Commit 6ebb017d authored Jun 05, 2012 by Andrew Lunn Committed by Greg Kroah-Hartman Jun 12, 2012

printk: Fix alignment of buf causing crash on ARM EABI



Commit 7ff9554b, printk: convert
byte-buffer to variable-length record buffer, causes systems using
EABI to crash very early in the boot cycle. The first entry in struct
log is a u64, which for EABI must be 8 byte aligned.

Make use of __alignof__() so the compiler to decide the alignment, but
allow it to be overridden using CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS,
for systems which can perform unaligned access and want to save
a few bytes of space.

Tested on Orion5x and Kirkwood.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent bcc2c9c3

kernel/printk.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -227,10 +227,10 @@ static u32 clear_idx;
		#define LOG_LINE_MAX 1024

		/* record buffer */
		#if !defined(CONFIG_64BIT) \|\| defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
		#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
		#define LOG_ALIGN 4
		#else
		#define LOG_ALIGN 8
		#define LOG_ALIGN __alignof__(struct log)
		#endif
		#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
		static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);