Re: [PATCH v2 04/44] trace/ring_buffer: handle 64bit aligned structs
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2012-12-08 01:24:16
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On Wed, 2012-12-05 at 16:08 +0000, James Hogan wrote:
Some 32 bit architectures have 64 bit struct alignment (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_STRUCT instead of CONFIG_64BIT to decide alignment, and align buffer_data_page::data accordingly. Signed-off-by: James Hogan <redacted>
Acked-by: Steven Rostedt <rostedt@goodmis.org> -- Steve
quoted hunk ↗ jump to hunk
Cc: Frederic Weisbecker <redacted> Cc: Ingo Molnar <mingo@redhat.com> --- kernel/trace/ring_buffer.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b979426..c4dc029 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c@@ -177,7 +177,8 @@ 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) +#if !defined(CONFIG_HAVE_64BIT_ALIGNED_STRUCT) || \ + defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) # define RB_FORCE_8BYTE_ALIGNMENT 0 # define RB_ARCH_ALIGNMENT RB_ALIGNMENT #else@@ -185,6 +186,8 @@ 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 +336,7 @@ 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 */ }; /*