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Subject[PATCH 2/4] perf tools: Pass LINUX_VERSION_CODE to BPF program when compiling
Date
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

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
tools/perf/util/llvm-utils.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
index 80eecef..8ee25be 100644
--- a/tools/perf/util/llvm-utils.c
+++ b/tools/perf/util/llvm-utils.c
@@ -12,6 +12,7 @@

#define CLANG_BPF_CMD_DEFAULT_TEMPLATE \
"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
+ "-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE " \
"$CLANG_OPTIONS $KERNEL_INC_OPTIONS " \
"-Wno-unused-value -Wno-pointer-sign " \
"-working-directory $WORKING_DIR " \
@@ -324,11 +325,33 @@ get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
pr_debug("include option is set to %s\n", *kbuild_include_opts);
}

+static unsigned long
+fetch_kernel_version(void)
+{
+ struct utsname utsname;
+ int version, patchlevel, sublevel, err;
+
+ if (uname(&utsname))
+ return 0;
+
+ err = sscanf(utsname.release, "%d.%d.%d",
+ &version, &patchlevel, &sublevel);
+
+ if (err != 3) {
+ pr_debug("Unablt to get kernel version from uname '%s'\n",
+ utsname.release);
+ return 0;
+ }
+
+ return (version << 16) + (patchlevel << 8) + sublevel;
+}
+
int llvm__compile_bpf(const char *path, void **p_obj_buf,
size_t *p_obj_buf_sz)
{
int err, nr_cpus_avail;
char clang_path[PATH_MAX], nr_cpus_avail_str[64];
+ char linux_version_code_str[64];
const char *clang_opt = llvm_param.clang_opt;
const char *template = llvm_param.clang_bpf_cmd_template;
char *kbuild_dir = NULL, *kbuild_include_opts = NULL;
@@ -365,7 +388,11 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
nr_cpus_avail);

+ snprintf(linux_version_code_str, sizeof(linux_version_code_str),
+ "0x%lx", fetch_kernel_version());
+
force_set_env("NR_CPUS", nr_cpus_avail_str);
+ force_set_env("LINUX_VERSION_CODE", linux_version_code_str);
force_set_env("CLANG_EXEC", clang_path);
force_set_env("CLANG_OPTIONS", clang_opt);
force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
--
1.8.3.4


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