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x86/entry: Treat BUG/WARN as NMI-like entries

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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
This commit is contained in:
Andy Lutomirski
2020-06-11 20:26:38 -07:00
committed by Thomas Gleixner
parent f0178fc01f
commit 15a416e8aa
3 changed files with 52 additions and 29 deletions
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2
arch/x86/include/asm/idtentry.h
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@@ -543,7 +543,6 @@ SYM_CODE_END(spurious_entries_start)
DECLARE_IDTENTRY(X86_TRAP_DE, exc_divide_error);
DECLARE_IDTENTRY(X86_TRAP_OF, exc_overflow);
DECLARE_IDTENTRY(X86_TRAP_BR, exc_bounds);
DECLARE_IDTENTRY(X86_TRAP_UD, exc_invalid_op);
DECLARE_IDTENTRY(X86_TRAP_NM, exc_device_not_available);
DECLARE_IDTENTRY(X86_TRAP_OLD_MF, exc_coproc_segment_overrun);
DECLARE_IDTENTRY(X86_TRAP_SPURIOUS, exc_spurious_interrupt_bug);
@@ -561,6 +560,7 @@ DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP, exc_general_protection);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC, exc_alignment_check);
/* Raw exception entries which need extra work */
DECLARE_IDTENTRY_RAW(X86_TRAP_UD, exc_invalid_op);
DECLARE_IDTENTRY_RAW(X86_TRAP_BP, exc_int3);
DECLARE_IDTENTRY_RAW_ERRORCODE(X86_TRAP_PF, exc_page_fault);