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authorAndy Lutomirski <luto@kernel.org>2020-06-11 20:26:38 -0700
committerThomas Gleixner <tglx@linutronix.de>2020-06-12 12:12:57 +0200
commit15a416e8aaa758b5534f64a3972dae05275bc225 (patch)
treee4ae9ce3068dbd6df81a2a445be81e015a387aa5 /arch/x86/mm/extable.c
parentf0178fc01fe46bab6a95415f5647d1a74efcad1b (diff)
x86/entry: Treat BUG/WARN as NMI-like entries
BUG/WARN are cleverly optimized using UD2 to handle the BUG/WARN out of line in an exception fixup. But if BUG or WARN is issued in a funny RCU context, then the idtentry_enter...() path might helpfully WARN that the RCU context is invalid, which results in infinite recursion. Split the BUG/WARN handling into an nmi_enter()/nmi_exit() path in exc_invalid_op() to increase the chance to survive the experience. [ tglx: Make the declaration match the implementation ] Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/f8fe40e0088749734b4435b554f73eee53dcf7a8.1591932307.git.luto@kernel.org
Diffstat (limited to 'arch/x86/mm/extable.c')
-rw-r--r--arch/x86/mm/extable.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index b991aa4bdfae..1d6cb07f4f86 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -204,8 +204,19 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
if (fixup_exception(regs, trapnr, regs->orig_ax, 0))
return;
- if (fixup_bug(regs, trapnr))
- return;
+ if (trapnr == X86_TRAP_UD) {
+ if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) {
+ /* Skip the ud2. */
+ regs->ip += LEN_UD2;
+ return;
+ }
+
+ /*
+ * If this was a BUG and report_bug returns or if this
+ * was just a normal #UD, we want to continue onward and
+ * crash.
+ */
+ }
fail:
early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",