Re: [PATCH v9 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit()

On 04/12/25 1:51 PM, Jinjie Ruan wrote:

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.

Reviewed-by: Kevin Brodsky kevin.brodsky@arm.com Signed-off-by: Jinjie Ruan ruanjinjie@huawei.com

---

arch/arm64/include/asm/syscall.h | 4 ++-- arch/arm64/kernel/ptrace.c | 25 ++++++++++++++++--------- arch/arm64/kernel/syscall.c | 5 +++-- 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 5e4c7fc44f73..cef1d9ce6e1b 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -120,7 +120,7 @@ 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 3926ce6aa268..b962cbcca11d 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2381,9 +2381,8 @@ 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(); int ret;

if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { @@ -2396,19 +2395,27 @@ 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);

• audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],

• 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);
  

• }
• audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1], regs->regs[2], regs->regs[3]);

• return regs->syscallno;

• return syscall;

regs->syscallno still remains unchanged even if syscall is evaluated to be different ?

} -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..ec31f82d2e9f 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, scno, 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)