3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
commit 07d369857808b7e8e471bbbbb0074a6718f89b31 upstream.
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;
# 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 clear_tasks_mm_cpumask+0 p:probe/clear_tasks_mm_cpumask_1 clear_tasks_mm_cpumask+5 p:probe/clear_tasks_mm_cpumask_2 clear_tasks_mm_cpumask+8 p:probe/clear_tasks_mm_cpumask_3 clear_tasks_mm_cpumask+16 p:probe/clear_tasks_mm_cpumask_4 clear_tasks_mm_cpumask+82
Committer testing:
I managed to reproduce the above:
[root@quaco ~]# perf probe -D clear_tasks_mm_cpumask:1 p:probe/clear_tasks_mm_cpumask _text+919968 p:probe/clear_tasks_mm_cpumask_1 _text+919973 p:probe/clear_tasks_mm_cpumask_2 _text+919976 [root@quaco ~]#
But then when trying to actually put the probe in place, it fails if I use :0 as the offset:
[root@quaco ~]# perf probe -L clear_tasks_mm_cpumask | head -5 <clear_tasks_mm_cpumask@/usr/src/debug/kernel-5.2.fc30/linux-5.2.18-200.fc30.x86_64/kernel/cpu.c:0> 0 void clear_tasks_mm_cpumask(int cpu) 1 { 2 struct task_struct *p;
[root@quaco ~]# perf probe clear_tasks_mm_cpumask:0 Probe point 'clear_tasks_mm_cpumask' not found. Error: Failed to add events. [root@quaco
The next patch is needed to fix this case.
Fixes: 576b523721b7 ("perf probe: Fix probing symbols with optimization suffix") Reported-by: Arnaldo Carvalho de Melo acme@kernel.org Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Link: http://lore.kernel.org/lkml/157199318513.8075.10463906803299647907.stgit@dev... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -588,34 +588,26 @@ static int convert_to_trace_point(Dwarf_ Dwarf_Addr paddr, bool retprobe, 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; }
- /* Get an appropriate symbol from symtab */ + /* Try to get actual 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; + tp->offset = (unsigned long)(paddr - sym.st_value); tp->address = (unsigned long)paddr; tp->symbol = strdup(symbol);