Skip to content

Commit

Permalink
efi: Add support for using efivars as a pstore backend
Browse files Browse the repository at this point in the history 
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>
Signed-off-by: Tony Luck <tony.luck@intel.com>
  • Loading branch information
Matthew Garrett authored and Tony Luck committed Jul 22, 2011
1 parent dee28e7 commit 5ee9c19
Show file tree
Hide file tree
Showing 2 changed files with 195 additions and 2 deletions.
191 changes: 189 additions & 2 deletions drivers/firmware/efivars.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@
#include <linux/kobject.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/pstore.h>

#include <asm/uaccess.h>

Expand All @@ -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
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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);

Expand Down
6 changes: 6 additions & 0 deletions include/linux/efi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -211,6 +212,9 @@ typedef efi_status_t efi_set_virtual_address_map_t (unsigned long memory_map_siz
#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;
Expand Down Expand Up @@ -426,6 +430,8 @@ 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,
Expand Down

0 comments on commit 5ee9c19

Please sign in to comment.