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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 20:42:23 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 20:42:23 +0300 |
commit | 9e536c817960c698c23feed6f9bff6d192805543 (patch) | |
tree | 2c23baad1aebf254f5028b0d35556158a4577237 /arch | |
parent | ac74075e5d525f3e782f88ed8d8b1df35c1497e5 (diff) | |
parent | f94c91f7ba3ba7de2bc8aa31be28e1abb22f849e (diff) | |
download | linux-9e536c817960c698c23feed6f9bff6d192805543.tar.xz |
Merge tag 'x86_misc_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 fixes fromm Borislav Petkov:
- Ratelimit the message about writes to unrecognized MSRs so that they
don't spam the console log (Chris Down)
- Document how the /proc/cpuinfo machinery works for future reference
(Kyung Min Park, Ricardo Neri and Dave Hansen)
- Correct the current NMI's duration calculation (Libing Zhou)
* tag 'x86_misc_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/nmi: Fix nmi_handle() duration miscalculation
Documentation/x86: Add documentation for /proc/cpuinfo feature flags
x86/msr: Make source of unrecognised MSR writes unambiguous
x86/msr: Prevent userspace MSR access from dominating the console
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/msr.c | 18 | ||||
-rw-r--r-- | arch/x86/kernel/nmi.c | 5 |
2 files changed, 17 insertions, 6 deletions
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index 49dcfb85e773..c0d409810658 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -80,18 +80,30 @@ static ssize_t msr_read(struct file *file, char __user *buf, static int filter_write(u32 reg) { + /* + * MSRs writes usually happen all at once, and can easily saturate kmsg. + * Only allow one message every 30 seconds. + * + * It's possible to be smarter here and do it (for example) per-MSR, but + * it would certainly be more complex, and this is enough at least to + * avoid saturating the ring buffer. + */ + static DEFINE_RATELIMIT_STATE(fw_rs, 30 * HZ, 1); + switch (allow_writes) { case MSR_WRITES_ON: return 0; case MSR_WRITES_OFF: return -EPERM; default: break; } + if (!__ratelimit(&fw_rs)) + return 0; + if (reg == MSR_IA32_ENERGY_PERF_BIAS) return 0; - pr_err_ratelimited("Write to unrecognized MSR 0x%x by %s\n" - "Please report to x86@kernel.org\n", - reg, current->comm); + pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n", + reg, current->comm, current->pid); return 0; } diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 4fc9954a9560..47381666d6a5 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -102,7 +102,6 @@ fs_initcall(nmi_warning_debugfs); static void nmi_check_duration(struct nmiaction *action, u64 duration) { - u64 whole_msecs = READ_ONCE(action->max_duration); int remainder_ns, decimal_msecs; if (duration < nmi_longest_ns || duration < action->max_duration) @@ -110,12 +109,12 @@ static void nmi_check_duration(struct nmiaction *action, u64 duration) action->max_duration = duration; - remainder_ns = do_div(whole_msecs, (1000 * 1000)); + remainder_ns = do_div(duration, (1000 * 1000)); decimal_msecs = remainder_ns / 1000; printk_ratelimited(KERN_INFO "INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n", - action->handler, whole_msecs, decimal_msecs); + action->handler, duration, decimal_msecs); } static int nmi_handle(unsigned int type, struct pt_regs *regs) |