From e0d59733f6b1796b8d6692642c87d7dd862c3e3a Mon Sep 17 00:00:00 2001 From: Seiji Aguchi Date: Wed, 30 Oct 2013 15:27:26 -0400 Subject: efivars, efi-pstore: Hold off deletion of sysfs entry until the scan is completed Currently, when mounting pstore file system, a read callback of efi_pstore driver runs mutiple times as below. - In the first read callback, scan efivar_sysfs_list from head and pass a kmsg buffer of a entry to an upper pstore layer. - In the second read callback, rescan efivar_sysfs_list from the entry and pass another kmsg buffer to it. - Repeat the scan and pass until the end of efivar_sysfs_list. In this process, an entry is read across the multiple read function calls. To avoid race between the read and erasion, the whole process above is protected by a spinlock, holding in open() and releasing in close(). At the same time, kmemdup() is called to pass the buffer to pstore filesystem during it. And then, it causes a following lockdep warning. To make the dynamic memory allocation runnable without taking spinlock, holding off a deletion of sysfs entry if it happens while scanning it via efi_pstore, and deleting it after the scan is completed. To implement it, this patch introduces two flags, scanning and deleting, to efivar_entry. On the code basis, it seems that all the scanning and deleting logic is not needed because __efivars->lock are not dropped when reading from the EFI variable store. But, the scanning and deleting logic is still needed because an efi-pstore and a pstore filesystem works as follows. In case an entry(A) is found, the pointer is saved to psi->data. And efi_pstore_read() passes the entry(A) to a pstore filesystem by releasing __efivars->lock. And then, the pstore filesystem calls efi_pstore_read() again and the same entry(A), which is saved to psi->data, is used for resuming to scan a sysfs-list. So, to protect the entry(A), the logic is needed. [ 1.143710] ------------[ cut here ]------------ [ 1.144058] WARNING: CPU: 1 PID: 1 at kernel/lockdep.c:2740 lockdep_trace_alloc+0x104/0x110() [ 1.144058] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) [ 1.144058] Modules linked in: [ 1.144058] CPU: 1 PID: 1 Comm: systemd Not tainted 3.11.0-rc5 #2 [ 1.144058] 0000000000000009 ffff8800797e9ae0 ffffffff816614a5 ffff8800797e9b28 [ 1.144058] ffff8800797e9b18 ffffffff8105510d 0000000000000080 0000000000000046 [ 1.144058] 00000000000000d0 00000000000003af ffffffff81ccd0c0 ffff8800797e9b78 [ 1.144058] Call Trace: [ 1.144058] [] dump_stack+0x54/0x74 [ 1.144058] [] warn_slowpath_common+0x7d/0xa0 [ 1.144058] [] warn_slowpath_fmt+0x4c/0x50 [ 1.144058] [] ? vsscanf+0x57f/0x7b0 [ 1.144058] [] lockdep_trace_alloc+0x104/0x110 [ 1.144058] [] __kmalloc_track_caller+0x50/0x280 [ 1.144058] [] ? efi_pstore_read_func.part.1+0x12b/0x170 [ 1.144058] [] kmemdup+0x20/0x50 [ 1.144058] [] efi_pstore_read_func.part.1+0x12b/0x170 [ 1.144058] [] ? efi_pstore_read_func.part.1+0x170/0x170 [ 1.144058] [] efi_pstore_read_func+0xb4/0xe0 [ 1.144058] [] __efivar_entry_iter+0xfb/0x120 [ 1.144058] [] efi_pstore_read+0x3f/0x50 [ 1.144058] [] pstore_get_records+0x9a/0x150 [ 1.158207] [] ? selinux_d_instantiate+0x1c/0x20 [ 1.158207] [] ? parse_options+0x80/0x80 [ 1.158207] [] pstore_fill_super+0xa5/0xc0 [ 1.158207] [] mount_single+0xa2/0xd0 [ 1.158207] [] pstore_mount+0x18/0x20 [ 1.158207] [] mount_fs+0x39/0x1b0 [ 1.158207] [] ? __alloc_percpu+0x10/0x20 [ 1.158207] [] vfs_kern_mount+0x63/0xf0 [ 1.158207] [] do_mount+0x23e/0xa20 [ 1.158207] [] ? strndup_user+0x4b/0xf0 [ 1.158207] [] SyS_mount+0x83/0xc0 [ 1.158207] [] system_call_fastpath+0x16/0x1b [ 1.158207] ---[ end trace 61981bc62de9f6f4 ]--- Signed-off-by: Seiji Aguchi Tested-by: Madper Xie Cc: stable@kernel.org Signed-off-by: Matt Fleming --- drivers/firmware/efi/efi-pstore.c | 143 +++++++++++++++++++++++++++++++++++--- drivers/firmware/efi/efivars.c | 12 ++-- drivers/firmware/efi/vars.c | 12 +++- 3 files changed, 151 insertions(+), 16 deletions(-) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c index 5002d50..6ce31e9 100644 --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -18,14 +18,12 @@ module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644); static int efi_pstore_open(struct pstore_info *psi) { - efivar_entry_iter_begin(); psi->data = NULL; return 0; } static int efi_pstore_close(struct pstore_info *psi) { - efivar_entry_iter_end(); psi->data = NULL; return 0; } @@ -91,19 +89,125 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data) __efivar_entry_get(entry, &entry->var.Attributes, &entry->var.DataSize, entry->var.Data); size = entry->var.DataSize; + memcpy(*cb_data->buf, entry->var.Data, + (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size)); - *cb_data->buf = kmemdup(entry->var.Data, size, GFP_KERNEL); - if (*cb_data->buf == NULL) - return -ENOMEM; return size; } +/** + * efi_pstore_scan_sysfs_enter + * @entry: scanning entry + * @next: next entry + * @head: list head + */ +static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos, + struct efivar_entry *next, + struct list_head *head) +{ + pos->scanning = true; + if (&next->list != head) + next->scanning = true; +} + +/** + * __efi_pstore_scan_sysfs_exit + * @entry: deleting entry + * @turn_off_scanning: Check if a scanning flag should be turned off + */ +static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry, + bool turn_off_scanning) +{ + if (entry->deleting) { + list_del(&entry->list); + efivar_entry_iter_end(); + efivar_unregister(entry); + efivar_entry_iter_begin(); + } else if (turn_off_scanning) + entry->scanning = false; +} + +/** + * efi_pstore_scan_sysfs_exit + * @pos: scanning entry + * @next: next entry + * @head: list head + * @stop: a flag checking if scanning will stop + */ +static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos, + struct efivar_entry *next, + struct list_head *head, bool stop) +{ + __efi_pstore_scan_sysfs_exit(pos, true); + if (stop) + __efi_pstore_scan_sysfs_exit(next, &next->list != head); +} + +/** + * efi_pstore_sysfs_entry_iter + * + * @data: function-specific data to pass to callback + * @pos: entry to begin iterating from + * + * You MUST call efivar_enter_iter_begin() before this function, and + * efivar_entry_iter_end() afterwards. + * + * It is possible to begin iteration from an arbitrary entry within + * the list by passing @pos. @pos is updated on return to point to + * the next entry of the last one passed to efi_pstore_read_func(). + * To begin iterating from the beginning of the list @pos must be %NULL. + */ +static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos) +{ + struct efivar_entry *entry, *n; + struct list_head *head = &efivar_sysfs_list; + int size = 0; + + if (!*pos) { + list_for_each_entry_safe(entry, n, head, list) { + efi_pstore_scan_sysfs_enter(entry, n, head); + + size = efi_pstore_read_func(entry, data); + efi_pstore_scan_sysfs_exit(entry, n, head, size < 0); + if (size) + break; + } + *pos = n; + return size; + } + + list_for_each_entry_safe_from((*pos), n, head, list) { + efi_pstore_scan_sysfs_enter((*pos), n, head); + + size = efi_pstore_read_func((*pos), data); + efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0); + if (size) + break; + } + *pos = n; + return size; +} + +/** + * efi_pstore_read + * + * This function returns a size of NVRAM entry logged via efi_pstore_write(). + * The meaning and behavior of efi_pstore/pstore are as below. + * + * size > 0: Got data of an entry logged via efi_pstore_write() successfully, + * and pstore filesystem will continue reading subsequent entries. + * size == 0: Entry was not logged via efi_pstore_write(), + * and efi_pstore driver will continue reading subsequent entries. + * size < 0: Failed to get data of entry logging via efi_pstore_write(), + * and pstore will stop reading entry. + */ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, int *count, struct timespec *timespec, char **buf, bool *compressed, struct pstore_info *psi) { struct pstore_read_data data; + ssize_t size; data.id = id; data.type = type; @@ -112,8 +216,17 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, data.compressed = compressed; data.buf = buf; - return __efivar_entry_iter(efi_pstore_read_func, &efivar_sysfs_list, &data, - (struct efivar_entry **)&psi->data); + *data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL); + if (!*data.buf) + return -ENOMEM; + + efivar_entry_iter_begin(); + size = efi_pstore_sysfs_entry_iter(&data, + (struct efivar_entry **)&psi->data); + efivar_entry_iter_end(); + if (size <= 0) + kfree(*data.buf); + return size; } static int efi_pstore_write(enum pstore_type_id type, @@ -184,9 +297,17 @@ static int efi_pstore_erase_func(struct efivar_entry *entry, void *data) return 0; } + if (entry->scanning) { + /* + * Skip deletion because this entry will be deleted + * after scanning is completed. + */ + entry->deleting = true; + } else + list_del(&entry->list); + /* found */ __efivar_entry_delete(entry); - list_del(&entry->list); return 1; } @@ -214,10 +335,12 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, efivar_entry_iter_begin(); found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry); - efivar_entry_iter_end(); - if (found) + if (found && !entry->scanning) { + efivar_entry_iter_end(); efivar_unregister(entry); + } else + efivar_entry_iter_end(); return 0; } diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c index 933eb02..3dc2482 100644 --- a/drivers/firmware/efi/efivars.c +++ b/drivers/firmware/efi/efivars.c @@ -383,12 +383,16 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, else if (__efivar_entry_delete(entry)) err = -EIO; - efivar_entry_iter_end(); - - if (err) + if (err) { + efivar_entry_iter_end(); return err; + } - efivar_unregister(entry); + if (!entry->scanning) { + efivar_entry_iter_end(); + efivar_unregister(entry); + } else + efivar_entry_iter_end(); /* It's dead Jim.... */ return count; diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 391c67b..b22659c 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -683,8 +683,16 @@ struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid, if (!found) return NULL; - if (remove) - list_del(&entry->list); + if (remove) { + if (entry->scanning) { + /* + * The entry will be deleted + * after scanning is completed. + */ + entry->deleting = true; + } else + list_del(&entry->list); + } return entry; } -- cgit v1.1 From fdeadb43fdf1e7d5698c027b555c389174548e5a Mon Sep 17 00:00:00 2001 From: Madper Xie Date: Fri, 29 Nov 2013 15:58:57 +0800 Subject: efi-pstore: Make efi-pstore return a unique id Pstore fs expects that backends provide a unique id which could avoid pstore making entries as duplication or denominating entries the same name. So I combine the timestamp, part and count into id. Signed-off-by: Madper Xie Cc: Seiji Aguchi Cc: stable@vger.kernel.org Signed-off-by: Matt Fleming --- drivers/firmware/efi/efi-pstore.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c index 6ce31e9..743fd42 100644 --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -37,6 +37,12 @@ struct pstore_read_data { char **buf; }; +static inline u64 generic_id(unsigned long timestamp, + unsigned int part, int count) +{ + return (timestamp * 100 + part) * 1000 + count; +} + static int efi_pstore_read_func(struct efivar_entry *entry, void *data) { efi_guid_t vendor = LINUX_EFI_CRASH_GUID; @@ -55,7 +61,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data) if (sscanf(name, "dump-type%u-%u-%d-%lu-%c", cb_data->type, &part, &cnt, &time, &data_type) == 5) { - *cb_data->id = part; + *cb_data->id = generic_id(time, part, cnt); *cb_data->count = cnt; cb_data->timespec->tv_sec = time; cb_data->timespec->tv_nsec = 0; @@ -65,7 +71,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data) *cb_data->compressed = false; } else if (sscanf(name, "dump-type%u-%u-%d-%lu", cb_data->type, &part, &cnt, &time) == 4) { - *cb_data->id = part; + *cb_data->id = generic_id(time, part, cnt); *cb_data->count = cnt; cb_data->timespec->tv_sec = time; cb_data->timespec->tv_nsec = 0; @@ -77,7 +83,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data) * which doesn't support holding * multiple logs, remains. */ - *cb_data->id = part; + *cb_data->id = generic_id(time, part, 0); *cb_data->count = 0; cb_data->timespec->tv_sec = time; cb_data->timespec->tv_nsec = 0; @@ -320,14 +326,16 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, char name[DUMP_NAME_LEN]; efi_char16_t efi_name[DUMP_NAME_LEN]; int found, i; + unsigned int part; - sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count, - time.tv_sec); + do_div(id, 1000); + part = do_div(id, 100); + sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec); for (i = 0; i < DUMP_NAME_LEN; i++) efi_name[i] = name[i]; - edata.id = id; + edata.id = part; edata.type = type; edata.count = count; edata.time = time; -- cgit v1.1 From fce7d3bfc0ae70ca2a57868f2a9708b13185fd1f Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 16 Dec 2013 14:39:40 +0000 Subject: x86/efi: Don't select EFI from certain special ACPI drivers Commit 7ea6c6c1 ("Move cper.c from drivers/acpi/apei to drivers/firmware/efi") results in CONFIG_EFI being enabled even when the user doesn't want this. Since ACPI APEI used to build fine without UEFI (and as far as I know also has no functional depency on it), at least in that case using a reverse dependency is wrong (and a straight one isn't needed). Whether the same is true for ACPI_EXTLOG I don't know - if there is a functional dependency, it should depend on EFI rather than selecting it. It certainly has (currently) no build dependency. Adjust Kconfig and build logic so that the bad dependency gets avoided. Signed-off-by: Jan Beulich Acked-by: Tony Luck Cc: Matt Fleming Link: http://lkml.kernel.org/r/52AF1EBC020000780010DBF9@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- drivers/firmware/Makefile | 1 + drivers/firmware/efi/Kconfig | 6 +++--- drivers/firmware/efi/Makefile | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/firmware') diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile index 299fad6b5..5373dc5 100644 --- a/drivers/firmware/Makefile +++ b/drivers/firmware/Makefile @@ -14,3 +14,4 @@ obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o obj-$(CONFIG_GOOGLE_FIRMWARE) += google/ obj-$(CONFIG_EFI) += efi/ +obj-$(CONFIG_UEFI_CPER) += efi/ diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 3150aa4..6aecbc8 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -36,7 +36,7 @@ config EFI_VARS_PSTORE_DEFAULT_DISABLE backend for pstore by default. This setting can be overridden using the efivars module's pstore_disable parameter. -config UEFI_CPER - def_bool n - endmenu + +config UEFI_CPER + bool diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index 9ba156d..6c2a41e 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -1,7 +1,7 @@ # # Makefile for linux kernel # -obj-y += efi.o vars.o +obj-$(CONFIG_EFI) += efi.o vars.o obj-$(CONFIG_EFI_VARS) += efivars.o obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o obj-$(CONFIG_UEFI_CPER) += cper.o -- cgit v1.1 From df36ac1bc2a166eef90785d584e4cfed6f52bd32 Mon Sep 17 00:00:00 2001 From: "Luck, Tony" Date: Wed, 18 Dec 2013 15:17:10 -0800 Subject: pstore: Don't allow high traffic options on fragile devices Some pstore backing devices use on board flash as persistent storage. These have limited numbers of write cycles so it is a poor idea to use them from high frequency operations. Signed-off-by: Tony Luck Signed-off-by: Linus Torvalds --- drivers/firmware/efi/efi-pstore.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c index 743fd42..4b9dc83 100644 --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -356,6 +356,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, static struct pstore_info efi_pstore_info = { .owner = THIS_MODULE, .name = "efi", + .flags = PSTORE_FLAGS_FRAGILE, .open = efi_pstore_open, .close = efi_pstore_close, .read = efi_pstore_read, -- cgit v1.1