Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 14:11:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

x86: Reset the debug_stack update counter

Browse Source 
When an NMI goes off and it sees that it preempted the debug stack,
to keep the debug stack safe, it changes the IDT to point to one that
does not modify the stack on breakpoint (to allow breakpoints in NMIs).

But the variable that gets set to know to undo it on exit never gets
cleared on exit. Thus every NMI will reset it on exit the first time
it is done even if it does not need to be reset.

[ Added H. Peter Anvin's suggestion to use this_cpu_read/write ]

Cc: <stable@vger.kernel.org> # v3.3
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2012-05-30 11:43:19 -04:00 committed by Steven Rostedt
parent 8a4d0a687a
commit c0525a6972
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/kernel/nmi.c
View File

@ -444,14 +444,16 @@ static inline void nmi_nesting_preprocess(struct pt_regs *regs)
*/
if (unlikely(is_debug_stack(regs->sp))) {
debug_stack_set_zero();
__get_cpu_var(update_debug_stack) = 1;
this_cpu_write(update_debug_stack, 1);
}
}
static inline void nmi_nesting_postprocess(void)
{
if (unlikely(__get_cpu_var(update_debug_stack)))
if (unlikely(this_cpu_read(update_debug_stack))) {
debug_stack_reset();
this_cpu_write(update_debug_stack, 0);
}
}
#endif