diff options
| -rw-r--r-- | arch/Kconfig | 16 | ||||
| -rw-r--r-- | kernel/trace/ring_buffer.c | 17 |
2 files changed, 29 insertions, 4 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index ba4e966484ab..ddd4641446bd 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -143,6 +143,22 @@ 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 a6268e09160a..ddeb865706ba 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -129,7 +129,16 @@ 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 */ -#define RB_ALIGN_DATA __aligned(RB_ALIGNMENT) + +#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 RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX @@ -2719,7 +2728,7 @@ 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) { + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { event->type_len = 0; event->array[0] = length; } else @@ -2734,11 +2743,11 @@ static unsigned rb_calculate_event_length(unsigned length) if (!length) length++; - if (length > RB_MAX_SMALL_DATA) + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) length += sizeof(event.array[0]); length += RB_EVNT_HDR_SIZE; - length = ALIGN(length, RB_ALIGNMENT); + length = ALIGN(length, RB_ARCH_ALIGNMENT); /* * In case the time delta is larger than the 27 bits for it |