* [PATCH] powerpc: Fix program check handling when lockdep is enabled
@ 2012-02-21 7:32 Michael Ellerman
2012-02-21 8:19 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 2+ messages in thread
From: Michael Ellerman @ 2012-02-21 7:32 UTC (permalink / raw)
To: linuxppc-dev
In commit 54321242afe ("Disable interrupts early in Program Check"), we
switched from enabling to disabling interrupts in program_check_common.
Whereas ENABLE_INTS leaves r3 untouched, if lockdep is enabled DISABLE_INTS
calls into lockdep code and will clobber r3. That means we pass a bogus
struct pt_regs* into program_check_exception() and all hell breaks loose.
So load our regs pointer into r3 after we call DISABLE_INTS.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
arch/powerpc/kernel/exceptions-64s.S | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 3844ca7..15c5a4f 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -774,8 +774,8 @@ alignment_common:
program_check_common:
EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
bl .save_nvgprs
- addi r3,r1,STACK_FRAME_OVERHEAD
DISABLE_INTS
+ addi r3,r1,STACK_FRAME_OVERHEAD
bl .program_check_exception
b .ret_from_except
--
1.7.5.4
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] powerpc: Fix program check handling when lockdep is enabled
2012-02-21 7:32 [PATCH] powerpc: Fix program check handling when lockdep is enabled Michael Ellerman
@ 2012-02-21 8:19 ` Benjamin Herrenschmidt
0 siblings, 0 replies; 2+ messages in thread
From: Benjamin Herrenschmidt @ 2012-02-21 8:19 UTC (permalink / raw)
To: Michael Ellerman; +Cc: linuxppc-dev
On Tue, 2012-02-21 at 18:32 +1100, Michael Ellerman wrote:
> In commit 54321242afe ("Disable interrupts early in Program Check"), we
> switched from enabling to disabling interrupts in program_check_common.
>
> Whereas ENABLE_INTS leaves r3 untouched, if lockdep is enabled DISABLE_INTS
> calls into lockdep code and will clobber r3. That means we pass a bogus
> struct pt_regs* into program_check_exception() and all hell breaks loose.
>
> So load our regs pointer into r3 after we call DISABLE_INTS.
Ah nice catch, thanks !
Cheers,
Ben.
> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
> ---
> arch/powerpc/kernel/exceptions-64s.S | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index 3844ca7..15c5a4f 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -774,8 +774,8 @@ alignment_common:
> program_check_common:
> EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
> bl .save_nvgprs
> - addi r3,r1,STACK_FRAME_OVERHEAD
> DISABLE_INTS
> + addi r3,r1,STACK_FRAME_OVERHEAD
> bl .program_check_exception
> b .ret_from_except
>
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2012-02-21 7:32 [PATCH] powerpc: Fix program check handling when lockdep is enabled Michael Ellerman
2012-02-21 8:19 ` Benjamin Herrenschmidt
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