Merge branch 'x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 and EFI fixes from Peter Anvin:
 "Half of these are EFI-related:

  The by far biggest change is the change to hold off the deletion of a
  sysfs entry while a backend scan is in progress.  This is to avoid
  calling kmemdup() while under a spinlock.

  The other major change is for each entry in the EFI pstore backend to
  get a unique identifier, as required by the pstore filesystem proper.

  The other changes are:

  A fix to the recent consolidation and optimization of using "asm goto"
  with read-modify-write operation, which broke the bitops; specifically
  in such a way that we could end up generating invalid code.

  A build hack to make sure we compile with -mno-sse.  icc, and most
  likely future versions of gcc, can generate SSE instructions unless we
  tell it not to.

  A comment-only patch to a change the was due in part to an unpublished
  erratum; now when the erratum is published we want to add a comment
  explaining why"

* 'x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic, doc: Justification for disabling IO APIC before Local APIC
  x86, bitops: Correct the assembly constraints to testing bitops
  x86-64, build: Always pass in -mno-sse
  efi-pstore: Make efi-pstore return a unique id
  x86/efi: Fix earlyprintk off-by-one bug
  efivars, efi-pstore: Hold off deletion of sysfs entry until the scan is completed

12 files changed, 201 insertions, 37 deletions

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 41250fb33985..eda00f9be0cf 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -31,6 +31,9 @@ ifeq ($(CONFIG_X86_32),y)
 
         KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
 
+        # Don't autogenerate SSE instructions
+        KBUILD_CFLAGS += -mno-sse
+
         # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
         # with nonstandard options
         KBUILD_CFLAGS += -fno-pic
@@ -57,8 +60,11 @@ else
         KBUILD_AFLAGS += -m64
         KBUILD_CFLAGS += -m64
 
+        # Don't autogenerate SSE instructions
+        KBUILD_CFLAGS += -mno-sse
+
         # Use -mpreferred-stack-boundary=3 if supported.
-        KBUILD_CFLAGS += $(call cc-option,-mno-sse -mpreferred-stack-boundary=3)
+        KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)
 
         # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
         cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index da31c8b8a92d..b17f4f48ecd7 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -77,7 +77,7 @@ static inline void atomic_sub(int i, atomic_t *v)
  */
 static inline int atomic_sub_and_test(int i, atomic_t *v)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, i, "%0", "e");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e");
 }
 
 /**
@@ -141,7 +141,7 @@ static inline int atomic_inc_and_test(atomic_t *v)
  */
 static inline int atomic_add_negative(int i, atomic_t *v)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, i, "%0", "s");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", "s");
 }
 
 /**
diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
index 3f065c985aee..46e9052bbd28 100644
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -72,7 +72,7 @@ static inline void atomic64_sub(long i, atomic64_t *v)
  */
 static inline int atomic64_sub_and_test(long i, atomic64_t *v)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, i, "%0", "e");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, "er", i, "%0", "e");
 }
 
 /**
@@ -138,7 +138,7 @@ static inline int atomic64_inc_and_test(atomic64_t *v)
  */
 static inline int atomic64_add_negative(long i, atomic64_t *v)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, i, "%0", "s");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, "er", i, "%0", "s");
 }
 
 /**
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 6d76d0935989..9fc1af74dc83 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -205,7 +205,7 @@ static inline void change_bit(long nr, volatile unsigned long *addr)
  */
 static inline int test_and_set_bit(long nr, volatile unsigned long *addr)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, nr, "%0", "c");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", "c");
 }
 
 /**
@@ -251,7 +251,7 @@ static inline int __test_and_set_bit(long nr, volatile unsigned long *addr)
  */
 static inline int test_and_clear_bit(long nr, volatile unsigned long *addr)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, nr, "%0", "c");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", "c");
 }
 
 /**
@@ -304,7 +304,7 @@ static inline int __test_and_change_bit(long nr, volatile unsigned long *addr)
  */
 static inline int test_and_change_bit(long nr, volatile unsigned long *addr)
 {
-        GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, nr, "%0", "c");
+        GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", "c");
 }
 
 static __always_inline int constant_test_bit(long nr, const volatile unsigned long *addr)
diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
index 5b23e605e707..4ad6560847b1 100644
--- a/arch/x86/include/asm/local.h
+++ b/arch/x86/include/asm/local.h
@@ -52,7 +52,7 @@ static inline void local_sub(long i, local_t *l)
  */
 static inline int local_sub_and_test(long i, local_t *l)
 {
-        GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, i, "%0", "e");
+        GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", "e");
 }
 
 /**
@@ -92,7 +92,7 @@ static inline int local_inc_and_test(local_t *l)
  */
 static inline int local_add_negative(long i, local_t *l)
 {
-        GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, i, "%0", "s");
+        GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", "s");
 }
 
 /**
diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
index 1ff990f1de8e..8f7866a5b9a4 100644
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -16,8 +16,8 @@ cc_label:								\
 #define GEN_UNARY_RMWcc(op, var, arg0, cc)                              \
         __GEN_RMWcc(op " " arg0, var, cc)
 
-#define GEN_BINARY_RMWcc(op, var, val, arg0, cc)                        \
-        __GEN_RMWcc(op " %1, " arg0, var, cc, "er" (val))
+#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                  \
+        __GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val))
 
 #else /* !CC_HAVE_ASM_GOTO */
 
@@ -33,8 +33,8 @@ do {									\
 #define GEN_UNARY_RMWcc(op, var, arg0, cc)                              \
         __GEN_RMWcc(op " " arg0, var, cc)
 
-#define GEN_BINARY_RMWcc(op, var, val, arg0, cc)                        \
-        __GEN_RMWcc(op " %2, " arg0, var, cc, "er" (val))
+#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                  \
+        __GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val))
 
 #endif /* CC_HAVE_ASM_GOTO */
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index da3c599584a3..c752cb43e52f 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -558,6 +558,17 @@ void native_machine_shutdown(void)
 {
         /* Stop the cpus and apics */
 #ifdef CONFIG_X86_IO_APIC
+        /*
+         * Disabling IO APIC before local APIC is a workaround for
+         * erratum AVR31 in "Intel Atom Processor C2000 Product Family
+         * Specification Update". In this situation, interrupts that target
+         * a Logical Processor whose Local APIC is either in the process of
+         * being hardware disabled or software disabled are neither delivered
+         * nor discarded. When this erratum occurs, the processor may hang.
+         *
+         * Even without the erratum, it still makes sense to quiet IO APIC
+         * before disabling Local APIC.
+         */
         disable_IO_APIC();
 #endif
 
diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c
index 6599a0027b76..81b506d5befd 100644
--- a/arch/x86/platform/efi/early_printk.c
+++ b/arch/x86/platform/efi/early_printk.c
@@ -142,7 +142,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
                         efi_y += font->height;
                 }
 
-                if (efi_y + font->height >= si->lfb_height) {
+                if (efi_y + font->height > si->lfb_height) {
                         u32 i;
 
                         efi_y -= font->height;
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 5002d50e3781..743fd426f21b 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;
 }
@@ -39,6 +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;
@@ -57,7 +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;
@@ -67,7 +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;
@@ -79,7 +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;
@@ -91,19 +95,125 @@ 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 +222,17 @@ 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 +303,17 @@ 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;
 }
@@ -199,14 +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;
@@ -214,10 +343,12 @@ 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 933eb027d527..3dc248239197 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 391c67b182d9..b22659cccca4 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;
 }
diff --git a/include/linux/efi.h b/include/linux/efi.h
index bc5687d0f315..11ce6784a196 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -801,6 +801,8 @@ struct efivar_entry {
         struct efi_variable var;
         struct list_head list;
         struct kobject kobj;
+        bool scanning;
+        bool deleting;
 };
 
 
@@ -866,6 +868,8 @@ void efivar_run_worker(void);
 #if defined(CONFIG_EFI_VARS) || defined(CONFIG_EFI_VARS_MODULE)
 int efivars_sysfs_init(void);
 
+#define EFIVARS_DATA_SIZE_MAX 1024
+
 #endif /* CONFIG_EFI_VARS */
 
 #endif /* _LINUX_EFI_H */