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trace/ring_buffer: handle 64bit aligned structs 

Some 32 bit architectures require 64 bit values to be aligned (for
example Meta which has 64 bit read/write instructions). These require 8
byte alignment of event data too, so use
!CONFIG_HAVE_64BIT_ALIGNED_ACCESS instead of !CONFIG_64BIT ||
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS to decide alignment, and align
buffer_data_page::data accordingly.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org> (previous version subtly different)
This commit is contained in:
James Hogan 2012-05-30 12:11:19 +01:00
parent c19fa94a8f
commit 649508f684
1 changed files with 4 additions and 2 deletions
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6
kernel/trace/ring_buffer.c
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@ -177,7 +177,7 @@ void tracing_off_permanent(void)
#define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
#define RB_EVNT_MIN_SIZE 8U /* two 32bit words */
#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS
# define RB_FORCE_8BYTE_ALIGNMENT 0
# define RB_ARCH_ALIGNMENT RB_ALIGNMENT
#else
@ -185,6 +185,8 @@ void tracing_off_permanent(void)
# define RB_ARCH_ALIGNMENT 8U
#endif
#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT)
/* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */
#define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX
@ -333,7 +335,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
struct buffer_data_page {
u64 time_stamp; /* page time stamp */
local_t commit; /* write committed index */
unsigned char data[]; /* data of buffer page */
unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */
};
/*