On Sun, Mar 06, 2005 at 12:03:22PM -0800, Linus Torvalds wrote:
> I _think_ your test-case would work right if you just moved that code from
> the special-case in do_debug(), and moved it to the top of
> setup_sigcontext() instead. I've not tested it, though, and haven't really
> given it any "deep thought". Maybe somebody smarter can say "yeah, that's
> obviously the right thing to do" or "no, that won't work because.."
I bought it, but the GDB testsuite didn't. Both copies seem to be
necessary; there's generally no signal handler for SIGTRAP, so moving
it disables the test in the most common case. I didn't poke at it long
enough to figure out what the failing case was, but it introduced a
different situation which could leave TF enabled. This, however,
worked:
If a debugger set the TF bit, make sure to clear it when creating a
signal context. Otherwise, TF will be incorrectly restored by
sigreturn.
Signed-off-by: Daniel Jacobowitz <[EMAIL PROTECTED]>
===== arch/i386/kernel/signal.c 1.53 vs edited =====
--- 1.53/arch/i386/kernel/signal.c 2005-01-31 01:20:14 -05:00
+++ edited/arch/i386/kernel/signal.c 2005-03-06 15:36:41 -05:00
@@ -277,6 +277,18 @@
{
int tmp, err = 0;
+ /*
+ * If TF is set due to a debugger (PT_DTRACE), clear the TF
+ * flag so that register information in the sigcontext is
+ * correct.
+ */
+ if (unlikely(regs->eflags & TF_MASK)) {
+ if (likely(current->ptrace & PT_DTRACE)) {
+ current->ptrace &= ~PT_DTRACE;
+ regs->eflags &= ~TF_MASK;
+ }
+ }
+
tmp = 0;
__asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
--
Daniel Jacobowitz
CodeSourcery, LLC
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