From f0f23e5469dc80b482d985898a930be0e249a162 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Sat, 3 Nov 2018 16:38:16 -0700 Subject: pstore: Map PSTORE_TYPE_* to strings In later patches we will need to map types to names, so create a constant table for that which can also be used in different parts of old and new code. This saves the type in the PRZ which will be useful in later patches. Instead of having an explicit PSTORE_TYPE_UNKNOWN, just use ..._MAX. This includes removing the now redundant filename templates which can use a single format string. Also, there's no reason to limit the "is it still compressed?" test to only PSTORE_TYPE_DMESG when building the pstorefs filename. Records are zero-initialized, so a backend would need to have explicitly set compressed=1. Signed-off-by: Joel Fernandes (Google) Co-developed-by: Kees Cook Signed-off-by: Kees Cook --- drivers/acpi/apei/erst.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/acpi') diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c index 3c5ea7cb693e..a5e1d963208e 100644 --- a/drivers/acpi/apei/erst.c +++ b/drivers/acpi/apei/erst.c @@ -1035,7 +1035,7 @@ skip: CPER_SECTION_TYPE_MCE) == 0) record->type = PSTORE_TYPE_MCE; else - record->type = PSTORE_TYPE_UNKNOWN; + record->type = PSTORE_TYPE_MAX; if (rcd->hdr.validation_bits & CPER_VALID_TIMESTAMP) record->time.tv_sec = rcd->hdr.timestamp; -- cgit v1.2.3 From ea84b580b95521644429cc6748b6c2bf27c8b0f3 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 30 Nov 2018 14:36:58 -0800 Subject: pstore: Convert buf_lock to semaphore Instead of running with interrupts disabled, use a semaphore. This should make it easier for backends that may need to sleep (e.g. EFI) when performing a write: |BUG: sleeping function called from invalid context at kernel/sched/completion.c:99 |in_atomic(): 1, irqs_disabled(): 1, pid: 2236, name: sig-xstate-bum |Preemption disabled at: |[] pstore_dump+0x72/0x330 |CPU: 26 PID: 2236 Comm: sig-xstate-bum Tainted: G D 4.20.0-rc3 #45 |Call Trace: | dump_stack+0x4f/0x6a | ___might_sleep.cold.91+0xd3/0xe4 | __might_sleep+0x50/0x90 | wait_for_completion+0x32/0x130 | virt_efi_query_variable_info+0x14e/0x160 | efi_query_variable_store+0x51/0x1a0 | efivar_entry_set_safe+0xa3/0x1b0 | efi_pstore_write+0x109/0x140 | pstore_dump+0x11c/0x330 | kmsg_dump+0xa4/0xd0 | oops_exit+0x22/0x30 ... Reported-by: Sebastian Andrzej Siewior Fixes: 21b3ddd39fee ("efi: Don't use spinlocks for efi vars") Signed-off-by: Kees Cook --- arch/powerpc/kernel/nvram_64.c | 2 -- drivers/acpi/apei/erst.c | 1 - drivers/firmware/efi/efi-pstore.c | 4 +--- fs/pstore/platform.c | 44 ++++++++++++++++++++------------------- fs/pstore/ram.c | 1 - include/linux/pstore.h | 7 +++---- 6 files changed, 27 insertions(+), 32 deletions(-) (limited to 'drivers/acpi') diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c index 22e9d281324d..e7d4ce6964ae 100644 --- a/arch/powerpc/kernel/nvram_64.c +++ b/arch/powerpc/kernel/nvram_64.c @@ -563,8 +563,6 @@ static int nvram_pstore_init(void) nvram_pstore_info.buf = oops_data; nvram_pstore_info.bufsize = oops_data_sz; - spin_lock_init(&nvram_pstore_info.buf_lock); - rc = pstore_register(&nvram_pstore_info); if (rc && (rc != -EPERM)) /* Print error only when pstore.backend == nvram */ diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c index a5e1d963208e..9953e50667ec 100644 --- a/drivers/acpi/apei/erst.c +++ b/drivers/acpi/apei/erst.c @@ -1176,7 +1176,6 @@ static int __init erst_init(void) "Error Record Serialization Table (ERST) support is initialized.\n"); buf = kmalloc(erst_erange.size, GFP_KERNEL); - spin_lock_init(&erst_info.buf_lock); if (buf) { erst_info.buf = buf + sizeof(struct cper_pstore_record); erst_info.bufsize = erst_erange.size - diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c index cfe87b465819..0f7d97917197 100644 --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -259,8 +259,7 @@ static int efi_pstore_write(struct pstore_record *record) efi_name[i] = name[i]; ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES, - !pstore_cannot_block_path(record->reason), - record->size, record->psi->buf); + preemptible(), record->size, record->psi->buf); if (record->reason == KMSG_DUMP_OOPS) efivar_run_worker(); @@ -369,7 +368,6 @@ static __init int efivars_pstore_init(void) return -ENOMEM; efi_pstore_info.bufsize = 1024; - spin_lock_init(&efi_pstore_info.buf_lock); if (pstore_register(&efi_pstore_info)) { kfree(efi_pstore_info.buf); diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 2387cb74f729..2d1066ed3c28 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -161,26 +161,27 @@ static const char *get_reason_str(enum kmsg_dump_reason reason) } } -bool pstore_cannot_block_path(enum kmsg_dump_reason reason) +/* + * Should pstore_dump() wait for a concurrent pstore_dump()? If + * not, the current pstore_dump() will report a failure to dump + * and return. + */ +static bool pstore_cannot_wait(enum kmsg_dump_reason reason) { - /* - * In case of NMI path, pstore shouldn't be blocked - * regardless of reason. - */ + /* In NMI path, pstore shouldn't block regardless of reason. */ if (in_nmi()) return true; switch (reason) { /* In panic case, other cpus are stopped by smp_send_stop(). */ case KMSG_DUMP_PANIC: - /* Emergency restart shouldn't be blocked by spin lock. */ + /* Emergency restart shouldn't be blocked. */ case KMSG_DUMP_EMERG: return true; default: return false; } } -EXPORT_SYMBOL_GPL(pstore_cannot_block_path); #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS) static int zbufsize_deflate(size_t size) @@ -400,23 +401,23 @@ static void pstore_dump(struct kmsg_dumper *dumper, unsigned long total = 0; const char *why; unsigned int part = 1; - unsigned long flags = 0; - int is_locked; int ret; why = get_reason_str(reason); - if (pstore_cannot_block_path(reason)) { - is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags); - if (!is_locked) { - pr_err("pstore dump routine blocked in %s path, may corrupt error record\n" - , in_nmi() ? "NMI" : why); + if (down_trylock(&psinfo->buf_lock)) { + /* Failed to acquire lock: give up if we cannot wait. */ + if (pstore_cannot_wait(reason)) { + pr_err("dump skipped in %s path: may corrupt error record\n", + in_nmi() ? "NMI" : why); + return; + } + if (down_interruptible(&psinfo->buf_lock)) { + pr_err("could not grab semaphore?!\n"); return; } - } else { - spin_lock_irqsave(&psinfo->buf_lock, flags); - is_locked = 1; } + oopscount++; while (total < kmsg_bytes) { char *dst; @@ -433,7 +434,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, record.part = part; record.buf = psinfo->buf; - if (big_oops_buf && is_locked) { + if (big_oops_buf) { dst = big_oops_buf; dst_size = big_oops_buf_sz; } else { @@ -451,7 +452,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, dst_size, &dump_size)) break; - if (big_oops_buf && is_locked) { + if (big_oops_buf) { zipped_len = pstore_compress(dst, psinfo->buf, header_size + dump_size, psinfo->bufsize); @@ -474,8 +475,8 @@ static void pstore_dump(struct kmsg_dumper *dumper, total += record.size; part++; } - if (is_locked) - spin_unlock_irqrestore(&psinfo->buf_lock, flags); + + up(&psinfo->buf_lock); } static struct kmsg_dumper pstore_dumper = { @@ -594,6 +595,7 @@ int pstore_register(struct pstore_info *psi) psi->write_user = pstore_write_user_compat; psinfo = psi; mutex_init(&psinfo->read_mutex); + sema_init(&psinfo->buf_lock, 1); spin_unlock(&pstore_lock); if (owner && !try_module_get(owner)) { diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index 202eaa82bcc6..e6d9560ea455 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -815,7 +815,6 @@ static int ramoops_probe(struct platform_device *pdev) err = -ENOMEM; goto fail_clear; } - spin_lock_init(&cxt->pstore.buf_lock); cxt->pstore.flags = PSTORE_FLAGS_DMESG; if (cxt->console_size) diff --git a/include/linux/pstore.h b/include/linux/pstore.h index a9ec285d85d1..b146181e8709 100644 --- a/include/linux/pstore.h +++ b/include/linux/pstore.h @@ -26,7 +26,7 @@ #include #include #include -#include +#include #include #include @@ -99,7 +99,7 @@ struct pstore_record { * @owner: module which is responsible for this backend driver * @name: name of the backend driver * - * @buf_lock: spinlock to serialize access to @buf + * @buf_lock: semaphore to serialize access to @buf * @buf: preallocated crash dump buffer * @bufsize: size of @buf available for crash dump bytes (must match * smallest number of bytes available for writing to a @@ -184,7 +184,7 @@ struct pstore_info { struct module *owner; char *name; - spinlock_t buf_lock; + struct semaphore buf_lock; char *buf; size_t bufsize; @@ -210,7 +210,6 @@ struct pstore_info { extern int pstore_register(struct pstore_info *); extern void pstore_unregister(struct pstore_info *); -extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason); struct pstore_ftrace_record { unsigned long ip; -- cgit v1.2.3