[PATCH 10/13] perf machine: Update kernel map address and re-order properly

Arnaldo Carvalho de Melo
2019-03-29T13:38:52Z

From: Wei Li <liwei391@huawei.com>

Since commit 1fb87b8e9599 ("perf machine: Don't search for active kernel
start in __machine__create_kernel_maps"), the __machine__create_kernel_maps()
just create a map what start and end are both zero. Though the address will be
updated later, the order of map in the rbtree may be incorrect.

The commit ee05d21791db ("perf machine: Set main kernel end address properly")
fixed the logic in machine__create_kernel_maps(), but it's still wrong in
function machine__process_kernel_mmap_event().

To reproduce this issue, we need an environment which the module address
is before the kernel text segment. I tested it on an aarch64 machine with
kernel 4.19.25:

[root@localhost hulk]# grep _stext /proc/kallsyms
ffff000008081000 T _stext
[root@localhost hulk]# grep _etext /proc/kallsyms
ffff000009780000 R _etext
[root@localhost hulk]# tail /proc/modules
hisi_sas_v2_hw 77824 0 - Live 0xffff00000191d000
nvme_core 126976 7 nvme, Live 0xffff0000018b6000
mdio 20480 1 ixgbe, Live 0xffff0000018ab000
hisi_sas_main 106496 1 hisi_sas_v2_hw, Live 0xffff000001861000
hns_mdio 20480 2 - Live 0xffff000001822000
hnae 28672 3 hns_dsaf,hns_enet_drv, Live 0xffff000001815000
dm_mirror 40960 0 - Live 0xffff000001804000
dm_region_hash 32768 1 dm_mirror, Live 0xffff0000017f5000
dm_log 32768 2 dm_mirror,dm_region_hash, Live 0xffff0000017e7000
dm_mod 315392 17 dm_mirror,dm_log, Live 0xffff000001780000
[root@localhost hulk]#

Before fix:

[root@localhost bin]# perf record sleep 3
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.011 MB perf.data (9 samples) ]
[root@localhost bin]# perf buildid-list -i perf.data
4c4e46c971ca935f781e603a09b52a92e8bdfee8 [vdso]
[root@localhost bin]# perf buildid-list -i perf.data -H
0000000000000000000000000000000000000000 /proc/kcore
[root@localhost bin]#

After fix:

[root@localhost tools]# ./perf/perf record sleep 3
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.011 MB perf.data (9 samples) ]
[root@localhost tools]# ./perf/perf buildid-list -i perf.data
28a6c690262896dbd1b5e1011ed81623e6db0610 [kernel.kallsyms]
106c14ce6e4acea3453e484dc604d66666f08a2f [vdso]
[root@localhost tools]# ./perf/perf buildid-list -i perf.data -H
28a6c690262896dbd1b5e1011ed81623e6db0610 /proc/kcore

Signed-off-by: Wei Li <liwei391@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Li Bin <huawei.libin@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190228092003.34071-1-liwei391@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/machine.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 61959aba7e27..3c520baa198c 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1421,6 +1421,20 @@ static void machine__set_kernel_mmap(struct machine *machine,
machine->vmlinux_map->end = ~0ULL;
}

+static void machine__update_kernel_mmap(struct machine *machine,
+ u64 start, u64 end)
+{
+ struct map *map = machine__kernel_map(machine);
+
+ map__get(map);
+ map_groups__remove(&machine->kmaps, map);
+
+ machine__set_kernel_mmap(machine, start, end);
+
+ map_groups__insert(&machine->kmaps, map);
+ map__put(map);
+}
+
int machine__create_kernel_maps(struct machine *machine)
{
struct dso *kernel = machine__get_kernel(machine);
@@ -1453,17 +1467,11 @@ int machine__create_kernel_maps(struct machine *machine)
goto out_put;
}

- /* we have a real start address now, so re-order the kmaps */
- map = machine__kernel_map(machine);
-
- map__get(map);
- map_groups__remove(&machine->kmaps, map);
-
- /* assume it's the last in the kmaps */
- machine__set_kernel_mmap(machine, addr, ~0ULL);
-
- map_groups__insert(&machine->kmaps, map);
- map__put(map);
+ /*
+ * 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);
}

if (machine__create_extra_kernel_maps(machine, kernel))
@@ -1599,7 +1607,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
if (strstr(kernel->long_name, "vmlinux"))
dso__set_short_name(kernel, "[kernel.vmlinux]", false);

- machine__set_kernel_mmap(machine, event->mmap.start,
+ machine__update_kernel_mmap(machine, event->mmap.start,
event->mmap.start + event->mmap.len);

/*
--
2.20.1