linux/tools/perf/include/bpf/bpf.h

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// SPDX-License-Identifier: GPL-2.0
#ifndef _PERF_BPF_H
#define _PERF_BPF_H
perf bpf: Include uapi/linux/bpf.h from the 'perf trace' script's bpf.h The next example scripts need the definition for the BPF functions, i.e. things like BPF_FUNC_probe_read, and in time will require lots of other definitions found in uapi/linux/bpf.h, so include it from the bpf.h file included from the eBPF scripts build with clang via '-e bpf_script.c' like in this example: $ tail -8 tools/perf/examples/bpf/5sec.c #include <bpf.h> int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec) { return sec == 5; } license(GPL); $ That 'bpf.h' include in the 5sec.c eBPF example will come from a set of header files crafted for building eBPF objects, that in a end-user system will come from: /usr/lib/perf/include/bpf/bpf.h And will include <uapi/linux/bpf.h> either from the place where the kernel was built, or from a kernel-devel rpm package like: -working-directory /lib/modules/4.17.9-100.fc27.x86_64/build That is set up by tools/perf/util/llvm-utils.c, and can be overriden by setting the 'kbuild-dir' variable in the "llvm" ~/.perfconfig file, like: # cat ~/.perfconfig [llvm] kbuild-dir = /home/foo/git/build/linux This usually doesn't need any change, just documenting here my findings while working with this code. In the future we may want to instead just use what is in /usr/include/linux/bpf.h, that comes from the UAPI provided from the kernel sources, for now, to avoid getting the kernel's non-UAPI "linux/bpf.h" file, that will cause clang to fail and is not what we want anyway (no BPF function definitions, etc), do it explicitely by asking for "uapi/linux/bpf.h". Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-zd8zeyhr2sappevojdem9xxt@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-08-01 13:50:51 +00:00
#include <uapi/linux/bpf.h>
perf bpf: Add struct bpf_map struct A helper structure used by eBPF C program to describe map attributes to elf_bpf loader, to be used initially by the special __bpf_stdout__ map used to print strings into the perf ring buffer in BPF scripts, e.g.: Using the upcoming stdio.h and puts() macros to use the __bpf_stdout__ map to add strings to the ring buffer: # cat tools/perf/examples/bpf/hello.c #include <stdio.h> int syscall_enter(openat)(void *args) { puts("Hello, world\n"); return 0; } license(GPL); # # cat ~/.perfconfig [llvm] dump-obj = true # perf trace -e openat,tools/perf/examples/bpf/hello.c/call-graph=dwarf/ cat /etc/passwd > /dev/null LLVM: dumping tools/perf/examples/bpf/hello.o 0.016 ( ): __bpf_stdout__:Hello, world 0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC ) = 3 0.057 ( ): __bpf_stdout__:Hello, world 0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC ) = 3 0.417 ( ): __bpf_stdout__:Hello, world 0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd ) = 3 # # file tools/perf/examples/bpf/hello.o tools/perf/examples/bpf/hello.o: ELF 64-bit LSB relocatable, *unknown arch 0xf7* version 1 (SYSV), not stripped # readelf -SW tools/perf/examples/bpf/hello.o There are 10 section headers, starting at offset 0x208: Section Headers: [Nr] Name Type Address Off Size ES Flg Lk Inf Al [ 0] NULL 0000000000000000 000000 000000 00 0 0 0 [ 1] .strtab STRTAB 0000000000000000 000188 00007f 00 0 0 1 [ 2] .text PROGBITS 0000000000000000 000040 000000 00 AX 0 0 4 [ 3] syscalls:sys_enter_openat PROGBITS 0000000000000000 000040 000088 00 AX 0 0 8 [ 4] .relsyscalls:sys_enter_openat REL 0000000000000000 000178 000010 10 9 3 8 [ 5] maps PROGBITS 0000000000000000 0000c8 00001c 00 WA 0 0 4 [ 6] .rodata.str1.1 PROGBITS 0000000000000000 0000e4 00000e 01 AMS 0 0 1 [ 7] license PROGBITS 0000000000000000 0000f2 000004 00 WA 0 0 1 [ 8] version PROGBITS 0000000000000000 0000f8 000004 00 WA 0 0 4 [ 9] .symtab SYMTAB 0000000000000000 000100 000078 18 1 1 8 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings), I (info), L (link order), O (extra OS processing required), G (group), T (TLS), C (compressed), x (unknown), o (OS specific), E (exclude), p (processor specific) # readelf -s tools/perf/examples/bpf/hello.o Symbol table '.symtab' contains 5 entries: Num: Value Size Type Bind Vis Ndx Name 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000000000000 0 NOTYPE GLOBAL DEFAULT 5 __bpf_stdout__ 2: 0000000000000000 0 NOTYPE GLOBAL DEFAULT 7 _license 3: 0000000000000000 0 NOTYPE GLOBAL DEFAULT 8 _version 4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT 3 syscall_enter_openat # Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-81fg60om2ifnatsybzwmiga3@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-08-06 12:02:26 +00:00
/*
* A helper structure used by eBPF C program to describe map attributes to
* elf_bpf loader, taken from tools/testing/selftests/bpf/bpf_helpers.h:
*/
struct bpf_map {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
unsigned int map_flags;
unsigned int inner_map_idx;
unsigned int numa_node;
};
#define SEC(NAME) __attribute__((section(NAME), used))
#define probe(function, vars) \
SEC(#function "=" #function " " #vars) function
#define syscall_enter(name) \
SEC("syscalls:sys_enter_" #name) syscall_enter_ ## name
#define license(name) \
char _license[] SEC("license") = #name; \
int _version SEC("version") = LINUX_VERSION_CODE;
static int (*probe_read)(void *dst, int size, const void *unsafe_addr) = (void *)BPF_FUNC_probe_read;
static int (*probe_read_str)(void *dst, int size, const void *unsafe_addr) = (void *)BPF_FUNC_probe_read_str;
#endif /* _PERF_BPF_H */