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-rw-r--r--arch/x86/kernel/cpu/mce/severity.c477
1 files changed, 477 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
new file mode 100644
index 000000000..00483d1c2
--- /dev/null
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -0,0 +1,477 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MCE grading rules.
+ * Copyright 2008, 2009 Intel Corporation.
+ *
+ * Author: Andi Kleen
+ */
+#include <linux/kernel.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include <asm/mce.h>
+#include <asm/intel-family.h>
+#include <asm/traps.h>
+#include <asm/insn.h>
+#include <asm/insn-eval.h>
+
+#include "internal.h"
+
+/*
+ * Grade an mce by severity. In general the most severe ones are processed
+ * first. Since there are quite a lot of combinations test the bits in a
+ * table-driven way. The rules are simply processed in order, first
+ * match wins.
+ *
+ * Note this is only used for machine check exceptions, the corrected
+ * errors use much simpler rules. The exceptions still check for the corrected
+ * errors, but only to leave them alone for the CMCI handler (except for
+ * panic situations)
+ */
+
+enum context { IN_KERNEL = 1, IN_USER = 2, IN_KERNEL_RECOV = 3 };
+enum ser { SER_REQUIRED = 1, NO_SER = 2 };
+enum exception { EXCP_CONTEXT = 1, NO_EXCP = 2 };
+
+static struct severity {
+ u64 mask;
+ u64 result;
+ unsigned char sev;
+ unsigned char mcgmask;
+ unsigned char mcgres;
+ unsigned char ser;
+ unsigned char context;
+ unsigned char excp;
+ unsigned char covered;
+ unsigned char cpu_model;
+ unsigned char cpu_minstepping;
+ unsigned char bank_lo, bank_hi;
+ char *msg;
+} severities[] = {
+#define MCESEV(s, m, c...) { .sev = MCE_ ## s ## _SEVERITY, .msg = m, ## c }
+#define BANK_RANGE(l, h) .bank_lo = l, .bank_hi = h
+#define MODEL_STEPPING(m, s) .cpu_model = m, .cpu_minstepping = s
+#define KERNEL .context = IN_KERNEL
+#define USER .context = IN_USER
+#define KERNEL_RECOV .context = IN_KERNEL_RECOV
+#define SER .ser = SER_REQUIRED
+#define NOSER .ser = NO_SER
+#define EXCP .excp = EXCP_CONTEXT
+#define NOEXCP .excp = NO_EXCP
+#define BITCLR(x) .mask = x, .result = 0
+#define BITSET(x) .mask = x, .result = x
+#define MCGMASK(x, y) .mcgmask = x, .mcgres = y
+#define MASK(x, y) .mask = x, .result = y
+#define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
+#define MCI_UC_AR (MCI_STATUS_UC|MCI_STATUS_AR)
+#define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
+#define MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
+
+ MCESEV(
+ NO, "Invalid",
+ BITCLR(MCI_STATUS_VAL)
+ ),
+ MCESEV(
+ NO, "Not enabled",
+ EXCP, BITCLR(MCI_STATUS_EN)
+ ),
+ MCESEV(
+ PANIC, "Processor context corrupt",
+ BITSET(MCI_STATUS_PCC)
+ ),
+ /* When MCIP is not set something is very confused */
+ MCESEV(
+ PANIC, "MCIP not set in MCA handler",
+ EXCP, MCGMASK(MCG_STATUS_MCIP, 0)
+ ),
+ /* Neither return not error IP -- no chance to recover -> PANIC */
+ MCESEV(
+ PANIC, "Neither restart nor error IP",
+ EXCP, MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
+ ),
+ MCESEV(
+ PANIC, "In kernel and no restart IP",
+ EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
+ ),
+ MCESEV(
+ PANIC, "In kernel and no restart IP",
+ EXCP, KERNEL_RECOV, MCGMASK(MCG_STATUS_RIPV, 0)
+ ),
+ MCESEV(
+ KEEP, "Corrected error",
+ NOSER, BITCLR(MCI_STATUS_UC)
+ ),
+ /*
+ * known AO MCACODs reported via MCE or CMC:
+ *
+ * SRAO could be signaled either via a machine check exception or
+ * CMCI with the corresponding bit S 1 or 0. So we don't need to
+ * check bit S for SRAO.
+ */
+ MCESEV(
+ AO, "Action optional: memory scrubbing error",
+ SER, MASK(MCI_UC_AR|MCACOD_SCRUBMSK, MCI_STATUS_UC|MCACOD_SCRUB)
+ ),
+ MCESEV(
+ AO, "Action optional: last level cache writeback error",
+ SER, MASK(MCI_UC_AR|MCACOD, MCI_STATUS_UC|MCACOD_L3WB)
+ ),
+ /*
+ * Quirk for Skylake/Cascade Lake. Patrol scrubber may be configured
+ * to report uncorrected errors using CMCI with a special signature.
+ * UC=0, MSCOD=0x0010, MCACOD=binary(000X 0000 1100 XXXX) reported
+ * in one of the memory controller banks.
+ * Set severity to "AO" for same action as normal patrol scrub error.
+ */
+ MCESEV(
+ AO, "Uncorrected Patrol Scrub Error",
+ SER, MASK(MCI_STATUS_UC|MCI_ADDR|0xffffeff0, MCI_ADDR|0x001000c0),
+ MODEL_STEPPING(INTEL_FAM6_SKYLAKE_X, 4), BANK_RANGE(13, 18)
+ ),
+
+ /* ignore OVER for UCNA */
+ MCESEV(
+ UCNA, "Uncorrected no action required",
+ SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
+ ),
+ MCESEV(
+ PANIC, "Illegal combination (UCNA with AR=1)",
+ SER,
+ MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR)
+ ),
+ MCESEV(
+ KEEP, "Non signaled machine check",
+ SER, BITCLR(MCI_STATUS_S)
+ ),
+
+ MCESEV(
+ PANIC, "Action required with lost events",
+ SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
+ ),
+
+ /* known AR MCACODs: */
+#ifdef CONFIG_MEMORY_FAILURE
+ MCESEV(
+ KEEP, "Action required but unaffected thread is continuable",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR, MCI_UC_SAR|MCI_ADDR),
+ MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, MCG_STATUS_RIPV)
+ ),
+ MCESEV(
+ AR, "Action required: data load in error recoverable area of kernel",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
+ KERNEL_RECOV
+ ),
+ MCESEV(
+ AR, "Action required: data load error in a user process",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
+ USER
+ ),
+ MCESEV(
+ AR, "Action required: instruction fetch error in a user process",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
+ USER
+ ),
+ MCESEV(
+ PANIC, "Data load in unrecoverable area of kernel",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
+ KERNEL
+ ),
+ MCESEV(
+ PANIC, "Instruction fetch error in kernel",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
+ KERNEL
+ ),
+#endif
+ MCESEV(
+ PANIC, "Action required: unknown MCACOD",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
+ ),
+
+ MCESEV(
+ SOME, "Action optional: unknown MCACOD",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S)
+ ),
+ MCESEV(
+ SOME, "Action optional with lost events",
+ SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_S)
+ ),
+
+ MCESEV(
+ PANIC, "Overflowed uncorrected",
+ BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
+ ),
+ MCESEV(
+ UC, "Uncorrected",
+ BITSET(MCI_STATUS_UC)
+ ),
+ MCESEV(
+ SOME, "No match",
+ BITSET(0)
+ ) /* always matches. keep at end */
+};
+
+#define mc_recoverable(mcg) (((mcg) & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) == \
+ (MCG_STATUS_RIPV|MCG_STATUS_EIPV))
+
+static bool is_copy_from_user(struct pt_regs *regs)
+{
+ u8 insn_buf[MAX_INSN_SIZE];
+ unsigned long addr;
+ struct insn insn;
+ int ret;
+
+ if (!regs)
+ return false;
+
+ if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
+ return false;
+
+ ret = insn_decode_kernel(&insn, insn_buf);
+ if (ret < 0)
+ return false;
+
+ switch (insn.opcode.value) {
+ /* MOV mem,reg */
+ case 0x8A: case 0x8B:
+ /* MOVZ mem,reg */
+ case 0xB60F: case 0xB70F:
+ addr = (unsigned long)insn_get_addr_ref(&insn, regs);
+ break;
+ /* REP MOVS */
+ case 0xA4: case 0xA5:
+ addr = regs->si;
+ break;
+ default:
+ return false;
+ }
+
+ if (fault_in_kernel_space(addr))
+ return false;
+
+ current->mce_vaddr = (void __user *)addr;
+
+ return true;
+}
+
+/*
+ * If mcgstatus indicated that ip/cs on the stack were
+ * no good, then "m->cs" will be zero and we will have
+ * to assume the worst case (IN_KERNEL) as we actually
+ * have no idea what we were executing when the machine
+ * check hit.
+ * If we do have a good "m->cs" (or a faked one in the
+ * case we were executing in VM86 mode) we can use it to
+ * distinguish an exception taken in user from from one
+ * taken in the kernel.
+ */
+static noinstr int error_context(struct mce *m, struct pt_regs *regs)
+{
+ int fixup_type;
+ bool copy_user;
+
+ if ((m->cs & 3) == 3)
+ return IN_USER;
+
+ if (!mc_recoverable(m->mcgstatus))
+ return IN_KERNEL;
+
+ /* Allow instrumentation around external facilities usage. */
+ instrumentation_begin();
+ fixup_type = ex_get_fixup_type(m->ip);
+ copy_user = is_copy_from_user(regs);
+ instrumentation_end();
+
+ switch (fixup_type) {
+ case EX_TYPE_UACCESS:
+ case EX_TYPE_COPY:
+ if (!copy_user)
+ return IN_KERNEL;
+ m->kflags |= MCE_IN_KERNEL_COPYIN;
+ fallthrough;
+
+ case EX_TYPE_FAULT_MCE_SAFE:
+ case EX_TYPE_DEFAULT_MCE_SAFE:
+ m->kflags |= MCE_IN_KERNEL_RECOV;
+ return IN_KERNEL_RECOV;
+
+ default:
+ return IN_KERNEL;
+ }
+}
+
+/* See AMD PPR(s) section Machine Check Error Handling. */
+static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)
+{
+ char *panic_msg = NULL;
+ int ret;
+
+ /*
+ * Default return value: Action required, the error must be handled
+ * immediately.
+ */
+ ret = MCE_AR_SEVERITY;
+
+ /* Processor Context Corrupt, no need to fumble too much, die! */
+ if (m->status & MCI_STATUS_PCC) {
+ panic_msg = "Processor Context Corrupt";
+ ret = MCE_PANIC_SEVERITY;
+ goto out;
+ }
+
+ if (m->status & MCI_STATUS_DEFERRED) {
+ ret = MCE_DEFERRED_SEVERITY;
+ goto out;
+ }
+
+ /*
+ * If the UC bit is not set, the system either corrected or deferred
+ * the error. No action will be required after logging the error.
+ */
+ if (!(m->status & MCI_STATUS_UC)) {
+ ret = MCE_KEEP_SEVERITY;
+ goto out;
+ }
+
+ /*
+ * On MCA overflow, without the MCA overflow recovery feature the
+ * system will not be able to recover, panic.
+ */
+ if ((m->status & MCI_STATUS_OVER) && !mce_flags.overflow_recov) {
+ panic_msg = "Overflowed uncorrected error without MCA Overflow Recovery";
+ ret = MCE_PANIC_SEVERITY;
+ goto out;
+ }
+
+ if (!mce_flags.succor) {
+ panic_msg = "Uncorrected error without MCA Recovery";
+ ret = MCE_PANIC_SEVERITY;
+ goto out;
+ }
+
+ if (error_context(m, regs) == IN_KERNEL) {
+ panic_msg = "Uncorrected unrecoverable error in kernel context";
+ ret = MCE_PANIC_SEVERITY;
+ }
+
+out:
+ if (msg && panic_msg)
+ *msg = panic_msg;
+
+ return ret;
+}
+
+static noinstr int mce_severity_intel(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)
+{
+ enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
+ enum context ctx = error_context(m, regs);
+ struct severity *s;
+
+ for (s = severities;; s++) {
+ if ((m->status & s->mask) != s->result)
+ continue;
+ if ((m->mcgstatus & s->mcgmask) != s->mcgres)
+ continue;
+ if (s->ser == SER_REQUIRED && !mca_cfg.ser)
+ continue;
+ if (s->ser == NO_SER && mca_cfg.ser)
+ continue;
+ if (s->context && ctx != s->context)
+ continue;
+ if (s->excp && excp != s->excp)
+ continue;
+ if (s->cpu_model && boot_cpu_data.x86_model != s->cpu_model)
+ continue;
+ if (s->cpu_minstepping && boot_cpu_data.x86_stepping < s->cpu_minstepping)
+ continue;
+ if (s->bank_lo && (m->bank < s->bank_lo || m->bank > s->bank_hi))
+ continue;
+ if (msg)
+ *msg = s->msg;
+ s->covered = 1;
+
+ if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL)
+ return MCE_PANIC_SEVERITY;
+
+ return s->sev;
+ }
+}
+
+int noinstr mce_severity(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)
+{
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
+ boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
+ return mce_severity_amd(m, regs, msg, is_excp);
+ else
+ return mce_severity_intel(m, regs, msg, is_excp);
+}
+
+#ifdef CONFIG_DEBUG_FS
+static void *s_start(struct seq_file *f, loff_t *pos)
+{
+ if (*pos >= ARRAY_SIZE(severities))
+ return NULL;
+ return &severities[*pos];
+}
+
+static void *s_next(struct seq_file *f, void *data, loff_t *pos)
+{
+ if (++(*pos) >= ARRAY_SIZE(severities))
+ return NULL;
+ return &severities[*pos];
+}
+
+static void s_stop(struct seq_file *f, void *data)
+{
+}
+
+static int s_show(struct seq_file *f, void *data)
+{
+ struct severity *ser = data;
+ seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
+ return 0;
+}
+
+static const struct seq_operations severities_seq_ops = {
+ .start = s_start,
+ .next = s_next,
+ .stop = s_stop,
+ .show = s_show,
+};
+
+static int severities_coverage_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &severities_seq_ops);
+}
+
+static ssize_t severities_coverage_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(severities); i++)
+ severities[i].covered = 0;
+ return count;
+}
+
+static const struct file_operations severities_coverage_fops = {
+ .open = severities_coverage_open,
+ .release = seq_release,
+ .read = seq_read,
+ .write = severities_coverage_write,
+ .llseek = seq_lseek,
+};
+
+static int __init severities_debugfs_init(void)
+{
+ struct dentry *dmce;
+
+ dmce = mce_get_debugfs_dir();
+
+ debugfs_create_file("severities-coverage", 0444, dmce, NULL,
+ &severities_coverage_fops);
+ return 0;
+}
+late_initcall(severities_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */
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