On Mon, Feb 12, 2007 at 09:32:10AM +0000, Jan Beulich wrote:
> This breaks consumers of notify_die() relying on the proper trap number being
> passed, as the call to notify_die() from die() currently reads
> current->thread.trap_no.
Rats, good point.
> Also, you seem to leave other places where trap_no gets set untouched -
> is this intentional (do_debug - probably correct here, kernel_math_error -
> probably incorrect here)?
I did check the other trap handlers. kernel_math_error calls die,
which calls do_exit(SIGSEGV). This doesn't seem to allow the process
the opportunity to trap the SIGSEGV and examine the fault information.
> >I looked at i386, and there is a similar situation. In this case, there is
> >duplicate code setting task->thread.error_code and trapno. I deleted one,
> >leaving the copy that runs in the case of a userspace fault.
>
> Likewise.
Yup. How does this patch look to you? We set error_code and trap_no
for userspace faults and kernel faults which call die(). We don't set
them for kernelspace faults which are fixed up.
Index: linux-2.6/arch/i386/kernel/traps.c
===================================================================
--- linux-2.6.orig/arch/i386/kernel/traps.c
+++ linux-2.6/arch/i386/kernel/traps.c
@@ -619,6 +619,8 @@ gp_in_vm86:
gp_in_kernel:
if (!fixup_exception(regs)) {
+ current->thread.error_code = error_code;
+ current->thread.trap_no = 13;
if (notify_die(DIE_GPF, "general protection fault", regs,
error_code, 13, SIGSEGV) == NOTIFY_STOP)
return;
Index: linux-2.6/arch/x86_64/kernel/traps.c
===================================================================
--- linux-2.6.orig/arch/x86_64/kernel/traps.c
+++ linux-2.6/arch/x86_64/kernel/traps.c
@@ -605,8 +605,11 @@ static void __kprobes do_trap(int trapnr
fixup = search_exception_tables(regs->rip);
if (fixup)
regs->rip = fixup->fixup;
- else
+ else {
+ tsk->thread.error_code = error_code;
+ tsk->thread.trap_no = trapnr;
die(str, regs, error_code);
+ }
return;
}
}
--
Work email - jdike at linux dot intel dot com
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