Suggested by Roland.
Unlike powepc, x86 always calls tracehook_report_syscall_exit(step)
with step = 0, and sends the trap by hand.
This results in unnecessary SIGTRAP when PTRACE_SINGLESTEP follows
the syscall-exit stop.
Change syscall_trace_leave() to pass the correct "step" argument to
tracehook and remove the send_sigtrap() logic.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Roland McGrath <roland@xxxxxxxxxx>
---
arch/x86/kernel/ptrace.c | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)
--- TH/arch/x86/kernel/ptrace.c~5_X86_CONVERT_SYSCALL_LEAVE 2009-11-10 22:21:42.000000000 +0100
+++ TH/arch/x86/kernel/ptrace.c 2009-11-10 22:29:54.000000000 +0100
@@ -1528,29 +1528,22 @@ asmregparm long syscall_trace_enter(stru
asmregparm void syscall_trace_leave(struct pt_regs *regs)
{
+ bool step;
+
if (unlikely(current->audit_context))
audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_exit(regs, regs->ax);
- if (test_thread_flag(TIF_SYSCALL_TRACE))
- tracehook_report_syscall_exit(regs, 0);
-
/*
* If TIF_SYSCALL_EMU is set, we only get here because of
* TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP).
* We already reported this syscall instruction in
- * syscall_trace_enter(), so don't do any more now.
- */
- if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
- return;
-
- /*
- * If we are single-stepping, synthesize a trap to follow the
- * system call instruction.
+ * syscall_trace_enter().
*/
- if (test_thread_flag(TIF_SINGLESTEP) &&
- tracehook_consider_fatal_signal(current, SIGTRAP))
- send_sigtrap(current, regs, 0, TRAP_BRKPT);
+ step = unlikely(test_thread_flag(TIF_SINGLESTEP)) &&
+ !test_thread_flag(TIF_SYSCALL_EMU);
+ if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+ tracehook_report_syscall_exit(regs, step);
}
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