From: Markus Metzger Date: Fri, 19 Jan 2018 12:56:32 +0000 (+0100) Subject: btrace: improve enable error messages X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=17ad2a4f466f22b7a75b5ebf8a68446bb328c40c;p=deliverable%2Fbinutils-gdb.git btrace: improve enable error messages Improve the error message when GDB fails to start recording branch trace. This patch also removes a zero buffer size check for PT to align with BTS. The buffer size can not be configured to be zero. gdb/ * nat/linux-btrace.c (perf_event_pt_event_type): Improve error message. Remove parameter and change return type. Update callers. Move it. (linux_enable_bts, linux_enable_pt): Improve error message. (linux_enable_pt): Remove zero buffer size check. (linux_enable_btrace): Improve error messages. Remove NULL return check. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index df0283a8e2..769858b764 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2018-02-09 Markus Metzger + + * nat/linux-btrace.c (perf_event_pt_event_type): Improve error message. + Remove parameter and change return type. Update callers. Move it. + (linux_enable_bts, linux_enable_pt): Improve error message. + (linux_enable_pt): Remove zero buffer size check. + (linux_enable_btrace): Improve error messages. Remove NULL return + check. + 2018-02-09 Markus Metzger * btrace.c (btrace_enable): Remove target_supports_btrace call. diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c index 42f56f9ed3..301649b498 100644 --- a/gdb/nat/linux-btrace.c +++ b/gdb/nat/linux-btrace.c @@ -448,7 +448,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) errno = 0; scoped_fd fd (syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0)); if (fd.get () < 0) - return nullptr; + error (_("Failed to start recording: %s"), safe_strerror (errno)); /* Convert the requested size in bytes to pages (rounding up). */ pages = ((size_t) conf->size / PAGE_SIZE @@ -484,6 +484,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) if ((__u64) length != data_size + PAGE_SIZE) continue; + errno = 0; /* The number of pages we request needs to be a power of two. */ data.reset (nullptr, length, PROT_READ, MAP_SHARED, fd.get (), 0); if (data.get () != MAP_FAILED) @@ -491,7 +492,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) } if (pages == 0) - return nullptr; + error (_("Failed to map trace buffer: %s."), safe_strerror (errno)); struct perf_event_mmap_page *header = (struct perf_event_mmap_page *) data.get (); @@ -509,7 +510,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) /* Check for overflows. */ if ((__u64) size != data_size) - return nullptr; + error (_("Failed to determine trace buffer size.")); } #endif /* defined (PERF_ATTR_SIZE_VER5) */ @@ -528,21 +529,23 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) #if defined (PERF_ATTR_SIZE_VER5) -/* Determine the event type. - Returns zero on success and fills in TYPE; returns -1 otherwise. */ +/* Determine the event type. */ static int -perf_event_pt_event_type (int *type) +perf_event_pt_event_type () { - gdb_file_up file = - gdb_fopen_cloexec ("/sys/bus/event_source/devices/intel_pt/type", "r"); + static const char filename[] = "/sys/bus/event_source/devices/intel_pt/type"; + + errno = 0; + gdb_file_up file = gdb_fopen_cloexec (filename, "r"); if (file.get () == nullptr) - return -1; + error (_("Failed to open %s: %s."), filename, safe_strerror (errno)); - int found = fscanf (file.get (), "%d", type); - if (found == 1) - return 0; - return -1; + int type, found = fscanf (file.get (), "%d", &type); + if (found != 1) + error (_("Failed to read the PT event type from %s."), filename); + + return type; } /* Enable branch tracing in Intel Processor Trace format. */ @@ -552,14 +555,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) { struct btrace_tinfo_pt *pt; size_t pages; - int pid, pg, errcode, type; - - if (conf->size == 0) - return NULL; - - errcode = perf_event_pt_event_type (&type); - if (errcode != 0) - return NULL; + int pid, pg; pid = ptid_get_lwp (ptid); if (pid == 0) @@ -573,7 +569,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) pt = &tinfo->variant.pt; pt->attr.size = sizeof (pt->attr); - pt->attr.type = type; + pt->attr.type = perf_event_pt_event_type (); pt->attr.exclude_kernel = 1; pt->attr.exclude_hv = 1; @@ -582,13 +578,13 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) errno = 0; scoped_fd fd (syscall (SYS_perf_event_open, &pt->attr, pid, -1, -1, 0)); if (fd.get () < 0) - return nullptr; + error (_("Failed to start recording: %s"), safe_strerror (errno)); /* Allocate the configuration page. */ scoped_mmap data (nullptr, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd.get (), 0); if (data.get () == MAP_FAILED) - return nullptr; + error (_("Failed to map trace user page: %s."), safe_strerror (errno)); struct perf_event_mmap_page *header = (struct perf_event_mmap_page *) data.get (); @@ -630,6 +626,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) header->aux_size = data_size; + errno = 0; aux.reset (nullptr, length, PROT_READ, MAP_SHARED, fd.get (), header->aux_offset); if (aux.get () != MAP_FAILED) @@ -637,7 +634,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) } if (pages == 0) - return nullptr; + error (_("Failed to map trace buffer: %s."), safe_strerror (errno)); pt->pt.size = aux.size (); pt->pt.mem = (const uint8_t *) aux.release (); @@ -656,8 +653,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) static struct btrace_target_info * linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) { - errno = EOPNOTSUPP; - return NULL; + error (_("Intel Processor Trace support was disabled at compile time.")); } #endif /* !defined (PERF_ATTR_SIZE_VER5) */ @@ -667,27 +663,20 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) struct btrace_target_info * linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf) { - struct btrace_target_info *tinfo; - - tinfo = NULL; switch (conf->format) { case BTRACE_FORMAT_NONE: - break; + error (_("Bad branch trace format.")); + + default: + error (_("Unknown branch trace format.")); case BTRACE_FORMAT_BTS: - tinfo = linux_enable_bts (ptid, &conf->bts); - break; + return linux_enable_bts (ptid, &conf->bts); case BTRACE_FORMAT_PT: - tinfo = linux_enable_pt (ptid, &conf->pt); - break; + return linux_enable_pt (ptid, &conf->pt); } - - if (tinfo == NULL) - error (_("Unknown error.")); - - return tinfo; } /* Disable BTS tracing. */