bpftrace/bpftrace-0.11.0-Feature-detect-bpf_attach_kprobe-signature.patch
Jerome Marchand 172a6f7d2f Rebuild for LLVM 11
Resolves: bz#1897622
2020-11-13 18:36:13 +01:00

130 lines
5.2 KiB
Diff

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