Commit-ID: 8a524f803a3e0290cdba6d373361b2cef9752934
Gitweb: http://git.kernel.org/tip/8a524f803a3e0290cdba6d373361b2cef9752934
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 12 Jun 2017 13:52:46 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 12 Jun 2017 21:17:48 +0200
x86/debug: Handle early WARN_ONs proper
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: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0")
Reported-and-tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Frank Mehnert <frank.mehnert@xxxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Cc: Michael Thayer <michael.thayer@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170612180108.w4vgu2ckucmllf3a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
arch/x86/include/asm/extable.h | 1 +
arch/x86/kernel/traps.c | 2 +-
arch/x86/mm/extable.c | 3 +++
3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/extable.h b/arch/x86/include/asm/extable.h
index b8ad261..c66d19e 100644
--- a/arch/x86/include/asm/extable.h
+++ b/arch/x86/include/asm/extable.h
@@ -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);
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 3995d3a..bf54309 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -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;
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 35ea061..0ea8afc 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -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,
--
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