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| author |   Andy Lutomirski <luto@kernel.org> | 2020-06-11 20:26:38 -0700 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2020-06-12 12:12:57 +0200 |
| commit | 15a416e8aaa758b5534f64a3972dae05275bc225 (patch) | |
| tree | e4ae9ce3068dbd6df81a2a445be81e015a387aa5 /arch/x86/mm/extable.c | |
| parent | x86/entry: Unbreak __irqentry_text_start/end magic (diff) | |
| download | linux-dev-15a416e8aaa758b5534f64a3972dae05275bc225.tar.xz linux-dev-15a416e8aaa758b5534f64a3972dae05275bc225.zip | |
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.c | 15 |
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", |