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perf llvm: Pass LINUX_VERSION_CODE to BPF program when compiling
Arnaldo suggests to make LINUX_VERSION_CODE works like __func__ and __FILE__ so user don't need to care setting right linux version too much. In this patch, perf llvm transfers LINUX_VERSION_CODE macro through clang cmdline. [1] http://lkml.kernel.org/r/20151029223744.GK2923@kernel.org Committer notes: Before, forgetting to update the version: # uname -r 4.3.0-rc1+ # cat bpf.c __attribute__((section("fork=_do_fork"), used)) int fork(void *ctx) { return 1; } char _license[] __attribute__((section("license"), used)) = "GPL"; int _version __attribute__((section("version"), used)) = 0x40200; # # perf record -e bpf.c sleep 1 event syntax error: 'bpf.c' \___ Invalid argument: Are you root and runing a CONFIG_BPF_SYSCALL kernel? (add -v to see detail) Run 'perf list' for a list of valid events Usage: perf record [<options>] [<command>] or: perf record [<options>] -- <command> [<options>] -e, --event <event> event selector. use 'perf list' to list available events # After: # grep version bpf.c int _version __attribute__((section("version"), used)) = LINUX_VERSION_CODE; # perf record -e bpf.c sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.017 MB perf.data ] # perf evlist -v perf_bpf_probe:fork: type: 2, size: 112, config: 0x5ee, { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|RAW, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 # Suggested-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1446636007-239722-3-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -12,6 +12,7 @@
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#define CLANG_BPF_CMD_DEFAULT_TEMPLATE \
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"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
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"-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE " \
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"$CLANG_OPTIONS $KERNEL_INC_OPTIONS " \
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"-Wno-unused-value -Wno-pointer-sign " \
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"-working-directory $WORKING_DIR " \
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@ -324,11 +325,33 @@ get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
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pr_debug("include option is set to %s\n", *kbuild_include_opts);
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}
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static unsigned long
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fetch_kernel_version(void)
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{
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struct utsname utsname;
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int version, patchlevel, sublevel, err;
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if (uname(&utsname))
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return 0;
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err = sscanf(utsname.release, "%d.%d.%d",
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&version, &patchlevel, &sublevel);
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if (err != 3) {
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pr_debug("Unablt to get kernel version from uname '%s'\n",
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utsname.release);
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return 0;
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}
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return (version << 16) + (patchlevel << 8) + sublevel;
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}
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int llvm__compile_bpf(const char *path, void **p_obj_buf,
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size_t *p_obj_buf_sz)
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{
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int err, nr_cpus_avail;
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char clang_path[PATH_MAX], nr_cpus_avail_str[64];
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char linux_version_code_str[64];
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const char *clang_opt = llvm_param.clang_opt;
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const char *template = llvm_param.clang_bpf_cmd_template;
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char *kbuild_dir = NULL, *kbuild_include_opts = NULL;
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@ -365,7 +388,11 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
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snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
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nr_cpus_avail);
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snprintf(linux_version_code_str, sizeof(linux_version_code_str),
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"0x%lx", fetch_kernel_version());
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force_set_env("NR_CPUS", nr_cpus_avail_str);
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force_set_env("LINUX_VERSION_CODE", linux_version_code_str);
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force_set_env("CLANG_EXEC", clang_path);
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force_set_env("CLANG_OPTIONS", clang_opt);
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force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
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