From 649508f684751122aa302ab10f0f06cb4a88415b Mon Sep 17 00:00:00 2001
From: James Hogan <james.hogan@imgtec.com>
Date: Wed, 30 May 2012 12:11:19 +0100
Subject: [PATCH] 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)
---
kernel/trace/ring_buffer.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ce8514feedcd..cb4524fd0cb3 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -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 */
};
/*
--
2.30.2