From 54c734c8edf180cc540d376fa2cec1ad95020c72 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Wed, 24 Aug 2022 13:31:24 +0100 Subject: [PATCH] ANDROID: ring-buffer: Expose buffer_data_page material In preparation for allowing the write of ring-buffer compliant pages outside of ring_buffer.c move to the header, struct buffer_data_page and timestamp encoding functions. When I presented this work to the tracingsummit, rosted@ told me he saw some overlapping with an idea he had to enable him to map the tracing buffers in userspace. We designed together a solution that would enable both features. Problem now, if on one hand, the development of the new design has started already... it would nonetheless impose a significant revamp of this patchset, which wouldn't make it to Android14. Nothing technically wrong with anything here, but sending it to LKML wouldn't make sense, as I know already this isn't as "reusable" as the version agreed upon. Bug: 229972309 Change-Id: Icf3329bd899a3dd91279d1bbadaf2dc4e243455c Signed-off-by: Vincent Donnefort --- include/linux/ring_buffer.h | 44 ++++++++++++++++++++++++++++++++++++- kernel/trace/ring_buffer.c | 41 +--------------------------------- 2 files changed, 44 insertions(+), 41 deletions(-) diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 3c7d295746f6..8f911d7df536 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -3,8 +3,10 @@ #define _LINUX_RING_BUFFER_H #include -#include #include +#include + +#include struct trace_buffer; struct ring_buffer_iter; @@ -18,6 +20,8 @@ struct ring_buffer_event { u32 array[]; }; +#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) + /** * enum ring_buffer_type - internal ring buffer types * @@ -59,11 +63,49 @@ enum ring_buffer_type { RINGBUF_TYPE_TIME_STAMP, }; +#define TS_SHIFT 27 +#define TS_MASK ((1ULL << TS_SHIFT) - 1) +#define TS_DELTA_TEST (~TS_MASK) + +/* + * We need to fit the time_stamp delta into 27 bits. + */ +static inline int test_time_stamp(u64 delta) +{ + if (delta & TS_DELTA_TEST) + return 1; + return 0; +} + unsigned ring_buffer_event_length(struct ring_buffer_event *event); void *ring_buffer_event_data(struct ring_buffer_event *event); u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, struct ring_buffer_event *event); +#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) + +#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) + +#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) + +struct buffer_data_page { + u64 time_stamp; /* page time stamp */ + local_t commit; /* write committed index */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ +}; + /* * ring_buffer_discard_commit will remove an event that has not * been committed yet. If this is used, then ring_buffer_unlock_commit diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b21bf14bae9b..fb8762e8a12b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -132,23 +132,6 @@ int ring_buffer_print_entry_header(struct trace_seq *s) /* Used for individual buffers (after the counter) */ #define RB_BUFFER_OFF (1 << 20) -#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) - -#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) -#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 RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX @@ -291,10 +274,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); #define for_each_online_buffer_cpu(buffer, cpu) \ for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask) -#define TS_SHIFT 27 -#define TS_MASK ((1ULL << TS_SHIFT) - 1) -#define TS_DELTA_TEST (~TS_MASK) - static u64 rb_event_time_stamp(struct ring_buffer_event *event) { u64 ts; @@ -311,12 +290,6 @@ static u64 rb_event_time_stamp(struct ring_buffer_event *event) /* Missed count stored at end */ #define RB_MISSED_STORED (1 << 30) -struct buffer_data_page { - u64 time_stamp; /* page time stamp */ - local_t commit; /* write committed index */ - unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ -}; - /* * Note, the buffer_page list must be first. The buffer pages * are allocated in cache lines, which means that each buffer @@ -364,18 +337,6 @@ static void free_buffer_page(struct buffer_page *bpage) kfree(bpage); } -/* - * We need to fit the time_stamp delta into 27 bits. - */ -static inline int test_time_stamp(u64 delta) -{ - if (delta & TS_DELTA_TEST) - return 1; - return 0; -} - -#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) - /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) @@ -3488,7 +3449,7 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, return; /* - * If this interrupted another event, + * If this interrupted another event, */ if (atomic_inc_return(this_cpu_ptr(&checking)) != 1) goto out;