"Dmitry V. Levin" <l...@altlinux.org> writes:
> Invoke tracehook_report_syscall_entry once.
Thanks.
> Signed-off-by: Dmitry V. Levin <l...@altlinux.org>
> ---
> arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++---------------
> 1 file changed, 31 insertions(+), 23 deletions(-)
>
> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> index 714c3480c52d..8794d32c2d9e 100644
> --- a/arch/powerpc/kernel/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace.c
> @@ -3263,32 +3263,40 @@ static inline int do_seccomp(struct pt_regs *regs) {
> return 0; }
> */
> long do_syscall_trace_enter(struct pt_regs *regs)
> {
> + u32 cached_flags;
> +
Do you mind if I just call it "flags", I find "cached_flags" a bit
unwieldy for some reason.
I'm happy to fix it up when applying.
cheers
> user_exit();
>
> - if (test_thread_flag(TIF_SYSCALL_EMU)) {
> - /*
> - * A nonzero return code from tracehook_report_syscall_entry()
> - * tells us to prevent the syscall execution, but we are not
> - * going to execute it anyway.
> - *
> - * Returning -1 will skip the syscall execution. We want to
> - * avoid clobbering any register also, thus, not 'gotoing'
> - * skip label.
> - */
> - if (tracehook_report_syscall_entry(regs))
> - ;
> - return -1;
> - }
> + cached_flags = READ_ONCE(current_thread_info()->flags) &
> + (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
>
> - /*
> - * The tracer may decide to abort the syscall, if so tracehook
> - * will return !0. Note that the tracer may also just change
> - * regs->gpr[0] to an invalid syscall number, that is handled
> - * below on the exit path.
> - */
> - if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - tracehook_report_syscall_entry(regs))
> - goto skip;
> + if (cached_flags) {
> + int rc = tracehook_report_syscall_entry(regs);
> +
> + if (unlikely(cached_flags & _TIF_SYSCALL_EMU)) {
> + /*
> + * A nonzero return code from
> + * tracehook_report_syscall_entry() tells us
> + * to prevent the syscall execution, but
> + * we are not going to execute it anyway.
> + *
> + * Returning -1 will skip the syscall execution.
> + * We want to avoid clobbering any register also,
> + * thus, not 'gotoing' skip label.
> + */
> + return -1;
> + }
> +
> + if (rc) {
> + /*
> + * The tracer decided to abort the syscall.
> + * Note that the tracer may also just change
> + * regs->gpr[0] to an invalid syscall number,
> + * that is handled below on the exit path.
> + */
> + goto skip;
> + }
> + }
>
> /* Run seccomp after ptrace; allow it to set gpr[3]. */
> if (do_seccomp(regs))
> --
> ldv
