| Message ID | 20210629192945.1071862-1-jolsa@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | bpf, x86: Add bpf_get_func_ip helper | expand |
On Tue, 29 Jun 2021, Jiri Olsa wrote: > hi, > adding bpf_get_func_ip helper that returns IP address of the > caller function for trampoline and krobe programs. > > There're 2 specific implementation of the bpf_get_func_ip > helper, one for trampoline progs and one for kprobe/kretprobe > progs. > > The trampoline helper call is replaced/inlined by verifier > with simple move instruction. The kprobe/kretprobe is actual > helper call that returns prepared caller address. > > The trampoline extra 3 instructions for storing IP address > is now optional, which I'm not completely sure is necessary, > so I plan to do some benchmarks, if it's noticeable, hence > the RFC. I'm also not completely sure about the kprobe/kretprobe > implementation. > > Also available at: > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > bpf/get_func_ip > > thanks, > jirka > > This is great Jiri! Feel free to add for the series: Tested-by: Alan Maguire <alan.maguire@oracle.com> BTW I also verified that if we extend bpf_program__attach_kprobe() to support the function+offset format in the func_name argument for kprobes, the following test will pass too: __u64 test5_result = 0; SEC("kprobe/bpf_fentry_test5+0x6") int test5(struct pt_regs *ctx) { __u64 addr = bpf_get_func_ip(ctx); test5_result = (const void *) addr == (&bpf_fentry_test5 + 0x6); return 0; } Thanks! Alan > --- > Jiri Olsa (5): > bpf, x86: Store caller's ip in trampoline stack > bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip > bpf: Add bpf_get_func_ip helper for tracing programs > bpf: Add bpf_get_func_ip helper for kprobe programs > selftests/bpf: Add test for bpf_get_func_ip helper > > arch/x86/net/bpf_jit_comp.c | 19 +++++++++++++++++++ > include/linux/bpf.h | 5 +++++ > include/linux/filter.h | 3 ++- > include/uapi/linux/bpf.h | 7 +++++++ > kernel/bpf/trampoline.c | 12 +++++++++--- > kernel/bpf/verifier.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > kernel/trace/bpf_trace.c | 29 +++++++++++++++++++++++++++++ > kernel/trace/trace_kprobe.c | 20 ++++++++++++++++++-- > kernel/trace/trace_probe.h | 5 +++++ > tools/include/uapi/linux/bpf.h | 7 +++++++ > tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 42 ++++++++++++++++++++++++++++++++++++++++++ > tools/testing/selftests/bpf/progs/get_func_ip_test.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 12 files changed, 260 insertions(+), 6 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c > create mode 100644 tools/testing/selftests/bpf/progs/get_func_ip_test.c > >
On Thu, Jul 01, 2021 at 06:22:45PM +0100, Alan Maguire wrote: > On Tue, 29 Jun 2021, Jiri Olsa wrote: > > > hi, > > adding bpf_get_func_ip helper that returns IP address of the > > caller function for trampoline and krobe programs. > > > > There're 2 specific implementation of the bpf_get_func_ip > > helper, one for trampoline progs and one for kprobe/kretprobe > > progs. > > > > The trampoline helper call is replaced/inlined by verifier > > with simple move instruction. The kprobe/kretprobe is actual > > helper call that returns prepared caller address. > > > > The trampoline extra 3 instructions for storing IP address > > is now optional, which I'm not completely sure is necessary, > > so I plan to do some benchmarks, if it's noticeable, hence > > the RFC. I'm also not completely sure about the kprobe/kretprobe > > implementation. > > > > Also available at: > > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > > bpf/get_func_ip > > > > thanks, > > jirka > > > > > > This is great Jiri! Feel free to add for the series: > > Tested-by: Alan Maguire <alan.maguire@oracle.com> great, thanks for testing > > BTW I also verified that if we extend bpf_program__attach_kprobe() to > support the function+offset format in the func_name argument for kprobes, > the following test will pass too: > > __u64 test5_result = 0; > SEC("kprobe/bpf_fentry_test5+0x6") > int test5(struct pt_regs *ctx) > { > __u64 addr = bpf_get_func_ip(ctx); > > test5_result = (const void *) addr == (&bpf_fentry_test5 + 0x6); > return 0; > } right, I did not think of this test, I'll add it thanks, jirka
hi, adding bpf_get_func_ip helper that returns IP address of the caller function for trampoline and krobe programs. There're 2 specific implementation of the bpf_get_func_ip helper, one for trampoline progs and one for kprobe/kretprobe progs. The trampoline helper call is replaced/inlined by verifier with simple move instruction. The kprobe/kretprobe is actual helper call that returns prepared caller address. The trampoline extra 3 instructions for storing IP address is now optional, which I'm not completely sure is necessary, so I plan to do some benchmarks, if it's noticeable, hence the RFC. I'm also not completely sure about the kprobe/kretprobe implementation. Also available at: https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git bpf/get_func_ip thanks, jirka --- Jiri Olsa (5): bpf, x86: Store caller's ip in trampoline stack bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip bpf: Add bpf_get_func_ip helper for tracing programs bpf: Add bpf_get_func_ip helper for kprobe programs selftests/bpf: Add test for bpf_get_func_ip helper arch/x86/net/bpf_jit_comp.c | 19 +++++++++++++++++++ include/linux/bpf.h | 5 +++++ include/linux/filter.h | 3 ++- include/uapi/linux/bpf.h | 7 +++++++ kernel/bpf/trampoline.c | 12 +++++++++--- kernel/bpf/verifier.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 29 +++++++++++++++++++++++++++++ kernel/trace/trace_kprobe.c | 20 ++++++++++++++++++-- kernel/trace/trace_probe.h | 5 +++++ tools/include/uapi/linux/bpf.h | 7 +++++++ tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 42 ++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/progs/get_func_ip_test.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 12 files changed, 260 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c create mode 100644 tools/testing/selftests/bpf/progs/get_func_ip_test.c