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ACPI, APEI, GHES, printk support for recoverable error via NMI
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Some APEI GHES recoverable errors are reported via NMI, but printk is
not safe in NMI context.

To solve the issue, a lock-less memory allocator is used to allocate
memory in NMI handler, save the error record into the allocated
memory, put the error record into a lock-less list.  On the other
hand, an irq_work is used to delay the operation from NMI context to
IRQ context.  The irq_work IRQ handler will remove nodes from
lock-less list, printk the error record and do some further processing
include recovery operation, then free the memory.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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Huang Ying authored and Len Brown committed Aug 3, 2011
1 parent 7f18427 commit 67eb2e9
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Showing 2 changed files with 193 additions and 18 deletions.
2 changes: 2 additions & 0 deletions drivers/acpi/apei/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@ config ACPI_APEI_GHES
bool "APEI Generic Hardware Error Source"
depends on ACPI_APEI && X86
select ACPI_HED
select LLIST
select GENERIC_ALLOCATOR
help
Generic Hardware Error Source provides a way to report
platform hardware errors (such as that from chipset). It
Expand Down
209 changes: 191 additions & 18 deletions drivers/acpi/apei/ghes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
* For more information about Generic Hardware Error Source, please
* refer to ACPI Specification version 4.0, section 17.3.2.6
*
* Copyright 2010 Intel Corp.
* Copyright 2010,2011 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* This program is free software; you can redistribute it and/or
Expand Down Expand Up @@ -42,6 +42,9 @@
#include <linux/mutex.h>
#include <linux/ratelimit.h>
#include <linux/vmalloc.h>
#include <linux/irq_work.h>
#include <linux/llist.h>
#include <linux/genalloc.h>
#include <acpi/apei.h>
#include <acpi/atomicio.h>
#include <acpi/hed.h>
Expand All @@ -53,6 +56,15 @@
#define GHES_PFX "GHES: "

#define GHES_ESTATUS_MAX_SIZE 65536
#define GHES_ESOURCE_PREALLOC_MAX_SIZE 65536

#define GHES_ESTATUS_POOL_MIN_ALLOC_ORDER 3

#define GHES_ESTATUS_NODE_LEN(estatus_len) \
(sizeof(struct ghes_estatus_node) + (estatus_len))
#define GHES_ESTATUS_FROM_NODE(estatus_node) \
((struct acpi_hest_generic_status *) \
((struct ghes_estatus_node *)(estatus_node) + 1))

/*
* One struct ghes is created for each generic hardware error source.
Expand All @@ -77,6 +89,11 @@ struct ghes {
};
};

struct ghes_estatus_node {
struct llist_node llnode;
struct acpi_hest_generic *generic;
};

int ghes_disable;
module_param_named(disable, ghes_disable, bool, 0);

Expand Down Expand Up @@ -124,6 +141,19 @@ static struct vm_struct *ghes_ioremap_area;
static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);
static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);

/*
* printk is not safe in NMI context. So in NMI handler, we allocate
* required memory from lock-less memory allocator
* (ghes_estatus_pool), save estatus into it, put them into lock-less
* list (ghes_estatus_llist), then delay printk into IRQ context via
* irq_work (ghes_proc_irq_work). ghes_estatus_size_request record
* required pool size by all NMI error source.
*/
static struct gen_pool *ghes_estatus_pool;
static unsigned long ghes_estatus_pool_size_request;
static struct llist_head ghes_estatus_llist;
static struct irq_work ghes_proc_irq_work;

static int ghes_ioremap_init(void)
{
ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
Expand Down Expand Up @@ -183,6 +213,55 @@ static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
__flush_tlb_one(vaddr);
}

static int ghes_estatus_pool_init(void)
{
ghes_estatus_pool = gen_pool_create(GHES_ESTATUS_POOL_MIN_ALLOC_ORDER, -1);
if (!ghes_estatus_pool)
return -ENOMEM;
return 0;
}

static void ghes_estatus_pool_free_chunk_page(struct gen_pool *pool,
struct gen_pool_chunk *chunk,
void *data)
{
free_page(chunk->start_addr);
}

static void ghes_estatus_pool_exit(void)
{
gen_pool_for_each_chunk(ghes_estatus_pool,
ghes_estatus_pool_free_chunk_page, NULL);
gen_pool_destroy(ghes_estatus_pool);
}

static int ghes_estatus_pool_expand(unsigned long len)
{
unsigned long i, pages, size, addr;
int ret;

ghes_estatus_pool_size_request += PAGE_ALIGN(len);
size = gen_pool_size(ghes_estatus_pool);
if (size >= ghes_estatus_pool_size_request)
return 0;
pages = (ghes_estatus_pool_size_request - size) / PAGE_SIZE;
for (i = 0; i < pages; i++) {
addr = __get_free_page(GFP_KERNEL);
if (!addr)
return -ENOMEM;
ret = gen_pool_add(ghes_estatus_pool, addr, PAGE_SIZE, -1);
if (ret)
return ret;
}

return 0;
}

static void ghes_estatus_pool_shrink(unsigned long len)
{
ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
}

static struct ghes *ghes_new(struct acpi_hest_generic *generic)
{
struct ghes *ghes;
Expand Down Expand Up @@ -344,13 +423,13 @@ static void ghes_clear_estatus(struct ghes *ghes)
ghes->flags &= ~GHES_TO_CLEAR;
}

static void ghes_do_proc(struct ghes *ghes)
static void ghes_do_proc(const struct acpi_hest_generic_status *estatus)
{
int sev, processed = 0;
struct acpi_hest_generic_data *gdata;

sev = ghes_severity(ghes->estatus->error_severity);
apei_estatus_for_each_section(ghes->estatus, gdata) {
sev = ghes_severity(estatus->error_severity);
apei_estatus_for_each_section(estatus, gdata) {
#ifdef CONFIG_X86_MCE
if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
CPER_SEC_PLATFORM_MEM)) {
Expand All @@ -363,27 +442,37 @@ static void ghes_do_proc(struct ghes *ghes)
}
}

static void __ghes_print_estatus(const char *pfx, struct ghes *ghes)
static void __ghes_print_estatus(const char *pfx,
const struct acpi_hest_generic *generic,
const struct acpi_hest_generic_status *estatus)
{
if (pfx == NULL) {
if (ghes_severity(ghes->estatus->error_severity) <=
if (ghes_severity(estatus->error_severity) <=
GHES_SEV_CORRECTED)
pfx = KERN_WARNING HW_ERR;
else
pfx = KERN_ERR HW_ERR;
}
printk("%s""Hardware error from APEI Generic Hardware Error Source: %d\n",
pfx, ghes->generic->header.source_id);
apei_estatus_print(pfx, ghes->estatus);
pfx, generic->header.source_id);
apei_estatus_print(pfx, estatus);
}

static void ghes_print_estatus(const char *pfx, struct ghes *ghes)
static void ghes_print_estatus(const char *pfx,
const struct acpi_hest_generic *generic,
const struct acpi_hest_generic_status *estatus)
{
/* Not more than 2 messages every 5 seconds */
static DEFINE_RATELIMIT_STATE(ratelimit, 5*HZ, 2);
static DEFINE_RATELIMIT_STATE(ratelimit_corrected, 5*HZ, 2);
static DEFINE_RATELIMIT_STATE(ratelimit_uncorrected, 5*HZ, 2);
struct ratelimit_state *ratelimit;

if (__ratelimit(&ratelimit))
__ghes_print_estatus(pfx, ghes);
if (ghes_severity(estatus->error_severity) <= GHES_SEV_CORRECTED)
ratelimit = &ratelimit_corrected;
else
ratelimit = &ratelimit_uncorrected;
if (__ratelimit(ratelimit))
__ghes_print_estatus(pfx, generic, estatus);
}

static int ghes_proc(struct ghes *ghes)
Expand All @@ -393,8 +482,8 @@ static int ghes_proc(struct ghes *ghes)
rc = ghes_read_estatus(ghes, 0);
if (rc)
goto out;
ghes_print_estatus(NULL, ghes);
ghes_do_proc(ghes);
ghes_print_estatus(NULL, ghes->generic, ghes->estatus);
ghes_do_proc(ghes->estatus);

out:
ghes_clear_estatus(ghes);
Expand Down Expand Up @@ -453,6 +542,40 @@ static int ghes_notify_sci(struct notifier_block *this,
return ret;
}

static void ghes_proc_in_irq(struct irq_work *irq_work)
{
struct llist_node *llnode, *next, *tail = NULL;
struct ghes_estatus_node *estatus_node;
struct acpi_hest_generic_status *estatus;
u32 len, node_len;

/*
* Because the time order of estatus in list is reversed,
* revert it back to proper order.
*/
llnode = llist_del_all(&ghes_estatus_llist);
while (llnode) {
next = llnode->next;
llnode->next = tail;
tail = llnode;
llnode = next;
}
llnode = tail;
while (llnode) {
next = llnode->next;
estatus_node = llist_entry(llnode, struct ghes_estatus_node,
llnode);
estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
len = apei_estatus_len(estatus);
node_len = GHES_ESTATUS_NODE_LEN(len);
ghes_do_proc(estatus);
ghes_print_estatus(NULL, estatus_node->generic, estatus);
gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
node_len);
llnode = next;
}
}

static int ghes_notify_nmi(struct notifier_block *this,
unsigned long cmd, void *data)
{
Expand Down Expand Up @@ -482,20 +605,40 @@ static int ghes_notify_nmi(struct notifier_block *this,

if (sev_global >= GHES_SEV_PANIC) {
oops_begin();
__ghes_print_estatus(KERN_EMERG HW_ERR, ghes_global);
__ghes_print_estatus(KERN_EMERG HW_ERR, ghes_global->generic,
ghes_global->estatus);
/* reboot to log the error! */
if (panic_timeout == 0)
panic_timeout = ghes_panic_timeout;
panic("Fatal hardware error!");
}

list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
u32 len, node_len;
struct ghes_estatus_node *estatus_node;
struct acpi_hest_generic_status *estatus;
#endif
if (!(ghes->flags & GHES_TO_CLEAR))
continue;
/* Do not print estatus because printk is not NMI safe */
ghes_do_proc(ghes);
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
/* Save estatus for further processing in IRQ context */
len = apei_estatus_len(ghes->estatus);
node_len = GHES_ESTATUS_NODE_LEN(len);
estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool,
node_len);
if (estatus_node) {
estatus_node->generic = ghes->generic;
estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
memcpy(estatus, ghes->estatus, len);
llist_add(&estatus_node->llnode, &ghes_estatus_llist);
}
#endif
ghes_clear_estatus(ghes);
}
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
irq_work_queue(&ghes_proc_irq_work);
#endif

out:
raw_spin_unlock(&ghes_nmi_lock);
Expand All @@ -510,10 +653,26 @@ static struct notifier_block ghes_notifier_nmi = {
.notifier_call = ghes_notify_nmi,
};

static unsigned long ghes_esource_prealloc_size(
const struct acpi_hest_generic *generic)
{
unsigned long block_length, prealloc_records, prealloc_size;

block_length = min_t(unsigned long, generic->error_block_length,
GHES_ESTATUS_MAX_SIZE);
prealloc_records = max_t(unsigned long,
generic->records_to_preallocate, 1);
prealloc_size = min_t(unsigned long, block_length * prealloc_records,
GHES_ESOURCE_PREALLOC_MAX_SIZE);

return prealloc_size;
}

static int __devinit ghes_probe(struct platform_device *ghes_dev)
{
struct acpi_hest_generic *generic;
struct ghes *ghes = NULL;
unsigned long len;
int rc = -EINVAL;

generic = *(struct acpi_hest_generic **)ghes_dev->dev.platform_data;
Expand Down Expand Up @@ -579,6 +738,8 @@ static int __devinit ghes_probe(struct platform_device *ghes_dev)
mutex_unlock(&ghes_list_mutex);
break;
case ACPI_HEST_NOTIFY_NMI:
len = ghes_esource_prealloc_size(generic);
ghes_estatus_pool_expand(len);
mutex_lock(&ghes_list_mutex);
if (list_empty(&ghes_nmi))
register_die_notifier(&ghes_notifier_nmi);
Expand All @@ -603,6 +764,7 @@ static int __devexit ghes_remove(struct platform_device *ghes_dev)
{
struct ghes *ghes;
struct acpi_hest_generic *generic;
unsigned long len;

ghes = platform_get_drvdata(ghes_dev);
generic = ghes->generic;
Expand Down Expand Up @@ -633,6 +795,8 @@ static int __devexit ghes_remove(struct platform_device *ghes_dev)
* freed after NMI handler finishes.
*/
synchronize_rcu();
len = ghes_esource_prealloc_size(generic);
ghes_estatus_pool_shrink(len);
break;
default:
BUG();
Expand Down Expand Up @@ -673,14 +837,20 @@ static int __init ghes_init(void)
return -EINVAL;
}

init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);

rc = ghes_ioremap_init();
if (rc)
goto err;

rc = platform_driver_register(&ghes_platform_driver);
rc = ghes_estatus_pool_init();
if (rc)
goto err_ioremap_exit;

rc = platform_driver_register(&ghes_platform_driver);
if (rc)
goto err_pool_exit;

rc = apei_osc_setup();
if (rc == 0 && osc_sb_apei_support_acked)
pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.\n");
Expand All @@ -692,6 +862,8 @@ static int __init ghes_init(void)
pr_info(GHES_PFX "Failed to enable APEI firmware first mode.\n");

return 0;
err_pool_exit:
ghes_estatus_pool_exit();
err_ioremap_exit:
ghes_ioremap_exit();
err:
Expand All @@ -701,6 +873,7 @@ static int __init ghes_init(void)
static void __exit ghes_exit(void)
{
platform_driver_unregister(&ghes_platform_driver);
ghes_estatus_pool_exit();
ghes_ioremap_exit();
}

Expand Down

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