[PATCH 3.10 295/319] pstore/ram: Use memcpy_fromio() to save old buffer

Willy Tarreau
2017-02-05T19:43:41Z

From: Andrew Bresticker <abrestic@chromium.org>

commit d771fdf94180de2bd811ac90cba75f0f346abf8d upstream.

The ramoops buffer may be mapped as either I/O memory or uncached
memory. On ARM64, this results in a device-type (strongly-ordered)
mapping. Since unnaligned accesses to device-type memory will
generate an alignment fault (regardless of whether or not strict
alignment checking is enabled), it is not safe to use memcpy().
memcpy_fromio() is guaranteed to only use aligned accesses, so use
that instead.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Enric Balletbo Serra <enric.balletbo@collabora.com>
Reviewed-by: Puneet Kumar <puneetster@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
fs/pstore/ram_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index eb42483..7df456d 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -286,8 +286,8 @@ void persistent_ram_save_old(struct persistent_ram_zone *prz)
}

prz->old_log_size = size;
- memcpy(prz->old_log, &buffer->data[start], size - start);
- memcpy(prz->old_log + size - start, &buffer->data[0], start);
+ memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
+ memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
}

int notrace persistent_ram_write(struct persistent_ram_zone *prz,
--
2.8.0.rc2.1.gbe9624a