[PATCHv2 bpf-next 0/3] bpf: Support bpf_get_func_ip helper in uprobes

Jiri Olsa
2023-08-03T09:52:24Z

hi,
adding support for bpf_get_func_ip helper for uprobe program to return
probed address for both uprobe and return uprobe as suggested by Andrii
in [1].

We agreed that uprobe can have special use of bpf_get_func_ip helper
that differs from kprobe.

The kprobe bpf_get_func_ip returns:
- address of the function if probe is attach on function entry
for both kprobe and return kprobe
- 0 if the probe is not attach on function entry

The uprobe bpf_get_func_ip returns:
- address of the probe for both uprobe and return uprobe

The reason for this semantic change is that kernel can't really tell
if the probe user space address is function entry.

v2 changes:
- renamed bpf_prog_run_array_sleepable to bpf_prog_run_array_uprobe [Yafang Shao]
- return -EOPNOTSUPP in bpf_get_func_ip_uprobe for !CONFIG_UPROBES [Alan]
- added Tested-by [Alan]

Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
uprobe_get_func_ip

thanks,
jirka

[1] https://lore.kernel.org/bpf/CAEf4BzZ=xLVkG5eurEuvLU79wAMtwho7ReR+XJAgwhFF4M-7Cg@mail.gmail.com/
---
Jiri Olsa (3):
bpf: Add support for bpf_get_func_ip helper for uprobe program
selftests/bpf: Add bpf_get_func_ip tests for uprobe on function entry
selftests/bpf: Add bpf_get_func_ip test for uprobe inside function

include/linux/bpf.h | 5 +++++
include/uapi/linux/bpf.h | 7 ++++++-
kernel/trace/bpf_trace.c | 21 ++++++++++++++++++++-
kernel/trace/trace_probe.h | 5 +++++
kernel/trace/trace_uprobe.c | 5 -----
tools/include/uapi/linux/bpf.h | 7 ++++++-
tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
tools/testing/selftests/bpf/progs/get_func_ip_test.c | 25 +++++++++++++++++++++++--
tools/testing/selftests/bpf/progs/get_func_ip_uprobe_test.c | 18 ++++++++++++++++++
9 files changed, 133 insertions(+), 11 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/get_func_ip_uprobe_test.c