ptrace: x86: change syscall_trace_leave() to rely on tracehook when stepping (d5196503) · Commits · 戴 / test

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@redhat.com> Acked-by:

Roland McGrath <roland@redhat.com> Cc: <linux-arch@vger.kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/ptrace.c

+7 −14

Original line number	Diff line number	Diff line
		@@ -1767,29 +1767,22 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs)

		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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