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Subject[PATCH] powerpc/ptrace: cleanup do_syscall_trace_enter
Invoke tracehook_report_syscall_entry once.

Signed-off-by: Dmitry V. Levin <ldv@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;
+
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
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