diff options
Diffstat (limited to 'gdb/nat/linux-btrace.c')
| -rw-r--r-- | gdb/nat/linux-btrace.c | 113 |
1 files changed, 38 insertions, 75 deletions
diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c index 08eb49b31c8..5b2266104b8 100644 --- a/gdb/nat/linux-btrace.c +++ b/gdb/nat/linux-btrace.c @@ -59,45 +59,12 @@ struct perf_event_sample struct perf_event_bts bts; }; -/* Get the perf_event header. */ +/* Return non-zero if there is new data in PEVENT; zero otherwise. */ -static inline volatile struct perf_event_mmap_page * -perf_event_header (struct btrace_target_info* tinfo) -{ - return tinfo->buffer; -} - -/* Get the size of the perf_event mmap buffer. */ - -static inline size_t -perf_event_mmap_size (const struct btrace_target_info *tinfo) -{ - /* The branch trace buffer is preceded by a configuration page. */ - return (tinfo->size + 1) * PAGE_SIZE; -} - -/* Get the size of the perf_event buffer. */ - -static inline size_t -perf_event_buffer_size (struct btrace_target_info* tinfo) -{ - return tinfo->size * PAGE_SIZE; -} - -/* Get the start address of the perf_event buffer. */ - -static inline const uint8_t * -perf_event_buffer_begin (struct btrace_target_info* tinfo) -{ - return ((const uint8_t *) tinfo->buffer) + PAGE_SIZE; -} - -/* Get the end address of the perf_event buffer. */ - -static inline const uint8_t * -perf_event_buffer_end (struct btrace_target_info* tinfo) +static int +perf_event_new_data (const struct perf_event_buffer *pev) { - return perf_event_buffer_begin (tinfo) + perf_event_buffer_size (tinfo); + return *pev->data_head != pev->last_head; } /* Check whether an address is in the kernel. */ @@ -162,11 +129,12 @@ perf_event_sample_ok (const struct perf_event_sample *sample) static VEC (btrace_block_s) * perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin, - const uint8_t *end, const uint8_t *start, size_t size) + const uint8_t *end, const uint8_t *start, + unsigned long long size) { VEC (btrace_block_s) *btrace = NULL; struct perf_event_sample sample; - size_t read = 0; + unsigned long long read = 0; struct btrace_block block = { 0, 0 }; struct regcache *regcache; @@ -432,6 +400,7 @@ linux_supports_btrace (struct target_ops *ops, enum btrace_format format) struct btrace_target_info * linux_enable_btrace (ptid_t ptid) { + struct perf_event_mmap_page *header; struct btrace_target_info *tinfo; int pid, pg; @@ -467,15 +436,24 @@ linux_enable_btrace (ptid_t ptid) for (pg = 4; pg >= 0; --pg) { /* The number of pages we request needs to be a power of two. */ - tinfo->size = 1 << pg; - tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), - PROT_READ, MAP_SHARED, tinfo->file, 0); - if (tinfo->buffer == MAP_FAILED) - continue; - - return tinfo; + header = mmap (NULL, ((1 << pg) + 1) * PAGE_SIZE, PROT_READ, MAP_SHARED, + tinfo->file, 0); + if (header != MAP_FAILED) + break; } + if (header == MAP_FAILED) + goto err_file; + + tinfo->header = header; + tinfo->bts.mem = ((const uint8_t *) header) + PAGE_SIZE; + tinfo->bts.size = (1 << pg) * PAGE_SIZE; + tinfo->bts.data_head = &header->data_head; + tinfo->bts.last_head = 0; + + return tinfo; + + err_file: /* We were not able to allocate any buffer. */ close (tinfo->file); @@ -489,29 +467,13 @@ linux_enable_btrace (ptid_t ptid) enum btrace_error linux_disable_btrace (struct btrace_target_info *tinfo) { - int errcode; - - errno = 0; - errcode = munmap (tinfo->buffer, perf_event_mmap_size (tinfo)); - if (errcode != 0) - return BTRACE_ERR_UNKNOWN; - + munmap((void *) tinfo->header, tinfo->bts.size + PAGE_SIZE); close (tinfo->file); xfree (tinfo); return BTRACE_ERR_NONE; } -/* Check whether the branch trace has changed. */ - -static int -linux_btrace_has_changed (struct btrace_target_info *tinfo) -{ - volatile struct perf_event_mmap_page *header = perf_event_header (tinfo); - - return header->data_head != tinfo->data_head; -} - /* Read branch trace data in BTS format for the thread given by TINFO into BTRACE using the TYPE reading method. */ @@ -520,24 +482,25 @@ linux_read_bts (struct btrace_data_bts *btrace, struct btrace_target_info *tinfo, enum btrace_read_type type) { - volatile struct perf_event_mmap_page *header; + struct perf_event_buffer *pevent; const uint8_t *begin, *end, *start; - unsigned long data_head, data_tail, retries = 5; - size_t buffer_size, size; + unsigned long long data_head, data_tail, buffer_size, size; + unsigned int retries = 5; + + pevent = &tinfo->bts; /* For delta reads, we return at least the partial last block containing the current PC. */ - if (type == BTRACE_READ_NEW && !linux_btrace_has_changed (tinfo)) + if (type == BTRACE_READ_NEW && !perf_event_new_data (pevent)) return BTRACE_ERR_NONE; - header = perf_event_header (tinfo); - buffer_size = perf_event_buffer_size (tinfo); - data_tail = tinfo->data_head; + buffer_size = pevent->size; + data_tail = pevent->last_head; /* We may need to retry reading the trace. See below. */ while (retries--) { - data_head = header->data_head; + data_head = *pevent->data_head; /* Delete any leftover trace from the previous iteration. */ VEC_free (btrace_block_s, btrace->blocks); @@ -569,13 +532,13 @@ linux_read_bts (struct btrace_data_bts *btrace, } /* Data_head keeps growing; the buffer itself is circular. */ - begin = perf_event_buffer_begin (tinfo); + begin = pevent->mem; start = begin + data_head % buffer_size; if (data_head <= buffer_size) end = start; else - end = perf_event_buffer_end (tinfo); + end = begin + pevent->size; btrace->blocks = perf_event_read_bts (tinfo, begin, end, start, size); @@ -584,11 +547,11 @@ linux_read_bts (struct btrace_data_bts *btrace, kernel might be writing the last branch trace records. Let's check whether the data head moved while we read the trace. */ - if (data_head == header->data_head) + if (data_head == *pevent->data_head) break; } - tinfo->data_head = data_head; + pevent->last_head = data_head; /* Prune the incomplete last block (i.e. the first one of inferior execution) if we're not doing a delta read. There is no way of filling in its zeroed |