diff options
| author | Borislav Petkov <bp@suse.de> | 2021-10-05 19:54:47 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-12-13 14:12:21 +0100 |
| commit | 487d654db3edacc31dee86b10258cc740640fad8 (patch) | |
| tree | ac7f44aeb22c8b758b59336a96ddbed7c7bb22e7 /arch/x86/kernel/cpu/mce/core.c | |
| parent | 88f66a42353717e7fac31caf04f0acd2d7fbbf54 (diff) | |
x86/mce: Remove noinstr annotation from mce_setup()
Instead, sandwitch around the call which is done in noinstr context and
mark the caller - mce_gather_info() - as noinstr.
Also, document what the whole instrumentation strategy with #MC is going
to be in the future and where it all is supposed to be going to.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211208111343.8130-5-bp@alien8.de
Diffstat (limited to 'arch/x86/kernel/cpu/mce/core.c')
| -rw-r--r-- | arch/x86/kernel/cpu/mce/core.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 87a277fc80b4..c11fc8d6a4c5 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -127,7 +127,7 @@ static struct irq_work mce_irq_work; BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain); /* Do initial initialization of a struct mce */ -noinstr void mce_setup(struct mce *m) +void mce_setup(struct mce *m) { memset(m, 0, sizeof(struct mce)); m->cpu = m->extcpu = smp_processor_id(); @@ -430,9 +430,15 @@ static noinstr void mce_wrmsrl(u32 msr, u64 v) * check into our "mce" struct so that we can use it later to assess * the severity of the problem as we read per-bank specific details. */ -static inline void mce_gather_info(struct mce *m, struct pt_regs *regs) +static noinstr void mce_gather_info(struct mce *m, struct pt_regs *regs) { + /* + * Enable instrumentation around mce_setup() which calls external + * facilities. + */ + instrumentation_begin(); mce_setup(m); + instrumentation_end(); m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); if (regs) { @@ -1312,11 +1318,11 @@ static noinstr void unexpected_machine_check(struct pt_regs *regs) } /* - * The actual machine check handler. This only handles real - * exceptions when something got corrupted coming in through int 18. + * The actual machine check handler. This only handles real exceptions when + * something got corrupted coming in through int 18. * - * This is executed in NMI context not subject to normal locking rules. This - * implies that most kernel services cannot be safely used. Don't even + * This is executed in #MC context not subject to normal locking rules. + * This implies that most kernel services cannot be safely used. Don't even * think about putting a printk in there! * * On Intel systems this is entered on all CPUs in parallel through @@ -1328,6 +1334,14 @@ static noinstr void unexpected_machine_check(struct pt_regs *regs) * issues: if the machine check was due to a failure of the memory * backing the user stack, tracing that reads the user stack will cause * potentially infinite recursion. + * + * Currently, the #MC handler calls out to a number of external facilities + * and, therefore, allows instrumentation around them. The optimal thing to + * have would be to do the absolutely minimal work required in #MC context + * and have instrumentation disabled only around that. Further processing can + * then happen in process context where instrumentation is allowed. Achieving + * that requires careful auditing and modifications. Until then, the code + * allows instrumentation temporarily, where required. * */ noinstr void do_machine_check(struct pt_regs *regs) { |