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, 5 insertions, 2 deletions

diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 4660aaa3195e..c668c861c96c 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -17,11 +17,12 @@
 #ifndef __LINUX_PSTORE_RAM_H__
 #define __LINUX_PSTORE_RAM_H__
 
+#include <linux/compiler.h>
 #include <linux/device.h>
+#include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/types.h>
-#include <linux/init.h>
 
 struct persistent_ram_buffer;
 struct rs_control;
@@ -59,7 +60,9 @@ void persistent_ram_free(struct persistent_ram_zone *prz);
 void persistent_ram_zap(struct persistent_ram_zone *prz);
 
 int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
-	unsigned int count);
+			 unsigned int count);
+int persistent_ram_write_user(struct persistent_ram_zone *prz,
+			      const void __user *s, unsigned int count);
 
 void persistent_ram_save_old(struct persistent_ram_zone *prz);
 size_t persistent_ram_old_size(struct persistent_ram_zone *prz);