Messages in this thread Patch in this message | | | Date | Wed, 6 Feb 2019 09:39:49 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 4/6] perf thread-stack: Represent jmps to the start of a different symbol |
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Em Wed, Jan 09, 2019 at 11:18:33AM +0200, Adrian Hunter escreveu: > The compiler might optimize a call/ret combination by making it a jmp. > However the thread-stack does not presently cater for that, so that such > control flow is not visible in the call graph. Make it visible by recording > on the stack a branch to the start of a different symbol. Note, that means > when a ret pops the stack, all jmps must be popped off first. > > Example: > > $ cat jmp-to-fn.c > __attribute__((noinline)) int bar(void) > { > return -1; > } > > __attribute__((noinline)) int foo(void) > { > return bar() + 1; > } > > int main() > { > return foo(); > } > $ gcc -ggdb3 -Wall -Wextra -O2 -o jmp-to-fn jmp-to-fn.c > $ objdump -d jmp-to-fn > <SNIP> > 0000000000001040 <main>: > 1040: 31 c0 xor %eax,%eax > 1042: e9 09 01 00 00 jmpq 1150 <foo> > <SNIP> > 0000000000001140 <bar>: > 1140: b8 ff ff ff ff mov $0xffffffff,%eax > 1145: c3 retq > <SNIP> > 0000000000001150 <foo>: > 1150: 31 c0 xor %eax,%eax > 1152: e8 e9 ff ff ff callq 1140 <bar> > 1157: 83 c0 01 add $0x1,%eax > 115a: c3 retq > <SNIP> > $ perf record -o jmp-to-fn.perf.data -e intel_pt/cyc/u ./jmp-to-fn > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0,017 MB jmp-to-fn.perf.data ] > $ perf script -i jmp-to-fn.perf.data --itrace=be -s ~/libexec/perf-core/scripts/python/export-to-sqlite.py jmp-to-fn.db branches calls > 2019-01-08 13:24:58.783069 Creating database... > 2019-01-08 13:24:58.794650 Writing records... > 2019-01-08 13:24:59.008050 Adding indexes > 2019-01-08 13:24:59.015802 Done > $ ~/libexec/perf-core/scripts/python/exported-sql-viewer.py jmp-to-fn.db
So, while testing this I notice that we need to do the python3 conversions for these scripts as well:
[acme@quaco adrian]$ objdump -d jmp-to-fn > /tmp/bla [acme@quaco adrian]$ vim /tmp/bla [acme@quaco adrian]$ perf record -o jmp-to-fn.perf.data -e intel_pt/cyc/u ./jmp-to-fn Couldn't synthesize bpf events. [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.017 MB jmp-to-fn.perf.data ] [acme@quaco adrian]$ perf script -i jmp-to-fn.perf.data --itrace=be -s ~/libexec/perf-core/scripts/python/export-to-sqlite.py jmp-to-fn.db branches calls File "/home/acme/libexec/perf-core/scripts/python/export-to-sqlite.py", line 103 print datetime.datetime.today(), "Creating database..." ^ SyntaxError: invalid syntax Error running python script /home/acme/libexec/perf-core/scripts/python/export-to-sqlite.py [acme@quaco adrian]$
Mostly are simple, i.e. in this case we need something like:
print(str(datetime.datetime.today()) + "Creating database...")
for a really crude conversion, but one that would make this work with both python2 and python3 (make PYTHON=python3 when building perf).
> Before: > > main > -> bar > > After: > > main > -> foo > -> bar > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > --- > .../scripts/python/export-to-postgresql.py | 2 +- > tools/perf/scripts/python/export-to-sqlite.py | 2 +- > tools/perf/util/thread-stack.c | 30 +++++++++++++++++-- > tools/perf/util/thread-stack.h | 3 ++ > 4 files changed, 33 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/scripts/python/export-to-postgresql.py b/tools/perf/scripts/python/export-to-postgresql.py > index 0564dd7377f2..30130213da7e 100644 > --- a/tools/perf/scripts/python/export-to-postgresql.py > +++ b/tools/perf/scripts/python/export-to-postgresql.py > @@ -478,7 +478,7 @@ if perf_db_export_calls: > 'branch_count,' > 'call_id,' > 'return_id,' > - 'CASE WHEN flags=1 THEN \'no call\' WHEN flags=2 THEN \'no return\' WHEN flags=3 THEN \'no call/return\' ELSE \'\' END AS flags,' > + 'CASE WHEN flags=0 THEN \'\' WHEN flags=1 THEN \'no call\' WHEN flags=2 THEN \'no return\' WHEN flags=3 THEN \'no call/return\' WHEN flags=6 THEN \'jump\' ELSE flags END AS flags,' > 'parent_call_path_id' > ' FROM calls INNER JOIN call_paths ON call_paths.id = call_path_id') > > diff --git a/tools/perf/scripts/python/export-to-sqlite.py b/tools/perf/scripts/python/export-to-sqlite.py > index 245caf2643ed..ed237f2ed03f 100644 > --- a/tools/perf/scripts/python/export-to-sqlite.py > +++ b/tools/perf/scripts/python/export-to-sqlite.py > @@ -320,7 +320,7 @@ if perf_db_export_calls: > 'branch_count,' > 'call_id,' > 'return_id,' > - 'CASE WHEN flags=1 THEN \'no call\' WHEN flags=2 THEN \'no return\' WHEN flags=3 THEN \'no call/return\' ELSE \'\' END AS flags,' > + 'CASE WHEN flags=0 THEN \'\' WHEN flags=1 THEN \'no call\' WHEN flags=2 THEN \'no return\' WHEN flags=3 THEN \'no call/return\' WHEN flags=6 THEN \'jump\' ELSE flags END AS flags,' > 'parent_call_path_id' > ' FROM calls INNER JOIN call_paths ON call_paths.id = call_path_id') > > diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c > index 7f8eff018c16..f52c0f90915d 100644 > --- a/tools/perf/util/thread-stack.c > +++ b/tools/perf/util/thread-stack.c > @@ -38,6 +38,7 @@ > * @cp: call path > * @no_call: a 'call' was not seen > * @trace_end: a 'call' but trace ended > + * @non_call: a branch but not a 'call' to the start of a different symbol > */ > struct thread_stack_entry { > u64 ret_addr; > @@ -47,6 +48,7 @@ struct thread_stack_entry { > struct call_path *cp; > bool no_call; > bool trace_end; > + bool non_call; > }; > > /** > @@ -268,6 +270,8 @@ static int thread_stack__call_return(struct thread *thread, > cr.flags |= CALL_RETURN_NO_CALL; > if (no_return) > cr.flags |= CALL_RETURN_NO_RETURN; > + if (tse->non_call) > + cr.flags |= CALL_RETURN_NON_CALL; > > return crp->process(&cr, crp->data); > } > @@ -510,6 +514,7 @@ static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr, > tse->cp = cp; > tse->no_call = no_call; > tse->trace_end = trace_end; > + tse->non_call = false; > > return 0; > } > @@ -531,14 +536,16 @@ static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts, > timestamp, ref, false); > } > > - if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) { > + if (ts->stack[ts->cnt - 1].ret_addr == ret_addr && > + !ts->stack[ts->cnt - 1].non_call) { > return thread_stack__call_return(thread, ts, --ts->cnt, > timestamp, ref, false); > } else { > size_t i = ts->cnt - 1; > > while (i--) { > - if (ts->stack[i].ret_addr != ret_addr) > + if (ts->stack[i].ret_addr != ret_addr || > + ts->stack[i].non_call) > continue; > i += 1; > while (ts->cnt > i) { > @@ -757,6 +764,25 @@ int thread_stack__process(struct thread *thread, struct comm *comm, > err = thread_stack__trace_begin(thread, ts, sample->time, ref); > } else if (sample->flags & PERF_IP_FLAG_TRACE_END) { > err = thread_stack__trace_end(ts, sample, ref); > + } else if (sample->flags & PERF_IP_FLAG_BRANCH && > + from_al->sym != to_al->sym && to_al->sym && > + to_al->addr == to_al->sym->start) { > + struct call_path_root *cpr = ts->crp->cpr; > + struct call_path *cp; > + > + /* > + * The compiler might optimize a call/ret combination by making > + * it a jmp. Make that visible by recording on the stack a > + * branch to the start of a different symbol. Note, that means > + * when a ret pops the stack, all jmps must be popped off first. > + */ > + cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, > + to_al->sym, sample->addr, > + ts->kernel_start); > + err = thread_stack__push_cp(ts, 0, sample->time, ref, cp, false, > + false); > + if (!err) > + ts->stack[ts->cnt - 1].non_call = true; > } > > return err; > diff --git a/tools/perf/util/thread-stack.h b/tools/perf/util/thread-stack.h > index 1f626f4a1c40..b7c04e19ad41 100644 > --- a/tools/perf/util/thread-stack.h > +++ b/tools/perf/util/thread-stack.h > @@ -35,10 +35,13 @@ struct call_path; > * > * CALL_RETURN_NO_CALL: 'return' but no matching 'call' > * CALL_RETURN_NO_RETURN: 'call' but no matching 'return' > + * CALL_RETURN_NON_CALL: a branch but not a 'call' to the start of a different > + * symbol > */ > enum { > CALL_RETURN_NO_CALL = 1 << 0, > CALL_RETURN_NO_RETURN = 1 << 1, > + CALL_RETURN_NON_CALL = 1 << 2, > }; > > /** > -- > 2.17.1
--
- Arnaldo
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