[PATCHv5 00/15] bpf: Add trampoline and dispatcher to /proc/kallsyms

Jiri Olsa
2020-03-12T19:56:21Z

hi,
this patchset adds trampoline and dispatcher objects
to be visible in /proc/kallsyms. The last patch also
adds sorting for all bpf objects in /proc/kallsyms.

$ sudo cat /proc/kallsyms | tail -20
...
ffffffffa050f000 t bpf_prog_5a2b06eab81b8f51 [bpf]
ffffffffa0511000 t bpf_prog_6deef7357e7b4530 [bpf]
ffffffffa0542000 t bpf_trampoline_13832 [bpf]
ffffffffa0548000 t bpf_prog_96f1b5bf4e4cc6dc_mutex_lock [bpf]
ffffffffa0572000 t bpf_prog_d1c63e29ad82c4ab_bpf_prog1 [bpf]
ffffffffa0585000 t bpf_prog_e314084d332a5338__dissect [bpf]
ffffffffa0587000 t bpf_prog_59785a79eac7e5d2_mutex_unlock [bpf]
ffffffffa0589000 t bpf_prog_d0db6e0cac050163_mutex_lock [bpf]
ffffffffa058d000 t bpf_prog_d8f047721e4d8321_bpf_prog2 [bpf]
ffffffffa05df000 t bpf_trampoline_25637 [bpf]
ffffffffa05e3000 t bpf_prog_d8f047721e4d8321_bpf_prog2 [bpf]
ffffffffa05e5000 t bpf_prog_3b185187f1855c4c [bpf]
ffffffffa05e7000 t bpf_prog_d8f047721e4d8321_bpf_prog2 [bpf]
ffffffffa05eb000 t bpf_prog_93cebb259dd5c4b2_do_sys_open [bpf]
ffffffffa0677000 t bpf_dispatcher_xdp [bpf]

v5 changes:
- keeping just 1 bpf_tree for all the objects and adding flag
to recognize bpf_objects when searching for exception tables [Alexei]
- no need for is_bpf_image_address call in kernel_text_address [Alexei]
- removed the bpf_image tree, because it's no longer needed

v4 changes:
- add trampoline and dispatcher to kallsyms once the it's allocated [Alexei]
- omit the symbols sorting for kallsyms [Alexei]
- small title change in one patch [Song]
- some function renames:
bpf_get_prog_name to bpf_prog_ksym_set_name
bpf_get_prog_addr_region to bpf_prog_ksym_set_addr
- added acks to changelogs
- I checked and there'll be conflict on perftool side with
upcoming changes from Adrian Hunter (text poke events),
so I think it's better if Arnaldo takes the perf changes
via perf tree and we will solve all conflicts there

v3 changes:
- use container_of directly in bpf_get_ksym_start [Daniel]
- add more changelog explanations for ksym addresses [Daniel]

v2 changes:
- omit extra condition in __bpf_ksym_add for sorting code (Andrii)
- rename bpf_kallsyms_tree_ops to bpf_ksym_tree (Andrii)
- expose only executable code in kallsyms (Andrii)
- use full trampoline key as its kallsyms id (Andrii)
- explained the BPF_TRAMP_REPLACE case (Andrii)
- small format changes in bpf_trampoline_link_prog/bpf_trampoline_unlink_prog (Andrii)
- propagate error value in bpf_dispatcher_update and update kallsym if it's successful (Andrii)
- get rid of __always_inline for bpf_ksym_tree callbacks (Andrii)
- added KSYMBOL notification for bpf_image add/removal
- added perf tools changes to properly display trampoline/dispatcher

For perf tool to properly display trampoline/dispatcher you need
also Arnaldo's perf/urgent branch changes. I merged everything
into following branch:

git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git bpf/kallsyms

thanks,
jirka

---
Björn Töpel (1):
bpf: Add bpf_trampoline_ name prefix for DECLARE_BPF_DISPATCHER

Jiri Olsa (14):
x86/mm: Rename is_kernel_text to __is_kernel_text
bpf: Add struct bpf_ksym
bpf: Add name to struct bpf_ksym
bpf: Move lnode list node to struct bpf_ksym
bpf: Move ksym_tnode to bpf_ksym
bpf: Add bpf_ksym_find function
bpf: Add prog flag to struct bpf_ksym object
bpf: Add bpf_ksym_add/del functions
bpf: Add trampolines to kallsyms
bpf: Add dispatchers to kallsyms
bpf: Remove bpf_image tree
perf tools: Synthesize bpf_trampoline/dispatcher ksymbol event
perf tools: Set ksymbol dso as loaded on arrival
perf annotate: Add base support for bpf_image

arch/x86/mm/init_32.c | 14 +++++++++-----
include/linux/bpf.h | 65 ++++++++++++++++++++++++++++++++++++++++-------------------------
include/linux/filter.h | 15 ++++-----------
kernel/bpf/core.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------------------------------------------
kernel/bpf/dispatcher.c | 5 +++--
kernel/bpf/trampoline.c | 85 +++++++++++++++++++++++++------------------------------------------------------------
kernel/events/core.c | 9 ++++-----
kernel/extable.c | 2 --
net/core/filter.c | 5 ++---
tools/perf/util/annotate.c | 20 ++++++++++++++++++++
tools/perf/util/bpf-event.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/dso.c | 1 +
tools/perf/util/dso.h | 1 +
tools/perf/util/machine.c | 12 ++++++++++++
tools/perf/util/symbol.c | 1 +
15 files changed, 278 insertions(+), 169 deletions(-)