/* * Machine check handler. * * K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs. * Rest from unknown author(s). * 2004 Andi Kleen. Rewrote most of it. * Copyright 2008 Intel Corporation * Author: Andi Kleen */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "mce-internal.h" static DEFINE_MUTEX(mce_chrdev_read_mutex); #define mce_log_get_idx_check(p) \ ({ \ RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \ !lockdep_is_held(&mce_chrdev_read_mutex), \ "suspicious mce_log_get_idx_check() usage"); \ smp_load_acquire(&(p)); \ }) /* sysfs synchronization */ static DEFINE_MUTEX(mce_sysfs_mutex); #define CREATE_TRACE_POINTS #include #define SPINUNIT 100 /* 100ns */ DEFINE_PER_CPU(unsigned, mce_exception_count); struct mce_bank *mce_banks __read_mostly; struct mce_vendor_flags mce_flags __read_mostly; struct mca_config mca_cfg __read_mostly = { .bootlog = -1, /* * Tolerant levels: * 0: always panic on uncorrected errors, log corrected errors * 1: panic or SIGBUS on uncorrected errors, log corrected errors * 2: SIGBUS or log uncorrected errors (if possible), log corr. errors * 3: never panic or SIGBUS, log all errors (for testing only) */ .tolerant = 1, .monarch_timeout = -1 }; /* User mode helper program triggered by machine check event */ static unsigned long mce_need_notify; static char mce_helper[128]; static char *mce_helper_argv[2] = { mce_helper, NULL }; static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait); static DEFINE_PER_CPU(struct mce, mces_seen); static int cpu_missing; /* * MCA banks polled by the period polling timer for corrected events. * With Intel CMCI, this only has MCA banks which do not support CMCI (if any). */ DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = { [0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL }; /* * MCA banks controlled through firmware first for corrected errors. * This is a global list of banks for which we won't enable CMCI and we * won't poll. Firmware controls these banks and is responsible for * reporting corrected errors through GHES. Uncorrected/recoverable * errors are still notified through a machine check. */ mce_banks_t mce_banks_ce_disabled; static struct work_struct mce_work; static struct irq_work mce_irq_work; static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs); static int mce_usable_address(struct mce *m); /* * CPU/chipset specific EDAC code can register a notifier call here to print * MCE errors in a human-readable form. */ ATOMIC_NOTIFIER_HEAD(x86_mce_decoder_chain); /* Do initial initialization of a struct mce */ void mce_setup(struct mce *m) { memset(m, 0, sizeof(struct mce)); m->cpu = m->extcpu = smp_processor_id(); m->tsc = rdtsc(); /* We hope get_seconds stays lockless */ m->time = get_seconds(); m->cpuvendor = boot_cpu_data.x86_vendor; m->cpuid = cpuid_eax(1); m->socketid = cpu_data(m->extcpu).phys_proc_id; m->apicid = cpu_data(m->extcpu).initial_apicid; rdmsrl(MSR_IA32_MCG_CAP, m->mcgcap); m->microcode = boot_cpu_data.microcode; } DEFINE_PER_CPU(struct mce, injectm); EXPORT_PER_CPU_SYMBOL_GPL(injectm); /* * Lockless MCE logging infrastructure. * This avoids deadlocks on printk locks without having to break locks. Also * separate MCEs from kernel messages to avoid bogus bug reports. */ static struct mce_log mcelog = { .signature = MCE_LOG_SIGNATURE, .len = MCE_LOG_LEN, .recordlen = sizeof(struct mce), }; void mce_log(struct mce *mce) { unsigned next, entry; /* Emit the trace record: */ trace_mce_record(mce); if (!mce_gen_pool_add(mce)) irq_work_queue(&mce_irq_work); mce->finished = 0; wmb(); for (;;) { entry = mce_log_get_idx_check(mcelog.next); for (;;) { /* * When the buffer fills up discard new entries. * Assume that the earlier errors are the more * interesting ones: */ if (entry >= MCE_LOG_LEN) { set_bit(MCE_OVERFLOW, (unsigned long *)&mcelog.flags); return; } /* Old left over entry. Skip: */ if (mcelog.entry[entry].finished) { entry++; continue; } break; } smp_rmb(); next = entry + 1; if (cmpxchg(&mcelog.next, entry, next) == entry) break; } memcpy(mcelog.entry + entry, mce, sizeof(struct mce)); wmb(); mcelog.entry[entry].finished = 1; wmb(); mce->finished = 1; set_bit(0, &mce_need_notify); } void mce_inject_log(struct mce *m) { mutex_lock(&mce_chrdev_read_mutex); mce_log(m); mutex_unlock(&mce_chrdev_read_mutex); } EXPORT_SYMBOL_GPL(mce_inject_log); static struct notifier_block mce_srao_nb; void mce_register_decode_chain(struct notifier_block *nb) { /* Ensure SRAO notifier has the highest priority in the decode chain. */ if (nb != &mce_srao_nb && nb->priority == INT_MAX) nb->priority -= 1; atomic_notifier_chain_register(&x86_mce_decoder_chain, nb); } EXPORT_SYMBOL_GPL(mce_register_decode_chain); void mce_unregister_decode_chain(struct notifier_block *nb) { atomic_notifier_chain_unregister(&x86_mce_decoder_chain, nb); } EXPORT_SYMBOL_GPL(mce_unregister_decode_chain); static void print_mce(struct mce *m) { int ret = 0; pr_emerg(HW_ERR "CPU %d: Machine Check Exception: %Lx Bank %d: %016Lx\n", m->extcpu, m->mcgstatus, m->bank, m->status); if (m->ip) { pr_emerg(HW_ERR "RIP%s %02x:<%016Lx> ", !(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "", m->cs, m->ip); if (m->cs == __KERNEL_CS) print_symbol("{%s}", m->ip); pr_cont("\n"); } pr_emerg(HW_ERR "TSC %llx ", m->tsc); if (m->addr) pr_cont("ADDR %llx ", m->addr); if (m->misc) pr_cont("MISC %llx ", m->misc); pr_cont("\n"); /* * Note this output is parsed by external tools and old fields * should not be changed. */ pr_emerg(HW_ERR "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x microcode %x\n", m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid, m->microcode); /* * Print out human-readable details about the MCE error, * (if the CPU has an implementation for that) */ ret = atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m); if (ret == NOTIFY_STOP) return; pr_emerg_ratelimited(HW_ERR "Run the above through 'mcelog --ascii'\n"); } #define PANIC_TIMEOUT 5 /* 5 seconds */ static atomic_t mce_panicked; static int fake_panic; static atomic_t mce_fake_panicked; /* Panic in progress. Enable interrupts and wait for final IPI */ static void wait_for_panic(void) { long timeout = PANIC_TIMEOUT*USEC_PER_SEC; preempt_disable(); local_irq_enable(); while (timeout-- > 0) udelay(1); if (panic_timeout == 0) panic_timeout = mca_cfg.panic_timeout; panic("Panicing machine check CPU died"); } static void mce_panic(const char *msg, struct mce *final, char *exp) { int i, apei_err = 0; if (!fake_panic) { /* * Make sure only one CPU runs in machine check panic */ if (atomic_inc_return(&mce_panicked) > 1) wait_for_panic(); barrier(); bust_spinlocks(1); console_verbose(); } else { /* Don't log too much for fake panic */ if (atomic_inc_return(&mce_fake_panicked) > 1) return; } /* First print corrected ones that are still unlogged */ for (i = 0; i < MCE_LOG_LEN; i++) { struct mce *m = &mcelog.entry[i]; if (!(m->status & MCI_STATUS_VAL)) continue; if (!(m->status & MCI_STATUS_UC)) { print_mce(m); if (!apei_err) apei_err = apei_write_mce(m); } } /* Now print uncorrected but with the final one last */ for (i = 0; i < MCE_LOG_LEN; i++) { struct mce *m = &mcelog.entry[i]; if (!(m->status & MCI_STATUS_VAL)) continue; if (!(m->status & MCI_STATUS_UC)) continue; if (!final || memcmp(m, final, sizeof(struct mce))) { print_mce(m); if (!apei_err) apei_err = apei_write_mce(m); } } if (final) { print_mce(final); if (!apei_err) apei_err = apei_write_mce(final); } if (cpu_missing) pr_emerg(HW_ERR "Some CPUs didn't answer in synchronization\n"); if (exp) pr_emerg(HW_ERR "Machine check: %s\n", exp); if (!fake_panic) { if (panic_timeout == 0) panic_timeout = mca_cfg.panic_timeout; panic(msg); } else pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg); } /* Support code for software error injection */ static int msr_to_offset(u32 msr) { unsigned bank = __this_cpu_read(injectm.bank); if (msr == mca_cfg.rip_msr) return offsetof(struct mce, ip); if (msr == MSR_IA32_MCx_STATUS(bank)) return offsetof(struct mce, status); if (msr == MSR_IA32_MCx_ADDR(bank)) return offsetof(struct mce, addr); if (msr == MSR_IA32_MCx_MISC(bank)) return offsetof(struct mce, misc); if (msr == MSR_IA32_MCG_STATUS) return offsetof(struct mce, mcgstatus); return -1; } /* MSR access wrappers used for error injection */ static u64 mce_rdmsrl(u32 msr) { u64 v; if (__this_cpu_read(injectm.finished)) { int offset = msr_to_offset(msr); if (offset < 0) return 0; return *(u64 *)((char *)this_cpu_ptr(&injectm) + offset); } if (rdmsrl_safe(msr, &v)) { WARN_ONCE(1, "mce: Unable to read msr %d!\n", msr); /* * Return zero in case the access faulted. This should * not happen normally but can happen if the CPU does * something weird, or if the code is buggy. */ v = 0; } return v; } static void mce_wrmsrl(u32 msr, u64 v) { if (__this_cpu_read(injectm.finished)) { int offset = msr_to_offset(msr); if (offset >= 0) *(u64 *)((char *)this_cpu_ptr(&injectm) + offset) = v; return; } wrmsrl(msr, v); } /* * Collect all global (w.r.t. this processor) status about this machine * 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) { mce_setup(m); m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); if (regs) { /* * Get the address of the instruction at the time of * the machine check error. */ if (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) { m->ip = regs->ip; m->cs = regs->cs; /* * When in VM86 mode make the cs look like ring 3 * always. This is a lie, but it's better than passing * the additional vm86 bit around everywhere. */ if (v8086_mode(regs)) m->cs |= 3; } /* Use accurate RIP reporting if available. */ if (mca_cfg.rip_msr) m->ip = mce_rdmsrl(mca_cfg.rip_msr); } } int mce_available(struct cpuinfo_x86 *c) { if (mca_cfg.disabled) return 0; return cpu_has(c, X86_FEATURE_MCE) && cpu_has(c, X86_FEATURE_MCA); } static void mce_schedule_work(void) { if (!mce_gen_pool_empty() && keventd_up()) schedule_work(&mce_work); } static void mce_irq_work_cb(struct irq_work *entry) { mce_notify_irq(); mce_schedule_work(); } static void mce_report_event(struct pt_regs *regs) { if (regs->flags & (X86_VM_MASK|X86_EFLAGS_IF)) { mce_notify_irq(); /* * Triggering the work queue here is just an insurance * policy in case the syscall exit notify handler * doesn't run soon enough or ends up running on the * wrong CPU (can happen when audit sleeps) */ mce_schedule_work(); return; } irq_work_queue(&mce_irq_work); } static int srao_decode_notifier(struct notifier_block *nb, unsigned long val, void *data) { struct mce *mce = (struct mce *)data; unsigned long pfn; if (!mce) return NOTIFY_DONE; if (mce->usable_addr && (mce->severity == MCE_AO_SEVERITY)) { pfn = mce->addr >> PAGE_SHIFT; memory_failure(pfn, MCE_VECTOR, 0); } return NOTIFY_OK; } static struct notifier_block mce_srao_nb = { .notifier_call = srao_decode_notifier, .priority = INT_MAX, }; /* * Read ADDR and MISC registers. */ static void mce_read_aux(struct mce *m, int i) { if (m->status & MCI_STATUS_MISCV) m->misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i)); if (m->status & MCI_STATUS_ADDRV) { m->addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i)); /* * Mask the reported address by the reported granularity. */ if (mca_cfg.ser && (m->status & MCI_STATUS_MISCV)) { u8 shift = MCI_MISC_ADDR_LSB(m->misc); m->addr >>= shift; m->addr <<= shift; } } } static bool memory_error(struct mce *m) { struct cpuinfo_x86 *c = &boot_cpu_data; if (c->x86_vendor == X86_VENDOR_AMD) { /* * coming soon */ return false; } else if (c->x86_vendor == X86_VENDOR_INTEL) { /* * Intel SDM Volume 3B - 15.9.2 Compound Error Codes * * Bit 7 of the MCACOD field of IA32_MCi_STATUS is used for * indicating a memory error. Bit 8 is used for indicating a * cache hierarchy error. The combination of bit 2 and bit 3 * is used for indicating a `generic' cache hierarchy error * But we can't just blindly check the above bits, because if * bit 11 is set, then it is a bus/interconnect error - and * either way the above bits just gives more detail on what * bus/interconnect error happened. Note that bit 12 can be * ignored, as it's the "filter" bit. */ return (m->status & 0xef80) == BIT(7) || (m->status & 0xef00) == BIT(8) || (m->status & 0xeffc) == 0xc; } return false; } DEFINE_PER_CPU(unsigned, mce_poll_count); /* * Poll for corrected events or events that happened before reset. * Those are just logged through /dev/mcelog. * * This is executed in standard interrupt context. * * Note: spec recommends to panic for fatal unsignalled * errors here. However this would be quite problematic -- * we would need to reimplement the Monarch handling and * it would mess up the exclusion between exception handler * and poll hander -- * so we skip this for now. * These cases should not happen anyways, or only when the CPU * is already totally * confused. In this case it's likely it will * not fully execute the machine check handler either. */ bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b) { bool error_logged = false; struct mce m; int severity; int i; this_cpu_inc(mce_poll_count); mce_gather_info(&m, NULL); for (i = 0; i < mca_cfg.banks; i++) { if (!mce_banks[i].ctl || !test_bit(i, *b)) continue; m.misc = 0; m.addr = 0; m.bank = i; m.tsc = 0; barrier(); m.status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i)); if (!(m.status & MCI_STATUS_VAL)) continue; /* * Uncorrected or signalled events are handled by the exception * handler when it is enabled, so don't process those here. * * TBD do the same check for MCI_STATUS_EN here? */ if (!(flags & MCP_UC) && (m.status & (mca_cfg.ser ? MCI_STATUS_S : MCI_STATUS_UC))) continue; mce_read_aux(&m, i); if (!(flags & MCP_TIMESTAMP)) m.tsc = 0; severity = mce_severity(&m, mca_cfg.tolerant, NULL, false); /* * In the cases where we don't have a valid address after all, * do not add it into the ring buffer. */ if (severity == MCE_DEFERRED_SEVERITY && memory_error(&m)) { if (m.status & MCI_STATUS_ADDRV) { m.severity = severity; m.usable_addr = mce_usable_address(&m); if (!mce_gen_pool_add(&m)) mce_schedule_work(); } } /* * Don't get the IP here because it's unlikely to * have anything to do with the actual error location. */ if (!(flags & MCP_DONTLOG) && !mca_cfg.dont_log_ce) { error_logged = true; mce_log(&m); } /* * Clear state for this bank. */ mce_wrmsrl(MSR_IA32_MCx_STATUS(i), 0); } /* * Don't clear MCG_STATUS here because it's only defined for * exceptions. */ sync_core(); return error_logged; } EXPORT_SYMBOL_GPL(machine_check_poll); /* * Do a quick check if any of the events requires a panic. * This decides if we keep the events around or clear them. */ static int mce_no_way_out(struct mce *m, char **msg, unsigned long *validp, struct pt_regs *regs) { int i, ret = 0; char *tmp; for (i = 0; i < mca_cfg.banks; i++) { m->status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i)); if (m->status & MCI_STATUS_VAL) { __set_bit(i, validp); if (quirk_no_way_out) quirk_no_way_out(i, m, regs); } if (mce_severity(m, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) { m->bank = i; *msg = tmp; ret = 1; } } return ret; } /* * Variable to establish order between CPUs while scanning. * Each CPU spins initially until executing is equal its number. */ static atomic_t mce_executing; /* * Defines order of CPUs on entry. First CPU becomes Monarch. */ static atomic_t mce_callin; /* * Check if a timeout waiting for other CPUs happened. */ static int mce_timed_out(u64 *t, const char *msg) { /* * The others already did panic for some reason. * Bail out like in a timeout. * rmb() to tell the compiler that system_state * might have been modified by someone else. */ rmb(); if (atomic_read(&mce_panicked)) wait_for_panic(); if (!mca_cfg.monarch_timeout) goto out; if ((s64)*t < SPINUNIT) { if (mca_cfg.tolerant <= 1) mce_panic(msg, NULL, NULL); cpu_missing = 1; return 1; } *t -= SPINUNIT; out: touch_nmi_watchdog(); return 0; } /* * The Monarch's reign. The Monarch is the CPU who entered * the machine check handler first. It waits for the others to * raise the exception too and then grades them. When any * error is fatal panic. Only then let the others continue. * * The other CPUs entering the MCE handler will be controlled by the * Monarch. They are called Subjects. * * This way we prevent any potential data corruption in a unrecoverable case * and also makes sure always all CPU's errors are examined. * * Also this detects the case of a machine check event coming from outer * space (not detected by any CPUs) In this case some external agent wants * us to shut down, so panic too. * * The other CPUs might still decide to panic if the handler happens * in a unrecoverable place, but in this case the system is in a semi-stable * state and won't corrupt anything by itself. It's ok to let the others * continue for a bit first. * * All the spin loops have timeouts; when a timeout happens a CPU * typically elects itself to be Monarch. */ static void mce_reign(void) { int cpu; struct mce *m = NULL; int global_worst = 0; char *msg = NULL; char *nmsg = NULL; /* * This CPU is the Monarch and the other CPUs have run * through their handlers. * Grade the severity of the errors of all the CPUs. */ for_each_possible_cpu(cpu) { int severity = mce_severity(&per_cpu(mces_seen, cpu), mca_cfg.tolerant, &nmsg, true); if (severity > global_worst) { msg = nmsg; global_worst = severity; m = &per_cpu(mces_seen, cpu); } } /* * Cannot recover? Panic here then. * This dumps all the mces in the log buffer and stops the * other CPUs. */ if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) mce_panic("Fatal machine check", m, msg); /* * For UC somewhere we let the CPU who detects it handle it. * Also must let continue the others, otherwise the handling * CPU could deadlock on a lock. */ /* * No machine check event found. Must be some external * source or one CPU is hung. Panic. */ if (global_worst <= MCE_KEEP_SEVERITY && mca_cfg.tolerant < 3) mce_panic("Fatal machine check from unknown source", NULL, NULL); /* * Now clear all the mces_seen so that they don't reappear on * the next mce. */ for_each_possible_cpu(cpu) memset(&per_cpu(mces_seen, cpu), 0, sizeof(struct mce)); } static atomic_t global_nwo; /* * Start of Monarch synchronization. This waits until all CPUs have * entered the exception handler and then determines if any of them * saw a fatal event that requires panic. Then it executes them * in the entry order. * TBD double check parallel CPU hotunplug */ static int mce_start(int *no_way_out) { int order; int cpus = num_online_cpus(); u64 timeout = (u64)mca_cfg.monarch_timeout * NSEC_PER_USEC; if (!timeout) return -1; atomic_add(*no_way_out, &global_nwo); /* * global_nwo should be updated before mce_callin */ smp_wmb(); order = atomic_inc_return(&mce_callin); /* * Wait for everyone. */ while (atomic_read(&mce_callin) != cpus) { if (mce_timed_out(&timeout, "Timeout: Not all CPUs entered broadcast exception handler")) { atomic_set(&global_nwo, 0); return -1; } ndelay(SPINUNIT); } /* * mce_callin should be read before global_nwo */ smp_rmb(); if (order == 1) { /* * Monarch: Starts executing now, the others wait. */ atomic_set(&mce_executing, 1); } else { /* * Subject: Now start the scanning loop one by one in * the original callin order. * This way when there are any shared banks it will be * only seen by one CPU before cleared, avoiding duplicates. */ while (atomic_read(&mce_executing) < order) { if (mce_timed_out(&timeout, "Timeout: Subject CPUs unable to finish machine check processing")) { atomic_set(&global_nwo, 0); return -1; } ndelay(SPINUNIT); } } /* * Cache the global no_way_out state. */ *no_way_out = atomic_read(&global_nwo); return order; } /* * Synchronize between CPUs after main scanning loop. * This invokes the bulk of the Monarch processing. */ static int mce_end(int order) { int ret = -1; u64 timeout = (u64)mca_cfg.monarch_timeout * NSEC_PER_USEC; if (!timeout) goto reset; if (order < 0) goto reset; /* * Allow others to run. */ atomic_inc(&mce_executing); if (order == 1) { /* CHECKME: Can this race with a parallel hotplug? */ int cpus = num_online_cpus(); /* * Monarch: Wait for everyone to go through their scanning * loops. */ while (atomic_read(&mce_executing) <= cpus) { if (mce_timed_out(&timeout, "Timeout: Monarch CPU unable to finish machine check processing")) goto reset; ndelay(SPINUNIT); } mce_reign(); barrier(); ret = 0; } else { /* * Subject: Wait for Monarch to finish. */ while (atomic_read(&mce_executing) != 0) { if (mce_timed_out(&timeout, "Timeout: Monarch CPU did not finish machine check processing")) goto reset; ndelay(SPINUNIT); } /* * Don't reset anything. That's done by the Monarch. */ return 0; } /* * Reset all global state. */ reset: atomic_set(&global_nwo, 0); atomic_set(&mce_callin, 0); barrier(); /* * Let others run again. */ atomic_set(&mce_executing, 0); return ret; } /* * Check if the address reported by the CPU is in a format we can parse. * It would be possible to add code for most other cases, but all would * be somewhat complicated (e.g. segment offset would require an instruction * parser). So only support physical addresses up to page granuality for now. */ static int mce_usable_address(struct mce *m) { if (!(m->status & MCI_STATUS_MISCV) || !(m->status & MCI_STATUS_ADDRV)) return 0; if (MCI_MISC_ADDR_LSB(m->misc) > PAGE_SHIFT) return 0; if (MCI_MISC_ADDR_MODE(m->misc) != MCI_MISC_ADDR_PHYS) return 0; return 1; } static void mce_clear_state(unsigned long *toclear) { int i; for (i = 0; i < mca_cfg.banks; i++) { if (test_bit(i, toclear)) mce_wrmsrl(MSR_IA32_MCx_STATUS(i), 0); } } /* * 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 * think about putting a printk in there! * * On Intel systems this is entered on all CPUs in parallel through * MCE broadcast. However some CPUs might be broken beyond repair, * so be always careful when synchronizing with others. */ void do_machine_check(struct pt_regs *regs, long error_code) { struct mca_config *cfg = &mca_cfg; struct mce m, *final; int i; int worst = 0; int severity; /* * Establish sequential order between the CPUs entering the machine * check handler. */ int order = -1; /* * If no_way_out gets set, there is no safe way to recover from this * MCE. If mca_cfg.tolerant is cranked up, we'll try anyway. */ int no_way_out = 0; /* * If kill_it gets set, there might be a way to recover from this * error. */ int kill_it = 0; DECLARE_BITMAP(toclear, MAX_NR_BANKS); DECLARE_BITMAP(valid_banks, MAX_NR_BANKS); char *msg = "Unknown"; u64 recover_paddr = ~0ull; int flags = MF_ACTION_REQUIRED; /* * MCEs are always local on AMD. Same is determined by MCG_STATUS_LMCES * on Intel. */ int lmce = 1; /* If this CPU is offline, just bail out. */ if (cpu_is_offline(smp_processor_id())) { u64 mcgstatus; mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); if (mcgstatus & MCG_STATUS_RIPV) { mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); return; } } ist_enter(regs); this_cpu_inc(mce_exception_count); if (!cfg->banks) goto out; mce_gather_info(&m, regs); final = this_cpu_ptr(&mces_seen); *final = m; memset(valid_banks, 0, sizeof(valid_banks)); no_way_out = mce_no_way_out(&m, &msg, valid_banks, regs); barrier(); /* * When no restart IP might need to kill or panic. * Assume the worst for now, but if we find the * severity is MCE_AR_SEVERITY we have other options. */ if (!(m.mcgstatus & MCG_STATUS_RIPV)) kill_it = 1; /* * Check if this MCE is signaled to only this logical processor, * on Intel only. */ if (m.cpuvendor == X86_VENDOR_INTEL) lmce = m.mcgstatus & MCG_STATUS_LMCES; /* * Local machine check may already know that we have to panic. * Broadcast machine check begins rendezvous in mce_start() * Go through all banks in exclusion of the other CPUs. This way we * don't report duplicated events on shared banks because the first one * to see it will clear it. */ if (lmce) { if (no_way_out) mce_panic("Fatal local machine check", &m, msg); } else { order = mce_start(&no_way_out); } for (i = 0; i < cfg->banks; i++) { __clear_bit(i, toclear); if (!test_bit(i, valid_banks)) continue; if (!mce_banks[i].ctl) continue; m.misc = 0; m.addr = 0; m.bank = i; m.status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i)); if ((m.status & MCI_STATUS_VAL) == 0) continue; /* * Non uncorrected or non signaled errors are handled by * machine_check_poll. Leave them alone, unless this panics. */ if (!(m.status & (cfg->ser ? MCI_STATUS_S : MCI_STATUS_UC)) && !no_way_out) continue; /* * Set taint even when machine check was not enabled. */ add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); severity = mce_severity(&m, cfg->tolerant, NULL, true); /* * When machine check was for corrected/deferred handler don't * touch, unless we're panicing. */ if ((severity == MCE_KEEP_SEVERITY || severity == MCE_UCNA_SEVERITY) && !no_way_out) continue; __set_bit(i, toclear); if (severity == MCE_NO_SEVERITY) { /* * Machine check event was not enabled. Clear, but * ignore. */ continue; } mce_read_aux(&m, i); /* assuming valid severity level != 0 */ m.severity = severity; m.usable_addr = mce_usable_address(&m); mce_log(&m); if (severity > worst) { *final = m; worst = severity; } } /* mce_clear_state will clear *final, save locally for use later */ m = *final; if (!no_way_out) mce_clear_state(toclear); /* * Do most of the synchronization with other CPUs. * When there's any problem use only local no_way_out state. */ if (!lmce) { if (mce_end(order) < 0) no_way_out = worst >= MCE_PANIC_SEVERITY; } else { /* * If there was a fatal machine check we should have * already called mce_panic earlier in this function. * Since we re-read the banks, we might have found * something new. Check again to see if we found a * fatal error. We call "mce_severity()" again to * make sure we have the right "msg". */ if (worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) { mce_severity(&m, cfg->tolerant, &msg, true); mce_panic("Local fatal machine check!", &m, msg); } } /* * At insane "tolerant" levels we take no action. Otherwise * we only die if we have no other choice. For less serious * issues we try to recover, or limit damage to the current * process. */ if (cfg->tolerant < 3) { if (no_way_out) mce_panic("Fatal machine check on current CPU", &m, msg); if (worst == MCE_AR_SEVERITY) { recover_paddr = m.addr; if (!(m.mcgstatus & MCG_STATUS_RIPV)) flags |= MF_MUST_KILL; } else if (kill_it) { force_sig(SIGBUS, current); } } if (worst > 0) mce_report_event(regs); mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); out: sync_core(); if (recover_paddr == ~0ull) goto done; pr_err("Uncorrected hardware memory error in user-access at %llx", recover_paddr); /* * We must call memory_failure() here even if the current process is * doomed. We still need to mark the page as poisoned and alert any * other users of the page. */ ist_begin_non_atomic(regs); local_irq_enable(); if (memory_failure(recover_paddr >> PAGE_SHIFT, MCE_VECTOR, flags) < 0) { pr_err("Memory error not recovered"); force_sig(SIGBUS, current); } local_irq_disable(); ist_end_non_atomic(); done: ist_exit(regs); } EXPORT_SYMBOL_GPL(do_machine_check); #ifndef CONFIG_MEMORY_FAILURE int memory_failure(unsigned long pfn, int vector, int flags) { /* mce_severity() should not hand us an ACTION_REQUIRED error */ BUG_ON(flags & MF_ACTION_REQUIRED); pr_err("Uncorrected memory error in page 0x%lx ignored\n" "Rebuild kernel with CONFIG_MEMORY_FAILURE=y for smarter handling\n", pfn); return 0; } #endif /* * Action optional processing happens here (picking up * from the list of faulting pages that do_machine_check() * placed into the genpool). */ static void mce_process_work(struct work_struct *dummy) { mce_gen_pool_process(); } #ifdef CONFIG_X86_MCE_INTEL /*** * mce_log_therm_throt_event - Logs the thermal throttling event to mcelog * @cpu: The CPU on which the event occurred. * @status: Event status information * * This function should be called by the thermal interrupt after the * event has been processed and the decision was made to log the event * further. * * The status parameter will be saved to the 'status' field of 'struct mce' * and historically has been the register value of the * MSR_IA32_THERMAL_STATUS (Intel) msr. */ void mce_log_therm_throt_event(__u64 status) { struct mce m; mce_setup(&m); m.bank = MCE_THERMAL_BANK; m.status = status; mce_log(&m); } #endif /* CONFIG_X86_MCE_INTEL */ /* * Periodic polling timer for "silent" machine check errors. If the * poller finds an MCE, poll 2x faster. When the poller finds no more * errors, poll 2x slower (up to check_interval seconds). */ static unsigned long check_interval = INITIAL_CHECK_INTERVAL; static DEFINE_PER_CPU(unsigned long, mce_next_interval); /* in jiffies */ static DEFINE_PER_CPU(struct timer_list, mce_timer); static unsigned long mce_adjust_timer_default(unsigned long interval) { return interval; } static unsigned long (*mce_adjust_timer)(unsigned long interval) = mce_adjust_timer_default; static void __restart_timer(struct timer_list *t, unsigned long interval) { unsigned long when = jiffies + interval; unsigned long flags; local_irq_save(flags); if (timer_pending(t)) { if (time_before(when, t->expires)) mod_timer_pinned(t, when); } else { t->expires = round_jiffies(when); add_timer_on(t, smp_processor_id()); } local_irq_restore(flags); } static void mce_timer_fn(unsigned long data) { struct timer_list *t = this_cpu_ptr(&mce_timer); int cpu = smp_processor_id(); unsigned long iv; WARN_ON(cpu != data); iv = __this_cpu_read(mce_next_interval); if (mce_available(this_cpu_ptr(&cpu_info))) { machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_poll_banks)); if (mce_intel_cmci_poll()) { iv = mce_adjust_timer(iv); goto done; } } /* * Alert userspace if needed. If we logged an MCE, reduce the polling * interval, otherwise increase the polling interval. */ if (mce_notify_irq()) iv = max(iv / 2, (unsigned long) HZ/100); else iv = min(iv * 2, round_jiffies_relative(check_interval * HZ)); done: __this_cpu_write(mce_next_interval, iv); __restart_timer(t, iv); } /* * Ensure that the timer is firing in @interval from now. */ void mce_timer_kick(unsigned long interval) { struct timer_list *t = this_cpu_ptr(&mce_timer); unsigned long iv = __this_cpu_read(mce_next_interval); __restart_timer(t, interval); if (interval < iv) __this_cpu_write(mce_next_interval, interval); } /* Must not be called in IRQ context where del_timer_sync() can deadlock */ static void mce_timer_delete_all(void) { int cpu; for_each_online_cpu(cpu) del_timer_sync(&per_cpu(mce_timer, cpu)); } static void mce_do_trigger(struct work_struct *work) { call_usermodehelper(mce_helper, mce_helper_argv, NULL, UMH_NO_WAIT); } static DECLARE_WORK(mce_trigger_work, mce_do_trigger); /* * Notify the user(s) about new machine check events. * Can be called from interrupt context, but not from machine check/NMI * context. */ int mce_notify_irq(void) { /* Not more than two messages every minute */ static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2); if (test_and_clear_bit(0, &mce_need_notify)) { /* wake processes polling /dev/mcelog */ wake_up_interruptible(&mce_chrdev_wait); if (mce_helper[0]) schedule_work(&mce_trigger_work); if (__ratelimit(&ratelimit)) pr_info(HW_ERR "Machine check events logged\n"); return 1; } return 0; } EXPORT_SYMBOL_GPL(mce_notify_irq); static int __mcheck_cpu_mce_banks_init(void) { int i; u8 num_banks = mca_cfg.banks; mce_banks = kzalloc(num_banks * sizeof(struct mce_bank), GFP_KERNEL); if (!mce_banks) return -ENOMEM; for (i = 0; i < num_banks; i++) { struct mce_bank *b = &mce_banks[i]; b->ctl = -1ULL; b->init = 1; } return 0; } /* * Initialize Machine Checks for a CPU. */ static int __mcheck_cpu_cap_init(void) { unsigned b; u64 cap; rdmsrl(MSR_IA32_MCG_CAP, cap); b = cap & MCG_BANKCNT_MASK; if (!mca_cfg.banks) pr_info("CPU supports %d MCE banks\n", b); if (b > MAX_NR_BANKS) { pr_warn("Using only %u machine check banks out of %u\n", MAX_NR_BANKS, b); b = MAX_NR_BANKS; } /* Don't support asymmetric configurations today */ WARN_ON(mca_cfg.banks != 0 && b != mca_cfg.banks); mca_cfg.banks = b; if (!mce_banks) { int err = __mcheck_cpu_mce_banks_init(); if (err) return err; } /* Use accurate RIP reporting if available. */ if ((cap & MCG_EXT_P) && MCG_EXT_CNT(cap) >= 9) mca_cfg.rip_msr = MSR_IA32_MCG_EIP; if (cap & MCG_SER_P) mca_cfg.ser = true; return 0; } static void __mcheck_cpu_init_generic(void) { enum mcp_flags m_fl = 0; mce_banks_t all_banks; u64 cap; int i; if (!mca_cfg.bootlog) m_fl = MCP_DONTLOG; /* * Log the machine checks left over from the previous reset. */ bitmap_fill(all_banks, MAX_NR_BANKS); machine_check_poll(MCP_UC | m_fl, &all_banks); cr4_set_bits(X86_CR4_MCE); rdmsrl(MSR_IA32_MCG_CAP, cap); if (cap & MCG_CTL_P) wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff); for (i = 0; i < mca_cfg.banks; i++) { struct mce_bank *b = &mce_banks[i]; if (!b->init) continue; wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl); wrmsrl(MSR_IA32_MCx_STATUS(i), 0); } } /* * During IFU recovery Sandy Bridge -EP4S processors set the RIPV and * EIPV bits in MCG_STATUS to zero on the affected logical processor (SDM * Vol 3B Table 15-20). But this confuses both the code that determines * whether the machine check occurred in kernel or user mode, and also * the severity assessment code. Pretend that EIPV was set, and take the * ip/cs values from the pt_regs that mce_gather_info() ignored earlier. */ static void quirk_sandybridge_ifu(int bank, struct mce *m, struct pt_regs *regs) { if (bank != 0) return; if ((m->mcgstatus & (MCG_STATUS_EIPV|MCG_STATUS_RIPV)) != 0) return; if ((m->status & (MCI_STATUS_OVER|MCI_STATUS_UC| MCI_STATUS_EN|MCI_STATUS_MISCV|MCI_STATUS_ADDRV| MCI_STATUS_PCC|MCI_STATUS_S|MCI_STATUS_AR| MCACOD)) != (MCI_STATUS_UC|MCI_STATUS_EN| MCI_STATUS_MISCV|MCI_STATUS_ADDRV|MCI_STATUS_S| MCI_STATUS_AR|MCACOD_INSTR)) return; m->mcgstatus |= MCG_STATUS_EIPV; m->ip = regs->ip; m->cs = regs->cs; } /* Add per CPU specific workarounds here */ static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c) { struct mca_config *cfg = &mca_cfg; if (c->x86_vendor == X86_VENDOR_UNKNOWN) { pr_info("unknown CPU type - not enabling MCE support\n"); return -EOPNOTSUPP; } /* This should be disabled by the BIOS, but isn't always */ if (c->x86_vendor == X86_VENDOR_AMD) { if (c->x86 == 15 && cfg->banks > 4) { /* * disable GART TBL walk error reporting, which * trips off incorrectly with the IOMMU & 3ware * & Cerberus: */ clear_bit(10, (unsigned long *)&mce_banks[4].ctl); } if (c->x86 <= 17 && cfg->bootlog < 0) { /* * Lots of broken BIOS around that don't clear them * by default and leave crap in there. Don't log: */ cfg->bootlog = 0; } /* * Various K7s with broken bank 0 around. Always disable * by default. */ if (c->x86 == 6 && cfg->banks > 0) mce_banks[0].ctl = 0; /* * overflow_recov is supported for F15h Models 00h-0fh * even though we don't have a CPUID bit for it. */ if (c->x86 == 0x15 && c->x86_model <= 0xf) mce_flags.overflow_recov = 1; /* * Turn off MC4_MISC thresholding banks on all models since * they're not supported there. */ if (c->x86 == 0x15) { int i; u64 hwcr; bool need_toggle; u32 msrs[] = { 0x00000413, /* MC4_MISC0 */ 0xc0000408, /* MC4_MISC1 */ }; rdmsrl(MSR_K7_HWCR, hwcr); /* McStatusWrEn has to be set */ need_toggle = !(hwcr & BIT(18)); if (need_toggle) wrmsrl(MSR_K7_HWCR, hwcr | BIT(18)); /* Clear CntP bit safely */ for (i = 0; i < ARRAY_SIZE(msrs); i++) msr_clear_bit(msrs[i], 62); /* restore old settings */ if (need_toggle) wrmsrl(MSR_K7_HWCR, hwcr); } } if (c->x86_vendor == X86_VENDOR_INTEL) { /* * SDM documents that on family 6 bank 0 should not be written * because it aliases to another special BIOS controlled * register. * But it's not aliased anymore on model 0x1a+ * Don't ignore bank 0 completely because there could be a * valid event later, merely don't write CTL0. */ if (c->x86 == 6 && c->x86_model < 0x1A && cfg->banks > 0) mce_banks[0].init = 0; /* * All newer Intel systems support MCE broadcasting. Enable * synchronization with a one second timeout. */ if ((c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xe)) && cfg->monarch_timeout < 0) cfg->monarch_timeout = USEC_PER_SEC; /* * There are also broken BIOSes on some Pentium M and * earlier systems: */ if (c->x86 == 6 && c->x86_model <= 13 && cfg->bootlog < 0) cfg->bootlog = 0; if (c->x86 == 6 && c->x86_model == 45) quirk_no_way_out = quirk_sandybridge_ifu; } if (cfg->monarch_timeout < 0) cfg->monarch_timeout = 0; if (cfg->bootlog != 0) cfg->panic_timeout = 30; return 0; } static int __mcheck_cpu_ancient_init(struct cpuinfo_x86 *c) { if (c->x86 != 5) return 0; switch (c->x86_vendor) { case X86_VENDOR_INTEL: intel_p5_mcheck_init(c); return 1; break; case X86_VENDOR_CENTAUR: winchip_mcheck_init(c); return 1; break; default: return 0; } return 0; } static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c) { switch (c->x86_vendor) { case X86_VENDOR_INTEL: mce_intel_feature_init(c); mce_adjust_timer = cmci_intel_adjust_timer; break; case X86_VENDOR_AMD: { u32 ebx = cpuid_ebx(0x80000007); mce_amd_feature_init(c); mce_flags.overflow_recov = !!(ebx & BIT(0)); mce_flags.succor = !!(ebx & BIT(1)); mce_flags.smca = !!(ebx & BIT(3)); break; } default: break; } } static void __mcheck_cpu_clear_vendor(struct cpuinfo_x86 *c) { switch (c->x86_vendor) { case X86_VENDOR_INTEL: mce_intel_feature_clear(c); break; default: break; } } static void mce_start_timer(unsigned int cpu, struct timer_list *t) { unsigned long iv = check_interval * HZ; if (mca_cfg.ignore_ce || !iv) return; per_cpu(mce_next_interval, cpu) = iv; t->expires = round_jiffies(jiffies + iv); add_timer_on(t, cpu); } static void __mcheck_cpu_init_timer(void) { struct timer_list *t = this_cpu_ptr(&mce_timer); unsigned int cpu = smp_processor_id(); setup_timer(t, mce_timer_fn, cpu); mce_start_timer(cpu, t); } /* Handle unconfigured int18 (should never happen) */ static void unexpected_machine_check(struct pt_regs *regs, long error_code) { pr_err("CPU#%d: Unexpected int18 (Machine Check)\n", smp_processor_id()); } /* Call the installed machine check handler for this CPU setup. */ void (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check; dotraplinkage void do_mce(struct pt_regs *regs, long error_code) { machine_check_vector(regs, error_code); } /* * Called for each booted CPU to set up machine checks. * Must be called with preempt off: */ void mcheck_cpu_init(struct cpuinfo_x86 *c) { if (mca_cfg.disabled) return; if (__mcheck_cpu_ancient_init(c)) return; if (!mce_available(c)) return; if (__mcheck_cpu_cap_init() < 0 || __mcheck_cpu_apply_quirks(c) < 0) { mca_cfg.disabled = true; return; } if (mce_gen_pool_init()) { mca_cfg.disabled = true; pr_emerg("Couldn't allocate MCE records pool!\n"); return; } machine_check_vector = do_machine_check; __mcheck_cpu_init_generic(); __mcheck_cpu_init_vendor(c); __mcheck_cpu_init_timer(); } /* * Called for each booted CPU to clear some machine checks opt-ins */ void mcheck_cpu_clear(struct cpuinfo_x86 *c) { if (mca_cfg.disabled) return; if (!mce_available(c)) return; /* * Possibly to clear general settings generic to x86 * __mcheck_cpu_clear_generic(c); */ __mcheck_cpu_clear_vendor(c); } /* * mce_chrdev: Character device /dev/mcelog to read and clear the MCE log. */ static DEFINE_SPINLOCK(mce_chrdev_state_lock); static int mce_chrdev_open_count; /* #times opened */ static int mce_chrdev_open_exclu; /* already open exclusive? */ static int mce_chrdev_open(struct inode *inode, struct file *file) { spin_lock(&mce_chrdev_state_lock); if (mce_chrdev_open_exclu || (mce_chrdev_open_count && (file->f_flags & O_EXCL))) { spin_unlock(&mce_chrdev_state_lock); return -EBUSY; } if (file->f_flags & O_EXCL) mce_chrdev_open_exclu = 1; mce_chrdev_open_count++; spin_unlock(&mce_chrdev_state_lock); return nonseekable_open(inode, file); } static int mce_chrdev_release(struct inode *inode, struct file *file) { spin_lock(&mce_chrdev_state_lock); mce_chrdev_open_count--; mce_chrdev_open_exclu = 0; spin_unlock(&mce_chrdev_state_lock); return 0; } static void collect_tscs(void *data) { unsigned long *cpu_tsc = (unsigned long *)data; cpu_tsc[smp_processor_id()] = rdtsc(); } static int mce_apei_read_done; /* Collect MCE record of previous boot in persistent storage via APEI ERST. */ static int __mce_read_apei(char __user **ubuf, size_t usize) { int rc; u64 record_id; struct mce m; if (usize < sizeof(struct mce)) return -EINVAL; rc = apei_read_mce(&m, &record_id); /* Error or no more MCE record */ if (rc <= 0) { mce_apei_read_done = 1; /* * When ERST is disabled, mce_chrdev_read() should return * "no record" instead of "no device." */ if (rc == -ENODEV) return 0; return rc; } rc = -EFAULT; if (copy_to_user(*ubuf, &m, sizeof(struct mce))) return rc; /* * In fact, we should have cleared the record after that has * been flushed to the disk or sent to network in * /sbin/mcelog, but we have no interface to support that now, * so just clear it to avoid duplication. */ rc = apei_clear_mce(record_id); if (rc) { mce_apei_read_done = 1; return rc; } *ubuf += sizeof(struct mce); return 0; } static ssize_t mce_chrdev_read(struct file *filp, char __user *ubuf, size_t usize, loff_t *off) { char __user *buf = ubuf; unsigned long *cpu_tsc; unsigned prev, next; int i, err; cpu_tsc = kmalloc(nr_cpu_ids * sizeof(long), GFP_KERNEL); if (!cpu_tsc) return -ENOMEM; mutex_lock(&mce_chrdev_read_mutex); if (!mce_apei_read_done) { err = __mce_read_apei(&buf, usize); if (err || buf != ubuf) goto out; } next = mce_log_get_idx_check(mcelog.next); /* Only supports full reads right now */ err = -EINVAL; if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) goto out; err = 0; prev = 0; do { for (i = prev; i < next; i++) { unsigned long start = jiffies; struct mce *m = &mcelog.entry[i]; while (!m->finished) { if (time_after_eq(jiffies, start + 2)) { memset(m, 0, sizeof(*m)); goto timeout; } cpu_relax(); } smp_rmb(); err |= copy_to_user(buf, m, sizeof(*m)); buf += sizeof(*m); timeout: ; } memset(mcelog.entry + prev, 0, (next - prev) * sizeof(struct mce)); prev = next; next = cmpxchg(&mcelog.next, prev, 0); } while (next != prev); synchronize_sched(); /* * Collect entries that were still getting written before the * synchronize. */ on_each_cpu(collect_tscs, cpu_tsc, 1); for (i = next; i < MCE_LOG_LEN; i++) { struct mce *m = &mcelog.entry[i]; if (m->finished && m->tsc < cpu_tsc[m->cpu]) { err |= copy_to_user(buf, m, sizeof(*m)); smp_rmb(); buf += sizeof(*m); memset(m, 0, sizeof(*m)); } } if (err) err = -EFAULT; out: mutex_unlock(&mce_chrdev_read_mutex); kfree(cpu_tsc); return err ? err : buf - ubuf; } static unsigned int mce_chrdev_poll(struct file *file, poll_table *wait) { poll_wait(file, &mce_chrdev_wait, wait); if (READ_ONCE(mcelog.next)) return POLLIN | POLLRDNORM; if (!mce_apei_read_done && apei_check_mce()) return POLLIN | POLLRDNORM; return 0; } static long mce_chrdev_ioctl(struct file *f, unsigned int cmd, unsigned long arg) { int __user *p = (int __user *)arg; if (!capable(CAP_SYS_ADMIN)) return -EPERM; switch (cmd) { case MCE_GET_RECORD_LEN: return put_user(sizeof(struct mce), p); case MCE_GET_LOG_LEN: return put_user(MCE_LOG_LEN, p); case MCE_GETCLEAR_FLAGS: { unsigned flags; do { flags = mcelog.flags; } while (cmpxchg(&mcelog.flags, flags, 0) != flags); return put_user(flags, p); } default: return -ENOTTY; } } static ssize_t (*mce_write)(struct file *filp, const char __user *ubuf, size_t usize, loff_t *off); void register_mce_write_callback(ssize_t (*fn)(struct file *filp, const char __user *ubuf, size_t usize, loff_t *off)) { mce_write = fn; } EXPORT_SYMBOL_GPL(register_mce_write_callback); static ssize_t mce_chrdev_write(struct file *filp, const char __user *ubuf, size_t usize, loff_t *off) { if (mce_write) return mce_write(filp, ubuf, usize, off); else return -EINVAL; } static const struct file_operations mce_chrdev_ops = { .open = mce_chrdev_open, .release = mce_chrdev_release, .read = mce_chrdev_read, .write = mce_chrdev_write, .poll = mce_chrdev_poll, .unlocked_ioctl = mce_chrdev_ioctl, .llseek = no_llseek, }; static struct miscdevice mce_chrdev_device = { MISC_MCELOG_MINOR, "mcelog", &mce_chrdev_ops, }; static void __mce_disable_bank(void *arg) { int bank = *((int *)arg); __clear_bit(bank, this_cpu_ptr(mce_poll_banks)); cmci_disable_bank(bank); } void mce_disable_bank(int bank) { if (bank >= mca_cfg.banks) { pr_warn(FW_BUG "Ignoring request to disable invalid MCA bank %d.\n", bank); return; } set_bit(bank, mce_banks_ce_disabled); on_each_cpu(__mce_disable_bank, &bank, 1); } /* * mce=off Disables machine check * mce=no_cmci Disables CMCI * mce=no_lmce Disables LMCE * mce=dont_log_ce Clears corrected events silently, no log created for CEs. * mce=ignore_ce Disables polling and CMCI, corrected events are not cleared. * mce=TOLERANCELEVEL[,monarchtimeout] (number, see above) * monarchtimeout is how long to wait for other CPUs on machine * check, or 0 to not wait * mce=bootlog Log MCEs from before booting. Disabled by default on AMD. * mce=nobootlog Don't log MCEs from before booting. * mce=bios_cmci_threshold Don't program the CMCI threshold */ static int __init mcheck_enable(char *str) { struct mca_config *cfg = &mca_cfg; if (*str == 0) { enable_p5_mce(); return 1; } if (*str == '=') str++; if (!strcmp(str, "off")) cfg->disabled = true; else if (!strcmp(str, "no_cmci")) cfg->cmci_disabled = true; else if (!strcmp(str, "no_lmce")) cfg->lmce_disabled = true; else if (!strcmp(str, "dont_log_ce")) cfg->dont_log_ce = true; else if (!strcmp(str, "ignore_ce")) cfg->ignore_ce = true; else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog")) cfg->bootlog = (str[0] == 'b'); else if (!strcmp(str, "bios_cmci_threshold")) cfg->bios_cmci_threshold = true; else if (isdigit(str[0])) { if (get_option(&str, &cfg->tolerant) == 2) get_option(&str, &(cfg->monarch_timeout)); } else { pr_info("mce argument %s ignored. Please use /sys\n", str); return 0; } return 1; } __setup("mce", mcheck_enable); int __init mcheck_init(void) { mcheck_intel_therm_init(); mce_register_decode_chain(&mce_srao_nb); mcheck_vendor_init_severity(); INIT_WORK(&mce_work, mce_process_work); init_irq_work(&mce_irq_work, mce_irq_work_cb); return 0; } /* * mce_syscore: PM support */ /* * Disable machine checks on suspend and shutdown. We can't really handle * them later. */ static void mce_disable_error_reporting(void) { int i; for (i = 0; i < mca_cfg.banks; i++) { struct mce_bank *b = &mce_banks[i]; if (b->init) wrmsrl(MSR_IA32_MCx_CTL(i), 0); } return; } static void vendor_disable_error_reporting(void) { /* * Don't clear on Intel CPUs. Some of these MSRs are socket-wide. * Disabling them for just a single offlined CPU is bad, since it will * inhibit reporting for all shared resources on the socket like the * last level cache (LLC), the integrated memory controller (iMC), etc. */ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) return; mce_disable_error_reporting(); } static int mce_syscore_suspend(void) { vendor_disable_error_reporting(); return 0; } static void mce_syscore_shutdown(void) { vendor_disable_error_reporting(); } /* * On resume clear all MCE state. Don't want to see leftovers from the BIOS. * Only one CPU is active at this time, the others get re-added later using * CPU hotplug: */ static void mce_syscore_resume(void) { __mcheck_cpu_init_generic(); __mcheck_cpu_init_vendor(raw_cpu_ptr(&cpu_info)); } static struct syscore_ops mce_syscore_ops = { .suspend = mce_syscore_suspend, .shutdown = mce_syscore_shutdown, .resume = mce_syscore_resume, }; /* * mce_device: Sysfs support */ static void mce_cpu_restart(void *data) { if (!mce_available(raw_cpu_ptr(&cpu_info))) return; __mcheck_cpu_init_generic(); __mcheck_cpu_init_timer(); } /* Reinit MCEs after user configuration changes */ static void mce_restart(void) { mce_timer_delete_all(); on_each_cpu(mce_cpu_restart, NULL, 1); } /* Toggle features for corrected errors */ static void mce_disable_cmci(void *data) { if (!mce_available(raw_cpu_ptr(&cpu_info))) return; cmci_clear(); } static void mce_enable_ce(void *all) { if (!mce_available(raw_cpu_ptr(&cpu_info))) return; cmci_reenable(); cmci_recheck(); if (all) __mcheck_cpu_init_timer(); } static struct bus_type mce_subsys = { .name = "machinecheck", .dev_name = "machinecheck", }; DEFINE_PER_CPU(struct device *, mce_device); void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu); static inline struct mce_bank *attr_to_bank(struct device_attribute *attr) { return container_of(attr, struct mce_bank, attr); } static ssize_t show_bank(struct device *s, struct device_attribute *attr, char *buf) { return sprintf(buf, "%llx\n", attr_to_bank(attr)->ctl); } static ssize_t set_bank(struct device *s, struct device_attribute *attr, const char *buf, size_t size) { u64 new; if (kstrtou64(buf, 0, &new) < 0) return -EINVAL; attr_to_bank(attr)->ctl = new; mce_restart(); return size; } static ssize_t show_trigger(struct device *s, struct device_attribute *attr, char *buf) { strcpy(buf, mce_helper); strcat(buf, "\n"); return strlen(mce_helper) + 1; } static ssize_t set_trigger(struct device *s, struct device_attribute *attr, const char *buf, size_t siz) { char *p; strncpy(mce_helper, buf, sizeof(mce_helper)); mce_helper[sizeof(mce_helper)-1] = 0; p = strchr(mce_helper, '\n'); if (p) *p = 0; return strlen(mce_helper) + !!p; } static ssize_t set_ignore_ce(struct device *s, struct device_attribute *attr, const char *buf, size_t size) { u64 new; if (kstrtou64(buf, 0, &new) < 0) return -EINVAL; mutex_lock(&mce_sysfs_mutex); if (mca_cfg.ignore_ce ^ !!new) { if (new) { /* disable ce features */ mce_timer_delete_all(); on_each_cpu(mce_disable_cmci, NULL, 1); mca_cfg.ignore_ce = true; } else { /* enable ce features */ mca_cfg.ignore_ce = false; on_each_cpu(mce_enable_ce, (void *)1, 1); } } mutex_unlock(&mce_sysfs_mutex); return size; } static ssize_t set_cmci_disabled(struct device *s, struct device_attribute *attr, const char *buf, size_t size) { u64 new; if (kstrtou64(buf, 0, &new) < 0) return -EINVAL; mutex_lock(&mce_sysfs_mutex); if (mca_cfg.cmci_disabled ^ !!new) { if (new) { /* disable cmci */ on_each_cpu(mce_disable_cmci, NULL, 1); mca_cfg.cmci_disabled = true; } else { /* enable cmci */ mca_cfg.cmci_disabled = false; on_each_cpu(mce_enable_ce, NULL, 1); } } mutex_unlock(&mce_sysfs_mutex); return size; } static ssize_t store_int_with_restart(struct device *s, struct device_attribute *attr, const char *buf, size_t size) { unsigned long old_check_interval = check_interval; ssize_t ret = device_store_ulong(s, attr, buf, size); if (check_interval == old_check_interval) return ret; mutex_lock(&mce_sysfs_mutex); mce_restart(); mutex_unlock(&mce_sysfs_mutex); return ret; } static DEVICE_ATTR(trigger, 0644, show_trigger, set_trigger); static DEVICE_INT_ATTR(tolerant, 0644, mca_cfg.tolerant); static DEVICE_INT_ATTR(monarch_timeout, 0644, mca_cfg.monarch_timeout); static DEVICE_BOOL_ATTR(dont_log_ce, 0644, mca_cfg.dont_log_ce); static struct dev_ext_attribute dev_attr_check_interval = { __ATTR(check_interval, 0644, device_show_int, store_int_with_restart), &check_interval }; static struct dev_ext_attribute dev_attr_ignore_ce = { __ATTR(ignore_ce, 0644, device_show_bool, set_ignore_ce), &mca_cfg.ignore_ce }; static struct dev_ext_attribute dev_attr_cmci_disabled = { __ATTR(cmci_disabled, 0644, device_show_bool, set_cmci_disabled), &mca_cfg.cmci_disabled }; static struct device_attribute *mce_device_attrs[] = { &dev_attr_tolerant.attr, &dev_attr_check_interval.attr, &dev_attr_trigger, &dev_attr_monarch_timeout.attr, &dev_attr_dont_log_ce.attr, &dev_attr_ignore_ce.attr, &dev_attr_cmci_disabled.attr, NULL }; static cpumask_var_t mce_device_initialized; static void mce_device_release(struct device *dev) { kfree(dev); } /* Per cpu device init. All of the cpus still share the same ctrl bank: */ static int mce_device_create(unsigned int cpu) { struct device *dev; int err; int i, j; if (!mce_available(&boot_cpu_data)) return -EIO; dev = kzalloc(sizeof *dev, GFP_KERNEL); if (!dev) return -ENOMEM; dev->id = cpu; dev->bus = &mce_subsys; dev->release = &mce_device_release; err = device_register(dev); if (err) { put_device(dev); return err; } for (i = 0; mce_device_attrs[i]; i++) { err = device_create_file(dev, mce_device_attrs[i]); if (err) goto error; } for (j = 0; j < mca_cfg.banks; j++) { err = device_create_file(dev, &mce_banks[j].attr); if (err) goto error2; } cpumask_set_cpu(cpu, mce_device_initialized); per_cpu(mce_device, cpu) = dev; return 0; error2: while (--j >= 0) device_remove_file(dev, &mce_banks[j].attr); error: while (--i >= 0) device_remove_file(dev, mce_device_attrs[i]); device_unregister(dev); return err; } static void mce_device_remove(unsigned int cpu) { struct device *dev = per_cpu(mce_device, cpu); int i; if (!cpumask_test_cpu(cpu, mce_device_initialized)) return; for (i = 0; mce_device_attrs[i]; i++) device_remove_file(dev, mce_device_attrs[i]); for (i = 0; i < mca_cfg.banks; i++) device_remove_file(dev, &mce_banks[i].attr); device_unregister(dev); cpumask_clear_cpu(cpu, mce_device_initialized); per_cpu(mce_device, cpu) = NULL; } /* Make sure there are no machine checks on offlined CPUs. */ static void mce_disable_cpu(void *h) { unsigned long action = *(unsigned long *)h; if (!mce_available(raw_cpu_ptr(&cpu_info))) return; if (!(action & CPU_TASKS_FROZEN)) cmci_clear(); vendor_disable_error_reporting(); } static void mce_reenable_cpu(void *h) { unsigned long action = *(unsigned long *)h; int i; if (!mce_available(raw_cpu_ptr(&cpu_info))) return; if (!(action & CPU_TASKS_FROZEN)) cmci_reenable(); for (i = 0; i < mca_cfg.banks; i++) { struct mce_bank *b = &mce_banks[i]; if (b->init) wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl); } } /* Get notified when a cpu comes on/off. Be hotplug friendly. */ static int mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned long)hcpu; struct timer_list *t = &per_cpu(mce_timer, cpu); switch (action & ~CPU_TASKS_FROZEN) { case CPU_ONLINE: mce_device_create(cpu); if (threshold_cpu_callback) threshold_cpu_callback(action, cpu); break; case CPU_DEAD: if (threshold_cpu_callback) threshold_cpu_callback(action, cpu); mce_device_remove(cpu); mce_intel_hcpu_update(cpu); /* intentionally ignoring frozen here */ if (!(action & CPU_TASKS_FROZEN)) cmci_rediscover(); break; case CPU_DOWN_PREPARE: smp_call_function_single(cpu, mce_disable_cpu, &action, 1); del_timer_sync(t); break; case CPU_DOWN_FAILED: smp_call_function_single(cpu, mce_reenable_cpu, &action, 1); mce_start_timer(cpu, t); break; } return NOTIFY_OK; } static struct notifier_block mce_cpu_notifier = { .notifier_call = mce_cpu_callback, }; static __init void mce_init_banks(void) { int i; for (i = 0; i < mca_cfg.banks; i++) { struct mce_bank *b = &mce_banks[i]; struct device_attribute *a = &b->attr; sysfs_attr_init(&a->attr); a->attr.name = b->attrname; snprintf(b->attrname, ATTR_LEN, "bank%d", i); a->attr.mode = 0644; a->show = show_bank; a->store = set_bank; } } static __init int mcheck_init_device(void) { int err; int i = 0; if (!mce_available(&boot_cpu_data)) { err = -EIO; goto err_out; } if (!zalloc_cpumask_var(&mce_device_initialized, GFP_KERNEL)) { err = -ENOMEM; goto err_out; } mce_init_banks(); err = subsys_system_register(&mce_subsys, NULL); if (err) goto err_out_mem; cpu_notifier_register_begin(); for_each_online_cpu(i) { err = mce_device_create(i); if (err) { /* * Register notifier anyway (and do not unreg it) so * that we don't leave undeleted timers, see notifier * callback above. */ __register_hotcpu_notifier(&mce_cpu_notifier); cpu_notifier_register_done(); goto err_device_create; } } __register_hotcpu_notifier(&mce_cpu_notifier); cpu_notifier_register_done(); register_syscore_ops(&mce_syscore_ops); /* register character device /dev/mcelog */ err = misc_register(&mce_chrdev_device); if (err) goto err_register; return 0; err_register: unregister_syscore_ops(&mce_syscore_ops); err_device_create: /* * We didn't keep track of which devices were created above, but * even if we had, the set of online cpus might have changed. * Play safe and remove for every possible cpu, since * mce_device_remove() will do the right thing. */ for_each_possible_cpu(i) mce_device_remove(i); err_out_mem: free_cpumask_var(mce_device_initialized); err_out: pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err); return err; } device_initcall_sync(mcheck_init_device); /* * Old style boot options parsing. Only for compatibility. */ static int __init mcheck_disable(char *str) { mca_cfg.disabled = true; return 1; } __setup("nomce", mcheck_disable); #ifdef CONFIG_DEBUG_FS struct dentry *mce_get_debugfs_dir(void) { static struct dentry *dmce; if (!dmce) dmce = debugfs_create_dir("mce", NULL); return dmce; } static void mce_reset(void) { cpu_missing = 0; atomic_set(&mce_fake_panicked, 0); atomic_set(&mce_executing, 0); atomic_set(&mce_callin, 0); atomic_set(&global_nwo, 0); } static int fake_panic_get(void *data, u64 *val) { *val = fake_panic; return 0; } static int fake_panic_set(void *data, u64 val) { mce_reset(); fake_panic = val; return 0; } DEFINE_SIMPLE_ATTRIBUTE(fake_panic_fops, fake_panic_get, fake_panic_set, "%llu\n"); static int __init mcheck_debugfs_init(void) { struct dentry *dmce, *ffake_panic; dmce = mce_get_debugfs_dir(); if (!dmce) return -ENOMEM; ffake_panic = debugfs_create_file("fake_panic", 0444, dmce, NULL, &fake_panic_fops); if (!ffake_panic) return -ENOMEM; return 0; } #else static int __init mcheck_debugfs_init(void) { return -EINVAL; } #endif static int __init mcheck_late_init(void) { mcheck_debugfs_init(); /* * Flush out everything that has been logged during early boot, now that * everything has been initialized (workqueues, decoders, ...). */ mce_schedule_work(); return 0; } late_initcall(mcheck_late_init);