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Subject[PATCH 4/9] ACPI, APEI, GHES, printk support for recoverable error via NMI
Date
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, a 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>
---
drivers/acpi/apei/Kconfig | 2
drivers/acpi/apei/ghes.c | 193 ++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 181 insertions(+), 14 deletions(-)
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -12,6 +12,8 @@ config ACPI_APEI_GHES
tristate "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
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -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
@@ -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>
@@ -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.
@@ -77,6 +89,11 @@ struct ghes {
};
};

+struct ghes_estatus_node {
+ struct llist_node llnode;
+ struct acpi_hest_generic *generic;
+};
+
static int ghes_panic_timeout __read_mostly = 30;

/*
@@ -121,6 +138,19 @@ static struct vm_struct *ghes_ioremap_ar
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,
@@ -180,6 +210,55 @@ static void ghes_iounmap_irq(void __iome
__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;
@@ -341,13 +420,13 @@ static void ghes_clear_estatus(struct gh
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)) {
@@ -360,13 +439,15 @@ static void ghes_do_proc(struct ghes *gh
}
}

-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);

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
@@ -375,8 +456,8 @@ static void ghes_print_estatus(const cha
if (__ratelimit(&ratelimit)) {
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);
}
}

@@ -387,8 +468,8 @@ 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);
@@ -447,6 +528,40 @@ static int ghes_notify_sci(struct notifi
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)
{
@@ -476,7 +591,8 @@ static int ghes_notify_nmi(struct notifi

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;
@@ -484,12 +600,31 @@ static int ghes_notify_nmi(struct notifi
}

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);
@@ -504,10 +639,26 @@ static struct notifier_block ghes_notifi
.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;
@@ -573,6 +724,8 @@ static int __devinit ghes_probe(struct p
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);
@@ -597,6 +750,7 @@ static int __devexit ghes_remove(struct
{
struct ghes *ghes;
struct acpi_hest_generic *generic;
+ unsigned long len;

ghes = platform_get_drvdata(ghes_dev);
generic = ghes->generic;
@@ -627,6 +781,8 @@ static int __devexit ghes_remove(struct
* freed after NMI handler finishes.
*/
synchronize_rcu();
+ len = ghes_esource_prealloc_size(generic);
+ ghes_estatus_pool_shrink(len);
break;
default:
BUG();
@@ -662,15 +818,23 @@ 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;
+
return 0;
+err_pool_exit:
+ ghes_estatus_pool_exit();
err_ioremap_exit:
ghes_ioremap_exit();
err:
@@ -680,6 +844,7 @@ err:
static void __exit ghes_exit(void)
{
platform_driver_unregister(&ghes_platform_driver);
+ ghes_estatus_pool_exit();
ghes_ioremap_exit();
}


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