The generic syscall syscall_exit_work() has the following content:
| audit_syscall_exit(regs)
| trace_sys_exit(regs, ...)
| ptrace_report_syscall_exit(regs, step)
The generic syscall syscall_exit_to_user_mode_work() has
the following form:
| unsigned long work = READ_ONCE(current_thread_info()->syscall_work)
| rseq_syscall()
| if (unlikely(work & SYSCALL_WORK_EXIT))
| syscall_exit_work(regs, work)
In preparation for moving arm64 over to the generic entry code,
rework el0_svc_common() as below:
- Rename syscall_trace_exit() to syscall_exit_work().
- Add syscall_exit_to_user_mode_prepare() function to replace
the combination of read_thread_flags() and syscall_exit_work(),
also move the syscall exit check logic into it. Move has_syscall_work()
helper into asm/syscall.h for reuse.
- As currently rseq_syscall() is always called and itself is controlled
by the CONFIG_DEBUG_RSEQ macro, so the CONFIG_DEBUG_RSEQ check
is removed.
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/arm64/include/asm/syscall.h | 7 ++++++-
arch/arm64/kernel/ptrace.c | 14 +++++++++++---
arch/arm64/kernel/syscall.c | 20 +-------------------
3 files changed, 18 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 dfdd886dc0a9..233a7688ac94 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2409,10 +2409,8 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
return syscall;
}
-void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
+static void syscall_exit_work(struct pt_regs *regs, unsigned long flags)
{
- rseq_syscall(regs);
-
audit_syscall_exit(regs);
if (flags & _TIF_SYSCALL_TRACEPOINT)
@@ -2422,6 +2420,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
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_exit_work(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/syscall.c b/arch/arm64/kernel/syscall.c
index ec31f82d2e9f..65021d0f49e1 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[])
{
@@ -130,21 +125,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
}
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