This H/W error log driver (a.k.a eMCA driver) is implemented based on
http://www.intel.com/content/www/us/en/architecture-and-technology/enhanced-mca-logging-xeon-paper.html

After errors are captured, more valuable information can be
got via this new enhanced H/W error log driver.

v3 -> v2: fix a MACRO definition error and some cleanup
v2 -> v1: eliminate spin_lock & minor fixes suggested by Boris

Signed-off-by: Chen, Gong <gong.c...@linux.intel.com>
---
 arch/x86/include/asm/mce.h       |   5 +
 arch/x86/kernel/cpu/mcheck/mce.c |  20 +++
 drivers/acpi/Kconfig             |  20 +++
 drivers/acpi/Makefile            |   2 +
 drivers/acpi/acpi_extlog.c       | 319 +++++++++++++++++++++++++++++++++++++++
 drivers/acpi/bus.c               |   3 +-
 include/linux/acpi.h             |   1 +
 7 files changed, 369 insertions(+), 1 deletion(-)
 create mode 100644 drivers/acpi/acpi_extlog.c

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index cbe6b9e..072b2f8 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -16,6 +16,7 @@
 #define MCG_EXT_CNT_SHIFT      16
 #define MCG_EXT_CNT(c)         (((c) & MCG_EXT_CNT_MASK) >> MCG_EXT_CNT_SHIFT)
 #define MCG_SER_P              (1ULL<<24)   /* MCA recovery/new status bits */
+#define MCG_ELOG_P             (1ULL<<26)   /* Extended error log supported */
 
 /* MCG_STATUS register defines */
 #define MCG_STATUS_RIPV  (1ULL<<0)   /* restart ip valid */
@@ -186,6 +187,10 @@ enum mcp_flags {
        MCP_UC = (1 << 1),              /* log uncorrected errors */
        MCP_DONTLOG = (1 << 2),         /* only clear, don't log */
 };
+
+void register_elog_handler(int (*f)(const char *, int, int));
+void unregister_elog_handler(int (*f)(const char *, int, int));
+
 void machine_check_poll(enum mcp_flags flags, mce_banks_t *b);
 
 int mce_notify_irq(void);
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index b3218cd..981e0d3 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -48,6 +48,8 @@
 
 #include "mce-internal.h"
 
+static int (*mce_ext_err_print)(const char *, int, int);
+
 static DEFINE_MUTEX(mce_chrdev_read_mutex);
 
 #define rcu_dereference_check_mce(p) \
@@ -576,6 +578,21 @@ static void mce_read_aux(struct mce *m, int i)
 
 DEFINE_PER_CPU(unsigned, mce_poll_count);
 
+void register_elog_handler(int (*f)(const char *, int, int))
+{
+       mce_ext_err_print = f;
+}
+EXPORT_SYMBOL_GPL(register_elog_handler);
+
+void unregister_elog_handler(int (*f)(const char *, int, int))
+{
+       if (f) {
+               WARN_ON(mce_ext_err_print != f);
+               mce_ext_err_print = NULL;
+       }
+}
+EXPORT_SYMBOL_GPL(unregister_elog_handler);
+
 /*
  * Poll for corrected events or events that happened before reset.
  * Those are just logged through /dev/mcelog.
@@ -624,6 +641,9 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t 
*b)
                    (m.status & (mca_cfg.ser ? MCI_STATUS_S : MCI_STATUS_UC)))
                        continue;
 
+               if (mce_ext_err_print)
+                       mce_ext_err_print(NULL, m.extcpu, i);
+
                mce_read_aux(&m, i);
 
                if (!(flags & MCP_TIMESTAMP))
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 22327e6..c67ec61 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -372,4 +372,24 @@ config ACPI_BGRT
 
 source "drivers/acpi/apei/Kconfig"
 
+config ACPI_EXTLOG
+       tristate "Extended Error Log support"
+       depends on X86_MCE
+       default n
+       help
+         Certain usages such as Predictive Failure Analysis (PFA) require
+         more information about the error than what can be described in
+         processor machine check banks. Most server processors log
+         additional information about the error in processor uncore
+         registers. Since the addresses and layout of these registers vary
+         widely from one processor to another, system software cannot
+         readily make use of them. To complicate matters further, some of
+         the additional error information cannot be constructed space
+         between "additional" and "error" without detailed knowledge
+         about platform topology.
+
+         Enhanced MCA Logging allows firmware to provide additional error
+         information to system software, synchronous with MCE or CMCI. This
+         driver adds support for that functionality.
+
 endif  # ACPI
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index cdaf68b..bce34af 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -82,3 +82,5 @@ processor-$(CONFIG_CPU_FREQ)  += processor_perflib.o
 obj-$(CONFIG_ACPI_PROCESSOR_AGGREGATOR) += acpi_pad.o
 
 obj-$(CONFIG_ACPI_APEI)                += apei/
+
+obj-$(CONFIG_ACPI_EXTLOG)      += acpi_extlog.o
diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
new file mode 100644
index 0000000..afeab59
--- /dev/null
+++ b/drivers/acpi/acpi_extlog.c
@@ -0,0 +1,319 @@
+/*
+ * Extended Error Log driver
+ *
+ * Copyright (C) 2013 Intel Corp.
+ * Author: Chen, Gong <gong.c...@intel.com>
+ *
+ * This file is licensed under GPLv2.
+ */
+
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
+#include <linux/cper.h>
+#include <linux/ratelimit.h>
+#include <asm/mce.h>
+
+#include "apei/apei-internal.h"
+
+#define EXT_ELOG_ENTRY_MASK    GENMASK_ULL(51, 0) /* elog entry address mask */
+
+#define EXTLOG_DSM_REV         0x0
+#define        EXTLOG_FN_QUERY         0x0
+#define        EXTLOG_FN_ADDR          0x1
+
+#define FLAG_OS_OPTIN          BIT(0)
+#define EXTLOG_QUERY_L1_EXIST  BIT(1)
+#define ELOG_ENTRY_VALID       (1ULL<<63)
+#define ELOG_ENTRY_LEN         0x1000
+
+#define EMCA_BUG \
+       "Can not request iomem region <0x%016llx-0x%016llx> - eMCA disabled\n"
+
+struct extlog_l1_head {
+       u32 ver;        /* Header Version */
+       u32 hdr_len;    /* Header Length */
+       u64 total_len;  /* entire L1 Directory length including this header */
+       u64 elog_base;  /* MCA Error Log Directory base address */
+       u64 elog_len;   /* MCA Error Log Directory length */
+       u32 flags;      /* bit 0 - OS/VMM Opt-in */
+       u8  rev0[12];
+       u32 entries;    /* Valid L1 Directory entries per logical processor */
+       u8  rev1[12];
+};
+
+static u8 extlog_dsm_uuid[] = "663E35AF-CC10-41A4-88EA-5470AF055295";
+
+/* L1 table related physical address */
+static u64 elog_base;
+static size_t elog_size;
+static u64 l1_dirbase;
+static size_t l1_size;
+
+/* L1 table related virtual address */
+static void __iomem *extlog_l1_addr;
+static void __iomem *elog_addr;
+
+static void *elog_buf;
+
+static u64 *l1_entry_base;
+static u32 l1_percpu_entry;
+
+#define ELOG_IDX(cpu, bank) \
+       (cpu_physical_id(cpu) * l1_percpu_entry + (bank))
+
+#define ELOG_ENTRY_DATA(idx) \
+       (*(l1_entry_base + (idx)))
+
+#define ELOG_ENTRY_ADDR(phyaddr) \
+       (phyaddr - elog_base + (u8 *)elog_addr)
+
+static struct acpi_generic_status *extlog_elog_entry_check(int cpu, int bank)
+{
+       int idx;
+       u64 data;
+       struct acpi_generic_status *estatus;
+
+       WARN_ON(cpu < 0);
+       idx = ELOG_IDX(cpu, bank);
+       data = ELOG_ENTRY_DATA(idx);
+       if ((data & ELOG_ENTRY_VALID) == 0)
+               return NULL;
+
+       data &= EXT_ELOG_ENTRY_MASK;
+       estatus = (struct acpi_generic_status *)ELOG_ENTRY_ADDR(data);
+
+       /* if no valid data in elog entry, just return */
+       if (estatus->block_status == 0)
+               return NULL;
+
+       return estatus;
+}
+
+static void __print_extlog_rcd(const char *pfx,
+                              struct acpi_generic_status *estatus, int cpu)
+{
+       static atomic_t seqno;
+       unsigned int curr_seqno;
+       char pfx_seq[64];
+
+       if (!pfx) {
+               if (estatus->error_severity <= CPER_SEV_CORRECTED)
+                       pfx = KERN_INFO;
+               else
+                       pfx = KERN_ERR;
+       }
+       curr_seqno = atomic_inc_return(&seqno);
+       snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}", pfx, curr_seqno);
+       printk("%s""Hardware error detected on CPU%d\n", pfx_seq, cpu);
+       cper_estatus_print(pfx_seq, estatus);
+}
+
+static int print_extlog_rcd(const char *pfx,
+                           struct acpi_generic_status *estatus, int cpu)
+{
+       /* Not more than 2 messages every 5 seconds */
+       static DEFINE_RATELIMIT_STATE(ratelimit_corrected, 5*HZ, 2);
+       static DEFINE_RATELIMIT_STATE(ratelimit_uncorrected, 5*HZ, 2);
+       struct ratelimit_state *ratelimit;
+
+       if (estatus->error_severity == CPER_SEV_CORRECTED ||
+           (estatus->error_severity == CPER_SEV_INFORMATIONAL))
+               ratelimit = &ratelimit_corrected;
+       else
+               ratelimit = &ratelimit_uncorrected;
+       if (__ratelimit(ratelimit)) {
+               __print_extlog_rcd(pfx, estatus, cpu);
+               return 0;
+       }
+
+       return 1;
+}
+
+static int extlog_print(const char *pfx, int cpu, int bank)
+{
+       struct acpi_generic_status *estatus;
+       int rc;
+
+       estatus = extlog_elog_entry_check(cpu, bank);
+       if (estatus == NULL)
+               return -EINVAL;
+
+       memcpy(elog_buf, (void *)estatus, ELOG_ENTRY_LEN);
+       /* clear record status to enable BIOS to update it again */
+       estatus->block_status = 0;
+
+       rc = print_extlog_rcd(pfx, (struct acpi_generic_status *)elog_buf, cpu);
+
+       return rc;
+}
+
+static int extlog_get_dsm(acpi_handle handle, int rev, int func, u64 *ret)
+{
+       struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
+       struct acpi_object_list input;
+       union acpi_object params[4], *obj;
+       u8 uuid[16];
+       int i;
+
+       acpi_str_to_uuid(extlog_dsm_uuid, uuid);
+       input.count = 4;
+       input.pointer = params;
+       params[0].type = ACPI_TYPE_BUFFER;
+       params[0].buffer.length = 16;
+       params[0].buffer.pointer = uuid;
+       params[1].type = ACPI_TYPE_INTEGER;
+       params[1].integer.value = rev;
+       params[2].type = ACPI_TYPE_INTEGER;
+       params[2].integer.value = func;
+       params[3].type = ACPI_TYPE_PACKAGE;
+       params[3].package.count = 0;
+       params[3].package.elements = NULL;
+
+       if (ACPI_FAILURE(acpi_evaluate_object(handle, "_DSM", &input, &buf)))
+               return -1;
+
+       *ret = 0;
+       obj = (union acpi_object *)buf.pointer;
+       if (obj->type == ACPI_TYPE_INTEGER) {
+               *ret = obj->integer.value;
+       } else if (obj->type == ACPI_TYPE_BUFFER) {
+               if (obj->buffer.length <= 8) {
+                       for (i = 0; i < obj->buffer.length; i++)
+                               *ret |= (obj->buffer.pointer[i] << (i * 8));
+               }
+       }
+       kfree(buf.pointer);
+
+       return 0;
+}
+
+static bool extlog_get_l1addr(void)
+{
+       acpi_handle handle;
+       u64 ret;
+
+       if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
+               return false;
+
+       if (extlog_get_dsm(handle, EXTLOG_DSM_REV, EXTLOG_FN_QUERY, &ret) ||
+           !(ret & EXTLOG_QUERY_L1_EXIST))
+               return false;
+
+       if (extlog_get_dsm(handle, EXTLOG_DSM_REV, EXTLOG_FN_ADDR, &ret))
+               return false;
+
+       l1_dirbase = ret;
+       /* Spec says L1 directory must be 4K aligned, bail out if it isn't */
+       if (l1_dirbase & ((1 << 12) - 1)) {
+               pr_warn(FW_BUG "L1 Directory is invalid at physical %llx\n",
+                       l1_dirbase);
+               return false;
+       }
+
+       return true;
+}
+
+static int __init extlog_init(void)
+{
+       struct extlog_l1_head *l1_head;
+       void __iomem *extlog_l1_hdr;
+       size_t l1_hdr_size;
+       struct resource *r;
+       u64 cap;
+       int rc;
+
+       rc = -ENODEV;
+
+       rdmsrl(MSR_IA32_MCG_CAP, cap);
+       if (!(cap & MCG_ELOG_P))
+               return rc;
+
+       if (!extlog_get_l1addr())
+               return rc;
+
+       rc = -EINVAL;
+       /* get L1 header to fetch necessary information */
+       l1_hdr_size = sizeof(struct extlog_l1_head);
+       r = request_mem_region(l1_dirbase, l1_hdr_size, "L1 DIR HDR");
+       if (!r) {
+               pr_warn(FW_BUG EMCA_BUG,
+                       (unsigned long long)l1_dirbase,
+                       (unsigned long long)l1_dirbase + l1_hdr_size);
+               goto err;
+       }
+
+       extlog_l1_hdr = acpi_os_map_memory(l1_dirbase, l1_hdr_size);
+       l1_head = (struct extlog_l1_head *)extlog_l1_hdr;
+       l1_size = l1_head->total_len;
+       l1_percpu_entry = l1_head->entries;
+       elog_base = l1_head->elog_base;
+       elog_size = l1_head->elog_len;
+       acpi_os_unmap_memory(extlog_l1_hdr, l1_hdr_size);
+       release_mem_region(l1_dirbase, l1_hdr_size);
+
+       /* remap L1 header again based on completed information */
+       r = request_mem_region(l1_dirbase, l1_size, "L1 Table");
+       if (!r) {
+               pr_warn(FW_BUG EMCA_BUG,
+                       (unsigned long long)l1_dirbase,
+                       (unsigned long long)l1_dirbase + l1_size);
+               goto err;
+       }
+       extlog_l1_addr = acpi_os_map_memory(l1_dirbase, l1_size);
+       l1_entry_base = (u64 *)((u8 *)extlog_l1_addr + l1_hdr_size);
+
+       /* remap elog table */
+       r = request_mem_region(elog_base, elog_size, "Elog Table");
+       if (!r) {
+               pr_warn(FW_BUG EMCA_BUG,
+                       (unsigned long long)elog_base,
+                       (unsigned long long)elog_base + elog_size);
+               goto err_release_l1_dir;
+       }
+       elog_addr = acpi_os_map_memory(elog_base, elog_size);
+
+       rc = -ENOMEM;
+       /* allocate buffer to save elog record */
+       elog_buf = kmalloc(ELOG_ENTRY_LEN, GFP_KERNEL);
+       if (elog_buf == NULL)
+               goto err_release_elog;
+
+       register_elog_handler(extlog_print);
+       /* enable OS to be involved to take over management from BIOS */
+       ((struct extlog_l1_head *)extlog_l1_addr)->flags |= FLAG_OS_OPTIN;
+
+       return 0;
+
+err_release_elog:
+       if (elog_addr)
+               acpi_os_unmap_memory(elog_addr, elog_size);
+       release_mem_region(elog_base, elog_size);
+err_release_l1_dir:
+       if (extlog_l1_addr)
+               acpi_os_unmap_memory(extlog_l1_addr, l1_size);
+       release_mem_region(l1_dirbase, l1_size);
+err:
+       pr_warn(FW_BUG "Extended error log disabled because of problems parsing 
f/w tables\n");
+       return rc;
+}
+
+static void __exit extlog_exit(void)
+{
+       unregister_elog_handler(extlog_print);
+       ((struct extlog_l1_head *)extlog_l1_addr)->flags &= ~FLAG_OS_OPTIN;
+       if (extlog_l1_addr)
+               acpi_os_unmap_memory(extlog_l1_addr, l1_size);
+       if (elog_addr)
+               acpi_os_unmap_memory(elog_addr, elog_size);
+       release_mem_region(elog_base, elog_size);
+       release_mem_region(l1_dirbase, l1_size);
+       kfree(elog_buf);
+}
+
+module_init(extlog_init);
+module_exit(extlog_exit);
+
+MODULE_AUTHOR("Chen, Gong <gong.c...@intel.com>");
+MODULE_DESCRIPTION("Extended Error Log Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index b587ec8..e1bd9a1 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -174,7 +174,7 @@ static void acpi_print_osc_error(acpi_handle handle,
        printk("\n");
 }
 
-static acpi_status acpi_str_to_uuid(char *str, u8 *uuid)
+acpi_status acpi_str_to_uuid(char *str, u8 *uuid)
 {
        int i;
        static int opc_map_to_uuid[16] = {6, 4, 2, 0, 11, 9, 16, 14, 19, 21,
@@ -195,6 +195,7 @@ static acpi_status acpi_str_to_uuid(char *str, u8 *uuid)
        }
        return AE_OK;
 }
+EXPORT_SYMBOL_GPL(acpi_str_to_uuid);
 
 acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
 {
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index a5db4ae..c30bac8 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -311,6 +311,7 @@ struct acpi_osc_context {
 #define OSC_INVALID_REVISION_ERROR     8
 #define OSC_CAPABILITIES_MASK_ERROR    16
 
+acpi_status acpi_str_to_uuid(char *str, u8 *uuid);
 acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
 
 /* platform-wide _OSC bits */
-- 
1.8.4.rc3

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