pstore/pmsg: drop bounce buffer

Removing a bounce buffer copy operation in the pmsg driver path is
always better. We also gain in overall performance by not requesting
a vmalloc on every write as this can cause precious RT tasks, such
as user facing media operation, to stall while memory is being
reclaimed. Added a write_buf_user to the pstore functions, a backup
platform write_buf_user that uses the small buffer that is part of
the instance, and implemented a ramoops write_buf_user that only
supports PSTORE_TYPE_PMSG.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 50d475228d97..92013cc9cc8c 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -22,12 +22,13 @@
 #ifndef _LINUX_PSTORE_H
 #define _LINUX_PSTORE_H
 
-#include <linux/time.h>
+#include <linux/compiler.h>
+#include <linux/errno.h>
 #include <linux/kmsg_dump.h>
 #include <linux/mutex.h>
-#include <linux/types.h>
 #include <linux/spinlock.h>
-#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/types.h>
 
 /* types */
 enum pstore_type_id {
@@ -68,6 +69,10 @@ struct pstore_info {
 			enum kmsg_dump_reason reason, u64 *id,
 			unsigned int part, const char *buf, bool compressed,
 			size_t size, struct pstore_info *psi);
+	int		(*write_buf_user)(enum pstore_type_id type,
+			enum kmsg_dump_reason reason, u64 *id,
+			unsigned int part, const char __user *buf,
+			bool compressed, size_t size, struct pstore_info *psi);
 	int		(*erase)(enum pstore_type_id type, u64 id,
 			int count, struct timespec time,
 			struct pstore_info *psi);