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btrace: support decoder events

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Newer versions of libipt support instruction flow decoder events instead of
indicating those events with flags in struct pt_insn.  Add support for them in
GDB.

gdb/
	* btrace.c (handle_pt_insn_events): New.
	(ftrace_add_pt): Call handle_pt_insn_events.  Rename ERRCODE into
	STATUS.  Split into this and ...
	(handle_pt_insn_event_flags): ... this.
This commit is contained in:
Markus Metzger
2016-11-21 14:27:57 +01:00
parent c56ccc05b2
commit 13ace07792
2 changed files with 121 additions and 41 deletions
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7
gdb/ChangeLog
View File

@@ -1,3 +1,10 @@
2017-05-31 Markus Metzger <markus.t.metzger@intel.com>
* btrace.c (handle_pt_insn_events): New.
(ftrace_add_pt): Call handle_pt_insn_events. Rename ERRCODE into
STATUS. Split into this and ...
(handle_pt_insn_event_flags): ... this.
2017-05-31 Markus Metzger <markus.t.metzger@intel.com>
* configure.ac: Check for pt_insn_event, struct pt_insn.enabled,

155
gdb/btrace.c
View File

@@ -1187,6 +1187,103 @@ pt_btrace_insn (const struct pt_insn &insn)
pt_btrace_insn_flags (insn)};
}
/* Handle instruction decode events (libipt-v2). */
static int
handle_pt_insn_events (struct btrace_thread_info *btinfo,
struct pt_insn_decoder *decoder,
std::vector<unsigned int> &gaps, int status)
{
#if defined (HAVE_PT_INSN_EVENT)
while (status & pts_event_pending)
{
struct btrace_function *bfun;
struct pt_event event;
uint64_t offset;
status = pt_insn_event (decoder, &event, sizeof (event));
if (status < 0)
break;
switch (event.type)
{
default:
break;
case ptev_enabled:
if (event.variant.enabled.resumed == 0 && !btinfo->functions.empty ())
{
bfun = ftrace_new_gap (btinfo, BDE_PT_DISABLED, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Non-contiguous trace at instruction %u (offset = 0x%"
PRIx64 ")."), bfun->insn_offset - 1, offset);
}
break;
case ptev_overflow:
bfun = ftrace_new_gap (btinfo, BDE_PT_OVERFLOW, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Overflow at instruction %u (offset = 0x%" PRIx64 ")."),
bfun->insn_offset - 1, offset);
break;
}
}
#endif /* defined (HAVE_PT_INSN_EVENT) */
return status;
}
/* Handle events indicated by flags in INSN (libipt-v1). */
static void
handle_pt_insn_event_flags (struct btrace_thread_info *btinfo,
struct pt_insn_decoder *decoder,
const struct pt_insn &insn,
std::vector<unsigned int> &gaps)
{
#if defined (HAVE_STRUCT_PT_INSN_ENABLED)
/* Tracing is disabled and re-enabled each time we enter the kernel. Most
times, we continue from the same instruction we stopped before. This is
indicated via the RESUMED instruction flag. The ENABLED instruction flag
means that we continued from some other instruction. Indicate this as a
trace gap except when tracing just started. */
if (insn.enabled && !btinfo->functions.empty ())
{
struct btrace_function *bfun;
uint64_t offset;
bfun = ftrace_new_gap (btinfo, BDE_PT_DISABLED, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Non-contiguous trace at instruction %u (offset = 0x%" PRIx64
", pc = 0x%" PRIx64 ")."), bfun->insn_offset - 1, offset,
insn.ip);
}
#endif /* defined (HAVE_STRUCT_PT_INSN_ENABLED) */
#if defined (HAVE_STRUCT_PT_INSN_RESYNCED)
/* Indicate trace overflows. */
if (insn.resynced)
{
struct btrace_function *bfun;
uint64_t offset;
bfun = ftrace_new_gap (btinfo, BDE_PT_OVERFLOW, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Overflow at instruction %u (offset = 0x%" PRIx64 ", pc = 0x%"
PRIx64 ")."), bfun->insn_offset - 1, offset, insn.ip);
}
#endif /* defined (HAVE_STRUCT_PT_INSN_RESYNCED) */
}
/* Add function branch trace to BTINFO using DECODER. */
@@ -1198,58 +1295,34 @@ ftrace_add_pt (struct btrace_thread_info *btinfo,
{
struct btrace_function *bfun;
uint64_t offset;
int errcode;
int status;
for (;;)
{
struct pt_insn insn;
errcode = pt_insn_sync_forward (decoder);
if (errcode < 0)
status = pt_insn_sync_forward (decoder);
if (status < 0)
{
if (errcode != -pte_eos)
if (status != -pte_eos)
warning (_("Failed to synchronize onto the Intel Processor "
"Trace stream: %s."), pt_errstr (pt_errcode (errcode)));
"Trace stream: %s."), pt_errstr (pt_errcode (status)));
break;
}
for (;;)
{
errcode = pt_insn_next (decoder, &insn, sizeof(insn));
if (errcode < 0)
/* Handle events from the previous iteration or synchronization. */
status = handle_pt_insn_events (btinfo, decoder, gaps, status);
if (status < 0)
break;
/* Look for gaps in the trace - unless we're at the beginning. */
if (!btinfo->functions.empty ())
{
/* Tracing is disabled and re-enabled each time we enter the
kernel. Most times, we continue from the same instruction we
stopped before. This is indicated via the RESUMED instruction
flag. The ENABLED instruction flag means that we continued
from some other instruction. Indicate this as a trace gap. */
if (insn.enabled)
{
bfun = ftrace_new_gap (btinfo, BDE_PT_DISABLED, gaps);
status = pt_insn_next (decoder, &insn, sizeof(insn));
if (status < 0)
break;
pt_insn_get_offset (decoder, &offset);
warning (_("Non-contiguous trace at instruction %u (offset "
"= 0x%" PRIx64 ", pc = 0x%" PRIx64 ")."),
bfun->insn_offset - 1, offset, insn.ip);
}
}
/* Indicate trace overflows. */
if (insn.resynced)
{
bfun = ftrace_new_gap (btinfo, BDE_PT_OVERFLOW, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Overflow at instruction %u (offset = 0x%" PRIx64
", pc = 0x%" PRIx64 ")."), bfun->insn_offset - 1,
offset, insn.ip);
}
/* Handle events indicated by flags in INSN. */
handle_pt_insn_event_flags (btinfo, decoder, insn, gaps);
bfun = ftrace_update_function (btinfo, insn.ip);
@@ -1260,17 +1333,17 @@ ftrace_add_pt (struct btrace_thread_info *btinfo,
ftrace_update_insns (bfun, &btinsn);
}
if (errcode == -pte_eos)
if (status == -pte_eos)
break;
/* Indicate the gap in the trace. */
bfun = ftrace_new_gap (btinfo, errcode, gaps);
bfun = ftrace_new_gap (btinfo, status, gaps);
pt_insn_get_offset (decoder, &offset);
warning (_("Decode error (%d) at instruction %u (offset = 0x%" PRIx64
", pc = 0x%" PRIx64 "): %s."), errcode, bfun->insn_offset - 1,
offset, insn.ip, pt_errstr (pt_errcode (errcode)));
", pc = 0x%" PRIx64 "): %s."), status, bfun->insn_offset - 1,
offset, insn.ip, pt_errstr (pt_errcode (status)));
}
}