130 lines
5.2 KiB
Diff
130 lines
5.2 KiB
Diff
From 00687a3538755b60c2b205963c8ae49b4681e642 Mon Sep 17 00:00:00 2001
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From: Viktor Malik <viktor.malik@gmail.com>
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Date: Wed, 12 Aug 2020 09:45:29 +0200
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Subject: [PATCH 1/2] Feature-detect bpf_attach_kprobe signature
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The function has 6 parameters in current versions of BCC and 5
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parameters in older versions.
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This is detected in CMake using CHECK_CXX_SOURCE_COMPILES. For static
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compilation, we also need to retrieve and link static libbpf, libelf,
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and libz. This may cause libbpf, libelf and libz to be searched for
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twice, but it should be fine since CMake caches results.
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Fixes iovisor#1027.
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---
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cmake/FindLibBcc.cmake | 24 ++++++++++++++++++++++++
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src/CMakeLists.txt | 3 +++
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src/attached_probe.cpp | 31 ++++++++++++++-----------------
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tests/CMakeLists.txt | 3 +++
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4 files changed, 44 insertions(+), 17 deletions(-)
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diff --git a/cmake/FindLibBcc.cmake b/cmake/FindLibBcc.cmake
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index 9d30b04..ec21627 100644
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--- a/cmake/FindLibBcc.cmake
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+++ b/cmake/FindLibBcc.cmake
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@@ -70,3 +70,27 @@ include (FindPackageHandleStandardArgs)
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FIND_PACKAGE_HANDLE_STANDARD_ARGS(LibBcc "Please install the bcc library package, which is required. Depending on your distro, it may be called bpfcclib or bcclib (Ubuntu), bcc-devel (Fedora), or something else. If unavailable, install bcc from source (github.com/iovisor/bcc)."
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LIBBCC_LIBRARIES
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LIBBCC_INCLUDE_DIRS)
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+
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+# Check bpf_attach_kprobe signature
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+if(${LIBBCC_FOUND})
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+if(STATIC_LINKING)
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+ # libbcc.a is not statically linked with libbpf.a, libelf.a, and libz.a.
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+ # If we do a static bpftrace build, we must link them in.
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+ find_package(LibBpf)
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+ find_package(LibElf)
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+ find_package(LibZ)
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+ SET(CMAKE_REQUIRED_LIBRARIES ${LIBBCC_BPF_LIBRARY_STATIC} ${LIBBPF_LIBRARIES} ${LIBELF_LIBRARIES} ${LIBZ_LIBRARIES})
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+else()
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+ SET(CMAKE_REQUIRED_LIBRARIES ${LIBBCC_LIBRARIES})
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+endif()
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+INCLUDE(CheckCXXSourceCompiles)
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+CHECK_CXX_SOURCE_COMPILES("
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+#include <bcc/libbpf.h>
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+
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+int main(void) {
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+ bpf_attach_kprobe(0, BPF_PROBE_ENTRY, \"\", \"\", 0, 0);
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+ return 0;
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+}
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+" LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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+SET(CMAKE_REQUIRED_LIBRARIES)
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+endif()
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diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
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index 487fa9b..35d2400 100644
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--- a/src/CMakeLists.txt
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+++ b/src/CMakeLists.txt
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@@ -79,6 +79,9 @@ if(HAVE_BFD_DISASM)
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target_link_libraries(bpftrace ${LIBOPCODES_LIBRARIES})
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endif(STATIC_LINKING)
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endif(HAVE_BFD_DISASM)
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+if(LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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+ target_compile_definitions(bpftrace PRIVATE LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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+endif(LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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if (ALLOW_UNSAFE_PROBE)
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target_compile_definitions(bpftrace PRIVATE HAVE_UNSAFE_PROBE)
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diff --git a/src/attached_probe.cpp b/src/attached_probe.cpp
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index 587a115..afad9ed 100644
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--- a/src/attached_probe.cpp
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+++ b/src/attached_probe.cpp
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@@ -754,26 +754,23 @@ void AttachedProbe::load_prog()
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}
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}
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-// XXX(mmarchini): bcc changed the signature of bpf_attach_kprobe, adding a new
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-// int parameter at the end. Since there's no reliable way to feature-detect
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-// this, we create a function pointer with the long signature and cast
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-// bpf_attach_kprobe to this function pointer. If we're on an older bcc
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-// version, bpf_attach_kprobe call will be augmented with an extra register
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-// being used for the last parameter, even though this register won't be used
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-// inside the function. Since the register won't be used this is kinda safe,
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-// although not ideal.
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-typedef int (*attach_probe_wrapper_signature)(int, enum bpf_probe_attach_type, const char*, const char*, uint64_t, int);
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-
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void AttachedProbe::attach_kprobe(bool safe_mode)
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{
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resolve_offset_kprobe(safe_mode);
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- int perf_event_fd = cast_signature<attach_probe_wrapper_signature>(
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- &bpf_attach_kprobe)(progfd_,
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- attachtype(probe_.type),
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- eventname().c_str(),
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- probe_.attach_point.c_str(),
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- offset_,
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- 0);
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+#ifdef LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE
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+ int perf_event_fd = bpf_attach_kprobe(progfd_,
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+ attachtype(probe_.type),
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+ eventname().c_str(),
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+ probe_.attach_point.c_str(),
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+ offset_,
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+ 0);
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+#else
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+ int perf_event_fd = bpf_attach_kprobe(progfd_,
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+ attachtype(probe_.type),
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+ eventname().c_str(),
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+ probe_.attach_point.c_str(),
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+ offset_);
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+#endif
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if (perf_event_fd < 0) {
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if (probe_.orig_name != probe_.name) {
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diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
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index 4104a57..ed0ccf8 100644
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--- a/tests/CMakeLists.txt
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+++ b/tests/CMakeLists.txt
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@@ -100,6 +100,9 @@ if(HAVE_BFD_DISASM)
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target_link_libraries(bpftrace_test ${LIBOPCODES_LIBRARIES})
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endif(STATIC_LINKING)
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endif(HAVE_BFD_DISASM)
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+if(LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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+ target_compile_definitions(bpftrace_test PRIVATE LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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+endif(LIBBCC_ATTACH_KPROBE_SIX_ARGS_SIGNATURE)
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target_link_libraries(bpftrace_test arch ast parser resources)
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--
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2.25.4
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