	ASSERT_TRUE(info->instruction_pointer) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+	ASSERT_TRUE(info->stack_pointer) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+	ASSERT_EQ(exp_exit->is_error, info->exit.is_error) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+	ASSERT_EQ(exp_exit->rval, info->exit.rval) {
+		LOG_KILL_TRACEE("%s: exit stop mismatch", text);
+	}
+}
+
+TEST(set_syscall_info)
+{
+	const pid_t tracer_pid = getpid();
+	const kernel_ulong_t dummy[] = {
+		(kernel_ulong_t) 0xdad0bef0bad0fed0ULL,
+		(kernel_ulong_t) 0xdad1bef1bad1fed1ULL,
+		(kernel_ulong_t) 0xdad2bef2bad2fed2ULL,
+		(kernel_ulong_t) 0xdad3bef3bad3fed3ULL,
+		(kernel_ulong_t) 0xdad4bef4bad4fed4ULL,
+		(kernel_ulong_t) 0xdad5bef5bad5fed5ULL,
+	};
+	int splice_in[2], splice_out[2];
+
+	ASSERT_EQ(0, pipe(splice_in));
+	ASSERT_EQ(0, pipe(splice_out));
+	ASSERT_EQ(sizeof(dummy), write(splice_in[1], dummy, sizeof(dummy)));
+
+	const struct {
+		struct si_entry entry[2];
+		struct si_exit exit[2];
+	} si[] = {
+		/* change scno, keep non-error rval */
+		{
+			{
+				{
+					__NR_gettid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_getppid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 0, tracer_pid }, { 0, tracer_pid }
+			}
+		},
+
+		/* set scno to -1, keep error rval */
+		{
+			{
+				{
+					__NR_chdir,
+					{
+						(uintptr_t) ".",
+						dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					-1,
+					{
+						(uintptr_t) ".",
+						dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 1, -ENOSYS }, { 1, -ENOSYS }
+			}
+		},
+
+		/* keep scno, change non-error rval */
+		{
+			{
+				{
+					__NR_getppid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_getppid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 0, tracer_pid }, { 0, tracer_pid + 1 }
+			}
+		},
+
+		/* change arg1, keep non-error rval */
+		{
+			{
+				{
+					__NR_chdir,
+					{
+						(uintptr_t) "",
+						dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_chdir,
+					{
+						(uintptr_t) ".",
+						dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 0, 0 }, { 0, 0 }
+			}
+		},
+
+		/* set scno to -1, change error rval to non-error */
+		{
+			{
+				{
+					__NR_gettid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					-1,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 1, -ENOSYS }, { 0, tracer_pid }
+			}
+		},
+
+		/* change scno, change non-error rval to error */
+		{
+			{
+				{
+					__NR_chdir,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_getppid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 0, tracer_pid }, { 1, -EISDIR }
+			}
+		},
+
+		/* change scno and all args, change non-error rval */
+		{
+			{
+				{
+					__NR_gettid,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_splice,
+					{
+						splice_in[0], 0, splice_out[1], 0,
+						sizeof(dummy), SPLICE_F_NONBLOCK
+					}
+				}
+			}, {
+				{ 0, sizeof(dummy) }, { 0, sizeof(dummy) + 1 }
+			}
+		},
+
+		/* change arg1, no exit stop */
+		{
+			{
+				{
+					__NR_exit_group,
+					{
+						dummy[0], dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}, {
+					__NR_exit_group,
+					{
+						0, dummy[1], dummy[2],
+						dummy[3], dummy[4], dummy[5]
+					}
+				}
+			}, {
+				{ 0, 0 }, { 0, 0 }
+			}
+		},
+	};
+
+	long rc;
+	unsigned int i;
+
+	tracee_pid = fork();
+
+	ASSERT_LE(0, tracee_pid) {
+		TH_LOG("fork: %m");
+	}
+
+	if (tracee_pid == 0) {
+		/* get the pid before PTRACE_TRACEME */
+		tracee_pid = getpid();
+		ASSERT_EQ(0, sys_ptrace(PTRACE_TRACEME, 0, 0, 0)) {
+			TH_LOG("PTRACE_TRACEME: %m");
+		}
+		ASSERT_EQ(0, kill(tracee_pid, SIGSTOP)) {
+			/* cannot happen */
+			TH_LOG("kill SIGSTOP: %m");
+		}
+		for (i = 0; i < ARRAY_SIZE(si); ++i) {
+			rc = syscall(si[i].entry[0].nr,
+				     si[i].entry[0].args[0],
+				     si[i].entry[0].args[1],
+				     si[i].entry[0].args[2],
+				     si[i].entry[0].args[3],
+				     si[i].entry[0].args[4],
+				     si[i].entry[0].args[5]);
+			if (si[i].exit[1].is_error) {
+				if (rc != -1 || errno != -si[i].exit[1].rval)
+					break;
+			} else {
+				if (rc != si[i].exit[1].rval)
+					break;
+			}
+		}
+		/*
+		 * Something went wrong, but in this state tracee
+		 * cannot reliably issue syscalls, so just crash.
+		 */
+		*(volatile unsigned char *) (uintptr_t) i = 42;
+		/* unreachable */
+		_exit(i + 1);
+	}
+
+	for (ptrace_stop = 0; ; ++ptrace_stop) {
+		struct ptrace_syscall_info info = {
+			.op = 0xff	/* invalid PTRACE_SYSCALL_INFO_* op */
+		};
+		const size_t size = sizeof(info);
+		const int expected_entry_size =
+			(void *) &info.entry.args[6] - (void *) &info;
+		const int expected_exit_size =
+			(void *) (&info.exit.is_error + 1) -
+			(void *) &info;
+		int status;
+
+		ASSERT_EQ(tracee_pid, wait(&status)) {
+			/* cannot happen */
+			LOG_KILL_TRACEE("wait: %m");
+		}
+		if (WIFEXITED(status)) {
+			tracee_pid = 0;	/* the tracee is no more */
+			ASSERT_EQ(0, WEXITSTATUS(status)) {
+				LOG_KILL_TRACEE("unexpected exit status %u",
+						WEXITSTATUS(status));
+			}
+			break;
+		}
+		ASSERT_FALSE(WIFSIGNALED(status)) {
+			tracee_pid = 0;	/* the tracee is no more */
+			LOG_KILL_TRACEE("unexpected signal %u",
+					WTERMSIG(status));
+		}
+		ASSERT_TRUE(WIFSTOPPED(status)) {
+			/* cannot happen */
+			LOG_KILL_TRACEE("unexpected wait status %#x", status);
+		}
+
+		ASSERT_LT(ptrace_stop, ARRAY_SIZE(si) * 2) {
+			LOG_KILL_TRACEE("ptrace stop overflow");
+		}
+
+		switch (WSTOPSIG(status)) {
+		case SIGSTOP:
+			ASSERT_EQ(0, ptrace_stop) {
+				LOG_KILL_TRACEE("unexpected signal stop");
+			}
+			ASSERT_EQ(0, sys_ptrace(PTRACE_SETOPTIONS, tracee_pid,
+						0, PTRACE_O_TRACESYSGOOD)) {
+				LOG_KILL_TRACEE("PTRACE_SETOPTIONS: %m");
+			}
+			break;
+
+		case SIGTRAP | 0x80:
+			ASSERT_LT(0, ptrace_stop) {
+				LOG_KILL_TRACEE("unexpected syscall stop");
+			}
+			ASSERT_LT(0, (rc = sys_ptrace(PTRACE_GET_SYSCALL_INFO,
+						      tracee_pid, size,
+						      (uintptr_t) &info))) {
+				LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #1: %m");
+			}
+			if (ptrace_stop & 1) {
+				/* entering syscall */
+				const struct si_entry *exp_entry =
+					&si[ptrace_stop / 2].entry[0];
+				const struct si_entry *set_entry =
+					&si[ptrace_stop / 2].entry[1];
+
+				/* check ptrace_syscall_info before the changes */
+				ASSERT_EQ(expected_entry_size, rc) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #1"
+							": entry stop mismatch");
+				}
+				check_psi_entry(_metadata, &info, exp_entry,
+						"PTRACE_GET_SYSCALL_INFO #1");
+
+				/* apply the changes */
+				info.entry.nr = set_entry->nr;
+				for (i = 0; i < ARRAY_SIZE(set_entry->args); ++i)
+					info.entry.args[i] = set_entry->args[i];
+				ASSERT_EQ(0, sys_ptrace(PTRACE_SET_SYSCALL_INFO,
+							tracee_pid, size,
+							(uintptr_t) &info)) {
+					LOG_KILL_TRACEE("PTRACE_SET_SYSCALL_INFO: %m");
+				}
+
+				/* check ptrace_syscall_info after the changes */
+				memset(&info, 0, sizeof(info));
+				info.op = 0xff;
+				ASSERT_LT(0, (rc = sys_ptrace(PTRACE_GET_SYSCALL_INFO,
+							      tracee_pid, size,
+							      (uintptr_t) &info))) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO: %m");
+				}
+				ASSERT_EQ(expected_entry_size, rc) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #2"
+							": entry stop mismatch");
+				}
+				check_psi_entry(_metadata, &info, set_entry,
+						"PTRACE_GET_SYSCALL_INFO #2");
+			} else {
+				/* exiting syscall */
+				const struct si_exit *exp_exit =
+					&si[ptrace_stop / 2 - 1].exit[0];
+				const struct si_exit *set_exit =
+					&si[ptrace_stop / 2 - 1].exit[1];
+
+				/* check ptrace_syscall_info before the changes */
+				ASSERT_EQ(expected_exit_size, rc) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #1"
+							": exit stop mismatch");
+				}
+				check_psi_exit(_metadata, &info, exp_exit,
+						"PTRACE_GET_SYSCALL_INFO #1");
+
+				/* apply the changes */
+				info.exit.is_error = set_exit->is_error;
+				info.exit.rval = set_exit->rval;
+				ASSERT_EQ(0, sys_ptrace(PTRACE_SET_SYSCALL_INFO,
+							tracee_pid, size,
+							(uintptr_t) &info)) {
+					LOG_KILL_TRACEE("PTRACE_SET_SYSCALL_INFO: %m");
+				}
+
+				/* check ptrace_syscall_info after the changes */
+				memset(&info, 0, sizeof(info));
+				info.op = 0xff;
+				ASSERT_LT(0, (rc = sys_ptrace(PTRACE_GET_SYSCALL_INFO,
+							      tracee_pid, size,
+							      (uintptr_t) &info))) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #2: %m");
+				}
+				ASSERT_EQ(expected_exit_size, rc) {
+					LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO #2"
+							": exit stop mismatch");
+				}
+				check_psi_exit(_metadata, &info, set_exit,
+						"PTRACE_GET_SYSCALL_INFO #2");
+			}
+			break;
+
+		default:
+			LOG_KILL_TRACEE("unexpected stop signal %u",
+					WSTOPSIG(status));
+			abort();
+		}
+
+		ASSERT_EQ(0, sys_ptrace(PTRACE_SYSCALL, tracee_pid, 0, 0)) {
+			LOG_KILL_TRACEE("PTRACE_SYSCALL: %m");
+		}
+	}
+
+	ASSERT_EQ(ptrace_stop, ARRAY_SIZE(si) * 2);
+}
+
+TEST_HARNESS_MAIN
-- 
ldv

^ permalink raw reply related	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-28  9:16 ` [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value() Dmitry V. Levin
@ 2025-01-28 15:04   ` Christophe Leroy
  2025-01-28 16:17     ` Dmitry V. Levin
  2025-01-30  8:33   ` Sven Schnelle
  1 sibling, 1 reply; 17+ messages in thread
From: Christophe Leroy @ 2025-01-28 15:04 UTC (permalink / raw)
  To: Dmitry V. Levin, Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Will Deacon, Guo Ren, Brian Cain,
	Huacai Chen, WANG Xuerui, Thomas Bogendoerfer, Dinh Nguyen,
	Jonas Bonn, Stefan Kristiansson, Stafford Horne,
	James E.J. Bottomley, Helge Deller, Madhavan Srinivasan,
	Michael Ellerman, Nicholas Piggin, Naveen N Rao, Paul Walmsley,
	Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik,
	Alexander Gordeev, Christian Borntraeger, Sven Schnelle,
	Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz,
	David S. Miller, Andreas Larsson, Richard Weinberger,
	Anton Ivanov, Johannes Berg, Thomas Gleixner, Ingo Molnar,
	Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Chris Zankel,
	Max Filippov, Arnd Bergmann, linux-snps-arc, linux-kernel,
	linux-arm-kernel, linux-csky, linux-hexagon, loongarch,
	linux-mips, linux-openrisc, linux-parisc, linuxppc-dev,
	linux-riscv, linux-s390, linux-sh, sparclinux, linux-um,
	linux-arch



Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> architectures to implement PTRACE_SET_SYSCALL_INFO API.

The subject is misleading. syscall_set_return_value() already exists on 
most architectures and was not addressed by commit 7962c2eddbfe.

Maybe it would be better to handle syscall_set_return_value() in a 
separate commit.

> 
> This partially reverts commit 7962c2eddbfe ("arch: remove unused
> function syscall_set_arguments()") by reusing some of old
> syscall_set_arguments() implementations.
> 
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>   arch/arc/include/asm/syscall.h        | 14 +++++++++++
>   arch/arm/include/asm/syscall.h        | 13 ++++++++++
>   arch/arm64/include/asm/syscall.h      | 13 ++++++++++
>   arch/csky/include/asm/syscall.h       | 13 ++++++++++
>   arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
>   arch/loongarch/include/asm/syscall.h  |  8 ++++++
>   arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
>   arch/nios2/include/asm/syscall.h      | 11 ++++++++
>   arch/openrisc/include/asm/syscall.h   |  7 ++++++
>   arch/parisc/include/asm/syscall.h     | 12 +++++++++
>   arch/powerpc/include/asm/syscall.h    | 10 ++++++++
>   arch/riscv/include/asm/syscall.h      |  9 +++++++
>   arch/s390/include/asm/syscall.h       | 12 +++++++++
>   arch/sh/include/asm/syscall_32.h      | 12 +++++++++
>   arch/sparc/include/asm/syscall.h      | 10 ++++++++
>   arch/um/include/asm/syscall-generic.h | 14 +++++++++++
>   arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
>   arch/xtensa/include/asm/syscall.h     | 11 ++++++++
>   include/asm-generic/syscall.h         | 16 ++++++++++++
>   19 files changed, 267 insertions(+)
> 
> diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h
> index 9709256e31c8..89c1e1736356 100644
> --- a/arch/arc/include/asm/syscall.h
> +++ b/arch/arc/include/asm/syscall.h
> @@ -67,6 +67,20 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>   	}
>   }
>   
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      unsigned long *args)
> +{
> +	unsigned long *inside_ptregs = &regs->r0;
> +	unsigned int n = 6;
> +	unsigned int i = 0;
> +
> +	while (n--) {
> +		*inside_ptregs = args[i++];
> +		inside_ptregs--;
> +	}
> +}
> +
>   static inline int
>   syscall_get_arch(struct task_struct *task)
>   {
> diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
> index fe4326d938c1..21927fa0ae2b 100644
> --- a/arch/arm/include/asm/syscall.h
> +++ b/arch/arm/include/asm/syscall.h
> @@ -80,6 +80,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	memcpy(args, &regs->ARM_r0 + 1, 5 * sizeof(args[0]));
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->ARM_r0, args, 6 * sizeof(args[0]));
> +	/*
> +	 * Also copy the first argument into ARM_ORIG_r0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->ARM_ORIG_r0 = regs->ARM_r0;
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	/* ARM tasks don't change audit architectures on the fly. */
> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index ab8e14b96f68..76020b66286b 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -73,6 +73,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->regs[0], args, 6 * sizeof(args[0]));
> +	/*
> +	 * Also copy the first argument into orig_x0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->orig_x0 = regs->regs[0];
> +}
> +
>   /*
>    * We don't care about endianness (__AUDIT_ARCH_LE bit) here because
>    * AArch64 has the same system calls both on little- and big- endian.
> diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
> index 0de5734950bf..30403f7a0487 100644
> --- a/arch/csky/include/asm/syscall.h
> +++ b/arch/csky/include/asm/syscall.h
> @@ -59,6 +59,19 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>   	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
>   }
>   
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      const unsigned long *args)
> +{
> +	memcpy(&regs->a0, args, 6 * sizeof(regs->a0));
> +	/*
> +	 * Also copy the first argument into orig_x0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->orig_a0 = regs->a0;
> +}
> +
>   static inline int
>   syscall_get_arch(struct task_struct *task)
>   {
> diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h
> index f6e454f18038..1024a6548d78 100644
> --- a/arch/hexagon/include/asm/syscall.h
> +++ b/arch/hexagon/include/asm/syscall.h
> @@ -33,6 +33,13 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	memcpy(args, &(&regs->r00)[0], 6 * sizeof(args[0]));
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	memcpy(&(&regs->r00)[0], args, 6 * sizeof(args[0]));
> +}
> +
>   static inline long syscall_get_error(struct task_struct *task,
>   				     struct pt_regs *regs)
>   {
> @@ -45,6 +52,13 @@ static inline long syscall_get_return_value(struct task_struct *task,
>   	return regs->r00;
>   }
>   
> +static inline void syscall_set_return_value(struct task_struct *task,
> +					    struct pt_regs *regs,
> +					    int error, long val)
> +{
> +	regs->r00 = (long) error ?: val;
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	return AUDIT_ARCH_HEXAGON;
> diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
> index e286dc58476e..ff415b3c0a8e 100644
> --- a/arch/loongarch/include/asm/syscall.h
> +++ b/arch/loongarch/include/asm/syscall.h
> @@ -61,6 +61,14 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	memcpy(&args[1], &regs->regs[5], 5 * sizeof(long));
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	regs->orig_a0 = args[0];
> +	memcpy(&regs->regs[5], &args[1], 5 * sizeof(long));
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	return AUDIT_ARCH_LOONGARCH64;
> diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
> index b3f00ede8bb3..2dcc1d01b405 100644
> --- a/arch/mips/include/asm/syscall.h
> +++ b/arch/mips/include/asm/syscall.h
> @@ -74,6 +74,23 @@ static inline void mips_get_syscall_arg(unsigned long *arg,
>   #endif
>   }
>   
> +static inline void mips_set_syscall_arg(unsigned long *arg,
> +	struct task_struct *task, struct pt_regs *regs, unsigned int n)
> +{
> +#ifdef CONFIG_32BIT
> +	switch (n) {
> +	case 0: case 1: case 2: case 3:
> +		regs->regs[4 + n] = *arg;
> +		return;
> +	case 4: case 5: case 6: case 7:
> +		*arg = regs->pad0[n] = *arg;
> +		return;
> +	}
> +#else
> +	regs->regs[4 + n] = *arg;
> +#endif
> +}
> +
>   static inline long syscall_get_error(struct task_struct *task,
>   				     struct pt_regs *regs)
>   {
> @@ -120,6 +137,21 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   		mips_get_syscall_arg(args++, task, regs, i++);
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	unsigned int i = 0;
> +	unsigned int n = 6;
> +
> +	/* O32 ABI syscall() */
> +	if (mips_syscall_is_indirect(task, regs))
> +		i++;
> +
> +	while (n--)
> +		mips_set_syscall_arg(args++, task, regs, i++);
> +}
> +
>   extern const unsigned long sys_call_table[];
>   extern const unsigned long sys32_call_table[];
>   extern const unsigned long sysn32_call_table[];
> diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
> index fff52205fb65..526449edd768 100644
> --- a/arch/nios2/include/asm/syscall.h
> +++ b/arch/nios2/include/asm/syscall.h
> @@ -58,6 +58,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	*args   = regs->r9;
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +	struct pt_regs *regs, const unsigned long *args)
> +{
> +	regs->r4 = *args++;
> +	regs->r5 = *args++;
> +	regs->r6 = *args++;
> +	regs->r7 = *args++;
> +	regs->r8 = *args++;
> +	regs->r9 = *args;
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	return AUDIT_ARCH_NIOS2;
> diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
> index 903ed882bdec..e6383be2a195 100644
> --- a/arch/openrisc/include/asm/syscall.h
> +++ b/arch/openrisc/include/asm/syscall.h
> @@ -57,6 +57,13 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>   	memcpy(args, &regs->gpr[3], 6 * sizeof(args[0]));
>   }
>   
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      const unsigned long *args)
> +{
> +	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	return AUDIT_ARCH_OPENRISC;
> diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h
> index 00b127a5e09b..b146d0ae4c77 100644
> --- a/arch/parisc/include/asm/syscall.h
> +++ b/arch/parisc/include/asm/syscall.h
> @@ -29,6 +29,18 @@ static inline void syscall_get_arguments(struct task_struct *tsk,
>   	args[0] = regs->gr[26];
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *tsk,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	regs->gr[21] = args[5];
> +	regs->gr[22] = args[4];
> +	regs->gr[23] = args[3];
> +	regs->gr[24] = args[2];
> +	regs->gr[25] = args[1];
> +	regs->gr[26] = args[0];
> +}
> +
>   static inline long syscall_get_error(struct task_struct *task,
>   				     struct pt_regs *regs)
>   {
> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
> index 422d7735ace6..521f279e6b33 100644
> --- a/arch/powerpc/include/asm/syscall.h
> +++ b/arch/powerpc/include/asm/syscall.h
> @@ -114,6 +114,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	}
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
> +
> +	/* Also copy the first argument into orig_gpr3 */
> +	regs->orig_gpr3 = args[0];
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	if (is_tsk_32bit_task(task))
> diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
> index 121fff429dce..8d389ba995c8 100644
> --- a/arch/riscv/include/asm/syscall.h
> +++ b/arch/riscv/include/asm/syscall.h
> @@ -66,6 +66,15 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->orig_a0 = args[0];
> +	args++;
> +	memcpy(&regs->a1, args, 5 * sizeof(regs->a1));
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   #ifdef CONFIG_64BIT
> diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
> index 27e3d804b311..b3dd883699e7 100644
> --- a/arch/s390/include/asm/syscall.h
> +++ b/arch/s390/include/asm/syscall.h
> @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	args[0] = regs->orig_gpr2 & mask;
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int n = 6;
> +
> +	while (n-- > 0)
> +		if (n > 0)
> +			regs->gprs[2 + n] = args[n];
> +	regs->orig_gpr2 = args[0];
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   #ifdef CONFIG_COMPAT
> diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h
> index d87738eebe30..cb51a7528384 100644
> --- a/arch/sh/include/asm/syscall_32.h
> +++ b/arch/sh/include/asm/syscall_32.h
> @@ -57,6 +57,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	args[0] = regs->regs[4];
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->regs[1] = args[5];
> +	regs->regs[0] = args[4];
> +	regs->regs[7] = args[3];
> +	regs->regs[6] = args[2];
> +	regs->regs[5] = args[1];
> +	regs->regs[4] = args[0];
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	int arch = AUDIT_ARCH_SH;
> diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h
> index 20c109ac8cc9..62a5a78804c4 100644
> --- a/arch/sparc/include/asm/syscall.h
> +++ b/arch/sparc/include/asm/syscall.h
> @@ -117,6 +117,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	}
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < 6; i++)
> +		regs->u_regs[UREG_I0 + i] = args[i];
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   #if defined(CONFIG_SPARC64) && defined(CONFIG_COMPAT)
> diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
> index 172b74143c4b..2984feb9d576 100644
> --- a/arch/um/include/asm/syscall-generic.h
> +++ b/arch/um/include/asm/syscall-generic.h
> @@ -62,6 +62,20 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	*args   = UPT_SYSCALL_ARG6(r);
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	struct uml_pt_regs *r = &regs->regs;
> +
> +	UPT_SYSCALL_ARG1(r) = *args++;
> +	UPT_SYSCALL_ARG2(r) = *args++;
> +	UPT_SYSCALL_ARG3(r) = *args++;
> +	UPT_SYSCALL_ARG4(r) = *args++;
> +	UPT_SYSCALL_ARG5(r) = *args++;
> +	UPT_SYSCALL_ARG6(r) = *args;
> +}
> +
>   /* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
>   
>   #endif	/* __UM_SYSCALL_GENERIC_H */
> diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
> index 7c488ff0c764..b9c249dd9e3d 100644
> --- a/arch/x86/include/asm/syscall.h
> +++ b/arch/x86/include/asm/syscall.h
> @@ -90,6 +90,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	args[5] = regs->bp;
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->bx = args[0];
> +	regs->cx = args[1];
> +	regs->dx = args[2];
> +	regs->si = args[3];
> +	regs->di = args[4];
> +	regs->bp = args[5];
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	return AUDIT_ARCH_I386;
> @@ -121,6 +133,30 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   	}
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +# ifdef CONFIG_IA32_EMULATION
> +	if (task->thread_info.status & TS_COMPAT) {
> +		regs->bx = *args++;
> +		regs->cx = *args++;
> +		regs->dx = *args++;
> +		regs->si = *args++;
> +		regs->di = *args++;
> +		regs->bp = *args;
> +	} else
> +# endif
> +	{
> +		regs->di = *args++;
> +		regs->si = *args++;
> +		regs->dx = *args++;
> +		regs->r10 = *args++;
> +		regs->r8 = *args++;
> +		regs->r9 = *args;
> +	}
> +}
> +
>   static inline int syscall_get_arch(struct task_struct *task)
>   {
>   	/* x32 tasks should be considered AUDIT_ARCH_X86_64. */
> diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
> index 5ee974bf8330..f9a671cbf933 100644
> --- a/arch/xtensa/include/asm/syscall.h
> +++ b/arch/xtensa/include/asm/syscall.h
> @@ -68,6 +68,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
>   		args[i] = regs->areg[reg[i]];
>   }
>   
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	static const unsigned int reg[] = XTENSA_SYSCALL_ARGUMENT_REGS;
> +	unsigned int i;
> +
> +	for (i = 0; i < 6; ++i)
> +		regs->areg[reg[i]] = args[i];
> +}
> +
>   asmlinkage long xtensa_rt_sigreturn(void);
>   asmlinkage long xtensa_shmat(int, char __user *, int);
>   asmlinkage long xtensa_fadvise64_64(int, int,
> diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
> index 5a80fe728dc8..0f7b9a493de7 100644
> --- a/include/asm-generic/syscall.h
> +++ b/include/asm-generic/syscall.h
> @@ -117,6 +117,22 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
>   void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>   			   unsigned long *args);
>   
> +/**
> + * syscall_set_arguments - change system call parameter value
> + * @task:	task of interest, must be in system call entry tracing
> + * @regs:	task_pt_regs() of @task
> + * @args:	array of argument values to store
> + *
> + * Changes 6 arguments to the system call.
> + * The first argument gets value @args[0], and so on.
> + *
> + * It's only valid to call this when @task is stopped for tracing on
> + * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
> + * %SYSCALL_WORK_SYSCALL_AUDIT.
> + */
> +void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +			   const unsigned long *args);
> +
>   /**
>    * syscall_get_arch - return the AUDIT_ARCH for the current system call
>    * @task:	task of interest, must be blocked


^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 3/6] syscall.h: introduce syscall_set_nr()
  2025-01-28  9:16 ` [PATCH v3 3/6] syscall.h: introduce syscall_set_nr() Dmitry V. Levin
@ 2025-01-28 15:13   ` Christophe Leroy
  2025-01-28 16:25     ` Dmitry V. Levin
  0 siblings, 1 reply; 17+ messages in thread
From: Christophe Leroy @ 2025-01-28 15:13 UTC (permalink / raw)
  To: Dmitry V. Levin, Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Catalin Marinas, Will Deacon,
	Brian Cain, Huacai Chen, WANG Xuerui, Geert Uytterhoeven,
	Michal Simek, Thomas Bogendoerfer, Dinh Nguyen, Jonas Bonn,
	Stefan Kristiansson, Stafford Horne, James E.J. Bottomley,
	Helge Deller, Michael Ellerman, Nicholas Piggin, Naveen N Rao,
	Madhavan Srinivasan, Paul Walmsley, Palmer Dabbelt, Albert Ou,
	Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
	Christian Borntraeger, Sven Schnelle, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, linux-snps-arc,
	linux-kernel, linux-arm-kernel, linux-hexagon, loongarch,
	linux-m68k, linux-mips, linux-openrisc, linux-parisc,
	linuxppc-dev, linux-riscv, linux-s390, linux-sh, sparclinux,
	linux-um, linux-arch



Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> Similar to syscall_set_arguments() that complements
> syscall_get_arguments(), introduce syscall_set_nr()
> that complements syscall_get_nr().
> 
> syscall_set_nr() is going to be needed along with
> syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK
> architectures to implement PTRACE_SET_SYSCALL_INFO API.
> 
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>   arch/arc/include/asm/syscall.h        | 11 +++++++++++
>   arch/arm/include/asm/syscall.h        | 24 ++++++++++++++++++++++++
>   arch/arm64/include/asm/syscall.h      | 16 ++++++++++++++++
>   arch/hexagon/include/asm/syscall.h    |  7 +++++++
>   arch/loongarch/include/asm/syscall.h  |  7 +++++++
>   arch/m68k/include/asm/syscall.h       |  7 +++++++
>   arch/microblaze/include/asm/syscall.h |  7 +++++++
>   arch/mips/include/asm/syscall.h       | 14 ++++++++++++++
>   arch/nios2/include/asm/syscall.h      |  5 +++++
>   arch/openrisc/include/asm/syscall.h   |  6 ++++++
>   arch/parisc/include/asm/syscall.h     |  7 +++++++
>   arch/powerpc/include/asm/syscall.h    | 10 ++++++++++
>   arch/riscv/include/asm/syscall.h      |  7 +++++++
>   arch/s390/include/asm/syscall.h       | 12 ++++++++++++
>   arch/sh/include/asm/syscall_32.h      | 12 ++++++++++++
>   arch/sparc/include/asm/syscall.h      | 12 ++++++++++++
>   arch/um/include/asm/syscall-generic.h |  5 +++++
>   arch/x86/include/asm/syscall.h        |  7 +++++++
>   arch/xtensa/include/asm/syscall.h     |  7 +++++++
>   include/asm-generic/syscall.h         | 14 ++++++++++++++
>   20 files changed, 197 insertions(+)
> 

> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index 76020b66286b..712daa90e643 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -61,6 +61,22 @@ static inline void syscall_set_return_value(struct task_struct *task,
>   	regs->regs[0] = val;
>   }
>   
> +static inline void syscall_set_nr(struct task_struct *task,
> +				  struct pt_regs *regs,
> +				  int nr)
> +{
> +	regs->syscallno = nr;
> +	if (nr == -1) {
> +		/*
> +		 * When the syscall number is set to -1, the syscall will be
> +		 * skipped.  In this case the syscall return value has to be
> +		 * set explicitly, otherwise the first syscall argument is
> +		 * returned as the syscall return value.
> +		 */
> +		syscall_set_return_value(task, regs, -ENOSYS, 0);
> +	}
> +}
> +
>   #define SYSCALL_MAX_ARGS 6
>   
>   static inline void syscall_get_arguments(struct task_struct *task,

> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
> index 521f279e6b33..7505dcfed247 100644
> --- a/arch/powerpc/include/asm/syscall.h
> +++ b/arch/powerpc/include/asm/syscall.h
> @@ -39,6 +39,16 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
>   		return -1;
>   }
>   
> +static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
> +{
> +	/*
> +	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
> +	 * the target task is stopped for tracing on entering syscall, so
> +	 * there is no need to have the same check syscall_get_nr() has.
> +	 */
> +	regs->gpr[0] = nr;

Doesn't the same as for ARM64 apply here as well ?

> +}
> +
>   static inline void syscall_rollback(struct task_struct *task,
>   				    struct pt_regs *regs)
>   {

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request
  2025-01-28  9:16 ` [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request Dmitry V. Levin
@ 2025-01-28 15:21   ` Christophe Leroy
  2025-01-28 15:58     ` Dmitry V. Levin
  0 siblings, 1 reply; 17+ messages in thread
From: Christophe Leroy @ 2025-01-28 15:21 UTC (permalink / raw)
  To: Dmitry V. Levin, Oleg Nesterov
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	linux-kernel, linux-api



Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
> PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of
> system calls the tracee is blocked in.
> 
> This API allows ptracers to obtain and modify system call details
> in a straightforward and architecture-agnostic way.
> 
> Current implementation supports changing only those bits of system call
> information that are used by strace, namely, syscall number, syscall
> arguments, and syscall return value.

How do you handle changes related to syscalls that call 
force_successful_syscall_return() ?


> 
> Support of changing additional details returned by PTRACE_GET_SYSCALL_INFO,
> such as instruction pointer and stack pointer, could be added later if
> needed, by using struct ptrace_syscall_info.flags to specify the additional
> details that should be set.  Currently, "flags", "reserved", and
> "seccomp.reserved2" fields of struct ptrace_syscall_info must be
> initialized with zeroes; "arch", "instruction_pointer", and "stack_pointer"
> fields are ignored.
> 
> PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
> PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations.
> Other operations could be added later if needed.
> 
> Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
> PTRACE_GET_SYSCALL_INFO, but it didn't happen.  The last straw that
> convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure
> to provide an API of changing the first system call argument on riscv
> architecture.
> 
> ptrace(2) man page:
> 
> long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
> ...
> PTRACE_SET_SYSCALL_INFO
>         Modify information about the system call that caused the stop.
>         The "data" argument is a pointer to struct ptrace_syscall_info
>         that specifies the system call information to be set.
>         The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).
> 
> Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> Reviewed-by: Alexey Gladkov <legion@kernel.org>
> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>   include/uapi/linux/ptrace.h |   7 ++-
>   kernel/ptrace.c             | 121 +++++++++++++++++++++++++++++++++++-
>   2 files changed, 126 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
> index 72c038fc71d0..5f8ef6156752 100644
> --- a/include/uapi/linux/ptrace.h
> +++ b/include/uapi/linux/ptrace.h
> @@ -74,6 +74,7 @@ struct seccomp_metadata {
>   };
>   
>   #define PTRACE_GET_SYSCALL_INFO		0x420e
> +#define PTRACE_SET_SYSCALL_INFO		0x4212
>   #define PTRACE_SYSCALL_INFO_NONE	0
>   #define PTRACE_SYSCALL_INFO_ENTRY	1
>   #define PTRACE_SYSCALL_INFO_EXIT	2
> @@ -81,7 +82,8 @@ struct seccomp_metadata {
>   
>   struct ptrace_syscall_info {
>   	__u8 op;	/* PTRACE_SYSCALL_INFO_* */
> -	__u8 pad[3];
> +	__u8 reserved;
> +	__u16 flags;
>   	__u32 arch;
>   	__u64 instruction_pointer;
>   	__u64 stack_pointer;
> @@ -98,6 +100,7 @@ struct ptrace_syscall_info {
>   			__u64 nr;
>   			__u64 args[6];
>   			__u32 ret_data;
> +			__u32 reserved2;
>   		} seccomp;
>   	};
>   };
> @@ -142,6 +145,8 @@ struct ptrace_sud_config {
>   	__u64 len;
>   };
>   
> +/* 0x4212 is PTRACE_SET_SYSCALL_INFO */
> +
>   /*
>    * These values are stored in task->ptrace_message
>    * by ptrace_stop to describe the current syscall-stop.
> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> index 22e7d74cf4cd..b9c1949186bf 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -944,7 +944,10 @@ ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
>   	ptrace_get_syscall_info_entry(child, regs, info);
>   	info->seccomp.ret_data = child->ptrace_message;
>   
> -	/* ret_data is the last field in struct ptrace_syscall_info.seccomp */
> +	/*
> +	 * ret_data is the last non-reserved field
> +	 * in struct ptrace_syscall_info.seccomp
> +	 */
>   	return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
>   }
>   
> @@ -1016,6 +1019,118 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
>   	write_size = min(actual_size, user_size);
>   	return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size;
>   }
> +
> +static int
> +ptrace_set_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
> +			      struct ptrace_syscall_info *info)
> +{
> +	unsigned long args[ARRAY_SIZE(info->entry.args)];
> +	int nr = info->entry.nr;
> +	int i;
> +
> +	/*
> +	 * Check that the syscall number specified in info->entry.nr
> +	 * is either a value of type "int" or a sign-extended value
> +	 * of type "int".
> +	 */
> +	if (nr != info->entry.nr)
> +		return -ERANGE;
> +
> +	for (i = 0; i < ARRAY_SIZE(args); i++) {
> +		args[i] = info->entry.args[i];
> +		/*
> +		 * Check that the syscall argument specified in
> +		 * info->entry.args[i] is either a value of type
> +		 * "unsigned long" or a sign-extended value of type "long".
> +		 */
> +		if (args[i] != info->entry.args[i])
> +			return -ERANGE;
> +	}
> +
> +	syscall_set_nr(child, regs, nr);
> +	/*
> +	 * If the syscall number is set to -1, setting syscall arguments is not
> +	 * just pointless, it would also clobber the syscall return value on
> +	 * those architectures that share the same register both for the first
> +	 * argument of syscall and its return value.
> +	 */
> +	if (nr != -1)
> +		syscall_set_arguments(child, regs, args);
> +
> +	return 0;
> +}
> +
> +static int
> +ptrace_set_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
> +				struct ptrace_syscall_info *info)
> +{
> +	/*
> +	 * info->entry is currently a subset of info->seccomp,
> +	 * info->seccomp.ret_data is currently ignored.
> +	 */
> +	return ptrace_set_syscall_info_entry(child, regs, info);
> +}
> +
> +static int
> +ptrace_set_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
> +			     struct ptrace_syscall_info *info)
> +{
> +	long rval = info->exit.rval;
> +
> +	/*
> +	 * Check that the return value specified in info->exit.rval
> +	 * is either a value of type "long" or a sign-extended value
> +	 * of type "long".
> +	 */
> +	if (rval != info->exit.rval)
> +		return -ERANGE;
> +
> +	if (info->exit.is_error)
> +		syscall_set_return_value(child, regs, rval, 0);
> +	else
> +		syscall_set_return_value(child, regs, 0, rval);
> +
> +	return 0;
> +}
> +
> +static int
> +ptrace_set_syscall_info(struct task_struct *child, unsigned long user_size,
> +			const void __user *datavp)
> +{
> +	struct pt_regs *regs = task_pt_regs(child);
> +	struct ptrace_syscall_info info;
> +
> +	if (user_size < sizeof(info))
> +		return -EINVAL;
> +
> +	/*
> +	 * The compatibility is tracked by info.op and info.flags: if user-space
> +	 * does not instruct us to use unknown extra bits from future versions
> +	 * of ptrace_syscall_info, we are not going to read them either.
> +	 */
> +	if (copy_from_user(&info, datavp, sizeof(info)))
> +		return -EFAULT;
> +
> +	/* Reserved for future use. */
> +	if (info.flags || info.reserved || info.seccomp.reserved2)
> +		return -EINVAL;
> +
> +	/* Changing the type of the system call stop is not supported yet. */
> +	if (ptrace_get_syscall_info_op(child) != info.op)
> +		return -EINVAL;
> +
> +	switch (info.op) {
> +	case PTRACE_SYSCALL_INFO_ENTRY:
> +		return ptrace_set_syscall_info_entry(child, regs, &info);
> +	case PTRACE_SYSCALL_INFO_EXIT:
> +		return ptrace_set_syscall_info_exit(child, regs, &info);
> +	case PTRACE_SYSCALL_INFO_SECCOMP:
> +		return ptrace_set_syscall_info_seccomp(child, regs, &info);
> +	default:
> +		/* Other types of system call stops are not supported yet. */
> +		return -EINVAL;
> +	}
> +}
>   #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
>   
>   int ptrace_request(struct task_struct *child, long request,
> @@ -1234,6 +1349,10 @@ int ptrace_request(struct task_struct *child, long request,
>   	case PTRACE_GET_SYSCALL_INFO:
>   		ret = ptrace_get_syscall_info(child, addr, datavp);
>   		break;
> +
> +	case PTRACE_SET_SYSCALL_INFO:
> +		ret = ptrace_set_syscall_info(child, addr, datavp);
> +		break;
>   #endif
>   
>   	case PTRACE_SECCOMP_GET_FILTER:


^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request
  2025-01-28 15:21   ` Christophe Leroy
@ 2025-01-28 15:58     ` Dmitry V. Levin
  0 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28 15:58 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: Oleg Nesterov, Alexey Gladkov, Charlie Jenkins,
	Eugene Syromyatnikov, Mike Frysinger, Renzo Davoli,
	Davide Berardi, strace-devel, linux-kernel, linux-api

On Tue, Jan 28, 2025 at 04:21:13PM +0100, Christophe Leroy wrote:
> Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> > PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
> > PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of
> > system calls the tracee is blocked in.
> > 
> > This API allows ptracers to obtain and modify system call details
> > in a straightforward and architecture-agnostic way.
> > 
> > Current implementation supports changing only those bits of system call
> > information that are used by strace, namely, syscall number, syscall
> > arguments, and syscall return value.
> 
> How do you handle changes related to syscalls that call 
> force_successful_syscall_return() ?

I don't see why these syscalls would need any special treatment.
If a tracer wants to set an error status for a syscall that cannot return
an error, it's up to the tracer to face the consequences.
Tracers can do it now via PTRACE_SETREGS* anyway.


-- 
ldv

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-28 15:04   ` Christophe Leroy
@ 2025-01-28 16:17     ` Dmitry V. Levin
  0 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28 16:17 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: Oleg Nesterov, linux-snps-arc, Rich Felker, Thomas Gleixner,
	Andreas Larsson, John Paul Adrian Glaubitz, x86, Arnd Bergmann,
	linux-mips, James E.J. Bottomley, Guo Ren, H. Peter Anvin,
	sparclinux, linux-hexagon, WANG Xuerui, Will Deacon,
	Eugene Syromyatnikov, Anton Ivanov, Jonas Bonn, linux-s390,
	Alexander Gordeev, Madhavan Srinivasan, Vasily Gorbik,
	Yoshinori Sato, linux-sh, Michael Ellerman, Helge Deller,
	Huacai Chen, Russell King, linux-csky, Dave Hansen, Ingo Molnar,
	Vineet Gupta, Christian Borntraeger, strace-devel, linux-arch,
	Albert Ou, Mike Frysinger, Davide Berardi, Renzo Davoli, linux-um,
	Heiko Carstens, Charlie Jenkins, Naveen N Rao, Nicholas Piggin,
	Stefan Kristiansson, Borislav Petkov, loongarch, Paul Walmsley,
	Stafford Horne, linux-arm-kernel, Brian Cain, Thomas Bogendoerfer,
	linux-parisc, linux-openrisc, linuxppc-dev, linux-kernel,
	Dinh Nguyen, linux-riscv, Palmer Dabbelt, Sven Schnelle,
	Richard Weinberger, Johannes Berg, Alexey Gladkov,
	David S. Miller

On Tue, Jan 28, 2025 at 04:04:34PM +0100, Christophe Leroy wrote:
> Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> > These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> > architectures to implement PTRACE_SET_SYSCALL_INFO API.
> 
> The subject is misleading. syscall_set_return_value() already exists on 
> most architectures and was not addressed by commit 7962c2eddbfe.
> 
> Maybe it would be better to handle syscall_set_return_value() in a 
> separate commit.

syscall_set_return_value() is being added only on hexagon.
I didn't think it worth a separate commit, but it's certainly possible
to split this commit into two.


-- 
ldv

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 3/6] syscall.h: introduce syscall_set_nr()
  2025-01-28 15:13   ` Christophe Leroy
@ 2025-01-28 16:25     ` Dmitry V. Levin
  0 siblings, 0 replies; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-28 16:25 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: Oleg Nesterov, linux-snps-arc, Rich Felker, Thomas Gleixner,
	Andreas Larsson, Catalin Marinas, John Paul Adrian Glaubitz, x86,
	Arnd Bergmann, linux-mips, James E.J. Bottomley, H. Peter Anvin,
	sparclinux, linux-hexagon, WANG Xuerui, Will Deacon,
	Eugene Syromyatnikov, Anton Ivanov, Jonas Bonn, linux-s390,
	Alexander Gordeev, Madhavan Srinivasan, Vasily Gorbik,
	Yoshinori Sato, linux-sh, Michael Ellerman, Helge Deller,
	Huacai Chen, Russell King, linux-riscv, Dave Hansen, Ingo Molnar,
	Geert Uytterhoeven, Vineet Gupta, Christian Borntraeger,
	strace-devel, linux-arch, Albert Ou, Mike Frysinger,
	Davide Berardi, Renzo Davoli, linux-um, Heiko Carstens,
	Charlie Jenkins, Naveen N Rao, Nicholas Piggin,
	Stefan Kristiansson, linux-m68k, Borislav Petkov, loongarch,
	Paul Walmsley, Stafford Horne, linux-arm-kernel, Brian Cain,
	Michal Simek, Thomas Bogendoerfer, linux-parisc, linux-openrisc,
	linuxppc-dev, linux-kernel, Dinh Nguyen, Palmer Dabbelt,
	Sven Schnelle, Richard Weinberger, Johannes Berg, Alexey Gladkov,
	David S. Miller

On Tue, Jan 28, 2025 at 04:13:52PM +0100, Christophe Leroy wrote:
> Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :
> > Similar to syscall_set_arguments() that complements
> > syscall_get_arguments(), introduce syscall_set_nr()
> > that complements syscall_get_nr().
> > 
> > syscall_set_nr() is going to be needed along with
> > syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK
> > architectures to implement PTRACE_SET_SYSCALL_INFO API.
> > 
> > Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> > Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> > Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> > ---
> >   arch/arc/include/asm/syscall.h        | 11 +++++++++++
> >   arch/arm/include/asm/syscall.h        | 24 ++++++++++++++++++++++++
> >   arch/arm64/include/asm/syscall.h      | 16 ++++++++++++++++
> >   arch/hexagon/include/asm/syscall.h    |  7 +++++++
> >   arch/loongarch/include/asm/syscall.h  |  7 +++++++
> >   arch/m68k/include/asm/syscall.h       |  7 +++++++
> >   arch/microblaze/include/asm/syscall.h |  7 +++++++
> >   arch/mips/include/asm/syscall.h       | 14 ++++++++++++++
> >   arch/nios2/include/asm/syscall.h      |  5 +++++
> >   arch/openrisc/include/asm/syscall.h   |  6 ++++++
> >   arch/parisc/include/asm/syscall.h     |  7 +++++++
> >   arch/powerpc/include/asm/syscall.h    | 10 ++++++++++
> >   arch/riscv/include/asm/syscall.h      |  7 +++++++
> >   arch/s390/include/asm/syscall.h       | 12 ++++++++++++
> >   arch/sh/include/asm/syscall_32.h      | 12 ++++++++++++
> >   arch/sparc/include/asm/syscall.h      | 12 ++++++++++++
> >   arch/um/include/asm/syscall-generic.h |  5 +++++
> >   arch/x86/include/asm/syscall.h        |  7 +++++++
> >   arch/xtensa/include/asm/syscall.h     |  7 +++++++
> >   include/asm-generic/syscall.h         | 14 ++++++++++++++
> >   20 files changed, 197 insertions(+)
> > 
> 
> > diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> > index 76020b66286b..712daa90e643 100644
> > --- a/arch/arm64/include/asm/syscall.h
> > +++ b/arch/arm64/include/asm/syscall.h
> > @@ -61,6 +61,22 @@ static inline void syscall_set_return_value(struct task_struct *task,
> >   	regs->regs[0] = val;
> >   }
> >   
> > +static inline void syscall_set_nr(struct task_struct *task,
> > +				  struct pt_regs *regs,
> > +				  int nr)
> > +{
> > +	regs->syscallno = nr;
> > +	if (nr == -1) {
> > +		/*
> > +		 * When the syscall number is set to -1, the syscall will be
> > +		 * skipped.  In this case the syscall return value has to be
> > +		 * set explicitly, otherwise the first syscall argument is
> > +		 * returned as the syscall return value.
> > +		 */
> > +		syscall_set_return_value(task, regs, -ENOSYS, 0);
> > +	}
> > +}
> > +
> >   #define SYSCALL_MAX_ARGS 6
> >   
> >   static inline void syscall_get_arguments(struct task_struct *task,
> 
> > diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
> > index 521f279e6b33..7505dcfed247 100644
> > --- a/arch/powerpc/include/asm/syscall.h
> > +++ b/arch/powerpc/include/asm/syscall.h
> > @@ -39,6 +39,16 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
> >   		return -1;
> >   }
> >   
> > +static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
> > +{
> > +	/*
> > +	 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
> > +	 * the target task is stopped for tracing on entering syscall, so
> > +	 * there is no need to have the same check syscall_get_nr() has.
> > +	 */
> > +	regs->gpr[0] = nr;
> 
> Doesn't the same as for ARM64 apply here as well ?

I carefully checked all affected architectures and added that
syscall_set_return_value() call only where I think it's needed.

On powerpc it's not needed with the current implementation: their
do_seccomp() sets -ENOSYS before __secure_computing() invocation, and
their do_syscall_trace_enter() sets -ENOSYS in case of an invalid syscall
number.


-- 
ldv

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API
  2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
                   ` (5 preceding siblings ...)
  2025-01-28  9:16 ` [PATCH v3 6/6] selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO Dmitry V. Levin
@ 2025-01-29 18:51 ` Oleg Nesterov
  6 siblings, 0 replies; 17+ messages in thread
From: Oleg Nesterov @ 2025-01-29 18:51 UTC (permalink / raw)
  To: Dmitry V. Levin
  Cc: Alexey Gladkov, Charlie Jenkins, Eugene Syromyatnikov,
	Mike Frysinger, Renzo Davoli, Davide Berardi, strace-devel,
	Vineet Gupta, Russell King, Will Deacon, Guo Ren, Brian Cain,
	Huacai Chen, WANG Xuerui, Geert Uytterhoeven, Michal Simek,
	Thomas Bogendoerfer, Dinh Nguyen, Jonas Bonn, Stefan Kristiansson,
	Stafford Horne, James E.J. Bottomley, Helge Deller,
	Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
	Madhavan Srinivasan, Paul Walmsley, Palmer Dabbelt, Albert Ou,
	Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
	Christian Borntraeger, Sven Schnelle, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, Shuah Khan,
	linux-snps-arc, linux-kernel, linux-arm-kernel, linux-csky,
	linux-hexagon, loongarch, linux-m68k, linux-mips, linux-openrisc,
	linux-parisc, linuxppc-dev, linux-riscv, linux-s390, linux-sh,
	sparclinux, linux-um, linux-arch, linux-kselftest, linux-api

On 01/28, Dmitry V. Levin wrote:
>
>     * ptrace: Add explicit padding to the end of struct ptrace_syscall_info,
>       simplify obtaining of user ptrace_syscall_info,
>       do not introduce PTRACE_SYSCALL_INFO_SIZE_VER0
>     * ptrace: Change the return type of ptrace_set_syscall_info_* functions
>       from "unsigned long" to "int"
>     * ptrace: Add -ERANGE check to ptrace_set_syscall_info_exit,
>       add comments to -ERANGE checks
>     * ptrace: Update comments about supported syscall stops
>     * selftests: Extend set_syscall_info test, fix for mips n32

Again, I can't review 1-3, I know nothing about the non-x86 architectures.

As for 4-6, feel free to add

Reviewed-by: Oleg Nesterov <oleg@redhat.com>


^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-28  9:16 ` [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value() Dmitry V. Levin
  2025-01-28 15:04   ` Christophe Leroy
@ 2025-01-30  8:33   ` Sven Schnelle
  2025-01-30 11:22     ` Dmitry V. Levin
  1 sibling, 1 reply; 17+ messages in thread
From: Sven Schnelle @ 2025-01-30  8:33 UTC (permalink / raw)
  To: Dmitry V. Levin
  Cc: Oleg Nesterov, Alexey Gladkov, Charlie Jenkins,
	Eugene Syromyatnikov, Mike Frysinger, Renzo Davoli,
	Davide Berardi, strace-devel, Vineet Gupta, Russell King,
	Will Deacon, Guo Ren, Brian Cain, Huacai Chen, WANG Xuerui,
	Thomas Bogendoerfer, Dinh Nguyen, Jonas Bonn, Stefan Kristiansson,
	Stafford Horne, James E.J. Bottomley, Helge Deller,
	Madhavan Srinivasan, Michael Ellerman, Nicholas Piggin,
	Christophe Leroy, Naveen N Rao, Paul Walmsley, Palmer Dabbelt,
	Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
	Christian Borntraeger, Yoshinori Sato, Rich Felker,
	John Paul Adrian Glaubitz, David S. Miller, Andreas Larsson,
	Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
	Chris Zankel, Max Filippov, Arnd Bergmann, linux-snps-arc,
	linux-kernel, linux-arm-kernel, linux-csky, linux-hexagon,
	loongarch, linux-mips, linux-openrisc, linux-parisc, linuxppc-dev,
	linux-riscv, linux-s390, linux-sh, sparclinux, linux-um,
	linux-arch

"Dmitry V. Levin" <ldv@strace.io> writes:

> These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> architectures to implement PTRACE_SET_SYSCALL_INFO API.
>
> This partially reverts commit 7962c2eddbfe ("arch: remove unused
> function syscall_set_arguments()") by reusing some of old
> syscall_set_arguments() implementations.
>
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>  arch/arc/include/asm/syscall.h        | 14 +++++++++++
>  arch/arm/include/asm/syscall.h        | 13 ++++++++++
>  arch/arm64/include/asm/syscall.h      | 13 ++++++++++
>  arch/csky/include/asm/syscall.h       | 13 ++++++++++
>  arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
>  arch/loongarch/include/asm/syscall.h  |  8 ++++++
>  arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
>  arch/nios2/include/asm/syscall.h      | 11 ++++++++
>  arch/openrisc/include/asm/syscall.h   |  7 ++++++
>  arch/parisc/include/asm/syscall.h     | 12 +++++++++
>  arch/powerpc/include/asm/syscall.h    | 10 ++++++++
>  arch/riscv/include/asm/syscall.h      |  9 +++++++
>  arch/s390/include/asm/syscall.h       | 12 +++++++++
>  arch/sh/include/asm/syscall_32.h      | 12 +++++++++
>  arch/sparc/include/asm/syscall.h      | 10 ++++++++
>  arch/um/include/asm/syscall-generic.h | 14 +++++++++++
>  arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
>  arch/xtensa/include/asm/syscall.h     | 11 ++++++++
>  include/asm-generic/syscall.h         | 16 ++++++++++++
>  19 files changed, 267 insertions(+)
>
> diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
> index 27e3d804b311..b3dd883699e7 100644
> --- a/arch/s390/include/asm/syscall.h
> +++ b/arch/s390/include/asm/syscall.h
> @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	args[0] = regs->orig_gpr2 & mask;
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int n = 6;
> +
> +	while (n-- > 0)
> +		if (n > 0)
> +			regs->gprs[2 + n] = args[n];
> +	regs->orig_gpr2 = args[0];
> +}

Could that be changed to something like:

for (int n = 1; n < 6; n++)
        regs->gprs[2 + n] = args[n];
regs->orig_gpr2 = args[0];

I think this is way easier to parse.

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-30  8:33   ` Sven Schnelle
@ 2025-01-30 11:22     ` Dmitry V. Levin
  2025-01-30 11:36       ` Sven Schnelle
  0 siblings, 1 reply; 17+ messages in thread
From: Dmitry V. Levin @ 2025-01-30 11:22 UTC (permalink / raw)
  To: Sven Schnelle
  Cc: linux-snps-arc, Rich Felker, Thomas Gleixner, Andreas Larsson,
	John Paul Adrian Glaubitz, x86, Arnd Bergmann, linux-kernel,
	James E.J. Bottomley, Guo Ren, linux-csky, H. Peter Anvin,
	sparclinux, linux-hexagon, WANG Xuerui, Will Deacon,
	Eugene Syromyatnikov, Anton Ivanov, Jonas Bonn, linux-s390,
	Alexander Gordeev, Madhavan Srinivasan, Vasily Gorbik,
	Yoshinori Sato, linux-sh, Michael Ellerman, Helge Deller,
	Huacai Chen, Russell King, Christophe Leroy, Dave Hansen,
	Ingo Molnar, Vineet Gupta, Christian Borntraeger, strace-devel,
	linux-arch, Albert Ou, Mike Frysinger, Davide Berardi,
	Renzo Davoli, linux-um, Heiko Carstens, Charlie Jenkins,
	Naveen N Rao, Nicholas Piggin, Stefan Kristiansson,
	Borislav Petkov, loongarch, Paul Walmsley, Stafford Horne,
	linux-arm-kernel, Brian Cain, Thomas Bogendoerfer, linux-parisc,
	linux-openrisc, linux-mips, linuxppc-dev, Oleg Nesterov,
	Dinh Nguyen, linux-riscv, Palmer Dabbelt, Richard Weinberger,
	Johannes Berg, Alexey Gladkov, David S. Miller

On Thu, Jan 30, 2025 at 09:33:03AM +0100, Sven Schnelle wrote:
> "Dmitry V. Levin" <ldv@strace.io> writes:
> 
> > These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> > architectures to implement PTRACE_SET_SYSCALL_INFO API.
> >
> > This partially reverts commit 7962c2eddbfe ("arch: remove unused
> > function syscall_set_arguments()") by reusing some of old
> > syscall_set_arguments() implementations.
> >
> > Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> > Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> > Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
> > ---
> >  arch/arc/include/asm/syscall.h        | 14 +++++++++++
> >  arch/arm/include/asm/syscall.h        | 13 ++++++++++
> >  arch/arm64/include/asm/syscall.h      | 13 ++++++++++
> >  arch/csky/include/asm/syscall.h       | 13 ++++++++++
> >  arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
> >  arch/loongarch/include/asm/syscall.h  |  8 ++++++
> >  arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
> >  arch/nios2/include/asm/syscall.h      | 11 ++++++++
> >  arch/openrisc/include/asm/syscall.h   |  7 ++++++
> >  arch/parisc/include/asm/syscall.h     | 12 +++++++++
> >  arch/powerpc/include/asm/syscall.h    | 10 ++++++++
> >  arch/riscv/include/asm/syscall.h      |  9 +++++++
> >  arch/s390/include/asm/syscall.h       | 12 +++++++++
> >  arch/sh/include/asm/syscall_32.h      | 12 +++++++++
> >  arch/sparc/include/asm/syscall.h      | 10 ++++++++
> >  arch/um/include/asm/syscall-generic.h | 14 +++++++++++
> >  arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
> >  arch/xtensa/include/asm/syscall.h     | 11 ++++++++
> >  include/asm-generic/syscall.h         | 16 ++++++++++++
> >  19 files changed, 267 insertions(+)
> >
> > diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
> > index 27e3d804b311..b3dd883699e7 100644
> > --- a/arch/s390/include/asm/syscall.h
> > +++ b/arch/s390/include/asm/syscall.h
> > @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
> >  	args[0] = regs->orig_gpr2 & mask;
> >  }
> >  
> > +static inline void syscall_set_arguments(struct task_struct *task,
> > +					 struct pt_regs *regs,
> > +					 const unsigned long *args)
> > +{
> > +	unsigned int n = 6;
> > +
> > +	while (n-- > 0)
> > +		if (n > 0)
> > +			regs->gprs[2 + n] = args[n];
> > +	regs->orig_gpr2 = args[0];
> > +}
> 
> Could that be changed to something like:
> 
> for (int n = 1; n < 6; n++)
>         regs->gprs[2 + n] = args[n];
> regs->orig_gpr2 = args[0];
> 
> I think this is way easier to parse.

I don't mind changing syscall_set_arguments() this way, but it just
mirrors syscall_get_arguments(), so I think it would be better if these
two functions were written in the same style.  Would you like to change
syscall_get_arguments() as well?


-- 
ldv

^ permalink raw reply	[flat|nested] 17+ messages in thread

* Re: [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()
  2025-01-30 11:22     ` Dmitry V. Levin
@ 2025-01-30 11:36       ` Sven Schnelle
  0 siblings, 0 replies; 17+ messages in thread
From: Sven Schnelle @ 2025-01-30 11:36 UTC (permalink / raw)
  To: Dmitry V. Levin
  Cc: linux-snps-arc, Rich Felker, Thomas Gleixner, Andreas Larsson,
	John Paul Adrian Glaubitz, x86, Arnd Bergmann, linux-kernel,
	James E.J. Bottomley, Guo Ren, linux-csky, H. Peter Anvin,
	sparclinux, linux-hexagon, WANG Xuerui, Will Deacon,
	Eugene Syromyatnikov, Anton Ivanov, Jonas Bonn, linux-s390,
	Alexander Gordeev, Madhavan Srinivasan, Vasily Gorbik,
	Yoshinori Sato, linux-sh, Michael Ellerman, Helge Deller,
	Huacai Chen, Russell King, Christophe Leroy, Dave Hansen,
	Ingo Molnar, Vineet Gupta, Christian Borntraeger, strace-devel,
	linux-arch, Albert Ou, Mike Frysinger, Davide Berardi,
	Renzo Davoli, linux-um, Heiko Carstens, Charlie Jenkins,
	Naveen N Rao, Nicholas Piggin, Stefan Kristiansson,
	Borislav Petkov, loongarch, Paul Walmsley, Stafford Horne,
	linux-arm-kernel, Brian Cain, Thomas Bogendoerfer, linux-parisc,
	linux-openrisc, linux-mips, linuxppc-dev, Oleg Nesterov,
	Dinh Nguyen, linux-riscv, Palmer Dabbelt, Richard Weinberger,
	Johannes Berg, Alexey Gladkov, David S. Miller

"Dmitry V. Levin" <ldv@strace.io> writes:

> On Thu, Jan 30, 2025 at 09:33:03AM +0100, Sven Schnelle wrote:
>> "Dmitry V. Levin" <ldv@strace.io> writes:
>> 
>> > These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
>> > architectures to implement PTRACE_SET_SYSCALL_INFO API.
>> >
>> > This partially reverts commit 7962c2eddbfe ("arch: remove unused
>> > function syscall_set_arguments()") by reusing some of old
>> > syscall_set_arguments() implementations.
>> >
>> > Signed-off-by: Dmitry V. Levin <ldv@strace.io>
>> > Tested-by: Charlie Jenkins <charlie@rivosinc.com>
>> > Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
>> > ---
>> >  arch/arc/include/asm/syscall.h        | 14 +++++++++++
>> >  arch/arm/include/asm/syscall.h        | 13 ++++++++++
>> >  arch/arm64/include/asm/syscall.h      | 13 ++++++++++
>> >  arch/csky/include/asm/syscall.h       | 13 ++++++++++
>> >  arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
>> >  arch/loongarch/include/asm/syscall.h  |  8 ++++++
>> >  arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
>> >  arch/nios2/include/asm/syscall.h      | 11 ++++++++
>> >  arch/openrisc/include/asm/syscall.h   |  7 ++++++
>> >  arch/parisc/include/asm/syscall.h     | 12 +++++++++
>> >  arch/powerpc/include/asm/syscall.h    | 10 ++++++++
>> >  arch/riscv/include/asm/syscall.h      |  9 +++++++
>> >  arch/s390/include/asm/syscall.h       | 12 +++++++++
>> >  arch/sh/include/asm/syscall_32.h      | 12 +++++++++
>> >  arch/sparc/include/asm/syscall.h      | 10 ++++++++
>> >  arch/um/include/asm/syscall-generic.h | 14 +++++++++++
>> >  arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
>> >  arch/xtensa/include/asm/syscall.h     | 11 ++++++++
>> >  include/asm-generic/syscall.h         | 16 ++++++++++++
>> >  19 files changed, 267 insertions(+)
>> >
>> > diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
>> > index 27e3d804b311..b3dd883699e7 100644
>> > --- a/arch/s390/include/asm/syscall.h
>> > +++ b/arch/s390/include/asm/syscall.h
>> > @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>> >  	args[0] = regs->orig_gpr2 & mask;
>> >  }
>> >  
>> > +static inline void syscall_set_arguments(struct task_struct *task,
>> > +					 struct pt_regs *regs,
>> > +					 const unsigned long *args)
>> > +{
>> > +	unsigned int n = 6;
>> > +
>> > +	while (n-- > 0)
>> > +		if (n > 0)
>> > +			regs->gprs[2 + n] = args[n];
>> > +	regs->orig_gpr2 = args[0];
>> > +}
>> 
>> Could that be changed to something like:
>> 
>> for (int n = 1; n < 6; n++)
>>         regs->gprs[2 + n] = args[n];
>> regs->orig_gpr2 = args[0];
>> 
>> I think this is way easier to parse.
>
> I don't mind changing syscall_set_arguments() this way, but it just
> mirrors syscall_get_arguments(), so I think it would be better if these
> two functions were written in the same style.  Would you like to change
> syscall_get_arguments() as well?

Oh. I'll prepare a patch for syscall_get_arguments(), wasn't aware
that this function looks the same. I'll send this via the s390 tree, so
it's independent of your patch series. Thanks!

^ permalink raw reply	[flat|nested] 17+ messages in thread

end of thread, other threads:[~2025-01-30 11:38 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-01-28  9:14 [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Dmitry V. Levin
2025-01-28  9:16 ` [PATCH v3 1/6] mips: fix mips_get_syscall_arg() for o32 Dmitry V. Levin
2025-01-28  9:16 ` [PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value() Dmitry V. Levin
2025-01-28 15:04   ` Christophe Leroy
2025-01-28 16:17     ` Dmitry V. Levin
2025-01-30  8:33   ` Sven Schnelle
2025-01-30 11:22     ` Dmitry V. Levin
2025-01-30 11:36       ` Sven Schnelle
2025-01-28  9:16 ` [PATCH v3 3/6] syscall.h: introduce syscall_set_nr() Dmitry V. Levin
2025-01-28 15:13   ` Christophe Leroy
2025-01-28 16:25     ` Dmitry V. Levin
2025-01-28  9:16 ` [PATCH v3 4/6] ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op Dmitry V. Levin
2025-01-28  9:16 ` [PATCH v3 5/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO request Dmitry V. Levin
2025-01-28 15:21   ` Christophe Leroy
2025-01-28 15:58     ` Dmitry V. Levin
2025-01-28  9:16 ` [PATCH v3 6/6] selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO Dmitry V. Levin
2025-01-29 18:51 ` [PATCH v3 0/6] ptrace: introduce PTRACE_SET_SYSCALL_INFO API Oleg Nesterov

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