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  A comment-only patch to a change the was due in part to an unpublished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

3 files changed, 165 insertions, 22 deletions

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;
 }