[tip: core/entry] ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag

tip-bot2 for Gabriel Krisman Bertazi
2020-11-16T21:11:59Z

The following commit has been merged into the core/entry branch of tip:

Commit-ID: 64eb35f701f04b30706e21d1b02636b5d31a37d2
Gitweb: https://git.kernel.org/tip/64eb35f701f04b30706e21d1b02636b5d31a37d2
Author: Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate: Mon, 16 Nov 2020 12:42:03 -05:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag

On architectures using the generic syscall entry code the architecture
independent syscall work is moved to flags in thread_info::syscall_work.
This removes architecture dependencies and frees up TIF bits.

Define SYSCALL_WORK_SYSCALL_EMU, use it in the generic entry code and
convert the code which uses the TIF specific helper functions to use the
new *_syscall_work() helpers which either resolve to the new mode for users
of the generic entry code or to the TIF based functions for the other
architectures.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20201116174206.2639648-8-krisman@collabora.com
---
include/linux/entry-common.h | 8 ++------
include/linux/thread_info.h | 2 ++
include/linux/tracehook.h | 2 +-
kernel/entry/common.c | 19 ++++++++++---------
kernel/fork.c | 4 ++--
kernel/ptrace.c | 10 +++++-----
6 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index ae426ab..b30f82b 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -13,10 +13,6 @@
* Define dummy _TIF work flags if not defined by the architecture or for
* disabled functionality.
*/
-#ifndef _TIF_SYSCALL_EMU
-# define _TIF_SYSCALL_EMU (0)
-#endif
-
#ifndef _TIF_SYSCALL_AUDIT
# define _TIF_SYSCALL_AUDIT (0)
#endif
@@ -42,7 +38,6 @@

#define SYSCALL_ENTER_WORK \
(_TIF_SYSCALL_AUDIT | \
- _TIF_SYSCALL_EMU | \
ARCH_SYSCALL_ENTER_WORK)

/*
@@ -58,7 +53,8 @@

#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
SYSCALL_WORK_SYSCALL_TRACEPOINT | \
- SYSCALL_WORK_SYSCALL_TRACE)
+ SYSCALL_WORK_SYSCALL_TRACE | \
+ SYSCALL_WORK_SYSCALL_EMU)
#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE)

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 761a459..85b8a42 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -39,11 +39,13 @@ enum syscall_work_bit {
SYSCALL_WORK_BIT_SECCOMP,
SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
SYSCALL_WORK_BIT_SYSCALL_TRACE,
+ SYSCALL_WORK_BIT_SYSCALL_EMU,
};

#define SYSCALL_WORK_SECCOMP BIT(SYSCALL_WORK_BIT_SECCOMP)
#define SYSCALL_WORK_SYSCALL_TRACEPOINT BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)
#define SYSCALL_WORK_SYSCALL_TRACE BIT(SYSCALL_WORK_BIT_SYSCALL_TRACE)
+#define SYSCALL_WORK_SYSCALL_EMU BIT(SYSCALL_WORK_BIT_SYSCALL_EMU)

#include <asm/thread_info.h>

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 3f20368..54b9252 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -84,7 +84,7 @@ static inline int ptrace_report_syscall(struct pt_regs *regs,
* @regs: user register state of current task
*
* This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
- * %TIF_SYSCALL_EMU have been set, when the current task has just
+ * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
* entered the kernel for a system call. Full user register state is
* available here. Changing the values in @regs can affect the system
* call number and arguments to be tried. It is safe to block here,
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 917328a..90533f3 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -47,9 +47,9 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
long ret = 0;

/* Handle ptrace */
- if (work & SYSCALL_WORK_SYSCALL_TRACE || ti_work & _TIF_SYSCALL_EMU) {
+ if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
ret = arch_syscall_enter_tracehook(regs);
- if (ret || (ti_work & _TIF_SYSCALL_EMU))
+ if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
return -1L;
}

@@ -208,21 +208,22 @@ static void exit_to_user_mode_prepare(struct pt_regs *regs)
}

#ifndef _TIF_SINGLESTEP
-static inline bool report_single_step(unsigned long ti_work)
+static inline bool report_single_step(unsigned long work)
{
return false;
}
#else
/*
- * If TIF_SYSCALL_EMU is set, then the only reason to report is when
+ * If SYSCALL_EMU is set, then the only reason to report is when
* TIF_SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
* instruction has been already reported in syscall_enter_from_user_mode().
*/
-#define SYSEMU_STEP (_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)
-
-static inline bool report_single_step(unsigned long ti_work)
+static inline bool report_single_step(unsigned long work)
{
- return (ti_work & SYSEMU_STEP) == _TIF_SINGLESTEP;
+ if (!(work & SYSCALL_WORK_SYSCALL_EMU))
+ return false;
+
+ return !!(current_thread_info()->flags & _TIF_SINGLESTEP);
}
#endif

@@ -236,7 +237,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
trace_sys_exit(regs, syscall_get_return_value(current, regs));

- step = report_single_step(ti_work);
+ step = report_single_step(work);
if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
arch_syscall_exit_tracehook(regs, step);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 99f68c2..02b689a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2159,8 +2159,8 @@ static __latent_entropy struct task_struct *copy_process(
*/
user_disable_single_step(p);
clear_task_syscall_work(p, SYSCALL_TRACE);
-#ifdef TIF_SYSCALL_EMU
- clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
+ clear_task_syscall_work(p, SYSCALL_EMU);
#endif
clear_tsk_latency_tracing(p);

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 55a2bc3..237bcd6 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -118,8 +118,8 @@ void __ptrace_unlink(struct task_struct *child)
BUG_ON(!child->ptrace);

clear_task_syscall_work(child, SYSCALL_TRACE);
-#ifdef TIF_SYSCALL_EMU
- clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
+ clear_task_syscall_work(child, SYSCALL_EMU);
#endif

child->parent = child->real_parent;
@@ -816,11 +816,11 @@ static int ptrace_resume(struct task_struct *child, long request,
else
clear_task_syscall_work(child, SYSCALL_TRACE);

-#ifdef TIF_SYSCALL_EMU
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
- set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+ set_task_syscall_work(child, SYSCALL_EMU);
else
- clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+ clear_task_syscall_work(child, SYSCALL_EMU);
#endif

if (is_singleblock(request)) {