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Date: Tue, 18 Feb 2014 18:08:47 -0300
From: Arnaldo Carvalho de Melo <acme@...radead.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
David Ahern <dsahern@...il.com>,
"David A. Long" <dave.long@...aro.org>,
Ingo Molnar <mingo@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Oleg Nesterov <oleg@...hat.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Steven Rostedt <rostedt@...dmis.org>,
yrl.pp-manager.tt@...achi.com,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 28/32] perf probe: Find given address from offline dwarf
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Find the given address from offline dwarfs instead of online kernel
dwarfs.
On the KASLR enabled kernel, the kernel text section is loaded with
random offset, and the debuginfo__new_online_kernel can't handle it. So
let's move to the offline dwarf loader instead of using the online dwarf
loader.
As a result, since we don't need debuginfo__new_online_kernel any more,
this also removes the functions related to that.
Without this change;
# ./perf probe -l
probe:t_show (on _stext+901288 with m v)
probe:t_show_1 (on _stext+939624 with m v t)
probe:t_show_2 (on _stext+980296 with m v fmt)
probe:t_show_3 (on _stext+1014392 with m v file)
With this change;
# ./perf probe -l
probe:t_show (on t_show@...ux-3/kernel/trace/ftrace.c with m v)
probe:t_show_1 (on t_show@...ux-3/kernel/trace/trace.c with m v t)
probe:t_show_2 (on t_show@...nel/trace/trace_printk.c with m v fmt)
probe:t_show_3 (on t_show@...nel/trace/trace_events.c with m v file)
Changes from v2:
- Instead of retrying, directly opens offline dwarf.
- Remove debuginfo__new_online_kernel and related functions.
- Refer map->reloc to get the correct address of a symbol.
- Add a special case for handling ref_reloc_sym based address.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: David Ahern <dsahern@...il.com>
Cc: "David A. Long" <dave.long@...aro.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: yrl.pp-manager.tt@...achi.com
Link: http://lkml.kernel.org/r/20140206053218.29635.74821.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/util/probe-event.c | 40 +++++++++++++-------
tools/perf/util/probe-finder.c | 86 ------------------------------------------
tools/perf/util/probe-finder.h | 1 -
3 files changed, 26 insertions(+), 101 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 1ce2cb9845b6..8e34c8d47813 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -248,6 +248,18 @@ static struct debuginfo *open_debuginfo(const char *module)
return debuginfo__new(path);
}
+static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
+{
+ /* kmap->ref_reloc_sym should be set if host_machine is initialized */
+ struct kmap *kmap;
+
+ if (map__load(host_machine->vmlinux_maps[MAP__FUNCTION], NULL) < 0)
+ return NULL;
+
+ kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
+ return kmap->ref_reloc_sym;
+}
+
/*
* Convert trace point to probe point with debuginfo
* Currently only handles kprobes.
@@ -256,18 +268,27 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
struct perf_probe_point *pp)
{
struct symbol *sym;
+ struct ref_reloc_sym *reloc_sym;
struct map *map;
- u64 addr;
+ u64 addr = 0;
int ret = -ENOENT;
struct debuginfo *dinfo;
- sym = __find_kernel_function_by_name(tp->symbol, &map);
- if (sym) {
- addr = map->unmap_ip(map, sym->start + tp->offset);
+ /* ref_reloc_sym is just a label. Need a special fix*/
+ reloc_sym = __kernel_get_ref_reloc_sym();
+ if (reloc_sym && strcmp(tp->symbol, reloc_sym->name) == 0)
+ addr = reloc_sym->unrelocated_addr + tp->offset;
+ else {
+ sym = __find_kernel_function_by_name(tp->symbol, &map);
+ if (sym)
+ addr = map->unmap_ip(map, sym->start + tp->offset) -
+ map->reloc;
+ }
+ if (addr) {
pr_debug("try to find %s+%ld@%" PRIx64 "\n", tp->symbol,
tp->offset, addr);
- dinfo = debuginfo__new_online_kernel(addr);
+ dinfo = open_debuginfo(tp->module);
if (dinfo) {
ret = debuginfo__find_probe_point(dinfo,
(unsigned long)addr, pp);
@@ -383,15 +404,6 @@ static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
return ret;
}
-static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
-{
- /* kmap->ref_reloc_sym should be set if host_machine is initialized */
- struct kmap *kmap;
-
- kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
- return kmap->ref_reloc_sym;
-}
-
/* Post processing the probe events */
static int post_process_probe_trace_events(struct probe_trace_event *tevs,
int ntevs, const char *module,
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index e5e589fdef9b..4f6e277c457c 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -89,79 +89,6 @@ error:
return -ENOENT;
}
-#if _ELFUTILS_PREREQ(0, 148)
-/* This method is buggy if elfutils is older than 0.148 */
-static int __linux_kernel_find_elf(Dwfl_Module *mod,
- void **userdata,
- const char *module_name,
- Dwarf_Addr base,
- char **file_name, Elf **elfp)
-{
- int fd;
- const char *path = kernel_get_module_path(module_name);
-
- pr_debug2("Use file %s for %s\n", path, module_name);
- if (path) {
- fd = open(path, O_RDONLY);
- if (fd >= 0) {
- *file_name = strdup(path);
- return fd;
- }
- }
- /* If failed, try to call standard method */
- return dwfl_linux_kernel_find_elf(mod, userdata, module_name, base,
- file_name, elfp);
-}
-
-static const Dwfl_Callbacks kernel_callbacks = {
- .find_debuginfo = dwfl_standard_find_debuginfo,
- .debuginfo_path = &debuginfo_path,
-
- .find_elf = __linux_kernel_find_elf,
- .section_address = dwfl_linux_kernel_module_section_address,
-};
-
-/* Get a Dwarf from live kernel image */
-static int debuginfo__init_online_kernel_dwarf(struct debuginfo *dbg,
- Dwarf_Addr addr)
-{
- dbg->dwfl = dwfl_begin(&kernel_callbacks);
- if (!dbg->dwfl)
- return -EINVAL;
-
- /* Load the kernel dwarves: Don't care the result here */
- dwfl_linux_kernel_report_kernel(dbg->dwfl);
- dwfl_linux_kernel_report_modules(dbg->dwfl);
-
- dbg->dbg = dwfl_addrdwarf(dbg->dwfl, addr, &dbg->bias);
- /* Here, check whether we could get a real dwarf */
- if (!dbg->dbg) {
- pr_debug("Failed to find kernel dwarf at %lx\n",
- (unsigned long)addr);
- dwfl_end(dbg->dwfl);
- memset(dbg, 0, sizeof(*dbg));
- return -ENOENT;
- }
-
- return 0;
-}
-#else
-/* With older elfutils, this just support kernel module... */
-static int debuginfo__init_online_kernel_dwarf(struct debuginfo *dbg,
- Dwarf_Addr addr __maybe_unused)
-{
- const char *path = kernel_get_module_path("kernel");
-
- if (!path) {
- pr_err("Failed to find vmlinux path\n");
- return -ENOENT;
- }
-
- pr_debug2("Use file %s for debuginfo\n", path);
- return debuginfo__init_offline_dwarf(dbg, path);
-}
-#endif
-
struct debuginfo *debuginfo__new(const char *path)
{
struct debuginfo *dbg = zalloc(sizeof(*dbg));
@@ -174,19 +101,6 @@ struct debuginfo *debuginfo__new(const char *path)
return dbg;
}
-struct debuginfo *debuginfo__new_online_kernel(unsigned long addr)
-{
- struct debuginfo *dbg = zalloc(sizeof(*dbg));
-
- if (!dbg)
- return NULL;
-
- if (debuginfo__init_online_kernel_dwarf(dbg, (Dwarf_Addr)addr) < 0)
- zfree(&dbg);
-
- return dbg;
-}
-
void debuginfo__delete(struct debuginfo *dbg)
{
if (dbg) {
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 592c4dac3be9..3fc597365ce6 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -31,7 +31,6 @@ struct debuginfo {
};
extern struct debuginfo *debuginfo__new(const char *path);
-extern struct debuginfo *debuginfo__new_online_kernel(unsigned long addr);
extern void debuginfo__delete(struct debuginfo *dbg);
/* Find probe_trace_events specified by perf_probe_event from debuginfo */
--
1.8.1.4
--
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