[PATCH v7 00/11] arm64: entry: Convert to Generic Entry

[PATCH v7 00/11] arm64: entry: Convert to Generic Entry

[Jinjie Ruan]

Currently, x86, Riscv, Loongarch use the Generic Entry which makes
maintainers' work easier and codes more elegant. arm64 has already
successfully switched to the Generic IRQ Entry in commit
b3cf07851b6c ("arm64: entry: Switch to generic IRQ entry"), it is
time to completely convert arm64 to Generic Entry.

The goal is to bring arm64 in line with other architectures that already
use the generic entry infrastructure, reducing duplicated code and
making it easier to share future changes in entry/exit paths, such as
"Syscall User Dispatch".

This patch set is rebased on v6.18-rc6.

The performance benchmarks from perf bench basic syscall on
real hardware are below:

| Metric     | W/O Generic Framework | With Generic Framework | Change |
| ---------- | --------------------- | ---------------------- | ------ |
| Total time | 2.813 [sec]           | 2.930 [sec]            |  ↑4%   |
| usecs/op   | 0.281349              | 0.293006               |  ↑4%   |
| ops/sec    | 3,554,299             | 3,412,894              |  ↓4%   |

Compared to earlier with arch specific handling, the performance decreased
by approximately 4%.

It was tested ok with following test cases on QEMU virt platform:
 - Perf tests.
 - Different `dynamic preempt` mode switch.
 - Pseudo NMI tests.
 - Stress-ng CPU stress test.
 - MTE test case in Documentation/arch/arm64/memory-tagging-extension.rst
   and all test cases in tools/testing/selftests/arm64/mte/*.
 - "sud" selftest testcase.
 - get_syscall_info, peeksiginfo in tools/testing/selftests/ptrace.

The test QEMU configuration is as follows:

	qemu-system-aarch64 \
		-M virt,gic-version=3,virtualization=on,mte=on \
		-cpu max,pauth-impdef=on \
		-kernel Image \
		-smp 8,sockets=1,cores=4,threads=2 \
		-m 512m \
		-nographic \
		-no-reboot \
		-device virtio-rng-pci \
		-append "root=/dev/vda rw console=ttyAMA0 kgdboc=ttyAMA0,115200 \
			earlycon preempt=voluntary irqchip.gicv3_pseudo_nmi=1" \
		-drive if=none,file=images/rootfs.ext4,format=raw,id=hd0 \
		-device virtio-blk-device,drive=hd0 \

Chanegs in v7:
- Support "Syscall User Dispatch" by implementing
  arch_syscall_is_vdso_sigreturn() as kemal suggested.
- Add aarch64 support for "sud" selftest testcase, which tested ok with
  the patch series.
- Fix the kernel test robot warning for arch_ptrace_report_syscall_entry()
  and arch_ptrace_report_syscall_exit() in asm/entry-common.h.
- Add perf syscall performance test.
- Link to v6: https://lore.kernel.org/all/20250916082611.2972008-1-ruanjinjie@huawei.com/

Changes in v6:
- Rebased on v6.17-rc5-next as arm64 generic irq entry has merged.
- Update the commit message.
- Link to v5: https://lore.kernel.org/all/20241206101744.4161990-1-ruanjinjie@huawei.com/

Changes in v5:
- Not change arm32 and keep inerrupts_enabled() macro for gicv3 driver.
- Move irqentry_state definition into arch/arm64/kernel/entry-common.c.
- Avoid removing the __enter_from_*() and __exit_to_*() wrappers.
- Update "irqentry_state_t ret/irq_state" to "state"
  to keep it consistently.
- Use generic irq entry header for PREEMPT_DYNAMIC after split
  the generic entry.
- Also refactor the ARM64 syscall code.
- Introduce arch_ptrace_report_syscall_entry/exit(), instead of
  arch_pre/post_report_syscall_entry/exit() to simplify code.
- Make the syscall patches clear separation.
- Update the commit message.
- Link to v4: https://lore.kernel.org/all/20241025100700.3714552-1-ruanjinjie@huawei.com/

Changes in v4:
- Rework/cleanup split into a few patches as Mark suggested.
- Replace interrupts_enabled() macro with regs_irqs_disabled(), instead
  of left it here.
- Remove rcu and lockdep state in pt_regs by using temporary
  irqentry_state_t as Mark suggested.
- Remove some unnecessary intermediate functions to make it clear.
- Rework preempt irq and PREEMPT_DYNAMIC code
  to make the switch more clear.
- arch_prepare_*_entry/exit() -> arch_pre_*_entry/exit().
- Expand the arch functions comment.
- Make arch functions closer to its caller.
- Declare saved_reg in for block.
- Remove arch_exit_to_kernel_mode_prepare(), arch_enter_from_kernel_mode().
- Adjust "Add few arch functions to use generic entry" patch to be
  the penultimate.
- Update the commit message.
- Add suggested-by.
- Link to v3: https://lore.kernel.org/all/20240629085601.470241-1-ruanjinjie@huawei.com/

Changes in v3:
- Test the MTE test cases.
- Handle forget_syscall() in arch_post_report_syscall_entry()
- Make the arch funcs not use __weak as Thomas suggested, so move
  the arch funcs to entry-common.h, and make arch_forget_syscall() folded
  in arch_post_report_syscall_entry() as suggested.
- Move report_single_step() to thread_info.h for arm64
- Change __always_inline() to inline, add inline for the other arch funcs.
- Remove unused signal.h for entry-common.h.
- Add Suggested-by.
- Update the commit message.

Changes in v2:
- Add tested-by.
- Fix a bug that not call arch_post_report_syscall_entry() in
  syscall_trace_enter() if ptrace_report_syscall_entry() return not zero.
- Refactor report_syscall().
- Add comment for arch_prepare_report_syscall_exit().
- Adjust entry-common.h header file inclusion to alphabetical order.
- Update the commit message.

Jinjie Ruan (10):
  arm64/ptrace: Split report_syscall()
  arm64/ptrace: Refactor syscall_trace_enter/exit()
  arm64/ptrace: Refator el0_svc_common()
  entry: Add syscall_exit_to_user_mode_prepare() helper
  arm64/ptrace: Handle ptrace_report_syscall_entry() error
  arm64/ptrace: Expand secure_computing() in place
  arm64/ptrace: Use syscall_get_arguments() heleper
  entry: Add arch_ptrace_report_syscall_entry/exit()
  entry: Add has_syscall_work() helper
  arm64: entry: Convert to generic entry

kemal (1):
  selftests: sud_test: Support aarch64

 arch/arm64/Kconfig                            |  2 +-
 arch/arm64/include/asm/entry-common.h         | 69 ++++++++++++++
 arch/arm64/include/asm/syscall.h              | 29 +++++-
 arch/arm64/include/asm/thread_info.h          | 22 +----
 arch/arm64/kernel/debug-monitors.c            |  7 ++
 arch/arm64/kernel/ptrace.c                    | 90 -------------------
 arch/arm64/kernel/signal.c                    |  2 +-
 arch/arm64/kernel/syscall.c                   | 31 ++-----
 include/linux/entry-common.h                  | 42 ++++++---
 kernel/entry/syscall-common.c                 | 43 ++++++++-
 .../syscall_user_dispatch/sud_test.c          |  4 +
 11 files changed, 188 insertions(+), 153 deletions(-)

-- 
2.34.1

[PATCH v7 01/11] arm64/ptrace: Split report_syscall()

[Jinjie Ruan]

The generic syscall entry code has the form:

| syscall_trace_enter()
| {
|	ptrace_report_syscall_entry()
| }
|
| syscall_exit_work()
| {
|	ptrace_report_syscall_exit()
| }

In preparation for moving arm64 over to the generic entry code, split
report_syscall() to two separate enter and exit functions to align
the structure of the arm64 code with syscall_trace_enter() and
syscall_exit_work() from the generic entry code.

No functional changes.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/ptrace.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 4b001121c72d..5534c175ceb7 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2317,7 +2317,7 @@ enum ptrace_syscall_dir {
 	PTRACE_SYSCALL_EXIT,
 };
 
-static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
+static void report_syscall_enter(struct pt_regs *regs)
 {
 	int regno;
 	unsigned long saved_reg;
@@ -2340,13 +2340,24 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
 	 */
 	regno = (is_compat_task() ? 12 : 7);
 	saved_reg = regs->regs[regno];
-	regs->regs[regno] = dir;
+	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
 
-	if (dir == PTRACE_SYSCALL_ENTER) {
-		if (ptrace_report_syscall_entry(regs))
-			forget_syscall(regs);
-		regs->regs[regno] = saved_reg;
-	} else if (!test_thread_flag(TIF_SINGLESTEP)) {
+	if (ptrace_report_syscall_entry(regs))
+		forget_syscall(regs);
+	regs->regs[regno] = saved_reg;
+}
+
+static void report_syscall_exit(struct pt_regs *regs)
+{
+	int regno;
+	unsigned long saved_reg;
+
+	/* See comment for report_syscall_enter() above */
+	regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[regno];
+	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
+
+	if (!test_thread_flag(TIF_SINGLESTEP)) {
 		ptrace_report_syscall_exit(regs, 0);
 		regs->regs[regno] = saved_reg;
 	} else {
@@ -2366,7 +2377,7 @@ int syscall_trace_enter(struct pt_regs *regs)
 	unsigned long flags = read_thread_flags();
 
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		report_syscall(regs, PTRACE_SYSCALL_ENTER);
+		report_syscall_enter(regs);
 		if (flags & _TIF_SYSCALL_EMU)
 			return NO_SYSCALL;
 	}
@@ -2394,7 +2405,7 @@ void syscall_trace_exit(struct pt_regs *regs)
 		trace_sys_exit(regs, syscall_get_return_value(current, regs));
 
 	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
-		report_syscall(regs, PTRACE_SYSCALL_EXIT);
+		report_syscall_exit(regs);
 
 	rseq_syscall(regs);
 }
-- 
2.34.1

[PATCH v7 02/11] arm64/ptrace: Refactor syscall_trace_enter/exit()

[Jinjie Ruan]

The generic syscall entry code has the following form, which use
the input syscall work flag and syscall number:

| syscall_trace_enter(struct pt_regs *regs, long syscall,
|		      unsigned long work)
|
| syscall_exit_work(struct pt_regs *regs, unsigned long work)

In preparation for moving arm64 over to the generic entry code,
refactor syscall_trace_enter/exit() to also pass thread flags, and
get syscall number by syscall_get_nr() helper.

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/include/asm/syscall.h |  4 ++--
 arch/arm64/kernel/ptrace.c       | 24 +++++++++++++++---------
 arch/arm64/kernel/syscall.c      |  5 +++--
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 712daa90e643..d69f590a989b 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -114,7 +114,7 @@ static inline int syscall_get_arch(struct task_struct *task)
 	return AUDIT_ARCH_AARCH64;
 }
 
-int syscall_trace_enter(struct pt_regs *regs);
-void syscall_trace_exit(struct pt_regs *regs);
+int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
+void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
 
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 5534c175ceb7..bbb868f6b292 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2372,10 +2372,8 @@ static void report_syscall_exit(struct pt_regs *regs)
 	}
 }
 
-int syscall_trace_enter(struct pt_regs *regs)
+int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 {
-	unsigned long flags = read_thread_flags();
-
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
 		report_syscall_enter(regs);
 		if (flags & _TIF_SYSCALL_EMU)
@@ -2386,19 +2384,27 @@ int syscall_trace_enter(struct pt_regs *regs)
 	if (secure_computing() == -1)
 		return NO_SYSCALL;
 
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
-		trace_sys_enter(regs, regs->syscallno);
+	/* Either of the above might have changed the syscall number */
+	syscall = syscall_get_nr(current, regs);
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
+		trace_sys_enter(regs, syscall);
 
-	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
+		/*
+		 * Probes or BPF hooks in the tracepoint may have changed the
+		 * system call number as well.
+		 */
+		 syscall = syscall_get_nr(current, regs);
+	}
+
+	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
 			    regs->regs[2], regs->regs[3]);
 
 	return regs->syscallno;
 }
 
-void syscall_trace_exit(struct pt_regs *regs)
+void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
 {
-	unsigned long flags = read_thread_flags();
-
 	audit_syscall_exit(regs);
 
 	if (flags & _TIF_SYSCALL_TRACEPOINT)
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index aba7ca6bca2d..6e3fe760e0bb 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -124,7 +124,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		 */
 		if (scno == NO_SYSCALL)
 			syscall_set_return_value(current, regs, -ENOSYS, 0);
-		scno = syscall_trace_enter(regs);
+		scno = syscall_trace_enter(regs, regs->syscallno, flags);
 		if (scno == NO_SYSCALL)
 			goto trace_exit;
 	}
@@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 	}
 
 trace_exit:
-	syscall_trace_exit(regs);
+	flags = read_thread_flags();
+	syscall_trace_exit(regs, flags);
 }
 
 void do_el0_svc(struct pt_regs *regs)
-- 
2.34.1

[PATCH v7 03/11] arm64/ptrace: Refator el0_svc_common()

[Jinjie Ruan]

Compared to the generic entry code, arm64 terminate the process
after report_syscall_exit() if the syscall is issued within
a restartable sequence.

In preparation for moving arm64 over to the generic entry code,
refactor el0_svc_common() as below:

- Extract syscall_exit_to_user_mode_prepare() to replace the
  the combination of read_thread_flags() and syscall_trace_exit(),
  also move the syscall exit check logic into it.

- Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is
  not needed.

- Move has_syscall_work() helper into asm/syscall.h, which will be
  reused by ptrace.c.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/include/asm/syscall.h |  7 ++++++-
 arch/arm64/kernel/ptrace.c       | 10 +++++++++-
 arch/arm64/kernel/syscall.c      | 26 +++++---------------------
 3 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index d69f590a989b..6225981fbbdb 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -114,7 +114,12 @@ static inline int syscall_get_arch(struct task_struct *task)
 	return AUDIT_ARCH_AARCH64;
 }
 
+static inline bool has_syscall_work(unsigned long flags)
+{
+	return unlikely(flags & _TIF_SYSCALL_WORK);
+}
+
 int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
-void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
+void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
 
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index bbb868f6b292..95984bbf53db 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 	return regs->syscallno;
 }
 
-void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
+static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
 {
 	audit_syscall_exit(regs);
 
@@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
 
 	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
 		report_syscall_exit(regs);
+}
+
+void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
+{
+	unsigned long flags = read_thread_flags();
 
 	rseq_syscall(regs);
+
+	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
+		syscall_trace_exit(regs, flags);
 }
 
 /*
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 6e3fe760e0bb..9713b038d750 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
 	choose_random_kstack_offset(get_random_u16());
 }
 
-static inline bool has_syscall_work(unsigned long flags)
-{
-	return unlikely(flags & _TIF_SYSCALL_WORK);
-}
-
 static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 			   const syscall_fn_t syscall_table[])
 {
@@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		if (scno == NO_SYSCALL)
 			syscall_set_return_value(current, regs, -ENOSYS, 0);
 		scno = syscall_trace_enter(regs, regs->syscallno, flags);
-		if (scno == NO_SYSCALL)
-			goto trace_exit;
+		if (scno == NO_SYSCALL) {
+			syscall_exit_to_user_mode_prepare(regs);
+			return;
+		}
 	}
 
 	invoke_syscall(regs, scno, sc_nr, syscall_table);
 
-	/*
-	 * The tracing status may have changed under our feet, so we have to
-	 * check again. However, if we were tracing entry, then we always trace
-	 * exit regardless, as the old entry assembly did.
-	 */
-	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
-		flags = read_thread_flags();
-		if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))
-			return;
-	}
-
-trace_exit:
-	flags = read_thread_flags();
-	syscall_trace_exit(regs, flags);
+	syscall_exit_to_user_mode_prepare(regs);
 }
 
 void do_el0_svc(struct pt_regs *regs)
-- 
2.34.1

[PATCH v7 04/11] entry: Add syscall_exit_to_user_mode_prepare() helper

[Jinjie Ruan]

In the generic entry code, the part before
syscall_exit_to_user_mode_work() calls syscall_exit_work(), which
serves the same purpose as syscall_exit_to_user_mode_prepare()
in arm64.

In preparation for moving arm64 over to the generic entry
code, extract syscall_exit_to_user_mode_prepare() helper from
syscall_exit_to_user_mode_work().

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 include/linux/entry-common.h | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 7177436f0f9e..cd6dacb2d8bf 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -137,20 +137,11 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l
  */
 void syscall_exit_work(struct pt_regs *regs, unsigned long work);
 
-/**
- * syscall_exit_to_user_mode_work - Handle work before returning to user mode
- * @regs:	Pointer to currents pt_regs
- *
- * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
- * exit_to_user_mode() to perform the final transition to user mode.
- *
- * Calling convention is the same as for syscall_exit_to_user_mode() and it
- * returns with all work handled and interrupts disabled. The caller must
- * invoke exit_to_user_mode() before actually switching to user mode to
- * make the final state transitions. Interrupts must stay disabled between
- * return from this function and the invocation of exit_to_user_mode().
+/*
+ * Syscall specific exit to user mode preparation. Runs with interrupts
+ * enabled.
  */
-static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
+static __always_inline void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long nr = syscall_get_nr(current, regs);
@@ -171,6 +162,24 @@ static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
 	 */
 	if (unlikely(work & SYSCALL_WORK_EXIT))
 		syscall_exit_work(regs, work);
+}
+
+/**
+ * syscall_exit_to_user_mode_work - Handle work before returning to user mode
+ * @regs:	Pointer to currents pt_regs
+ *
+ * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
+ * exit_to_user_mode() to perform the final transition to user mode.
+ *
+ * Calling convention is the same as for syscall_exit_to_user_mode() and it
+ * returns with all work handled and interrupts disabled. The caller must
+ * invoke exit_to_user_mode() before actually switching to user mode to
+ * make the final state transitions. Interrupts must stay disabled between
+ * return from this function and the invocation of exit_to_user_mode().
+ */
+static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
+{
+	syscall_exit_to_user_mode_prepare(regs);
 	local_irq_disable_exit_to_user();
 	exit_to_user_mode_prepare(regs);
 }
-- 
2.34.1

[PATCH v7 05/11] arm64/ptrace: Handle ptrace_report_syscall_entry() error

[Jinjie Ruan]

The generic entry handle error of ptrace_report_syscall_entry(), but
arm64 not.

As the comment said, the calling arch code should abort the system
call and must prevent normal entry so no system call is
made if ptrace_report_syscall_entry() return nonzero.

In preparation for moving arm64 over to the generic entry code,
return early if ptrace_report_syscall_entry() encounters an error.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/ptrace.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 95984bbf53db..707951ad5d24 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2317,10 +2317,10 @@ enum ptrace_syscall_dir {
 	PTRACE_SYSCALL_EXIT,
 };
 
-static void report_syscall_enter(struct pt_regs *regs)
+static int report_syscall_enter(struct pt_regs *regs)
 {
-	int regno;
 	unsigned long saved_reg;
+	int regno, ret;
 
 	/*
 	 * We have some ABI weirdness here in the way that we handle syscall
@@ -2342,9 +2342,13 @@ static void report_syscall_enter(struct pt_regs *regs)
 	saved_reg = regs->regs[regno];
 	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
 
-	if (ptrace_report_syscall_entry(regs))
+	ret = ptrace_report_syscall_entry(regs);
+	if (ret)
 		forget_syscall(regs);
+
 	regs->regs[regno] = saved_reg;
+
+	return ret;
 }
 
 static void report_syscall_exit(struct pt_regs *regs)
@@ -2374,9 +2378,11 @@ static void report_syscall_exit(struct pt_regs *regs)
 
 int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 {
+	int ret;
+
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		report_syscall_enter(regs);
-		if (flags & _TIF_SYSCALL_EMU)
+		ret = report_syscall_enter(regs);
+		if (ret || (flags & _TIF_SYSCALL_EMU))
 			return NO_SYSCALL;
 	}
 
-- 
2.34.1

[PATCH v7 06/11] arm64/ptrace: Expand secure_computing() in place

[Jinjie Ruan]

The generic entry expand secure_computing() in place and call
__secure_computing() directly.

In order to switch to the generic entry for arm64, refactor
secure_computing() for syscall_trace_enter().

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/ptrace.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 707951ad5d24..9af3046a2ce9 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2387,8 +2387,11 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 	}
 
 	/* Do the secure computing after ptrace; failures should be fast. */
-	if (secure_computing() == -1)
-		return NO_SYSCALL;
+	if (flags & _TIF_SECCOMP) {
+		ret = __secure_computing(NULL);
+		if (ret == -1L)
+			return NO_SYSCALL;
+	}
 
 	/* Either of the above might have changed the syscall number */
 	syscall = syscall_get_nr(current, regs);
-- 
2.34.1

[PATCH v7 07/11] arm64/ptrace: Use syscall_get_arguments() heleper

[Jinjie Ruan]

The generic entry check audit context first and use
syscall_get_arguments() helper.

In order to switch to the generic entry for arm64,

- Also use the helper.

- Extract the syscall_enter_audit() helper to make it clear.

- Check audit context for syscall_enter_audit(), which only adds
  one additional check without any other differences as
  audit_syscall_entry() check it first otherwise do nothing.

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/ptrace.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 9af3046a2ce9..9455ccf1ecc1 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2376,6 +2376,17 @@ static void report_syscall_exit(struct pt_regs *regs)
 	}
 }
 
+static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
+{
+	if (unlikely(audit_context())) {
+		unsigned long args[6];
+
+		syscall_get_arguments(current, regs, args);
+		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
+	}
+
+}
+
 int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 {
 	int ret;
@@ -2406,8 +2417,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 		 syscall = syscall_get_nr(current, regs);
 	}
 
-	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
-			    regs->regs[2], regs->regs[3]);
+	syscall_enter_audit(regs, syscall);
 
 	return regs->syscallno;
 }
-- 
2.34.1

[PATCH v7 08/11] entry: Add arch_ptrace_report_syscall_entry/exit()

[Jinjie Ruan]

Differ from generic entry, due to historical reasons, ARM64 need to
save/restore during syscall entry/exit because ARM64 use a scratch
register (ip(r12) on AArch32, x7 on AArch64) to denote syscall entry/exit.

In preparation for moving arm64 over to the generic entry code,
add arch_ptrace_report_syscall_entry/exit() as the default
ptrace_report_syscall_entry/exit() implementation. This allows
arm64 to implement the architecture specific version.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Suggested-by: Kevin Brodsky <kevin.brodsky@arm.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 kernel/entry/syscall-common.c | 43 +++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/kernel/entry/syscall-common.c b/kernel/entry/syscall-common.c
index 66e6ba7fa80c..27310e611567 100644
--- a/kernel/entry/syscall-common.c
+++ b/kernel/entry/syscall-common.c
@@ -17,6 +17,25 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 	}
 }
 
+/**
+ * arch_ptrace_report_syscall_entry - Architecture specific
+ *				      ptrace_report_syscall_entry().
+ *
+ * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
+ * Defaults to ptrace_report_syscall_entry.
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_entry()
+ * implementation.
+ */
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
+
+#ifndef arch_ptrace_report_syscall_entry
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
+{
+	return ptrace_report_syscall_entry(regs);
+}
+#endif
+
 long syscall_trace_enter(struct pt_regs *regs, long syscall,
 				unsigned long work)
 {
@@ -34,7 +53,7 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall,
 
 	/* Handle ptrace */
 	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
-		ret = ptrace_report_syscall_entry(regs);
+		ret = arch_ptrace_report_syscall_entry(regs);
 		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
 			return -1L;
 	}
@@ -84,6 +103,26 @@ static inline bool report_single_step(unsigned long work)
 	return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
 }
 
+/**
+ * arch_ptrace_report_syscall_exit - Architecture specific
+ *				     ptrace_report_syscall_exit.
+ *
+ * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit().
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_exit
+ * implementation.
+ */
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step);
+
+#ifndef arch_ptrace_report_syscall_exit
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step)
+{
+	ptrace_report_syscall_exit(regs, step);
+}
+#endif
+
 void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 {
 	bool step;
@@ -108,5 +147,5 @@ void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 
 	step = report_single_step(work);
 	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
-		ptrace_report_syscall_exit(regs, step);
+		arch_ptrace_report_syscall_exit(regs, step);
 }
-- 
2.34.1

[PATCH v7 09/11] entry: Add has_syscall_work() helper

[Jinjie Ruan]

Add has_syscall_work() helper to facilitate reuse of this
function in other places.

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 include/linux/entry-common.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index cd6dacb2d8bf..e0f94e937e84 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -44,6 +44,11 @@
 				 SYSCALL_WORK_SYSCALL_EXIT_TRAP	|	\
 				 ARCH_SYSCALL_WORK_EXIT)
 
+static inline bool has_syscall_work(unsigned long work)
+{
+	return unlikely(work & SYSCALL_WORK_ENTER);
+}
+
 /**
  * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
  * @regs:	Pointer to currents pt_regs
@@ -91,7 +96,7 @@ static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *re
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 
-	if (work & SYSCALL_WORK_ENTER)
+	if (has_syscall_work(work))
 		syscall = syscall_trace_enter(regs, syscall, work);
 
 	return syscall;
-- 
2.34.1

[PATCH v7 10/11] arm64: entry: Convert to generic entry

[Jinjie Ruan]

Currently, x86, Riscv, Loongarch use the generic entry which makes
maintainers' work easier and codes more elegant. arm64 has already
switched to the generic IRQ entry, so completely convert arm64 to use
the generic entry infrastructure from kernel/entry/*.

The changes are below:
 - Remove TIF_SYSCALL_* flag, _TIF_WORK_MASK, _TIF_SYSCALL_WORK.

 - Implement arch_ptrace_report_syscall_entry/exit() with
   report_syscall_enter/exit() to do arm64-specific save/restore
   during syscall entry/exit.

 - Remove arm64 syscall_trace_enter(), syscall_exit_to_user_mode_prepare(),
   and related sub-functions including syscall_trace_exit() and
   syscall_enter_audit(), by calling generic entry's functions with similar
   functionality.

- Implement arch_syscall_is_vdso_sigreturn() to support
  "Syscall User Dispatch".

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/Kconfig                    |   2 +-
 arch/arm64/include/asm/entry-common.h |  69 +++++++++++++
 arch/arm64/include/asm/syscall.h      |  30 +++++-
 arch/arm64/include/asm/thread_info.h  |  22 +----
 arch/arm64/kernel/debug-monitors.c    |   7 ++
 arch/arm64/kernel/ptrace.c            | 134 --------------------------
 arch/arm64/kernel/signal.c            |   2 +-
 arch/arm64/kernel/syscall.c           |   6 +-
 8 files changed, 108 insertions(+), 164 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6663ffd23f25..1463ff15d67a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -152,9 +152,9 @@ config ARM64
 	select GENERIC_CPU_DEVICES
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_EARLY_IOREMAP
+	select GENERIC_ENTRY
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IOREMAP
-	select GENERIC_IRQ_ENTRY
 	select GENERIC_IRQ_IPI
 	select GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD
 	select GENERIC_IRQ_PROBE
diff --git a/arch/arm64/include/asm/entry-common.h b/arch/arm64/include/asm/entry-common.h
index cab8cd78f693..ee4dda1b01a2 100644
--- a/arch/arm64/include/asm/entry-common.h
+++ b/arch/arm64/include/asm/entry-common.h
@@ -11,6 +11,11 @@
 #include <asm/mte.h>
 #include <asm/stacktrace.h>
 
+enum ptrace_syscall_dir {
+	PTRACE_SYSCALL_ENTER = 0,
+	PTRACE_SYSCALL_EXIT,
+};
+
 #define ARCH_EXIT_TO_USER_MODE_WORK (_TIF_MTE_ASYNC_FAULT | _TIF_FOREIGN_FPSTATE)
 
 static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
@@ -54,4 +59,68 @@ static inline bool arch_irqentry_exit_need_resched(void)
 
 #define arch_irqentry_exit_need_resched arch_irqentry_exit_need_resched
 
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
+{
+	unsigned long saved_reg;
+	int regno, ret;
+
+	/*
+	 * We have some ABI weirdness here in the way that we handle syscall
+	 * exit stops because we indicate whether or not the stop has been
+	 * signalled from syscall entry or syscall exit by clobbering a general
+	 * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee
+	 * and restoring its old value after the stop. This means that:
+	 *
+	 * - Any writes by the tracer to this register during the stop are
+	 *   ignored/discarded.
+	 *
+	 * - The actual value of the register is not available during the stop,
+	 *   so the tracer cannot save it and restore it later.
+	 *
+	 * - Syscall stops behave differently to seccomp and pseudo-step traps
+	 *   (the latter do not nobble any registers).
+	 */
+	regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[regno];
+	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
+
+	ret = ptrace_report_syscall_entry(regs);
+	if (ret)
+		forget_syscall(regs);
+
+	regs->regs[regno] = saved_reg;
+
+	return ret;
+}
+
+#define arch_ptrace_report_syscall_entry arch_ptrace_report_syscall_entry
+
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step)
+{
+	unsigned long saved_reg;
+	int regno;
+
+	/* See comment for arch_ptrace_report_syscall_entry() */
+	regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[regno];
+	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
+
+	if (!step) {
+		ptrace_report_syscall_exit(regs, 0);
+		regs->regs[regno] = saved_reg;
+	} else {
+		regs->regs[regno] = saved_reg;
+
+		/*
+		 * Signal a pseudo-step exception since we are stepping but
+		 * tracer modifications to the registers may have rewound the
+		 * state machine.
+		 */
+		ptrace_report_syscall_exit(regs, 1);
+	}
+}
+
+#define arch_ptrace_report_syscall_exit arch_ptrace_report_syscall_exit
+
 #endif /* _ASM_ARM64_ENTRY_COMMON_H */
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 6225981fbbdb..c91938718468 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -9,6 +9,8 @@
 #include <linux/compat.h>
 #include <linux/err.h>
 
+#include <asm/vdso.h>
+
 typedef long (*syscall_fn_t)(const struct pt_regs *regs);
 
 extern const syscall_fn_t sys_call_table[];
@@ -114,12 +116,30 @@ static inline int syscall_get_arch(struct task_struct *task)
 	return AUDIT_ARCH_AARCH64;
 }
 
-static inline bool has_syscall_work(unsigned long flags)
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
 {
-	return unlikely(flags & _TIF_SYSCALL_WORK);
-}
+	unsigned long vdso = (unsigned long)current->mm->context.vdso;
+	unsigned long vdso_pages, vdso_text_len;
+	unsigned long pc = regs->pc - 4;
 
-int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
-void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
+#ifdef CONFIG_COMPAT
+	if (is_compat_task()) {
+		vdso = (unsigned long)current->mm->context.sigpage;
+		if (pc >= vdso && pc < vdso + PAGE_SIZE)
+			return true;
+
+		return false;
+	}
+#endif
+	if (regs->syscallno != __NR_rt_sigreturn)
+		return false;
+
+	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+	vdso_text_len = vdso_pages << PAGE_SHIFT;
+	if (pc < vdso || pc >= vdso + vdso_text_len)
+		return false;
+
+	return true;
+}
 
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index f241b8601ebd..0c083be23018 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -43,6 +43,7 @@ struct thread_info {
 	void			*scs_sp;
 #endif
 	u32			cpu;
+	unsigned long		syscall_work;   /* SYSCALL_WORK_ flags */
 };
 
 #define thread_saved_pc(tsk)	\
@@ -65,11 +66,6 @@ void arch_setup_new_exec(void);
 #define TIF_UPROBE		5	/* uprobe breakpoint or singlestep */
 #define TIF_MTE_ASYNC_FAULT	6	/* MTE Asynchronous Tag Check Fault */
 #define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
-#define TIF_SYSCALL_TRACE	8	/* syscall trace active */
-#define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
-#define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
-#define TIF_SECCOMP		11	/* syscall secure computing */
-#define TIF_SYSCALL_EMU		12	/* syscall emulation active */
 #define TIF_PATCH_PENDING	13	/* pending live patching update */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_FREEZE		19
@@ -92,30 +88,14 @@ void arch_setup_new_exec(void);
 #define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
-#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
-#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
-#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
-#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
 #define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
-#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 #define _TIF_SVE		(1 << TIF_SVE)
 #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_TSC_SIGSEGV	(1 << TIF_TSC_SIGSEGV)
 
-#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \
-				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
-				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
-				 _TIF_NOTIFY_SIGNAL | _TIF_SIGPENDING | \
-				 _TIF_PATCH_PENDING)
-
-#define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
-				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
-				 _TIF_SYSCALL_EMU)
-
 #ifdef CONFIG_SHADOW_CALL_STACK
 #define INIT_SCS							\
 	.scs_base	= init_shadow_call_stack,			\
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 29307642f4c9..e67643a70405 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -385,11 +385,18 @@ void user_enable_single_step(struct task_struct *task)
 
 	if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP))
 		set_regs_spsr_ss(task_pt_regs(task));
+
+	/*
+	 * Ensure that a trap is triggered once stepping out of a system
+	 * call prior to executing any user instruction.
+	 */
+	set_task_syscall_work(task, SYSCALL_EXIT_TRAP);
 }
 NOKPROBE_SYMBOL(user_enable_single_step);
 
 void user_disable_single_step(struct task_struct *task)
 {
 	clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
+	clear_task_syscall_work(task, SYSCALL_EXIT_TRAP);
 }
 NOKPROBE_SYMBOL(user_disable_single_step);
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 9455ccf1ecc1..9e3b39e207d1 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -42,9 +42,6 @@
 #include <asm/traps.h>
 #include <asm/system_misc.h>
 
-#define CREATE_TRACE_POINTS
-#include <trace/events/syscalls.h>
-
 struct pt_regs_offset {
 	const char *name;
 	int offset;
@@ -2312,137 +2309,6 @@ long arch_ptrace(struct task_struct *child, long request,
 	return ptrace_request(child, request, addr, data);
 }
 
-enum ptrace_syscall_dir {
-	PTRACE_SYSCALL_ENTER = 0,
-	PTRACE_SYSCALL_EXIT,
-};
-
-static int report_syscall_enter(struct pt_regs *regs)
-{
-	unsigned long saved_reg;
-	int regno, ret;
-
-	/*
-	 * We have some ABI weirdness here in the way that we handle syscall
-	 * exit stops because we indicate whether or not the stop has been
-	 * signalled from syscall entry or syscall exit by clobbering a general
-	 * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee
-	 * and restoring its old value after the stop. This means that:
-	 *
-	 * - Any writes by the tracer to this register during the stop are
-	 *   ignored/discarded.
-	 *
-	 * - The actual value of the register is not available during the stop,
-	 *   so the tracer cannot save it and restore it later.
-	 *
-	 * - Syscall stops behave differently to seccomp and pseudo-step traps
-	 *   (the latter do not nobble any registers).
-	 */
-	regno = (is_compat_task() ? 12 : 7);
-	saved_reg = regs->regs[regno];
-	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
-
-	ret = ptrace_report_syscall_entry(regs);
-	if (ret)
-		forget_syscall(regs);
-
-	regs->regs[regno] = saved_reg;
-
-	return ret;
-}
-
-static void report_syscall_exit(struct pt_regs *regs)
-{
-	int regno;
-	unsigned long saved_reg;
-
-	/* See comment for report_syscall_enter() above */
-	regno = (is_compat_task() ? 12 : 7);
-	saved_reg = regs->regs[regno];
-	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
-
-	if (!test_thread_flag(TIF_SINGLESTEP)) {
-		ptrace_report_syscall_exit(regs, 0);
-		regs->regs[regno] = saved_reg;
-	} else {
-		regs->regs[regno] = saved_reg;
-
-		/*
-		 * Signal a pseudo-step exception since we are stepping but
-		 * tracer modifications to the registers may have rewound the
-		 * state machine.
-		 */
-		ptrace_report_syscall_exit(regs, 1);
-	}
-}
-
-static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
-{
-	if (unlikely(audit_context())) {
-		unsigned long args[6];
-
-		syscall_get_arguments(current, regs, args);
-		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
-	}
-
-}
-
-int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
-{
-	int ret;
-
-	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		ret = report_syscall_enter(regs);
-		if (ret || (flags & _TIF_SYSCALL_EMU))
-			return NO_SYSCALL;
-	}
-
-	/* Do the secure computing after ptrace; failures should be fast. */
-	if (flags & _TIF_SECCOMP) {
-		ret = __secure_computing(NULL);
-		if (ret == -1L)
-			return NO_SYSCALL;
-	}
-
-	/* Either of the above might have changed the syscall number */
-	syscall = syscall_get_nr(current, regs);
-
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
-		trace_sys_enter(regs, syscall);
-
-		/*
-		 * Probes or BPF hooks in the tracepoint may have changed the
-		 * system call number as well.
-		 */
-		 syscall = syscall_get_nr(current, regs);
-	}
-
-	syscall_enter_audit(regs, syscall);
-
-	return regs->syscallno;
-}
-
-static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
-{
-	audit_syscall_exit(regs);
-
-	if (flags & _TIF_SYSCALL_TRACEPOINT)
-		trace_sys_exit(regs, syscall_get_return_value(current, regs));
-
-	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
-		report_syscall_exit(regs);
-}
-
-void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
-{
-	unsigned long flags = read_thread_flags();
-
-	rseq_syscall(regs);
-
-	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
-		syscall_trace_exit(regs, flags);
-}
-
 /*
  * SPSR_ELx bits which are always architecturally RES0 per ARM DDI 0487D.a.
  * We permit userspace to set SSBS (AArch64 bit 12, AArch32 bit 23) which is
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 1110eeb21f57..d3ec1892b3c7 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -8,8 +8,8 @@
 
 #include <linux/cache.h>
 #include <linux/compat.h>
+#include <linux/entry-common.h>
 #include <linux/errno.h>
-#include <linux/irq-entry-common.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/freezer.h>
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 9713b038d750..61e24eba9a86 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -2,6 +2,7 @@
 
 #include <linux/compiler.h>
 #include <linux/context_tracking.h>
+#include <linux/entry-common.h>
 #include <linux/errno.h>
 #include <linux/nospec.h>
 #include <linux/ptrace.h>
@@ -68,6 +69,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
 static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 			   const syscall_fn_t syscall_table[])
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long flags = read_thread_flags();
 
 	regs->orig_x0 = regs->regs[0];
@@ -101,7 +103,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		return;
 	}
 
-	if (has_syscall_work(flags)) {
+	if (has_syscall_work(work)) {
 		/*
 		 * The de-facto standard way to skip a system call using ptrace
 		 * is to set the system call to -1 (NO_SYSCALL) and set x0 to a
@@ -119,7 +121,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		 */
 		if (scno == NO_SYSCALL)
 			syscall_set_return_value(current, regs, -ENOSYS, 0);
-		scno = syscall_trace_enter(regs, regs->syscallno, flags);
+		scno = syscall_trace_enter(regs, regs->syscallno, work);
 		if (scno == NO_SYSCALL) {
 			syscall_exit_to_user_mode_prepare(regs);
 			return;
-- 
2.34.1

[PATCH v7 11/11] selftests: sud_test: Support aarch64

[Jinjie Ruan]

From: kemal <kmal@cock.li>

Support aarch64 to test "Syscall User Dispatch" with sud_test
selftest testcase.

Signed-off-by: kemal <kmal@cock.li>
---
 tools/testing/selftests/syscall_user_dispatch/sud_test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/syscall_user_dispatch/sud_test.c b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
index 2eb2c06303f2..f53ebc89befc 100644
--- a/tools/testing/selftests/syscall_user_dispatch/sud_test.c
+++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
@@ -192,6 +192,10 @@ static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
 	((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A0] =
 			((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A7];
 #endif
+#ifdef __aarch64__
+	((ucontext_t *)ucontext)->uc_mcontext.regs[0] = (unsigned int)
+			((ucontext_t *)ucontext)->uc_mcontext.regs[8];
+#endif
 }
 
 int setup_sigsys_handler(void)
-- 
2.34.1

Re: [PATCH v7 04/11] entry: Add syscall_exit_to_user_mode_prepare() helper

[Thomas Gleixner]

On Mon, Nov 17 2025 at 21:30, Jinjie Ruan wrote:

> In the generic entry code, the part before
> syscall_exit_to_user_mode_work() calls syscall_exit_work(), which
> serves the same purpose as syscall_exit_to_user_mode_prepare()
> in arm64.
>
> In preparation for moving arm64 over to the generic entry
> code, extract syscall_exit_to_user_mode_prepare() helper from
> syscall_exit_to_user_mode_work().
>
> No functional changes.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Re: [PATCH v7 01/11] arm64/ptrace: Split report_syscall()

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> The generic syscall entry code has the form:
>
> | syscall_trace_enter()
> | {
> |	ptrace_report_syscall_entry()
> | }
> |
> | syscall_exit_work()
> | {
> |	ptrace_report_syscall_exit()
> | }
>
> In preparation for moving arm64 over to the generic entry code, split
> report_syscall() to two separate enter and exit functions to align
> the structure of the arm64 code with syscall_trace_enter() and
> syscall_exit_work() from the generic entry code.
>
> No functional changes.
>
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/ptrace.c | 29 ++++++++++++++++++++---------
>  1 file changed, 20 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 4b001121c72d..5534c175ceb7 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2317,7 +2317,7 @@ enum ptrace_syscall_dir {
>  	PTRACE_SYSCALL_EXIT,
>  };

This is now unused so it should be removed.

>  
> -static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
> +static void report_syscall_enter(struct pt_regs *regs)

Nit: better to call it "report_syscall_entry" to match its final name.

>  {
>  	int regno;
>  	unsigned long saved_reg;
> @@ -2340,13 +2340,24 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
>  	 */
>  	regno = (is_compat_task() ? 12 : 7);
>  	saved_reg = regs->regs[regno];
> -	regs->regs[regno] = dir;
> +	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
>  
> -	if (dir == PTRACE_SYSCALL_ENTER) {
> -		if (ptrace_report_syscall_entry(regs))
> -			forget_syscall(regs);
> -		regs->regs[regno] = saved_reg;
> -	} else if (!test_thread_flag(TIF_SINGLESTEP)) {
> +	if (ptrace_report_syscall_entry(regs))
> +		forget_syscall(regs);
> +	regs->regs[regno] = saved_reg;
> +}
> +
> +static void report_syscall_exit(struct pt_regs *regs)
> +{
> +	int regno;
> +	unsigned long saved_reg;
> +
> +	/* See comment for report_syscall_enter() above */
> +	regno = (is_compat_task() ? 12 : 7);

Probably best not to duplicate such magic numbers, moving this line to a
helper would be good.

- Kevin

> +	saved_reg = regs->regs[regno];
> +	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
> +
> +	if (!test_thread_flag(TIF_SINGLESTEP)) {
>  		ptrace_report_syscall_exit(regs, 0);
>  		regs->regs[regno] = saved_reg;
>  	} else {
> @@ -2366,7 +2377,7 @@ int syscall_trace_enter(struct pt_regs *regs)
>  	unsigned long flags = read_thread_flags();
>  
>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
> -		report_syscall(regs, PTRACE_SYSCALL_ENTER);
> +		report_syscall_enter(regs);
>  		if (flags & _TIF_SYSCALL_EMU)
>  			return NO_SYSCALL;
>  	}
> @@ -2394,7 +2405,7 @@ void syscall_trace_exit(struct pt_regs *regs)
>  		trace_sys_exit(regs, syscall_get_return_value(current, regs));
>  
>  	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
> -		report_syscall(regs, PTRACE_SYSCALL_EXIT);
> +		report_syscall_exit(regs);
>  
>  	rseq_syscall(regs);
>  }

Re: [PATCH v7 02/11] arm64/ptrace: Refactor syscall_trace_enter/exit()

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> [...]
>
> @@ -2386,19 +2384,27 @@ int syscall_trace_enter(struct pt_regs *regs)
>  	if (secure_computing() == -1)
>  		return NO_SYSCALL;
>  
> -	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
> -		trace_sys_enter(regs, regs->syscallno);
> +	/* Either of the above might have changed the syscall number */
> +	syscall = syscall_get_nr(current, regs);
> +
> +	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
> +		trace_sys_enter(regs, syscall);
>  
> -	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
> +		/*
> +		 * Probes or BPF hooks in the tracepoint may have changed the
> +		 * system call number as well.
> +		 */
> +		 syscall = syscall_get_nr(current, regs);
> +	}
> +
> +	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
>  			    regs->regs[2], regs->regs[3]);
>  
>  	return regs->syscallno;

It would be good to align the return with the generic version as well.

>  }
>  
> -void syscall_trace_exit(struct pt_regs *regs)
> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>  {
> -	unsigned long flags = read_thread_flags();
> -
>  	audit_syscall_exit(regs);
>  
>  	if (flags & _TIF_SYSCALL_TRACEPOINT)
> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> index aba7ca6bca2d..6e3fe760e0bb 100644
> --- a/arch/arm64/kernel/syscall.c
> +++ b/arch/arm64/kernel/syscall.c
> @@ -124,7 +124,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>  		 */
>  		if (scno == NO_SYSCALL)
>  			syscall_set_return_value(current, regs, -ENOSYS, 0);
> -		scno = syscall_trace_enter(regs);
> +		scno = syscall_trace_enter(regs, regs->syscallno, flags);

Nit: could use scno instead of regs->syscallno.

- Kevin

>  		if (scno == NO_SYSCALL)
>  			goto trace_exit;
>  	}
> @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>  	}
>  
>  trace_exit:
> -	syscall_trace_exit(regs);
> +	flags = read_thread_flags();
> +	syscall_trace_exit(regs, flags);
>  }
>  
>  void do_el0_svc(struct pt_regs *regs)

Re: [PATCH v7 03/11] arm64/ptrace: Refator el0_svc_common()

[Kevin Brodsky]

In subject: s/refator/refactor/

Also nit: this is less about ptrace than about syscall entry, so maybe
"arm64/syscall:"?

On 17/11/2025 14:30, Jinjie Ruan wrote:
> Compared to the generic entry code, arm64 terminate the process

s/terminate/terminates/ (similar observation for other commit messages)

> after report_syscall_exit() if the syscall is issued within
> a restartable sequence.

Presumably this implies that forcing SIGSEGV before or after calling the
tracing handlers makes no difference, if so it should be clarified.

> In preparation for moving arm64 over to the generic entry code,
> refactor el0_svc_common() as below:
>
> - Extract syscall_exit_to_user_mode_prepare() to replace the
>   the combination of read_thread_flags() and syscall_trace_exit(),
>   also move the syscall exit check logic into it.
>
> - Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is
>   not needed.
>
> - Move has_syscall_work() helper into asm/syscall.h, which will be
>   reused by ptrace.c.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/include/asm/syscall.h |  7 ++++++-
>  arch/arm64/kernel/ptrace.c       | 10 +++++++++-
>  arch/arm64/kernel/syscall.c      | 26 +++++---------------------
>  3 files changed, 20 insertions(+), 23 deletions(-)
>
> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index d69f590a989b..6225981fbbdb 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -114,7 +114,12 @@ static inline int syscall_get_arch(struct task_struct *task)
>  	return AUDIT_ARCH_AARCH64;
>  }
>  
> +static inline bool has_syscall_work(unsigned long flags)
> +{
> +	return unlikely(flags & _TIF_SYSCALL_WORK);
> +}
> +
>  int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
>  
>  #endif	/* __ASM_SYSCALL_H */
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index bbb868f6b292..95984bbf53db 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  	return regs->syscallno;
>  }
>  
> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
> +static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>  {
>  	audit_syscall_exit(regs);
>  
> @@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>  
>  	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
>  		report_syscall_exit(regs);
> +}
> +
> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
> +{
> +	unsigned long flags = read_thread_flags();
>  
>  	rseq_syscall(regs);
> +
> +	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
> +		syscall_trace_exit(regs, flags);

Since we're trying to align as much with the generic code as possible,
we might as well rename this function to syscall_exit_work() as well.

>  }
>  
>  /*
> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> index 6e3fe760e0bb..9713b038d750 100644
> --- a/arch/arm64/kernel/syscall.c
> +++ b/arch/arm64/kernel/syscall.c
> @@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
>  	choose_random_kstack_offset(get_random_u16());
>  }
>  
> -static inline bool has_syscall_work(unsigned long flags)
> -{
> -	return unlikely(flags & _TIF_SYSCALL_WORK);
> -}
> -
>  static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>  			   const syscall_fn_t syscall_table[])
>  {
> @@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>  		if (scno == NO_SYSCALL)
>  			syscall_set_return_value(current, regs, -ENOSYS, 0);
>  		scno = syscall_trace_enter(regs, regs->syscallno, flags);
> -		if (scno == NO_SYSCALL)
> -			goto trace_exit;

Why not keep the goto instead of duplicating the call? It could be
renamed if necessary.

- Kevin

> +		if (scno == NO_SYSCALL) {
> +			syscall_exit_to_user_mode_prepare(regs);
> +			return;
> +		}
>  	}
>  
>  	invoke_syscall(regs, scno, sc_nr, syscall_table);
>  
> -	/*
> -	 * The tracing status may have changed under our feet, so we have to
> -	 * check again. However, if we were tracing entry, then we always trace
> -	 * exit regardless, as the old entry assembly did.
> -	 */
> -	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
> -		flags = read_thread_flags();
> -		if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))
> -			return;
> -	}
> -
> -trace_exit:
> -	flags = read_thread_flags();
> -	syscall_trace_exit(regs, flags);
> +	syscall_exit_to_user_mode_prepare(regs);
>  }
>  
>  void do_el0_svc(struct pt_regs *regs)

Re: [PATCH v7 04/11] entry: Add syscall_exit_to_user_mode_prepare() helper

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> In the generic entry code, the part before
> syscall_exit_to_user_mode_work() calls syscall_exit_work(), which
> serves the same purpose as syscall_exit_to_user_mode_prepare()
> in arm64.

This is really hard to parse, I suppose the point is that the beginning
of syscall_exit_to_user_mode_work() can be reused on arm64 and therefore
it makes sense to split it?

> In preparation for moving arm64 over to the generic entry
> code, extract syscall_exit_to_user_mode_prepare() helper from
> syscall_exit_to_user_mode_work().
>
> No functional changes.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>

The position of this patch in the series seems a little arbitrary (it
has no dependency on other patches), it might make more sense to group
it with the other generic patches (i.e. move it to patch 7).

Otherwise:

Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>

- Kevin

> ---
>  include/linux/entry-common.h | 35 ++++++++++++++++++++++-------------
>  1 file changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index 7177436f0f9e..cd6dacb2d8bf 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -137,20 +137,11 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l
>   */
>  void syscall_exit_work(struct pt_regs *regs, unsigned long work);
>  
> -/**
> - * syscall_exit_to_user_mode_work - Handle work before returning to user mode
> - * @regs:	Pointer to currents pt_regs
> - *
> - * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
> - * exit_to_user_mode() to perform the final transition to user mode.
> - *
> - * Calling convention is the same as for syscall_exit_to_user_mode() and it
> - * returns with all work handled and interrupts disabled. The caller must
> - * invoke exit_to_user_mode() before actually switching to user mode to
> - * make the final state transitions. Interrupts must stay disabled between
> - * return from this function and the invocation of exit_to_user_mode().
> +/*
> + * Syscall specific exit to user mode preparation. Runs with interrupts
> + * enabled.
>   */
> -static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
> +static __always_inline void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
>  {
>  	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
>  	unsigned long nr = syscall_get_nr(current, regs);
> @@ -171,6 +162,24 @@ static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
>  	 */
>  	if (unlikely(work & SYSCALL_WORK_EXIT))
>  		syscall_exit_work(regs, work);
> +}
> +
> +/**
> + * syscall_exit_to_user_mode_work - Handle work before returning to user mode
> + * @regs:	Pointer to currents pt_regs
> + *
> + * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
> + * exit_to_user_mode() to perform the final transition to user mode.
> + *
> + * Calling convention is the same as for syscall_exit_to_user_mode() and it
> + * returns with all work handled and interrupts disabled. The caller must
> + * invoke exit_to_user_mode() before actually switching to user mode to
> + * make the final state transitions. Interrupts must stay disabled between
> + * return from this function and the invocation of exit_to_user_mode().
> + */
> +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
> +{
> +	syscall_exit_to_user_mode_prepare(regs);
>  	local_irq_disable_exit_to_user();
>  	exit_to_user_mode_prepare(regs);
>  }

Re: [PATCH v7 05/11] arm64/ptrace: Handle ptrace_report_syscall_entry() error

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> The generic entry handle error of ptrace_report_syscall_entry(), but
> arm64 not.

This suggests that arm64 ignores the error completely, which isn't the
case: no syscall will be performed, but tracing will still occur as normal.

What this patch seems to be doing is to abort the _enter sequence if
ptrace_report_syscall_entry() errors out. The commit title and message
should be reworded accordingly.

> As the comment said, the calling arch code should abort the system

Which comment?

> call and must prevent normal entry so no system call is
> made if ptrace_report_syscall_entry() return nonzero.

This is already the case since we're calling forget_syscall().

> In preparation for moving arm64 over to the generic entry code,
> return early if ptrace_report_syscall_entry() encounters an error.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/ptrace.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 95984bbf53db..707951ad5d24 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2317,10 +2317,10 @@ enum ptrace_syscall_dir {
>  	PTRACE_SYSCALL_EXIT,
>  };
>  
> -static void report_syscall_enter(struct pt_regs *regs)
> +static int report_syscall_enter(struct pt_regs *regs)
>  {
> -	int regno;
>  	unsigned long saved_reg;
> +	int regno, ret;
>  
>  	/*
>  	 * We have some ABI weirdness here in the way that we handle syscall
> @@ -2342,9 +2342,13 @@ static void report_syscall_enter(struct pt_regs *regs)
>  	saved_reg = regs->regs[regno];
>  	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
>  
> -	if (ptrace_report_syscall_entry(regs))
> +	ret = ptrace_report_syscall_entry(regs);
> +	if (ret)
>  		forget_syscall(regs);

The generic syscall_trace_enter() doesn't do this (i.e. setting
regs->syscallno to NO_SYSCALL). Is that an oversight or do we just not
need it? In principle this does have a visible effect (e.g. via
REGSET_SYSTEM_CALL).

- Kevin

> +
>  	regs->regs[regno] = saved_reg;
> +
> +	return ret;
>  }
>  
>  static void report_syscall_exit(struct pt_regs *regs)
> @@ -2374,9 +2378,11 @@ static void report_syscall_exit(struct pt_regs *regs)
>  
>  int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  {
> +	int ret;
> +
>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
> -		report_syscall_enter(regs);
> -		if (flags & _TIF_SYSCALL_EMU)
> +		ret = report_syscall_enter(regs);
> +		if (ret || (flags & _TIF_SYSCALL_EMU))
>  			return NO_SYSCALL;
>  	}
>  

Re: [PATCH v7 06/11] arm64/ptrace: Expand secure_computing() in place

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> The generic entry expand secure_computing() in place and call
> __secure_computing() directly.
>
> In order to switch to the generic entry for arm64, refactor
> secure_computing() for syscall_trace_enter().
>
> No functional changes.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/ptrace.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 707951ad5d24..9af3046a2ce9 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2387,8 +2387,11 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  	}
>  
>  	/* Do the secure computing after ptrace; failures should be fast. */
> -	if (secure_computing() == -1)
> -		return NO_SYSCALL;
> +	if (flags & _TIF_SECCOMP) {
> +		ret = __secure_computing(NULL);

No argument was passed to __secure_computing() in v6, as expected since
it was removed in v6.15. Not sure why this NULL reappeared.

> +		if (ret == -1L)

ret is an int, so should be -1, not -1L.

- Kevin

> +			return NO_SYSCALL;
> +	}
>  
>  	/* Either of the above might have changed the syscall number */
>  	syscall = syscall_get_nr(current, regs);

Re: [PATCH v7 07/11] arm64/ptrace: Use syscall_get_arguments() heleper

[Kevin Brodsky]

In subject: s/heleper/helper/

On 17/11/2025 14:30, Jinjie Ruan wrote:
> The generic entry check audit context first and use
> syscall_get_arguments() helper.
>
> In order to switch to the generic entry for arm64,
>
> - Also use the helper.
>
> - Extract the syscall_enter_audit() helper to make it clear.
>
> - Check audit context for syscall_enter_audit(), which only adds
>   one additional check without any other differences as
>   audit_syscall_entry() check it first otherwise do nothing.

Presumably this is to avoid an unnecessary memcpy(). Overall these
changes make syscall_enter_audit() exactly equivalent to the generic
one, would be good to spell it out.

> No functional changes.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/ptrace.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 9af3046a2ce9..9455ccf1ecc1 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2376,6 +2376,17 @@ static void report_syscall_exit(struct pt_regs *regs)
>  	}
>  }
>  
> +static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
> +{
> +	if (unlikely(audit_context())) {
> +		unsigned long args[6];
> +
> +		syscall_get_arguments(current, regs, args);
> +		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
> +	}
> +

Nit: empty line.

- Kevin

> +}
> +
>  int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  {
>  	int ret;
> @@ -2406,8 +2417,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  		 syscall = syscall_get_nr(current, regs);
>  	}
>  
> -	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
> -			    regs->regs[2], regs->regs[3]);
> +	syscall_enter_audit(regs, syscall);
>  
>  	return regs->syscallno;
>  }

Re: [PATCH v7 08/11] entry: Add arch_ptrace_report_syscall_entry/exit()

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> Differ from generic entry, due to historical reasons, ARM64 need to
> save/restore during syscall entry/exit because ARM64 use a scratch
> register (ip(r12) on AArch32, x7 on AArch64) to denote syscall entry/exit.
>
> In preparation for moving arm64 over to the generic entry code,
> add arch_ptrace_report_syscall_entry/exit() as the default
> ptrace_report_syscall_entry/exit() implementation. This allows
> arm64 to implement the architecture specific version.
>
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Suggested-by: Kevin Brodsky <kevin.brodsky@arm.com>

I don't think I suggested this patch. I see that I suggested renaming
some functions on v3, but I don't think that justifies a Suggested-by tag.

> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  kernel/entry/syscall-common.c | 43 +++++++++++++++++++++++++++++++++--
>  1 file changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/entry/syscall-common.c b/kernel/entry/syscall-common.c
> index 66e6ba7fa80c..27310e611567 100644
> --- a/kernel/entry/syscall-common.c
> +++ b/kernel/entry/syscall-common.c
> @@ -17,6 +17,25 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
>  	}
>  }
>  
> +/**
> + * arch_ptrace_report_syscall_entry - Architecture specific
> + *				      ptrace_report_syscall_entry().
> + *
> + * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
> + * Defaults to ptrace_report_syscall_entry.
> + *
> + * The main purpose is to support arch-specific ptrace_report_syscall_entry()
> + * implementation.
> + */
> +static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
> +
> +#ifndef arch_ptrace_report_syscall_entry
> +static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
> +{
> +	return ptrace_report_syscall_entry(regs);

I saw that Thomas suggested this approach on v4, and it makes sense to
me, but I find the naming surprising. If an architecture does need extra
handling, then the generic function should never be called from generic
code. So it seems to me that the more logical change would be:

* Rename: ptrace_report_syscall_entry -> __ptrace_report_syscall_entry
* Introduce ptrace_report_syscall_entry(), defaults to
__ptrace_report_syscall_entry()

All this would be done in <linux/ptrace.h>, where it clearly belongs.
The __ prefix makes it clear that the generic function is not the main
interface. Even better, no need to change any caller with that approach.

- Kevin

> +}
> +#endif
> +
>  long syscall_trace_enter(struct pt_regs *regs, long syscall,
>  				unsigned long work)
>  {
> @@ -34,7 +53,7 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall,
>  
>  	/* Handle ptrace */
>  	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
> -		ret = ptrace_report_syscall_entry(regs);
> +		ret = arch_ptrace_report_syscall_entry(regs);
>  		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
>  			return -1L;
>  	}
> @@ -84,6 +103,26 @@ static inline bool report_single_step(unsigned long work)
>  	return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
>  }
>  
> +/**
> + * arch_ptrace_report_syscall_exit - Architecture specific
> + *				     ptrace_report_syscall_exit.
> + *
> + * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit().
> + *
> + * The main purpose is to support arch-specific ptrace_report_syscall_exit
> + * implementation.
> + */
> +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
> +							    int step);
> +
> +#ifndef arch_ptrace_report_syscall_exit
> +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
> +							    int step)
> +{
> +	ptrace_report_syscall_exit(regs, step);
> +}
> +#endif
> +
>  void syscall_exit_work(struct pt_regs *regs, unsigned long work)
>  {
>  	bool step;
> @@ -108,5 +147,5 @@ void syscall_exit_work(struct pt_regs *regs, unsigned long work)
>  
>  	step = report_single_step(work);
>  	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
> -		ptrace_report_syscall_exit(regs, step);
> +		arch_ptrace_report_syscall_exit(regs, step);
>  }

Re: [PATCH v7 09/11] entry: Add has_syscall_work() helper

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> Add has_syscall_work() helper to facilitate reuse of this
> function in other places.
>
> No functional changes.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  include/linux/entry-common.h | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index cd6dacb2d8bf..e0f94e937e84 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -44,6 +44,11 @@
>  				 SYSCALL_WORK_SYSCALL_EXIT_TRAP	|	\
>  				 ARCH_SYSCALL_WORK_EXIT)
>  
> +static inline bool has_syscall_work(unsigned long work)
> +{
> +	return unlikely(work & SYSCALL_WORK_ENTER);

I'm not sure this is a good idea, since the generic syscall machinery
has two separate sets of flags (SYSCALL_WORK_ENTER and
SYSCALL_WORK_EXIT). Of course we could reflect that in the helper's
name, but since it's only used twice after patch 10, maybe we don't need
a helper at all.

- Kevin

> +}
> +
>  /**
>   * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
>   * @regs:	Pointer to currents pt_regs
> @@ -91,7 +96,7 @@ static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *re
>  {
>  	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
>  
> -	if (work & SYSCALL_WORK_ENTER)
> +	if (has_syscall_work(work))
>  		syscall = syscall_trace_enter(regs, syscall, work);
>  
>  	return syscall;

Re: [PATCH v7 10/11] arm64: entry: Convert to generic entry

[Kevin Brodsky]

On 17/11/2025 14:30, Jinjie Ruan wrote:
> [...]
>
> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index 6225981fbbdb..c91938718468 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -9,6 +9,8 @@
>  #include <linux/compat.h>
>  #include <linux/err.h>
>  
> +#include <asm/vdso.h>
> +
>  typedef long (*syscall_fn_t)(const struct pt_regs *regs);
>  
>  extern const syscall_fn_t sys_call_table[];
> @@ -114,12 +116,30 @@ static inline int syscall_get_arch(struct task_struct *task)
>  	return AUDIT_ARCH_AARCH64;
>  }
>  
> -static inline bool has_syscall_work(unsigned long flags)
> +static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
>  {
> -	return unlikely(flags & _TIF_SYSCALL_WORK);
> -}
> +	unsigned long vdso = (unsigned long)current->mm->context.vdso;
> +	unsigned long vdso_pages, vdso_text_len;
> +	unsigned long pc = regs->pc - 4;

On AArch32 (i.e. COMPAT), instructions may be 16-bit (in T32/Thumb), so
we shouldn't blindly use PC - 4.

>  
> -int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
> -void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
> +#ifdef CONFIG_COMPAT
> +	if (is_compat_task()) {
> +		vdso = (unsigned long)current->mm->context.sigpage;
> +		if (pc >= vdso && pc < vdso + PAGE_SIZE)

Just return that expression (instead of true/false).

I think the approach is reasonable, as we have 4 possible trampolines in
COMPAT and they all live in a dedicated page. I don't think we need to
worry about offsetting PC, because even if it points after the last
trampoline, it will still fall within the page. IOW, just use the
unmodified value of regs->pc.

> +			return true;
> +
> +		return false;
> +	}
> +#endif
> +	if (regs->syscallno != __NR_rt_sigreturn)
> +		return false;
> +
> +	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
> +	vdso_text_len = vdso_pages << PAGE_SHIFT;
> +	if (pc < vdso || pc >= vdso + vdso_text_len)
> +		return false;

Why not use the same approach as x86 and simply check that regs->pc
points after the trampoline? We already have a way to get the address of
the vDSO's sigreturn trampoline on arm64:
VDSO_SYMBOL(current->mm->context.vdso, sigtramp) (see signal.c). The
trampoline consists of two instructions that cannot be changed (pretty
much part of the ABI), so we could compare regs->pc with sigtramp + 8.

> +
> +	return true;
> +}
>  #endif	/* __ASM_SYSCALL_H */
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index f241b8601ebd..0c083be23018 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -43,6 +43,7 @@ struct thread_info {
>  	void			*scs_sp;
>  #endif
>  	u32			cpu;
> +	unsigned long		syscall_work;   /* SYSCALL_WORK_ flags */
>  };
>  
>  #define thread_saved_pc(tsk)	\
> @@ -65,11 +66,6 @@ void arch_setup_new_exec(void);
>  #define TIF_UPROBE		5	/* uprobe breakpoint or singlestep */
>  #define TIF_MTE_ASYNC_FAULT	6	/* MTE Asynchronous Tag Check Fault */
>  #define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
> -#define TIF_SYSCALL_TRACE	8	/* syscall trace active */
> -#define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
> -#define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
> -#define TIF_SECCOMP		11	/* syscall secure computing */
> -#define TIF_SYSCALL_EMU		12	/* syscall emulation active */
>  #define TIF_PATCH_PENDING	13	/* pending live patching update */
>  #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
>  #define TIF_FREEZE		19
> @@ -92,30 +88,14 @@ void arch_setup_new_exec(void);
>  #define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
>  #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
>  #define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
> -#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
> -#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
> -#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
> -#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
> -#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
>  #define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
>  #define _TIF_UPROBE		(1 << TIF_UPROBE)
> -#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
>  #define _TIF_32BIT		(1 << TIF_32BIT)
>  #define _TIF_SVE		(1 << TIF_SVE)
>  #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
>  #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
>  #define _TIF_TSC_SIGSEGV	(1 << TIF_TSC_SIGSEGV)
>  
> -#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \
> -				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
> -				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
> -				 _TIF_NOTIFY_SIGNAL | _TIF_SIGPENDING | \
> -				 _TIF_PATCH_PENDING)

AFAICT this was already unused before this series, since commit
b3cf07851b6c ("arm64: entry: Switch to generic IRQ entry"). It should be
removed in a separate commit.

> [...]
>
> -void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
> -{
> -	unsigned long flags = read_thread_flags();
> -
> -	rseq_syscall(regs);
> -
> -	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)

I believe switching to the generic function introduces a change here:
syscall_exit_work() is only called if a flag in SYSCALL_WORK_EXIT is
set, and this set does not include SYSCALL_EMU and SECCOMP. Practically
this means that audit_syscall_exit() will no longer be called if only
SECCOMP and/or SYSCALL_EMU is set.

It doesn't feel like a major behaviour change, but it should be pointed out.

- Kevin

> -		syscall_trace_exit(regs, flags);
> -}
>
> [...]

Re: [PATCH v7 01/11] arm64/ptrace: Split report_syscall()

[Jinjie Ruan]

On 2025/11/19 1:09, Kevin Brodsky wrote:
> On 17/11/2025 14:30, Jinjie Ruan wrote:
>> The generic syscall entry code has the form:
>>
>> | syscall_trace_enter()
>> | {
>> |	ptrace_report_syscall_entry()
>> | }
>> |
>> | syscall_exit_work()
>> | {
>> |	ptrace_report_syscall_exit()
>> | }
>>
>> In preparation for moving arm64 over to the generic entry code, split
>> report_syscall() to two separate enter and exit functions to align
>> the structure of the arm64 code with syscall_trace_enter() and
>> syscall_exit_work() from the generic entry code.
>>
>> No functional changes.
>>
>> Suggested-by: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/kernel/ptrace.c | 29 ++++++++++++++++++++---------
>>  1 file changed, 20 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index 4b001121c72d..5534c175ceb7 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -2317,7 +2317,7 @@ enum ptrace_syscall_dir {
>>  	PTRACE_SYSCALL_EXIT,
>>  };
> 
> This is now unused so it should be removed.

Sure.

> 
>>  
>> -static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
>> +static void report_syscall_enter(struct pt_regs *regs)
> 
> Nit: better to call it "report_syscall_entry" to match its final name.

That makes sense, thanks for the review.

> 
>>  {
>>  	int regno;
>>  	unsigned long saved_reg;
>> @@ -2340,13 +2340,24 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
>>  	 */
>>  	regno = (is_compat_task() ? 12 : 7);
>>  	saved_reg = regs->regs[regno];
>> -	regs->regs[regno] = dir;
>> +	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
>>  
>> -	if (dir == PTRACE_SYSCALL_ENTER) {
>> -		if (ptrace_report_syscall_entry(regs))
>> -			forget_syscall(regs);
>> -		regs->regs[regno] = saved_reg;
>> -	} else if (!test_thread_flag(TIF_SINGLESTEP)) {
>> +	if (ptrace_report_syscall_entry(regs))
>> +		forget_syscall(regs);
>> +	regs->regs[regno] = saved_reg;
>> +}
>> +
>> +static void report_syscall_exit(struct pt_regs *regs)
>> +{
>> +	int regno;
>> +	unsigned long saved_reg;
>> +
>> +	/* See comment for report_syscall_enter() above */
>> +	regno = (is_compat_task() ? 12 : 7);
> 
> Probably best not to duplicate such magic numbers, moving this line to a
> helper would be good.

That makes sense.  A helper will remove the duplicate.

> 
> - Kevin
> 
>> +	saved_reg = regs->regs[regno];
>> +	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
>> +
>> +	if (!test_thread_flag(TIF_SINGLESTEP)) {
>>  		ptrace_report_syscall_exit(regs, 0);
>>  		regs->regs[regno] = saved_reg;
>>  	} else {
>> @@ -2366,7 +2377,7 @@ int syscall_trace_enter(struct pt_regs *regs)
>>  	unsigned long flags = read_thread_flags();
>>  
>>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
>> -		report_syscall(regs, PTRACE_SYSCALL_ENTER);
>> +		report_syscall_enter(regs);
>>  		if (flags & _TIF_SYSCALL_EMU)
>>  			return NO_SYSCALL;
>>  	}
>> @@ -2394,7 +2405,7 @@ void syscall_trace_exit(struct pt_regs *regs)
>>  		trace_sys_exit(regs, syscall_get_return_value(current, regs));
>>  
>>  	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
>> -		report_syscall(regs, PTRACE_SYSCALL_EXIT);
>> +		report_syscall_exit(regs);
>>  
>>  	rseq_syscall(regs);
>>  }
> 

Re: [PATCH v7 02/11] arm64/ptrace: Refactor syscall_trace_enter/exit()

[Jinjie Ruan]

On 2025/11/19 1:09, Kevin Brodsky wrote:
> On 17/11/2025 14:30, Jinjie Ruan wrote:
>> [...]
>>
>> @@ -2386,19 +2384,27 @@ int syscall_trace_enter(struct pt_regs *regs)
>>  	if (secure_computing() == -1)
>>  		return NO_SYSCALL;
>>  
>> -	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
>> -		trace_sys_enter(regs, regs->syscallno);
>> +	/* Either of the above might have changed the syscall number */
>> +	syscall = syscall_get_nr(current, regs);
>> +
>> +	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
>> +		trace_sys_enter(regs, syscall);
>>  
>> -	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
>> +		/*
>> +		 * Probes or BPF hooks in the tracepoint may have changed the
>> +		 * system call number as well.
>> +		 */
>> +		 syscall = syscall_get_nr(current, regs);
>> +	}
>> +
>> +	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
>>  			    regs->regs[2], regs->regs[3]);
>>  
>>  	return regs->syscallno;
> 
> It would be good to align the return with the generic version as well.

Right, could be aligned with the return with the generic version.

> 
>>  }
>>  
>> -void syscall_trace_exit(struct pt_regs *regs)
>> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>>  {
>> -	unsigned long flags = read_thread_flags();
>> -
>>  	audit_syscall_exit(regs);
>>  
>>  	if (flags & _TIF_SYSCALL_TRACEPOINT)
>> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
>> index aba7ca6bca2d..6e3fe760e0bb 100644
>> --- a/arch/arm64/kernel/syscall.c
>> +++ b/arch/arm64/kernel/syscall.c
>> @@ -124,7 +124,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>>  		 */
>>  		if (scno == NO_SYSCALL)
>>  			syscall_set_return_value(current, regs, -ENOSYS, 0);
>> -		scno = syscall_trace_enter(regs);
>> +		scno = syscall_trace_enter(regs, regs->syscallno, flags);
> 
> Nit: could use scno instead of regs->syscallno.

That is ok.

> 
> - Kevin
> 
>>  		if (scno == NO_SYSCALL)
>>  			goto trace_exit;
>>  	}
>> @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>>  	}
>>  
>>  trace_exit:
>> -	syscall_trace_exit(regs);
>> +	flags = read_thread_flags();
>> +	syscall_trace_exit(regs, flags);
>>  }
>>  
>>  void do_el0_svc(struct pt_regs *regs)
> 

Re: [PATCH v7 03/11] arm64/ptrace: Refator el0_svc_common()

[Jinjie Ruan]

On 2025/11/19 1:10, Kevin Brodsky wrote:
> In subject: s/refator/refactor/
> 
> Also nit: this is less about ptrace than about syscall entry, so maybe
> "arm64/syscall:"?
> 
> On 17/11/2025 14:30, Jinjie Ruan wrote:
>> Compared to the generic entry code, arm64 terminate the process
> 
> s/terminate/terminates/ (similar observation for other commit messages)

Will update it.

> 
>> after report_syscall_exit() if the syscall is issued within
>> a restartable sequence.
> 
> Presumably this implies that forcing SIGSEGV before or after calling the
> tracing handlers makes no difference, if so it should be clarified.

It seems that it need a separate patch to clarify.

> 
>> In preparation for moving arm64 over to the generic entry code,
>> refactor el0_svc_common() as below:
>>
>> - Extract syscall_exit_to_user_mode_prepare() to replace the
>>   the combination of read_thread_flags() and syscall_trace_exit(),
>>   also move the syscall exit check logic into it.
>>
>> - Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is
>>   not needed.
>>
>> - Move has_syscall_work() helper into asm/syscall.h, which will be
>>   reused by ptrace.c.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/include/asm/syscall.h |  7 ++++++-
>>  arch/arm64/kernel/ptrace.c       | 10 +++++++++-
>>  arch/arm64/kernel/syscall.c      | 26 +++++---------------------
>>  3 files changed, 20 insertions(+), 23 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
>> index d69f590a989b..6225981fbbdb 100644
>> --- a/arch/arm64/include/asm/syscall.h
>> +++ b/arch/arm64/include/asm/syscall.h
>> @@ -114,7 +114,12 @@ static inline int syscall_get_arch(struct task_struct *task)
>>  	return AUDIT_ARCH_AARCH64;
>>  }
>>  
>> +static inline bool has_syscall_work(unsigned long flags)
>> +{
>> +	return unlikely(flags & _TIF_SYSCALL_WORK);
>> +}
>> +
>>  int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
>> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
>> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
>>  
>>  #endif	/* __ASM_SYSCALL_H */
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index bbb868f6b292..95984bbf53db 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>>  	return regs->syscallno;
>>  }
>>  
>> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>> +static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>>  {
>>  	audit_syscall_exit(regs);
>>  
>> @@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>>  
>>  	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
>>  		report_syscall_exit(regs);
>> +}
>> +
>> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
>> +{
>> +	unsigned long flags = read_thread_flags();
>>  
>>  	rseq_syscall(regs);
>> +
>> +	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
>> +		syscall_trace_exit(regs, flags);
> 
> Since we're trying to align as much with the generic code as possible,
> we might as well rename this function to syscall_exit_work() as well.

Yes, syscall_trace_exit() is very similar to syscall_exit_work().

> 
>>  }
>>  
>>  /*
>> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
>> index 6e3fe760e0bb..9713b038d750 100644
>> --- a/arch/arm64/kernel/syscall.c
>> +++ b/arch/arm64/kernel/syscall.c
>> @@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
>>  	choose_random_kstack_offset(get_random_u16());
>>  }
>>  
>> -static inline bool has_syscall_work(unsigned long flags)
>> -{
>> -	return unlikely(flags & _TIF_SYSCALL_WORK);
>> -}
>> -
>>  static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>>  			   const syscall_fn_t syscall_table[])
>>  {
>> @@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>>  		if (scno == NO_SYSCALL)
>>  			syscall_set_return_value(current, regs, -ENOSYS, 0);
>>  		scno = syscall_trace_enter(regs, regs->syscallno, flags);
>> -		if (scno == NO_SYSCALL)
>> -			goto trace_exit;
> 
> Why not keep the goto instead of duplicating the call? It could be
> renamed if necessary.

That is good.

> 
> - Kevin
> 
>> +		if (scno == NO_SYSCALL) {
>> +			syscall_exit_to_user_mode_prepare(regs);
>> +			return;
>> +		}
>>  	}
>>  
>>  	invoke_syscall(regs, scno, sc_nr, syscall_table);
>>  
>> -	/*
>> -	 * The tracing status may have changed under our feet, so we have to
>> -	 * check again. However, if we were tracing entry, then we always trace
>> -	 * exit regardless, as the old entry assembly did.
>> -	 */
>> -	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
>> -		flags = read_thread_flags();
>> -		if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))
>> -			return;
>> -	}
>> -
>> -trace_exit:
>> -	flags = read_thread_flags();
>> -	syscall_trace_exit(regs, flags);
>> +	syscall_exit_to_user_mode_prepare(regs);
>>  }
>>  
>>  void do_el0_svc(struct pt_regs *regs)
> 

Re: [PATCH v7 05/11] arm64/ptrace: Handle ptrace_report_syscall_entry() error

[Jinjie Ruan]

On 2025/11/19 1:12, Kevin Brodsky wrote:
> On 17/11/2025 14:30, Jinjie Ruan wrote:
>> The generic entry handle error of ptrace_report_syscall_entry(), but
>> arm64 not.
> 
> This suggests that arm64 ignores the error completely, which isn't the
> case: no syscall will be performed, but tracing will still occur as normal.
> 
> What this patch seems to be doing is to abort the _enter sequence if
> ptrace_report_syscall_entry() errors out. The commit title and message
> should be reworded accordingly.

You are right,the description is unclear .

> 
>> As the comment said, the calling arch code should abort the system
> 
> Which comment?

ptrace_report_syscall_entry()

> 
>> call and must prevent normal entry so no system call is
>> made if ptrace_report_syscall_entry() return nonzero.
> 
> This is already the case since we're calling forget_syscall().

Yes. it is similar with the generic entry returns NO_SYSCALL.

> 
>> In preparation for moving arm64 over to the generic entry code,
>> return early if ptrace_report_syscall_entry() encounters an error.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/kernel/ptrace.c | 16 +++++++++++-----
>>  1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index 95984bbf53db..707951ad5d24 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -2317,10 +2317,10 @@ enum ptrace_syscall_dir {
>>  	PTRACE_SYSCALL_EXIT,
>>  };
>>  
>> -static void report_syscall_enter(struct pt_regs *regs)
>> +static int report_syscall_enter(struct pt_regs *regs)
>>  {
>> -	int regno;
>>  	unsigned long saved_reg;
>> +	int regno, ret;
>>  
>>  	/*
>>  	 * We have some ABI weirdness here in the way that we handle syscall
>> @@ -2342,9 +2342,13 @@ static void report_syscall_enter(struct pt_regs *regs)
>>  	saved_reg = regs->regs[regno];
>>  	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
>>  
>> -	if (ptrace_report_syscall_entry(regs))
>> +	ret = ptrace_report_syscall_entry(regs);
>> +	if (ret)
>>  		forget_syscall(regs);
> 
> The generic syscall_trace_enter() doesn't do this (i.e. setting
> regs->syscallno to NO_SYSCALL). Is that an oversight or do we just not
> need it? In principle this does have a visible effect (e.g. via
> REGSET_SYSTEM_CALL).

We just not need it because the original syscall_trace_enter() need use
regs->syscallno as the return value, but now we return early by using
NO_SYSCALL.

> 
> - Kevin
> 
>> +
>>  	regs->regs[regno] = saved_reg;
>> +
>> +	return ret;
>>  }
>>  
>>  static void report_syscall_exit(struct pt_regs *regs)
>> @@ -2374,9 +2378,11 @@ static void report_syscall_exit(struct pt_regs *regs)
>>  
>>  int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>>  {
>> +	int ret;
>> +
>>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
>> -		report_syscall_enter(regs);
>> -		if (flags & _TIF_SYSCALL_EMU)
>> +		ret = report_syscall_enter(regs);
>> +		if (ret || (flags & _TIF_SYSCALL_EMU))
>>  			return NO_SYSCALL;
>>  	}
>>  
> 

Re: [PATCH v7 06/11] arm64/ptrace: Expand secure_computing() in place

[Jinjie Ruan]

On 2025/11/19 1:12, Kevin Brodsky wrote:
> On 17/11/2025 14:30, Jinjie Ruan wrote:
>> The generic entry expand secure_computing() in place and call
>> __secure_computing() directly.
>>
>> In order to switch to the generic entry for arm64, refactor
>> secure_computing() for syscall_trace_enter().
>>
>> No functional changes.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/kernel/ptrace.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index 707951ad5d24..9af3046a2ce9 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -2387,8 +2387,11 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>>  	}
>>  
>>  	/* Do the secure computing after ptrace; failures should be fast. */
>> -	if (secure_computing() == -1)
>> -		return NO_SYSCALL;
>> +	if (flags & _TIF_SECCOMP) {
>> +		ret = __secure_computing(NULL);
> 
> No argument was passed to __secure_computing() in v6, as expected since
> it was removed in v6.15. Not sure why this NULL reappeared.
> 
There is a typo here.

>> +		if (ret == -1L)
> 
> ret is an int, so should be -1, not -1L.

Right, not -1L.

> 
> - Kevin
> 
>> +			return NO_SYSCALL;
>> +	}
>>  
>>  	/* Either of the above might have changed the syscall number */
>>  	syscall = syscall_get_nr(current, regs);
>