[BUGFIX PATCH V2 0/6] perf/probe: Additional fixes for range only functions

[BUGFIX PATCH V2 0/6] perf/probe: Additional fixes for range only functions

[Masami Hiramatsu]

Hi Arnaldo,

I've updated examples in patch description in this v2.
No changes in the code itself. I ran it on Ubuntu 19.04
(linux-5.0.0-32-generic).

Please replace previous one with this.

Thank you,

---

Masami Hiramatsu (6):
      perf/probe: Fix wrong address verification
      perf/probe: Fix to probe a function which has no entry pc
      perf/probe: Fix to probe an inline function which has no entry pc
      perf/probe: Fix to list probe event with correct line number
      perf/probe: Fix to show inlined function callsite without entry_pc
      perf/probe: Fix to show ranges of variables in functions without entry_pc


 tools/perf/util/dwarf-aux.c    |    6 +++---
 tools/perf/util/probe-finder.c |   40 ++++++++++++++--------------------------
 2 files changed, 17 insertions(+), 29 deletions(-)

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>

[BUGFIX PATCH V2 1/6] perf/probe: Fix wrong address verification

[Masami Hiramatsu]

Since there are some DIE which has only ranges instead of the
combination of entrypc/highpc, address verification must use
dwarf_haspc() instead of dwarf_entrypc/dwarf_highpc.

Also, the ranges only DIE will have a partial code in different
section (e.g. unlikely code will be in text.unlikely as "FUNC.cold"
symbol). In that case, we can not use dwarf_entrypc() or
die_entrypc(), because the offset from original DIE can be
a minus value.

Instead, this simply gets the symbol and offset from symtab.

Without this patch;
  # tools/perf/perf probe -D clear_tasks_mm_cpumask:1
  Failed to get entry address of clear_tasks_mm_cpumask
    Error: Failed to add events.

And with this patch
  # perf probe -D clear_tasks_mm_cpumask:1
  p:probe/clear_tasks_mm_cpumask _text+632816
  p:probe/clear_tasks_mm_cpumask_1 _text+632821
  p:probe/clear_tasks_mm_cpumask_2 _text+632830

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Fixes: 576b523721b7 ("perf probe: Fix probing symbols with optimization suffix")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/probe-finder.c |   32 ++++++++++----------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index cd9f95e5044e..2b6513e5725c 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -604,38 +604,26 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
 				  const char *function,
 				  struct probe_trace_point *tp)
 {
-	Dwarf_Addr eaddr, highaddr;
+	Dwarf_Addr eaddr;
 	GElf_Sym sym;
 	const char *symbol;
 
 	/* Verify the address is correct */
-	if (dwarf_entrypc(sp_die, &eaddr) != 0) {
-		pr_warning("Failed to get entry address of %s\n",
-			   dwarf_diename(sp_die));
-		return -ENOENT;
-	}
-	if (dwarf_highpc(sp_die, &highaddr) != 0) {
-		pr_warning("Failed to get end address of %s\n",
-			   dwarf_diename(sp_die));
-		return -ENOENT;
-	}
-	if (paddr > highaddr) {
-		pr_warning("Offset specified is greater than size of %s\n",
+	if (!dwarf_haspc(sp_die, paddr)) {
+		pr_warning("Specified offset is out of %s\n",
 			   dwarf_diename(sp_die));
 		return -EINVAL;
 	}
 
-	symbol = dwarf_diename(sp_die);
+	/* Try to get actual symbol name from symtab */
+	symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
 	if (!symbol) {
-		/* Try to get the symbol name from symtab */
-		symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
-		if (!symbol) {
-			pr_warning("Failed to find symbol at 0x%lx\n",
-				   (unsigned long)paddr);
-			return -ENOENT;
-		}
-		eaddr = sym.st_value;
+		pr_warning("Failed to find symbol at 0x%lx\n",
+			   (unsigned long)paddr);
+		return -ENOENT;
 	}
+	eaddr = sym.st_value;
+
 	tp->offset = (unsigned long)(paddr - eaddr);
 	tp->address = (unsigned long)paddr;
 	tp->symbol = strdup(symbol);

[BUGFIX PATCH V2 2/6] perf/probe: Fix to probe a function which has no entry pc

[Masami Hiramatsu]

Fix perf probe to probe a function which has no entry pc or
low pc but only has ranges attribute.

probe_point_search_cb() uses dwarf_entrypc() to get the
probe address, but that doesn't work for the function DIE
which has only ranges attribute. Use die_entrypc() instead.

Without this fix,
  # perf probe -D clear_tasks_mm_cpumask:0
  Probe point 'clear_tasks_mm_cpumask' not found.
    Error: Failed to add events.

With this,
  # perf probe -D clear_tasks_mm_cpumask:0
  p:probe/clear_tasks_mm_cpumask _text+632816

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Fixes: e1ecbbc3fa83 ("perf probe: Fix to handle optimized not-inlined functions")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/probe-finder.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 2b6513e5725c..71633f55f045 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -982,7 +982,7 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 		param->retval = find_probe_point_by_line(pf);
 	} else if (die_is_func_instance(sp_die)) {
 		/* Instances always have the entry address */
-		dwarf_entrypc(sp_die, &pf->addr);
+		die_entrypc(sp_die, &pf->addr);
 		/* But in some case the entry address is 0 */
 		if (pf->addr == 0) {
 			pr_debug("%s has no entry PC. Skipped\n",

[BUGFIX PATCH V2 3/6] perf/probe: Fix to probe an inline function which has no entry pc

[Masami Hiramatsu]

Fix perf probe to probe an inlne function which has no entry pc
or low pc but only has ranges attribute.

This seems very rare case, but I could find a few examples, as
same as probe_point_search_cb(), use die_entrypc() to get the
entry address in probe_point_inline_cb() too.

Without this patch,
  # perf probe -D __amd_put_nb_event_constraints
  Failed to get entry address of __amd_put_nb_event_constraints.
  Probe point '__amd_put_nb_event_constraints' not found.
    Error: Failed to add events.

With this patch,
  # perf probe -D __amd_put_nb_event_constraints
  p:probe/__amd_put_nb_event_constraints _text+34059

Fixes: 4ea42b181434 ("perf: Add perf probe subcommand, a kprobe-event setup helper")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/probe-finder.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 71633f55f045..2fa932bcf960 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -930,7 +930,7 @@ static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
 		ret = find_probe_point_lazy(in_die, pf);
 	else {
 		/* Get probe address */
-		if (dwarf_entrypc(in_die, &addr) != 0) {
+		if (die_entrypc(in_die, &addr) != 0) {
 			pr_warning("Failed to get entry address of %s.\n",
 				   dwarf_diename(in_die));
 			return -ENOENT;

[BUGFIX PATCH V2 4/6] perf/probe: Fix to list probe event with correct line number

[Masami Hiramatsu]

Since debuginfo__find_probe_point() uses dwarf_entrypc() for
finding the entry address of the function on which a probe is,
it will fail when the function DIE has only ranges attribute.

To fix this issue, use die_entrypc() instead of dwarf_entrypc().

Without this fix, perf probe -l shows incorrect offset.

  # perf probe --force -a clear_tasks_mm_cpumask:0 clear_tasks_mm_cpumask:21
  Added new events:
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21)

  You can now use it in all perf tools, such as:

	perf record -e probe:clear_tasks_mm_cpumask_1 -aR sleep 1

  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579478000@linux-5.0.0/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask+18446744071579478067@linux-5.0.0/kernel/cpu.c)

With this,
  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@linux-5.0.0/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21@linux-5.0.0/kernel/cpu.c)

Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number with inline function")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/probe-finder.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 2fa932bcf960..88e17a4f5ac3 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1566,7 +1566,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
 		/* Get function entry information */
 		func = basefunc = dwarf_diename(&spdie);
 		if (!func ||
-		    dwarf_entrypc(&spdie, &baseaddr) != 0 ||
+		    die_entrypc(&spdie, &baseaddr) != 0 ||
 		    dwarf_decl_line(&spdie, &baseline) != 0) {
 			lineno = 0;
 			goto post;
@@ -1583,7 +1583,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
 		while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
 						&indie)) {
 			/* There is an inline function */
-			if (dwarf_entrypc(&indie, &_addr) == 0 &&
+			if (die_entrypc(&indie, &_addr) == 0 &&
 			    _addr == addr) {
 				/*
 				 * addr is at an inline function entry.

[BUGFIX PATCH V2 5/6] perf/probe: Fix to show inlined function callsite without entry_pc

[Masami Hiramatsu]

Fix perf-probe --line option to show inlined function callsite
lines even if the function DIE has only ranges.

Without this,
  # perf probe -L amd_put_event_constraints
  <amd_put_event_constraints@/build/linux-pvZVvI/linux-5.0.0/arch/x86/events/amd/core.c:0>
      0  static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
                                              struct perf_event *event)
      2  {
      3         if (amd_has_nb(cpuc) && amd_is_nb_event(&event->hw))
                        __amd_put_nb_event_constraints(cpuc, event);
      5  }


With this patch,
  # perf probe -L amd_put_event_constraints
  <amd_put_event_constraints@/build/linux-pvZVvI/linux-5.0.0/arch/x86/events/amd/core.c:0>
      0  static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
                                              struct perf_event *event)
      2  {
      3         if (amd_has_nb(cpuc) && amd_is_nb_event(&event->hw))
      4                 __amd_put_nb_event_constraints(cpuc, event);
      5  }

Fixes: 4cc9cec636e7 ("perf probe: Introduce lines walker interface")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/dwarf-aux.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 063f71da6b63..e0c507d6b3b4 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -695,7 +695,7 @@ static int __die_walk_funclines_cb(Dwarf_Die *in_die, void *data)
 	if (dwarf_tag(in_die) == DW_TAG_inlined_subroutine) {
 		fname = die_get_call_file(in_die);
 		lineno = die_get_call_lineno(in_die);
-		if (fname && lineno > 0 && dwarf_entrypc(in_die, &addr) == 0) {
+		if (fname && lineno > 0 && die_entrypc(in_die, &addr) == 0) {
 			lw->retval = lw->callback(fname, lineno, addr, lw->data);
 			if (lw->retval != 0)
 				return DIE_FIND_CB_END;

[BUGFIX PATCH V2 6/6] perf/probe: Fix to show ranges of variables in functions without entry_pc

[Masami Hiramatsu]

Fix to show ranges of variables (--range and --vars option) in
functions which DIE has only ranges but no entry_pc attribute.

Without this fix,
  # perf probe --range -V clear_tasks_mm_cpumask
  Available variables at clear_tasks_mm_cpumask
  	@<clear_tasks_mm_cpumask+0>
  		(No matched variables)

With this fix,
  # perf probe --range -V clear_tasks_mm_cpumask
  Available variables at clear_tasks_mm_cpumask
        @<clear_tasks_mm_cpumask+0>
                [VAL]   int     cpu     @<clear_tasks_mm_cpumask+[0-62,104-109,1881-1888]>


Fixes: 349e8d261131 ("perf probe: Add --range option to show a variable's location range")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/dwarf-aux.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index e0c507d6b3b4..ac82fd937e4b 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1019,7 +1019,7 @@ static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
 	bool first = true;
 	const char *name;
 
-	ret = dwarf_entrypc(sp_die, &entry);
+	ret = die_entrypc(sp_die, &entry);
 	if (ret)
 		return ret;
 
@@ -1082,7 +1082,7 @@ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
 	bool first = true;
 	const char *name;
 
-	ret = dwarf_entrypc(sp_die, &entry);
+	ret = die_entrypc(sp_die, &entry);
 	if (ret)
 		return ret;
 

Re: [BUGFIX PATCH V2 0/6] perf/probe: Additional fixes for range only functions

[Arnaldo Carvalho de Melo]

Em Sat, Oct 26, 2019 at 06:00:19PM +0900, Masami Hiramatsu escreveu:
> Hi Arnaldo,
> 
> I've updated examples in patch description in this v2.
> No changes in the code itself. I ran it on Ubuntu 19.04
> (linux-5.0.0-32-generic).
> 
> Please replace previous one with this.

Can you please take a look at my perf/core branch? I have these already
there:

5e72f4349eff perf probe: Fix to show ranges of variables in functions without entry_pc
50fc0fda5f2c perf probe: Fix to show inlined function callsite without entry_pc
d7bf48229b85 perf probe: Fix to list probe event with correct line number
39cee497850a perf probe: Fix to probe an inline function which has no entry pc
6150bad27ebd perf probe: Fix to probe a function which has no entry pc
fdaea9eea92d perf probe: Fix wrong address verification

And I added committer notes doing the tests.

- Arnaldo
 
> Thank you,
> 
> ---
> 
> Masami Hiramatsu (6):
>       perf/probe: Fix wrong address verification
>       perf/probe: Fix to probe a function which has no entry pc
>       perf/probe: Fix to probe an inline function which has no entry pc
>       perf/probe: Fix to list probe event with correct line number
>       perf/probe: Fix to show inlined function callsite without entry_pc
>       perf/probe: Fix to show ranges of variables in functions without entry_pc
> 
> 
>  tools/perf/util/dwarf-aux.c    |    6 +++---
>  tools/perf/util/probe-finder.c |   40 ++++++++++++++--------------------------
>  2 files changed, 17 insertions(+), 29 deletions(-)
> 
> --
> Masami Hiramatsu (Linaro) <mhiramat@kernel.org>

-- 

- Arnaldo

Re: [BUGFIX PATCH V2 0/6] perf/probe: Additional fixes for range only functions

[Masami Hiramatsu]

On Mon, 28 Oct 2019 11:16:55 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> Em Sat, Oct 26, 2019 at 06:00:19PM +0900, Masami Hiramatsu escreveu:
> > Hi Arnaldo,
> > 
> > I've updated examples in patch description in this v2.
> > No changes in the code itself. I ran it on Ubuntu 19.04
> > (linux-5.0.0-32-generic).
> > 
> > Please replace previous one with this.
> 
> Can you please take a look at my perf/core branch? I have these already
> there:
> 
> 5e72f4349eff perf probe: Fix to show ranges of variables in functions without entry_pc
> 50fc0fda5f2c perf probe: Fix to show inlined function callsite without entry_pc
> d7bf48229b85 perf probe: Fix to list probe event with correct line number
> 39cee497850a perf probe: Fix to probe an inline function which has no entry pc
> 6150bad27ebd perf probe: Fix to probe a function which has no entry pc
> fdaea9eea92d perf probe: Fix wrong address verification
> 
> And I added committer notes doing the tests.

Yes, I confirmed your comments on the patches. It looks good to me.

Thank you!

> 
> - Arnaldo
>  
> > Thank you,
> > 
> > ---
> > 
> > Masami Hiramatsu (6):
> >       perf/probe: Fix wrong address verification
> >       perf/probe: Fix to probe a function which has no entry pc
> >       perf/probe: Fix to probe an inline function which has no entry pc
> >       perf/probe: Fix to list probe event with correct line number
> >       perf/probe: Fix to show inlined function callsite without entry_pc
> >       perf/probe: Fix to show ranges of variables in functions without entry_pc
> > 
> > 
> >  tools/perf/util/dwarf-aux.c    |    6 +++---
> >  tools/perf/util/probe-finder.c |   40 ++++++++++++++--------------------------
> >  2 files changed, 17 insertions(+), 29 deletions(-)
> > 
> > --
> > Masami Hiramatsu (Linaro) <mhiramat@kernel.org>
> 
> -- 
> 
> - Arnaldo


-- 
Masami Hiramatsu <mhiramat@kernel.org>