MIPS: ftrace: Fix icache flush range error
authorViller Hsiao <villerhsiao@gmail.com>
Sat, 22 Feb 2014 07:46:49 +0000 (15:46 +0800)
committerRalf Baechle <ralf@linux-mips.org>
Mon, 17 Mar 2014 14:42:07 +0000 (15:42 +0100)
In 32-bit mode, the start address passed to flush_icache_range is
shifted by 4 bytes before the second safe_store_code() call.

This causes system crash from time to time because the first 4 bytes
might not be flushed properly. This bug exists since linux-3.8.

Also remove obsoleted comment while at it.

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: rostedt@goodmis.org
Cc: fweisbec@gmail.com
Cc: mingo@redhat.com
Cc: Qais.Yousef@imgtec.com
Patchwork: https://patchwork.linux-mips.org/patch/6586/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
arch/mips/kernel/ftrace.c

index 185ba25..374ed74 100644 (file)
@@ -111,11 +111,10 @@ static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
        safe_store_code(new_code1, ip, faulted);
        if (unlikely(faulted))
                return -EFAULT;
-       ip += 4;
-       safe_store_code(new_code2, ip, faulted);
+       safe_store_code(new_code2, ip + 4, faulted);
        if (unlikely(faulted))
                return -EFAULT;
-       flush_icache_range(ip, ip + 8); /* original ip + 12 */
+       flush_icache_range(ip, ip + 8);
        return 0;
 }
 #endif