From 86b3de60a0b634cdcef82d0a2091bc5444a00020 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Tue, 28 May 2019 09:36:19 -0400 Subject: [PATCH] ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS Commit c19fa94a8fed ("Add HAVE_64BIT_ALIGNED_ACCESS") added the config for architectures that required 64bit aligned access for all 64bit words. As the ftrace ring buffer stores data on 4 byte alignment, this config option was used to force it to store data on 8 byte alignment to make sure the data being stored and written directly into the ring buffer was 8 byte aligned as it would cause issues trying to write an 8 byte word on a 4 not 8 byte aligned memory location. But with the removal of the metag architecture, which was the only architecture to use this, there is no architecture supported by Linux that requires 8 byte aligne access for all 8 byte words (4 byte alignment is good enough). Removing this config can simplify the code a bit. Signed-off-by: Steven Rostedt (VMware) --- arch/Kconfig | 16 ---------------- kernel/trace/ring_buffer.c | 17 ++++------------- 2 files changed, 4 insertions(+), 29 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index c47b328eada0..665a7557b15c 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -128,22 +128,6 @@ config UPROBES managed by the kernel and kept transparent to the probed application. ) -config HAVE_64BIT_ALIGNED_ACCESS - def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS - help - Some architectures require 64 bit accesses to be 64 bit - aligned, which also requires structs containing 64 bit values - to be 64 bit aligned too. This includes some 32 bit - architectures which can do 64 bit accesses, as well as 64 bit - architectures without unaligned access. - - This symbol should be selected by an architecture if 64 bit - accesses are required to be 64 bit aligned in this way even - though it is not a 64 bit architecture. - - See Documentation/unaligned-memory-access.txt for more - information on the topic of unaligned memory accesses. - config HAVE_EFFICIENT_UNALIGNED_ACCESS bool help diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 05b0b3139ebc..66358d66c933 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -128,16 +128,7 @@ int ring_buffer_print_entry_header(struct trace_seq *s) #define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ - -#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS -# define RB_FORCE_8BYTE_ALIGNMENT 0 -# define RB_ARCH_ALIGNMENT RB_ALIGNMENT -#else -# define RB_FORCE_8BYTE_ALIGNMENT 1 -# define RB_ARCH_ALIGNMENT 8U -#endif - -#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) +#define RB_ALIGN_DATA __aligned(RB_ALIGNMENT) /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX @@ -2373,7 +2364,7 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, event->time_delta = delta; length -= RB_EVNT_HDR_SIZE; - if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { + if (length > RB_MAX_SMALL_DATA) { event->type_len = 0; event->array[0] = length; } else @@ -2388,11 +2379,11 @@ static unsigned rb_calculate_event_length(unsigned length) if (!length) length++; - if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) + if (length > RB_MAX_SMALL_DATA) length += sizeof(event.array[0]); length += RB_EVNT_HDR_SIZE; - length = ALIGN(length, RB_ARCH_ALIGNMENT); + length = ALIGN(length, RB_ALIGNMENT); /* * In case the time delta is larger than the 27 bits for it