From 649508f684751122aa302ab10f0f06cb4a88415b Mon Sep 17 00:00:00 2001 From: James Hogan 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 Cc: Frederic Weisbecker Cc: Ingo Molnar Acked-by: Steven Rostedt (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 ce8514fe..cb4524f 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 */ }; /* -- 2.7.4