* [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
@ 2019-01-22 14:11 Christophe Leroy
2019-01-23 8:56 ` Nicholas Piggin
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Christophe Leroy @ 2019-01-22 14:11 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Nicholas Piggin
Cc: linux-kernel, linuxppc-dev
Looks like book3s/32 doesn't set RI on machine check, so
checking RI before calling die() will always be fatal
allthought this is not an issue in most cases.
Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: stable@vger.kernel.org
---
arch/powerpc/kernel/traps.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 64936b60d521..c740f8bfccc9 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
if (check_io_access(regs))
goto bail;
- /* Must die if the interrupt is not recoverable */
- if (!(regs->msr & MSR_RI))
- nmi_panic(regs, "Unrecoverable Machine check");
-
if (!nested)
nmi_exit();
die("Machine check", regs, SIGBUS);
+ /* Must die if the interrupt is not recoverable */
+ if (!(regs->msr & MSR_RI))
+ nmi_panic(regs, "Unrecoverable Machine check");
+
return;
bail:
--
2.13.3
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
2019-01-22 14:11 [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32 Christophe Leroy
@ 2019-01-23 8:56 ` Nicholas Piggin
2019-02-22 9:47 ` Michael Ellerman
2020-09-11 9:15 ` [PATCH] " Michal Suchánek
2 siblings, 0 replies; 7+ messages in thread
From: Nicholas Piggin @ 2019-01-23 8:56 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Christophe Leroy, Michael Ellerman,
Paul Mackerras
Cc: linux-kernel, linuxppc-dev
Christophe Leroy's on January 23, 2019 12:11 am:
> Looks like book3s/32 doesn't set RI on machine check, so
> checking RI before calling die() will always be fatal
> allthought this is not an issue in most cases.
Oh good catch, this is a fix for powerpc/64 as well. I think actually
the panic was supposed to go in the bail: path, it's missing from
there.
But you may have a point, I don't know if we need to panic the box if
we have !RI in process context... Possible we might be able to remove
those panics and just turn them into die.
Thanks,
Nick
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: powerpc/traps: fix recoverability of machine check handling on book3s/32
2019-01-22 14:11 [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32 Christophe Leroy
2019-01-23 8:56 ` Nicholas Piggin
@ 2019-02-22 9:47 ` Michael Ellerman
2020-09-11 9:15 ` [PATCH] " Michal Suchánek
2 siblings, 0 replies; 7+ messages in thread
From: Michael Ellerman @ 2019-02-22 9:47 UTC (permalink / raw)
To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
Nicholas Piggin
Cc: linuxppc-dev, linux-kernel
On Tue, 2019-01-22 at 14:11:24 UTC, Christophe Leroy wrote:
> Looks like book3s/32 doesn't set RI on machine check, so
> checking RI before calling die() will always be fatal
> allthought this is not an issue in most cases.
>
> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: stable@vger.kernel.org
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/0bbea75c476b77fa7d7811d6be911cc7
cheers
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
2019-01-22 14:11 [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32 Christophe Leroy
2019-01-23 8:56 ` Nicholas Piggin
2019-02-22 9:47 ` Michael Ellerman
@ 2020-09-11 9:15 ` Michal Suchánek
2020-09-11 9:54 ` Christophe Leroy
2020-09-11 13:23 ` Michael Ellerman
2 siblings, 2 replies; 7+ messages in thread
From: Michal Suchánek @ 2020-09-11 9:15 UTC (permalink / raw)
To: Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Nicholas Piggin, linuxppc-dev, linux-kernel
Hello,
does this logic apply to "Unrecoverable System Reset" as well?
Thanks
Michal
On Tue, Jan 22, 2019 at 02:11:24PM +0000, Christophe Leroy wrote:
> Looks like book3s/32 doesn't set RI on machine check, so
> checking RI before calling die() will always be fatal
> allthought this is not an issue in most cases.
>
> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: stable@vger.kernel.org
> ---
> arch/powerpc/kernel/traps.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 64936b60d521..c740f8bfccc9 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
> if (check_io_access(regs))
> goto bail;
>
> - /* Must die if the interrupt is not recoverable */
> - if (!(regs->msr & MSR_RI))
> - nmi_panic(regs, "Unrecoverable Machine check");
> -
> if (!nested)
> nmi_exit();
>
> die("Machine check", regs, SIGBUS);
>
> + /* Must die if the interrupt is not recoverable */
> + if (!(regs->msr & MSR_RI))
> + nmi_panic(regs, "Unrecoverable Machine check");
> +
> return;
>
> bail:
> --
> 2.13.3
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
2020-09-11 9:15 ` [PATCH] " Michal Suchánek
@ 2020-09-11 9:54 ` Christophe Leroy
2020-09-11 13:23 ` Michael Ellerman
1 sibling, 0 replies; 7+ messages in thread
From: Christophe Leroy @ 2020-09-11 9:54 UTC (permalink / raw)
To: Michal Suchánek
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Nicholas Piggin, linuxppc-dev, linux-kernel
Hello,
Le 11/09/2020 à 11:15, Michal Suchánek a écrit :
> Hello,
>
> does this logic apply to "Unrecoverable System Reset" as well?
I don't know, I don't think I have any way the generate a System Reset
on my board to check it.
Christophe
>
> Thanks
>
> Michal
>
> On Tue, Jan 22, 2019 at 02:11:24PM +0000, Christophe Leroy wrote:
>> Looks like book3s/32 doesn't set RI on machine check, so
>> checking RI before calling die() will always be fatal
>> allthought this is not an issue in most cases.
>>
>> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
>> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Cc: stable@vger.kernel.org
>> ---
>> arch/powerpc/kernel/traps.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>> index 64936b60d521..c740f8bfccc9 100644
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
>> if (check_io_access(regs))
>> goto bail;
>>
>> - /* Must die if the interrupt is not recoverable */
>> - if (!(regs->msr & MSR_RI))
>> - nmi_panic(regs, "Unrecoverable Machine check");
>> -
>> if (!nested)
>> nmi_exit();
>>
>> die("Machine check", regs, SIGBUS);
>>
>> + /* Must die if the interrupt is not recoverable */
>> + if (!(regs->msr & MSR_RI))
>> + nmi_panic(regs, "Unrecoverable Machine check");
>> +
>> return;
>>
>> bail:
>> --
>> 2.13.3
>>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
2020-09-11 9:15 ` [PATCH] " Michal Suchánek
2020-09-11 9:54 ` Christophe Leroy
@ 2020-09-11 13:23 ` Michael Ellerman
2020-09-14 12:46 ` Michal Suchánek
1 sibling, 1 reply; 7+ messages in thread
From: Michael Ellerman @ 2020-09-11 13:23 UTC (permalink / raw)
To: Michal Suchánek, Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Nicholas Piggin,
linuxppc-dev, linux-kernel
Michal Suchánek <msuchanek@suse.de> writes:
> Hello,
>
> does this logic apply to "Unrecoverable System Reset" as well?
Which logic do you mean?
We do call die() before checking MSR_RI in system_reset_exception():
/*
* No debugger or crash dump registered, print logs then
* panic.
*/
die("System Reset", regs, SIGABRT);
mdelay(2*MSEC_PER_SEC); /* Wait a little while for others to print */
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
nmi_panic(regs, "System Reset");
out:
#ifdef CONFIG_PPC_BOOK3S_64
BUG_ON(get_paca()->in_nmi == 0);
if (get_paca()->in_nmi > 1)
die("Unrecoverable nested System Reset", regs, SIGABRT);
#endif
/* Must die if the interrupt is not recoverable */
if (!(regs->msr & MSR_RI))
die("Unrecoverable System Reset", regs, SIGABRT);
So you should see the output from die("System Reset", ...) even if
MSR[RI] was clear when you took the system reset.
cheers
> On Tue, Jan 22, 2019 at 02:11:24PM +0000, Christophe Leroy wrote:
>> Looks like book3s/32 doesn't set RI on machine check, so
>> checking RI before calling die() will always be fatal
>> allthought this is not an issue in most cases.
>>
>> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
>> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Cc: stable@vger.kernel.org
>> ---
>> arch/powerpc/kernel/traps.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>> index 64936b60d521..c740f8bfccc9 100644
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
>> if (check_io_access(regs))
>> goto bail;
>>
>> - /* Must die if the interrupt is not recoverable */
>> - if (!(regs->msr & MSR_RI))
>> - nmi_panic(regs, "Unrecoverable Machine check");
>> -
>> if (!nested)
>> nmi_exit();
>>
>> die("Machine check", regs, SIGBUS);
>>
>> + /* Must die if the interrupt is not recoverable */
>> + if (!(regs->msr & MSR_RI))
>> + nmi_panic(regs, "Unrecoverable Machine check");
>> +
>> return;
>>
>> bail:
>> --
>> 2.13.3
>>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32
2020-09-11 13:23 ` Michael Ellerman
@ 2020-09-14 12:46 ` Michal Suchánek
0 siblings, 0 replies; 7+ messages in thread
From: Michal Suchánek @ 2020-09-14 12:46 UTC (permalink / raw)
To: Michael Ellerman
Cc: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
Nicholas Piggin, linuxppc-dev, linux-kernel
On Fri, Sep 11, 2020 at 11:23:57PM +1000, Michael Ellerman wrote:
> Michal Suchánek <msuchanek@suse.de> writes:
> > Hello,
> >
> > does this logic apply to "Unrecoverable System Reset" as well?
>
> Which logic do you mean?
>
> We do call die() before checking MSR_RI in system_reset_exception():
>
> /*
> * No debugger or crash dump registered, print logs then
> * panic.
> */
> die("System Reset", regs, SIGABRT);
>
> mdelay(2*MSEC_PER_SEC); /* Wait a little while for others to print */
> add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
> nmi_panic(regs, "System Reset");
>
> out:
> #ifdef CONFIG_PPC_BOOK3S_64
> BUG_ON(get_paca()->in_nmi == 0);
> if (get_paca()->in_nmi > 1)
> die("Unrecoverable nested System Reset", regs, SIGABRT);
> #endif
> /* Must die if the interrupt is not recoverable */
> if (!(regs->msr & MSR_RI))
> die("Unrecoverable System Reset", regs, SIGABRT);
>
>
> So you should see the output from die("System Reset", ...) even if
> MSR[RI] was clear when you took the system reset.
Indeed, replied to the wrong patch. I was looking at daf00ae71dad
("powerpc/traps: restore recoverability of machine_check interrupts")
which has very similar commit message.
Sorry about the confusion.
Thanks
Michal
>
> cheers
>
> > On Tue, Jan 22, 2019 at 02:11:24PM +0000, Christophe Leroy wrote:
> >> Looks like book3s/32 doesn't set RI on machine check, so
> >> checking RI before calling die() will always be fatal
> >> allthought this is not an issue in most cases.
> >>
> >> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
> >> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
> >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> >> Cc: stable@vger.kernel.org
> >> ---
> >> arch/powerpc/kernel/traps.c | 8 ++++----
> >> 1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> >> index 64936b60d521..c740f8bfccc9 100644
> >> --- a/arch/powerpc/kernel/traps.c
> >> +++ b/arch/powerpc/kernel/traps.c
> >> @@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
> >> if (check_io_access(regs))
> >> goto bail;
> >>
> >> - /* Must die if the interrupt is not recoverable */
> >> - if (!(regs->msr & MSR_RI))
> >> - nmi_panic(regs, "Unrecoverable Machine check");
> >> -
> >> if (!nested)
> >> nmi_exit();
> >>
> >> die("Machine check", regs, SIGBUS);
> >>
> >> + /* Must die if the interrupt is not recoverable */
> >> + if (!(regs->msr & MSR_RI))
> >> + nmi_panic(regs, "Unrecoverable Machine check");
> >> +
> >> return;
> >>
> >> bail:
> >> --
> >> 2.13.3
> >>
^ permalink raw reply [flat|nested] 7+ messages in thread
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2019-01-22 14:11 [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32 Christophe Leroy
2019-01-23 8:56 ` Nicholas Piggin
2019-02-22 9:47 ` Michael Ellerman
2020-09-11 9:15 ` [PATCH] " Michal Suchánek
2020-09-11 9:54 ` Christophe Leroy
2020-09-11 13:23 ` Michael Ellerman
2020-09-14 12:46 ` Michal Suchánek
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