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Subject[PATCH 05/12] perf tools: Read also the end of the kernel
Date
We mark the end of kernel based on the first module,
but that could cover some bpf program maps. Reading
_etext symbol if it's present to get precise kernel
map end.

Link: http://lkml.kernel.org/n/tip-ynut991ttyyhvo1sbhlm4c42@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/util/machine.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 3c520baa198c..ad0205fbb506 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -924,7 +924,8 @@ const char *ref_reloc_sym_names[] = {"_text", "_stext", NULL};
* symbol_name if it's not that important.
*/
static int machine__get_running_kernel_start(struct machine *machine,
- const char **symbol_name, u64 *start)
+ const char **symbol_name,
+ u64 *start, u64 *end)
{
char filename[PATH_MAX];
int i, err = -1;
@@ -949,6 +950,11 @@ static int machine__get_running_kernel_start(struct machine *machine,
*symbol_name = name;

*start = addr;
+
+ err = kallsyms__get_function_start(filename, "_etext", &addr);
+ if (!err)
+ *end = addr;
+
return 0;
}

@@ -1440,7 +1446,7 @@ int machine__create_kernel_maps(struct machine *machine)
struct dso *kernel = machine__get_kernel(machine);
const char *name = NULL;
struct map *map;
- u64 addr = 0;
+ u64 start = 0, end = ~0ULL;
int ret;

if (kernel == NULL)
@@ -1459,9 +1465,9 @@ int machine__create_kernel_maps(struct machine *machine)
"continuing anyway...\n", machine->pid);
}

- if (!machine__get_running_kernel_start(machine, &name, &addr)) {
+ if (!machine__get_running_kernel_start(machine, &name, &start, &end)) {
if (name &&
- map__set_kallsyms_ref_reloc_sym(machine->vmlinux_map, name, addr)) {
+ map__set_kallsyms_ref_reloc_sym(machine->vmlinux_map, name, start)) {
machine__destroy_kernel_maps(machine);
ret = -1;
goto out_put;
@@ -1471,16 +1477,19 @@ int machine__create_kernel_maps(struct machine *machine)
* we have a real start address now, so re-order the kmaps
* assume it's the last in the kmaps
*/
- machine__update_kernel_mmap(machine, addr, ~0ULL);
+ machine__update_kernel_mmap(machine, start, end);
}

if (machine__create_extra_kernel_maps(machine, kernel))
pr_debug("Problems creating extra kernel maps, continuing anyway...\n");

- /* update end address of the kernel map using adjacent module address */
- map = map__next(machine__kernel_map(machine));
- if (map)
- machine__set_kernel_mmap(machine, addr, map->start);
+ if (end == ~0ULL) {
+ /* update end address of the kernel map using adjacent module address */
+ map = map__next(machine__kernel_map(machine));
+ if (map)
+ machine__set_kernel_mmap(machine, start, map->start);
+ }
+
out_put:
dso__put(kernel);
return ret;
--
2.20.1
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