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.
This commit is contained in:
Markus Metzger
parent
de6242d307
commit
17ad2a4f46
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@ -1,3 +1,12 @@
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2018-02-09 Markus Metzger <markus.t.metzger@intel.com>
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* nat/linux-btrace.c (perf_event_pt_event_type): Improve error message.
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Remove parameter and change return type. Update callers. Move it.
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(linux_enable_bts, linux_enable_pt): Improve error message.
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(linux_enable_pt): Remove zero buffer size check.
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(linux_enable_btrace): Improve error messages. Remove NULL return
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check.
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2018-02-09 Markus Metzger <markus.t.metzger@intel.com>
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* btrace.c (btrace_enable): Remove target_supports_btrace call.
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@ -448,7 +448,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
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errno = 0;
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scoped_fd fd (syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0));
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if (fd.get () < 0)
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return nullptr;
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error (_("Failed to start recording: %s"), safe_strerror (errno));
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/* Convert the requested size in bytes to pages (rounding up). */
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pages = ((size_t) conf->size / PAGE_SIZE
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@ -484,6 +484,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
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if ((__u64) length != data_size + PAGE_SIZE)
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continue;
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errno = 0;
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/* The number of pages we request needs to be a power of two. */
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data.reset (nullptr, length, PROT_READ, MAP_SHARED, fd.get (), 0);
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if (data.get () != MAP_FAILED)
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@ -491,7 +492,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
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}
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if (pages == 0)
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return nullptr;
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error (_("Failed to map trace buffer: %s."), safe_strerror (errno));
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struct perf_event_mmap_page *header = (struct perf_event_mmap_page *)
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data.get ();
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@ -509,7 +510,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
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/* Check for overflows. */
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if ((__u64) size != data_size)
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return nullptr;
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error (_("Failed to determine trace buffer size."));
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}
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#endif /* defined (PERF_ATTR_SIZE_VER5) */
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@ -528,21 +529,23 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
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#if defined (PERF_ATTR_SIZE_VER5)
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/* Determine the event type.
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Returns zero on success and fills in TYPE; returns -1 otherwise. */
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/* Determine the event type. */
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static int
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perf_event_pt_event_type (int *type)
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perf_event_pt_event_type ()
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{
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gdb_file_up file =
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gdb_fopen_cloexec ("/sys/bus/event_source/devices/intel_pt/type", "r");
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if (file.get () == nullptr)
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return -1;
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static const char filename[] = "/sys/bus/event_source/devices/intel_pt/type";
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int found = fscanf (file.get (), "%d", type);
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if (found == 1)
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return 0;
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return -1;
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errno = 0;
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gdb_file_up file = gdb_fopen_cloexec (filename, "r");
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if (file.get () == nullptr)
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error (_("Failed to open %s: %s."), filename, safe_strerror (errno));
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int type, found = fscanf (file.get (), "%d", &type);
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if (found != 1)
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error (_("Failed to read the PT event type from %s."), filename);
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return type;
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}
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/* Enable branch tracing in Intel Processor Trace format. */
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@ -552,14 +555,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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{
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struct btrace_tinfo_pt *pt;
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size_t pages;
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int pid, pg, errcode, type;
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if (conf->size == 0)
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return NULL;
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errcode = perf_event_pt_event_type (&type);
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if (errcode != 0)
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return NULL;
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int pid, pg;
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pid = ptid_get_lwp (ptid);
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if (pid == 0)
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@ -573,7 +569,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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pt = &tinfo->variant.pt;
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pt->attr.size = sizeof (pt->attr);
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pt->attr.type = type;
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pt->attr.type = perf_event_pt_event_type ();
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pt->attr.exclude_kernel = 1;
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pt->attr.exclude_hv = 1;
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@ -582,13 +578,13 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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errno = 0;
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scoped_fd fd (syscall (SYS_perf_event_open, &pt->attr, pid, -1, -1, 0));
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if (fd.get () < 0)
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return nullptr;
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error (_("Failed to start recording: %s"), safe_strerror (errno));
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/* Allocate the configuration page. */
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scoped_mmap data (nullptr, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,
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fd.get (), 0);
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if (data.get () == MAP_FAILED)
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return nullptr;
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error (_("Failed to map trace user page: %s."), safe_strerror (errno));
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struct perf_event_mmap_page *header = (struct perf_event_mmap_page *)
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data.get ();
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@ -630,6 +626,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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header->aux_size = data_size;
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errno = 0;
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aux.reset (nullptr, length, PROT_READ, MAP_SHARED, fd.get (),
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header->aux_offset);
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if (aux.get () != MAP_FAILED)
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@ -637,7 +634,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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}
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if (pages == 0)
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return nullptr;
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error (_("Failed to map trace buffer: %s."), safe_strerror (errno));
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pt->pt.size = aux.size ();
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pt->pt.mem = (const uint8_t *) aux.release ();
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@ -656,8 +653,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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static struct btrace_target_info *
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linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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{
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errno = EOPNOTSUPP;
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return NULL;
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error (_("Intel Processor Trace support was disabled at compile time."));
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}
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#endif /* !defined (PERF_ATTR_SIZE_VER5) */
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@ -667,27 +663,20 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
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struct btrace_target_info *
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linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
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{
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struct btrace_target_info *tinfo;
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tinfo = NULL;
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switch (conf->format)
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{
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case BTRACE_FORMAT_NONE:
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break;
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error (_("Bad branch trace format."));
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default:
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error (_("Unknown branch trace format."));
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case BTRACE_FORMAT_BTS:
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tinfo = linux_enable_bts (ptid, &conf->bts);
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break;
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return linux_enable_bts (ptid, &conf->bts);
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case BTRACE_FORMAT_PT:
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tinfo = linux_enable_pt (ptid, &conf->pt);
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break;
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return linux_enable_pt (ptid, &conf->pt);
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}
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if (tinfo == NULL)
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error (_("Unknown error."));
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return tinfo;
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}
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/* Disable BTS tracing. */
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