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Fix for infrequent failures of the x86 "bt" command to handle cases 

where a user space task with "resume_userspace" or "entry_INT80_32"
at the top of the stack, or which was interrupted by the crash NMI
while handling a timer interrupt.  Without the patch, the backtrace
would be proceeded with the error message "bt: cannot resolve stack
trace", and then dump the text symbols found on the stack and all
possible exception frames.
(anderson@redhat.com)
This commit is contained in:
Dave Anderson 2018-05-08 13:49:57 -04:00
parent 483f98dab7
commit 8a846ffa5c
1 changed files with 15 additions and 4 deletions
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19
lkcd_x86_trace.c
View File

@ -1953,13 +1953,24 @@ find_trace(
static int
kernel_entry_from_user_space(sframe_t *curframe, struct bt_info *bt)
{
ulong stack_segment;
if (is_kernel_thread(bt->tc->task))
return FALSE;
if (((curframe->fp + 4 + SIZE(pt_regs)) == GET_STACKTOP(bt->task)) &&
!is_kernel_thread(bt->tc->task))
return TRUE;
else if (userspace_return(curframe->fp+4, bt))
stack_segment = GET_STACK_ULONG(curframe->fp + 4 + SIZE(pt_regs) - sizeof(kaddr_t));
if ((curframe->fp + 4 + SIZE(pt_regs)) == GET_STACKTOP(bt->task)) {
if ((stack_segment == 0x7b) || (stack_segment == 0x2b))
return TRUE;
}
if ((curframe->fp + 4 + SIZE(pt_regs) + 8) == GET_STACKTOP(bt->task)) {
if ((stack_segment == 0x7b) || (stack_segment == 0x2b))
return TRUE;
}
if (userspace_return(curframe->fp+4, bt))
return TRUE;
else
return FALSE;