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authorLukas Larsson <[email protected]>2017-10-06 18:09:22 +0200
committerLukas Larsson <[email protected]>2017-10-09 11:51:28 +0200
commit01ee7763bcaf9192bedba2833f8b0717df1c4b23 (patch)
treeaa144d5030d8be5c3850db1cc9ff964aac465a16 /erts/emulator/beam/beam_bp.c
parentb4b81a3342af35308e87e34380d870c2464be697 (diff)
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erts: Fix caller trace for apply bifs
Bifs that are called through the export entry using i_call_last could have their cp set to return_trace, just like any other call. So we have to unwind the trace stack to get the correct cp. Not doing this creates a lot of issues for fprof.
Diffstat (limited to 'erts/emulator/beam/beam_bp.c')
-rw-r--r--erts/emulator/beam/beam_bp.c85
1 files changed, 51 insertions, 34 deletions
diff --git a/erts/emulator/beam/beam_bp.c b/erts/emulator/beam/beam_bp.c
index 950639f7ae..069e7391fd 100644
--- a/erts/emulator/beam/beam_bp.c
+++ b/erts/emulator/beam/beam_bp.c
@@ -642,6 +642,49 @@ erts_clear_export_break(Module* modp, ErtsCodeInfo *ci)
ASSERT(ci->u.gen_bp == NULL);
}
+/*
+ * If c_p->cp is a trace return instruction, we set cp
+ * to be the place where we again start to execute code.
+ *
+ * cp is used by match spec {caller} to get the calling
+ * function, and if we don't do this fixup it will be
+ * 'undefined'. This has the odd side effect of {caller}
+ * not really being which function is the caller, but
+ * rather which function we are about to return to.
+ */
+static void fixup_cp_before_trace(Process *c_p, int *return_to_trace)
+{
+ Eterm *cpp, *E = c_p->stop;
+ BeamInstr w = *c_p->cp;
+ if (w == (BeamInstr) BeamOp(op_return_trace)) {
+ cpp = &E[2];
+ } else if (w == (BeamInstr) BeamOp(op_i_return_to_trace)) {
+ *return_to_trace = 1;
+ cpp = &E[0];
+ } else if (w == (BeamInstr) BeamOp(op_i_return_time_trace)) {
+ cpp = &E[0];
+ } else {
+ cpp = NULL;
+ }
+ if (cpp) {
+ for (;;) {
+ BeamInstr w = *cp_val(*cpp);
+ if (w == (BeamInstr) BeamOp(op_return_trace)) {
+ cpp += 3;
+ } else if (w == (BeamInstr) BeamOp(op_i_return_to_trace)) {
+ *return_to_trace = 1;
+ cpp += 1;
+ } else if (w == (BeamInstr) BeamOp(op_i_return_time_trace)) {
+ cpp += 2;
+ } else {
+ break;
+ }
+ }
+ c_p->cp = (BeamInstr *) cp_val(*cpp);
+ ASSERT(is_CP(*cpp));
+ }
+}
+
BeamInstr
erts_generic_breakpoint(Process* c_p, ErtsCodeInfo *info, Eterm* reg)
{
@@ -752,6 +795,7 @@ erts_bif_trace(int bif_index, Process* p, Eterm* args, BeamInstr* I)
GenericBp* g;
GenericBpData* bp = NULL;
Uint bp_flags = 0;
+ int return_to_trace = 0;
ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
@@ -767,6 +811,8 @@ erts_bif_trace(int bif_index, Process* p, Eterm* args, BeamInstr* I)
*/
if (!applying) {
p->cp = I;
+ } else {
+ fixup_cp_before_trace(p, &return_to_trace);
}
if (bp_flags & (ERTS_BPF_LOCAL_TRACE|ERTS_BPF_GLOBAL_TRACE) &&
IS_TRACED_FL(p, F_TRACE_CALLS)) {
@@ -945,49 +991,20 @@ static ErtsTracer
do_call_trace(Process* c_p, ErtsCodeInfo* info, Eterm* reg,
int local, Binary* ms, ErtsTracer tracer)
{
- Eterm* cpp;
int return_to_trace = 0;
- BeamInstr w;
BeamInstr *cp_save = c_p->cp;
Uint32 flags;
Uint need = 0;
Eterm* E = c_p->stop;
- w = *c_p->cp;
- if (w == (BeamInstr) BeamOp(op_return_trace)) {
- cpp = &E[2];
- } else if (w == (BeamInstr) BeamOp(op_i_return_to_trace)) {
- return_to_trace = 1;
- cpp = &E[0];
- } else if (w == (BeamInstr) BeamOp(op_i_return_time_trace)) {
- cpp = &E[0];
- } else {
- cpp = NULL;
- }
- if (cpp) {
- for (;;) {
- BeamInstr w = *cp_val(*cpp);
- if (w == (BeamInstr) BeamOp(op_return_trace)) {
- cpp += 3;
- } else if (w == (BeamInstr) BeamOp(op_i_return_to_trace)) {
- return_to_trace = 1;
- cpp += 1;
- } else if (w == (BeamInstr) BeamOp(op_i_return_time_trace)) {
- cpp += 2;
- } else {
- break;
- }
- }
- cp_save = c_p->cp;
- c_p->cp = (BeamInstr *) cp_val(*cpp);
- ASSERT(is_CP(*cpp));
- }
+ fixup_cp_before_trace(c_p, &return_to_trace);
+
ERTS_SMP_UNREQ_PROC_MAIN_LOCK(c_p);
flags = erts_call_trace(c_p, info, ms, reg, local, &tracer);
ERTS_SMP_REQ_PROC_MAIN_LOCK(c_p);
- if (cpp) {
- c_p->cp = cp_save;
- }
+
+ /* restore cp after potential fixup */
+ c_p->cp = cp_save;
ASSERT(!ERTS_PROC_IS_EXITING(c_p));
if ((flags & MATCH_SET_RETURN_TO_TRACE) && !return_to_trace) {