linux-kernel - [PATCH 3.16 039/306] pstore/ram: Use memcpy

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Message-ID: <lsq.1487198500.314322497@decadent.org.uk>
Date:   Wed, 15 Feb 2017 22:41:40 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Enric Balletbo Serra" <enric.balletbo@...labora.com>,
        "Puneet Kumar" <puneetster@...omium.org>,
        "Andrew Bresticker" <abrestic@...omium.org>,
        "Kees Cook" <keescook@...omium.org>
Subject: [PATCH 3.16 039/306] pstore/ram: Use memcpy_fromio() to save old
 buffer

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Bresticker <abrestic@...omium.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@...omium.org>
Signed-off-by: Enric Balletbo Serra <enric.balletbo@...labora.com>
Reviewed-by: Puneet Kumar <puneetster@...omium.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/pstore/ram_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -286,8 +286,8 @@ void persistent_ram_save_old(struct pers
 	}
 
 	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,