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[IA64] Tighten up unw_unwind_to_user check 

Detect user space by the unwind frame with predicate PRED_USER_STACK
set, instead of a user space IP.  Tighten up the last ditch check for
running off the top of the kernel stack.

Based on a suggestion by David Mosberger, reworked to fit the current
tree.  This survives my stress test which used to break 2.6.9 kernels.
Unlike 2.6.11, the stress test now unwinds to the correct point, so
gdb can get the user space registers.

Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
hifive-unleashed-5.1
Keith Owens 2005-04-25 11:45:26 -07:00 committed by Tony Luck
parent 8297511530
commit e8d1cb2f28
1 changed files with 18 additions and 11 deletions
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29
arch/ia64/kernel/unwind.c
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@ -1943,23 +1943,30 @@ EXPORT_SYMBOL(unw_unwind);
int
unw_unwind_to_user (struct unw_frame_info *info)
{
unsigned long ip, sp;
unsigned long ip, sp, pr = 0;
while (unw_unwind(info) >= 0) {
if (unw_get_rp(info, &ip) < 0) {
unw_get_ip(info, &ip);
UNW_DPRINT(0, "unwind.%s: failed to read return pointer (ip=0x%lx)\n",
__FUNCTION__, ip);
unw_get_sp(info, &sp);
if ((long)((unsigned long)info->task + IA64_STK_OFFSET - sp)
< IA64_PT_REGS_SIZE) {
UNW_DPRINT(0, "unwind.%s: ran off the top of the kernel stack\n",
__FUNCTION__);
break;
}
if (unw_is_intr_frame(info) &&
(pr & (1UL << PRED_USER_STACK)))
return 0;
if (unw_get_pr (info, &pr) < 0) {
unw_get_rp(info, &ip);
UNW_DPRINT(0, "unwind.%s: failed to read "
"predicate register (ip=0x%lx)\n",
__FUNCTION__, ip);
return -1;
}
unw_get_sp(info, &sp);
if (sp >= (unsigned long)info->task + IA64_STK_OFFSET)
break;
if (ip < FIXADDR_USER_END)
return 0;
}
unw_get_ip(info, &ip);
UNW_DPRINT(0, "unwind.%s: failed to unwind to user-level (ip=0x%lx)\n", __FUNCTION__, ip);
UNW_DPRINT(0, "unwind.%s: failed to unwind to user-level (ip=0x%lx)\n",
__FUNCTION__, ip);
return -1;
}
EXPORT_SYMBOL(unw_unwind_to_user);