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x86/mce: Only restart instruction after machine check recovery if it is safe

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Section 15.3.1.2 of the software developer manual has this to say about the
RIPV bit in the IA32_MCG_STATUS register:

  RIPV (restart IP valid) flag, bit 0 — Indicates (when set) that program
  execution can be restarted reliably at the instruction pointed to by the
  instruction pointer pushed on the stack when the machine-check exception
  is generated.  When clear, the program cannot be reliably restarted at
  the pushed instruction pointer.

We need to save the state of this bit in do_machine_check() and use it
in mce_notify_process() to force a signal; even if memory_failure() says
it made a complete recovery ... e.g. replaced a clean LRU page.

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Tony Luck 2012-05-14 15:07:48 -07:00
parent d48b97b403
commit dad1743e59
1 changed files with 11 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

14
arch/x86/kernel/cpu/mcheck/mce.c
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@ -945,9 +945,10 @@ struct mce_info {
atomic_t inuse;
struct task_struct *t;
__u64 paddr;
int restartable;
} mce_info[MCE_INFO_MAX];
static void mce_save_info(__u64 addr)
static void mce_save_info(__u64 addr, int c)
{
struct mce_info *mi;
@ -955,6 +956,7 @@ static void mce_save_info(__u64 addr)
if (atomic_cmpxchg(&mi->inuse, 0, 1) == 0) {
mi->t = current;
mi->paddr = addr;
mi->restartable = c;
return;
}
}
@ -1130,7 +1132,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
mce_panic("Fatal machine check on current CPU", &m, msg);
if (worst == MCE_AR_SEVERITY) {
/* schedule action before return to userland */
mce_save_info(m.addr);
mce_save_info(m.addr, m.mcgstatus & MCG_STATUS_RIPV);
set_thread_flag(TIF_MCE_NOTIFY);
} else if (kill_it) {
force_sig(SIGBUS, current);
@ -1179,7 +1181,13 @@ void mce_notify_process(void)
pr_err("Uncorrected hardware memory error in user-access at %llx",
mi->paddr);
if (memory_failure(pfn, MCE_VECTOR, MF_ACTION_REQUIRED) < 0) {
/*
* We must call memory_failure() here even if the current process is
* doomed. We still need to mark the page as poisoned and alert any
* other users of the page.
*/
if (memory_failure(pfn, MCE_VECTOR, MF_ACTION_REQUIRED) < 0 ||
mi->restartable == 0) {
pr_err("Memory error not recovered");
force_sig(SIGBUS, current);
}