v3 -> v4: - Rebasing - Cast bpf_[per|this]_cpu_ptr's parameter to void __percpu * before passing into per_cpu_ptr.
v2 -> v3: - Rename functions and variables in verifier for better readability. - Stick to logging message convention in libbpf. - Move bpf_per_cpu_ptr and bpf_this_cpu_ptr from trace-specific helper set to base helper set. - More specific test in ksyms_btf. - Fix return type cast in bpf_*_cpu_ptr. - Fix btf leak in ksyms_btf selftest. - Fix return error code for kallsyms_find().
v1 -> v2: - Move check_pseudo_btf_id from check_ld_imm() to replace_map_fd_with_map_ptr() and rename the latter. - Add bpf_this_cpu_ptr(). - Use bpf_core_types_are_compat() in libbpf.c for checking type compatibility. - Rewrite typed ksym extern type in BTF with int to save space. - Minor revision of bpf_per_cpu_ptr()'s comments. - Avoid using long in tests that use skeleton. - Refactored test_ksyms.c by moving kallsyms_find() to trace_helpers.c - Fold the patches that sync include/linux/uapi and tools/include/linux/uapi.
rfc -> v1: - Encode VAR's btf_id for PSEUDO_BTF_ID. - More checks in verifier. Checking the btf_id passed as PSEUDO_BTF_ID is valid VAR, its name and type. - Checks in libbpf on type compatibility of ksyms. - Add bpf_per_cpu_ptr() to access kernel percpu vars. Introduced new ARG and RET types for this helper.
This patch series extends the previously added __ksym externs with btf support.
Right now the __ksym externs are treated as pure 64-bit scalar value. Libbpf replaces ld_imm64 insn of __ksym by its kernel address at load time. This patch series extend those externs with their btf info. Note that btf support for __ksym must come with the kernel btf that has VARs encoded to work properly. The corresponding chagnes in pahole is available at [1] (with a fix at [2] for gcc 4.9+).
The first 3 patches in this series add support for general kernel global variables, which include verifier checking (01/06), libpf support (02/06) and selftests for getting typed ksym extern's kernel address (03/06).
The next 3 patches extends that capability further by introducing helpers bpf_per_cpu_ptr() and bpf_this_cpu_ptr(), which allows accessing kernel percpu variables correctly (04/06 and 05/06).
The tests of this feature were performed against pahole that is extended with [1] and [2]. For kernel BTF that does not have VARs encoded, the selftests will be skipped.
[1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=f3d9054ba8... [2] https://www.spinics.net/lists/dwarves/msg00451.html
Hao Luo (6): bpf: Introduce pseudo_btf_id bpf/libbpf: BTF support for typed ksyms selftests/bpf: ksyms_btf to test typed ksyms bpf: Introduce bpf_per_cpu_ptr() bpf: Introducte bpf_this_cpu_ptr() bpf/selftests: Test for bpf_per_cpu_ptr() and bpf_this_cpu_ptr()
include/linux/bpf.h | 6 + include/linux/bpf_verifier.h | 7 + include/linux/btf.h | 26 +++ include/uapi/linux/bpf.h | 67 +++++- kernel/bpf/btf.c | 25 --- kernel/bpf/helpers.c | 32 +++ kernel/bpf/verifier.c | 190 ++++++++++++++++-- kernel/trace/bpf_trace.c | 4 + tools/include/uapi/linux/bpf.h | 67 +++++- tools/lib/bpf/libbpf.c | 112 +++++++++-- .../testing/selftests/bpf/prog_tests/ksyms.c | 38 ++-- .../selftests/bpf/prog_tests/ksyms_btf.c | 88 ++++++++ .../selftests/bpf/progs/test_ksyms_btf.c | 55 +++++ tools/testing/selftests/bpf/trace_helpers.c | 27 +++ tools/testing/selftests/bpf/trace_helpers.h | 4 + 15 files changed, 653 insertions(+), 95 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms_btf.c create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf.c