x86/debug: Handle early WARN_ONs proper (8a524f80) · Commits · 戴 / test

Hans managed to trigger a WARN very early in the boot which killed his (Virtual) box. The reason is that the recent rework of WARN() to use UD0 forgot to add the fixup_bug() call to early_fixup_exception(). As a result the kernel does not handle the WARN_ON injected UD0 exception and panics. Add the missing fixup call, so early UD's injected by WARN() get handled. Fixes: ("x86/debug: Implement __WARN() using UD0") Reported-and-tested-by:

Hans de Goede <hdegoede@redhat.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Frank Mehnert <frank.mehnert@oracle.com> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Michael Thayer <michael.thayer@oracle.com> Link: http://lkml.kernel.org/r/20170612180108.w4vgu2ckucmllf3a@hirez.programming.kicks-ass.net

arch/x86/include/asm/extable.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@ struct pt_regs;
		} while (0)

		extern int fixup_exception(struct pt_regs *regs, int trapnr);
		extern int fixup_bug(struct pt_regs *regs, int trapnr);
		extern bool ex_has_fault_handler(unsigned long ip);
		extern void early_fixup_exception(struct pt_regs *regs, int trapnr);

arch/x86/kernel/traps.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -182,7 +182,7 @@ int is_valid_bugaddr(unsigned long addr)
		return ud == INSN_UD0 \|\| ud == INSN_UD2;
		}

		static int fixup_bug(struct pt_regs *regs, int trapnr)
		int fixup_bug(struct pt_regs *regs, int trapnr)
		{
		if (trapnr != X86_TRAP_UD)
		return 0;

arch/x86/mm/extable.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -162,6 +162,9 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
		if (fixup_exception(regs, trapnr))
		return;

		if (fixup_bug(regs, trapnr))
		return;

		fail:
		early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",
		(unsigned)trapnr, (unsigned long)regs->cs, regs->ip,

Admin message