Re: [PATCH v4 11/16] powerpc/64s: machine check interrupt update NMI accounting
Nicholas Piggin writes:
> Excerpts from kbuild test robot's message of May 9, 2020 1:13 pm:
>> Hi Nicholas,
>>
>> I love your patch! Yet something to improve:
>
> ...
>
>> 1419 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
>> 1420 pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar,
>> regs->dsisr);
>> 1421 #else
>> 1422 pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar,
>> regs->dsisr);
>> 1423 #endif
>> 1424 #ifdef CONFIG_PPC64
>>> 1425pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d",
>>> regs->softe, (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
>
> Oh I meant to get rid of that hunk, it crept back in :(
>
> mpe if you could please take it out if you're merging this.
Yep. I just came here to tell you I'd dropped that hunk :)
> It was quite useful for debugging this stuff, I might do a proper patch
> for this, but for now not necessary (it doesn't matter for "normal"
> crashes only crash crashes).
Yeah would be good to print more of those flags.
cheers
Re: [PATCH v4 11/16] powerpc/64s: machine check interrupt update NMI accounting
Excerpts from kbuild test robot's message of May 9, 2020 1:13 pm:
> Hi Nicholas,
>
> I love your patch! Yet something to improve:
...
> 1419#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
> 1420pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar,
> regs->dsisr);
> 1421#else
> 1422pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar,
> regs->dsisr);
> 1423#endif
> 1424#ifdef CONFIG_PPC64
>> 1425 pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe,
>> (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
Oh I meant to get rid of that hunk, it crept back in :(
mpe if you could please take it out if you're merging this.
It was quite useful for debugging this stuff, I might do a proper patch
for this, but for now not necessary (it doesn't matter for "normal"
crashes only crash crashes).
Thanks,
Nick
Re: [PATCH v4 11/16] powerpc/64s: machine check interrupt update NMI accounting
Hi Nicholas,
I love your patch! Yet something to improve:
[auto build test ERROR on powerpc/next]
[also build test ERROR on tip/perf/core v5.7-rc4 next-20200508]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url:
https://github.com/0day-ci/linux/commits/Nicholas-Piggin/powerpc-machine-check-and-system-reset-fixes/20200509-030554
base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-randconfig-r002-20200509 (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0
reproduce:
wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross
ARCH=powerpc
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot
All errors (new ones prefixed by >>):
In file included from include/linux/kernel.h:15,
from include/asm-generic/bug.h:19,
from arch/powerpc/include/asm/bug.h:109,
from include/linux/bug.h:5,
from arch/powerpc/include/asm/mmu.h:130,
from arch/powerpc/include/asm/paca.h:18,
from arch/powerpc/include/asm/current.h:13,
from include/linux/sched.h:12,
from arch/powerpc/kernel/process.c:14:
arch/powerpc/kernel/process.c: In function 'show_regs':
>> arch/powerpc/kernel/process.c:1425:74: error: 'struct paca_struct' has no
>> member named 'in_nmi'
1425 | pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe,
(int)get_paca()->in_nmi, (int)get_paca()->in_mce);
|
^~
include/linux/printk.h:312:26: note: in definition of macro 'pr_cont'
312 | printk(KERN_CONT fmt, ##__VA_ARGS__)
| ^~~
>> arch/powerpc/kernel/process.c:1425:99: error: 'struct paca_struct' has no
>> member named 'in_mce'
1425 | pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe,
(int)get_paca()->in_nmi, (int)get_paca()->in_mce);
|
^~
include/linux/printk.h:312:26: note: in definition of macro 'pr_cont'
312 | printk(KERN_CONT fmt, ##__VA_ARGS__)
| ^~~
vim +1425 arch/powerpc/kernel/process.c
1401
1402 void show_regs(struct pt_regs * regs)
1403 {
1404 int i, trap;
1405
1406 show_regs_print_info(KERN_DEFAULT);
1407
1408 printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
1409 regs->nip, regs->link, regs->ctr);
1410 printk("REGS: %px TRAP: %04lx %s (%s)\n",
1411 regs, regs->trap, print_tainted(),
init_utsname()->release);
1412 printk("MSR: "REG" ", regs->msr);
1413 print_msr_bits(regs->msr);
1414 pr_cont(" CR: %08lx XER: %08lx\n", regs->ccr, regs->xer);
1415 trap = TRAP(regs);
1416 if ((TRAP(regs) != 0xc00) && cpu_has_feature(CPU_FTR_CFAR))
1417 pr_cont("CFAR: "REG" ", regs->orig_gpr3);
1418 if (trap == 0x200 || trap == 0x300 || trap == 0x600)
1419 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
1420 pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar,
regs->dsisr);
1421 #else
1422 pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar,
regs->dsisr);
1423 #endif
1424 #ifdef CONFIG_PPC64
> 1425 pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe,
> (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
1426 #endif
1427 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
1428 if (MSR_TM_ACTIVE(regs->msr))
1429 pr_cont("\nPACATMSCRATCH: %016llx ",
get_paca()->tm_scratch);
1430 #endif
1431
1432 for (i = 0; i < 32; i++) {
1433 if ((i % REGS_PER_LINE) == 0)
1434 pr_cont("\nGPR%02d: ", i);
1435 pr_cont(REG " ", regs->gpr[i]);
1436 if (i == LAST_VOLATILE && !FULL_REGS(regs))
1437 break;
1438 }
1439 pr_cont("\n");
1440 #ifdef CONFIG_KALLSYMS
1441 /*
1442 * Lookup NIP late so we have the best change of getting the
1443 * above info out without failing
1444 */
1445 printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
1446 printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
1447 #endif
1448 show_stack(current, (unsigned
[PATCH v4 11/16] powerpc/64s: machine check interrupt update NMI accounting
machine_check_early is taken as an NMI, so nmi_enter is used there.
machine_check_exception is no longer taken as an NMI (it's invoked
via irq_work in the case a machine check hits in kernel mode), so
remove the nmi_enter from that case.
In NMI context, hash faults don't try to refill the hash table, which
can lead to crashes accessing non-pinned kernel pages. System reset
still has this potential problem.
Signed-off-by: Nicholas Piggin
---
arch/powerpc/kernel/mce.c | 7 +++
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/traps.c | 14 +-
3 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 8077b5fb18a7..be7e3f92a7b5 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -574,6 +574,9 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
long machine_check_early(struct pt_regs *regs)
{
long handled = 0;
+ bool nested = in_nmi();
+ if (!nested)
+ nmi_enter();
hv_nmi_check_nonrecoverable(regs);
@@ -582,6 +585,10 @@ long machine_check_early(struct pt_regs *regs)
*/
if (ppc_md.machine_check_early)
handled = ppc_md.machine_check_early(regs);
+
+ if (!nested)
+ nmi_exit();
+
return handled;
}
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 9c21288f8645..44410dd3029f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1421,7 +1421,7 @@ void show_regs(struct pt_regs * regs)
pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
#endif
#ifdef CONFIG_PPC64
- pr_cont("IRQMASK: %lx ", regs->softe);
+ pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe,
(int)get_paca()->in_nmi, (int)get_paca()->in_mce);
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (MSR_TM_ACTIVE(regs->msr))
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 3fca22276bb1..9f6852322e59 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -823,7 +823,19 @@ int machine_check_generic(struct pt_regs *regs)
void machine_check_exception(struct pt_regs *regs)
{
int recover = 0;
- bool nested = in_nmi();
+ bool nested;
+
+ /*
+* BOOK3S_64 does not call this handler as a non-maskable interrupt
+* (it uses its own early real-mode handler to handle the MCE proper
+* and then raises irq_work to call this handler when interrupts are
+* enabled). Set nested = true for this case, which just makes it avoid
+* the nmi_enter/exit.
+*/
+ if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) || in_nmi())
+ nested = true;
+ else
+ nested = false;
if (!nested)
nmi_enter();
--
2.23.0
