Re: [RFC PATCH] x86 single-step (TF) vs system calls & traps

[Davide Libenzi]

On Thu, 1 Jul 2004, Roland McGrath wrote:

> > Here I meant that if you set SINGLESTEP|SYSGOOD, the patch will give you 
> > SIGTRAP|0x80, while if you set only SINGLESTEP the patch will give you 
> > SIGTRAP. Enforcing the SINGLESTEP|SYSGOOD is invalid or only gives SIGTRAP 
> > should be no more that three lines of code out of the fast path.
> 
> There is no "set SINGLESTEP|SYSGOOD".  PTRACE_SINGLESTEP is a one-time
> operation.  PTRACE_O_TRACESYSGOOD is a persistent flag you set when you
> intend to at some point use the PTRACE_SYSCALL operation.

Allrighty ...

Andrew, per Roland suggestion, can you please add the patch below to the 
bits you already have in -mm?


Signed-off-by: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>



- Davide



--- a/arch/i386/kernel/ptrace.c	2004-07-01 14:30:38.000000000 -0700
+++ b/arch/i386/kernel/ptrace.c	2004-07-01 14:32:44.000000000 -0700
@@ -546,8 +546,8 @@
 		return;
 	/* the 0x80 provides a way for the tracing parent to distinguish
 	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
+	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
+				 !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
 
 	/*
 	 * this isn't the same as continuing with a signal, but it will do
-
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