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Subject[PATCH V2 5/9] efi: Add support for using efivars as a pstore backend
Date
EFI provides an area of nonvolatile storage managed by the firmware. We
can use this as a pstore backend to maintain copies of oopses, aiding
diagnosis.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
drivers/firmware/efivars.c | 191 +++++++++++++++++++++++++++++++++++++++++++-
include/linux/efi.h | 6 ++
2 files changed, 195 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 5f29aaf..2bbb226 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -78,6 +78,7 @@
#include <linux/kobject.h>
#include <linux/device.h>
#include <linux/slab.h>
+#include <linux/pstore.h>

#include <asm/uaccess.h>

@@ -89,6 +90,8 @@ MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);

+#define DUMP_NAME_LEN 52
+
/*
* The maximum size of VariableName + Data = 1024
* Therefore, it's reasonable to save that much
@@ -161,18 +164,28 @@ utf8_strsize(efi_char16_t *data, unsigned long maxlength)
}

static efi_status_t
-get_var_data(struct efivars *efivars, struct efi_variable *var)
+get_var_data_locked(struct efivars *efivars, struct efi_variable *var)
{
efi_status_t status;

- spin_lock(&efivars->lock);
var->DataSize = 1024;
status = efivars->ops->get_variable(var->VariableName,
&var->VendorGuid,
&var->Attributes,
&var->DataSize,
var->Data);
+ return status;
+}
+
+static efi_status_t
+get_var_data(struct efivars *efivars, struct efi_variable *var)
+{
+ efi_status_t status;
+
+ spin_lock(&efivars->lock);
+ status = get_var_data_locked(efivars, var);
spin_unlock(&efivars->lock);
+
if (status != EFI_SUCCESS) {
printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
status);
@@ -387,12 +400,176 @@ static struct kobj_type efivar_ktype = {
.default_attrs = def_attrs,
};

+static struct pstore_info efi_pstore_info;
+
static inline void
efivar_unregister(struct efivar_entry *var)
{
kobject_put(&var->kobj);
}

+#ifdef CONFIG_PSTORE
+
+static int efi_pstore_open(struct pstore_info *psi)
+{
+ struct efivars *efivars = psi->data;
+
+ spin_lock(&efivars->lock);
+ efivars->walk_entry = list_first_entry(&efivars->list,
+ struct efivar_entry, list);
+ return 0;
+}
+
+static int efi_pstore_close(struct pstore_info *psi)
+{
+ struct efivars *efivars = psi->data;
+
+ spin_unlock(&efivars->lock);
+ return 0;
+}
+
+static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
+ struct timespec *timespec, struct pstore_info *psi)
+{
+ efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+ struct efivars *efivars = psi->data;
+ char name[DUMP_NAME_LEN];
+ int i;
+ unsigned int part, size;
+ unsigned long time;
+
+ while (&efivars->walk_entry->list != &efivars->list) {
+ if (!efi_guidcmp(efivars->walk_entry->var.VendorGuid,
+ vendor)) {
+ for (i = 0; i < DUMP_NAME_LEN; i++) {
+ name[i] = efivars->walk_entry->var.VariableName[i];
+ }
+ if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
+ *id = part;
+ timespec->tv_sec = time;
+ timespec->tv_nsec = 0;
+ get_var_data_locked(efivars, &efivars->walk_entry->var);
+ size = efivars->walk_entry->var.DataSize;
+ memcpy(psi->buf, efivars->walk_entry->var.Data, size);
+ efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
+ struct efivar_entry, list);
+ return size;
+ }
+ }
+ efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
+ struct efivar_entry, list);
+ }
+ return 0;
+}
+
+static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
+ size_t size, struct pstore_info *psi)
+{
+ char name[DUMP_NAME_LEN];
+ char stub_name[DUMP_NAME_LEN];
+ efi_char16_t efi_name[DUMP_NAME_LEN];
+ efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+ struct efivars *efivars = psi->data;
+ struct efivar_entry *entry, *found = NULL;
+ int i;
+
+ sprintf(stub_name, "dump-type%u-%u-", type, part);
+ sprintf(name, "%s%lu", stub_name, get_seconds());
+
+ spin_lock(&efivars->lock);
+
+ for (i = 0; i < DUMP_NAME_LEN; i++)
+ efi_name[i] = stub_name[i];
+
+ /*
+ * Clean up any entries with the same name
+ */
+
+ list_for_each_entry(entry, &efivars->list, list) {
+ get_var_data_locked(efivars, &entry->var);
+
+ for (i = 0; i < DUMP_NAME_LEN; i++) {
+ if (efi_name[i] == 0) {
+ found = entry;
+ efivars->ops->set_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+ 0, NULL);
+ break;
+ } else if (efi_name[i] != entry->var.VariableName[i]) {
+ break;
+ }
+ }
+ }
+
+ if (found)
+ list_del(&found->list);
+
+ for (i = 0; i < DUMP_NAME_LEN; i++)
+ efi_name[i] = name[i];
+
+ efivars->ops->set_variable(efi_name, &vendor,
+ EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+ size, psi->buf);
+
+ spin_unlock(&efivars->lock);
+
+ if (found)
+ efivar_unregister(found);
+
+ if (size)
+ efivar_create_sysfs_entry(efivars, utf8_strsize(efi_name, DUMP_NAME_LEN * 2),
+ efi_name, &vendor);
+
+ return part;
+};
+
+static int efi_pstore_erase(enum pstore_type_id type, u64 id,
+ struct pstore_info *psi)
+{
+ efi_pstore_write(type, id, 0, psi);
+
+ return 0;
+}
+#else
+static int efi_pstore_open(struct pstore_info *psi)
+{
+ return 0;
+}
+
+static int efi_pstore_close(struct pstore_info *psi)
+{
+ return 0;
+}
+
+static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
+ struct timespec *time, struct pstore_info *psi)
+{
+ return -1;
+}
+
+static u64 efi_pstore_write(enum pstore_type_id type, int part, size_t size,
+ struct pstore_info *psi)
+{
+ return 0;
+}
+
+static int efi_pstore_erase(enum pstore_type_id type, u64 id,
+ struct pstore_info *psi)
+{
+ return 0;
+}
+#endif
+
+static struct pstore_info efi_pstore_info = {
+ .owner = THIS_MODULE,
+ .name = "efi",
+ .open = efi_pstore_open,
+ .close = efi_pstore_close,
+ .read = efi_pstore_read,
+ .write = efi_pstore_write,
+ .erase = efi_pstore_erase,
+};

static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
@@ -763,6 +940,16 @@ int register_efivars(struct efivars *efivars,
if (error)
unregister_efivars(efivars);

+ efivars->efi_pstore_info = efi_pstore_info;
+
+ efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
+ if (efivars->efi_pstore_info.buf) {
+ efivars->efi_pstore_info.bufsize = 1024;
+ efivars->efi_pstore_info.data = efivars;
+ mutex_init(&efivars->efi_pstore_info.buf_mutex);
+ pstore_register(&efivars->efi_pstore_info);
+ }
+
out:
kfree(variable_name);

diff --git a/include/linux/efi.h b/include/linux/efi.h
index ec25726..2362a0b 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -19,6 +19,7 @@
#include <linux/rtc.h>
#include <linux/ioport.h>
#include <linux/pfn.h>
+#include <linux/pstore.h>

#include <asm/page.h>
#include <asm/system.h>
@@ -232,6 +233,9 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
#define UV_SYSTEM_TABLE_GUID \
EFI_GUID( 0x3b13a7d4, 0x633e, 0x11dd, 0x93, 0xec, 0xda, 0x25, 0x56, 0xd8, 0x95, 0x93 )

+#define LINUX_EFI_CRASH_GUID \
+ EFI_GUID( 0xcfc8fc79, 0xbe2e, 0x4ddc, 0x97, 0xf0, 0x9f, 0x98, 0xbf, 0xe2, 0x98, 0xa0 )
+
typedef struct {
efi_guid_t guid;
unsigned long table;
@@ -458,6 +462,8 @@ struct efivars {
struct kset *kset;
struct bin_attribute *new_var, *del_var;
const struct efivar_operations *ops;
+ struct efivar_entry *walk_entry;
+ struct pstore_info efi_pstore_info;
};

int register_efivars(struct efivars *efivars,
--
1.7.6


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