• Wang Nan's avatar
    perf test: Enhance the LLVM test: update basic BPF test program · b31de018
    Wang Nan authored
    This patch replaces the original toy BPF program with the previously
    introduced bpf-script-example.c. Dynamically embeddeding it into
    'llvm-src-base.c'.
    
    The newly introduced BPF program attaches a BPF program to
    'sys_epoll_pwait()'. perf itself never use that syscall, so further test
    can verify their result with it. The program would generate 1 sample in
    every 2 calls of epoll_pwait() system call.
    
    Since the resulting BPF object is useful per se for further tests,
    test_llvm__fetch_bpf_obj() is introduced for creating BPF objects from
    source. The LLVM test was rewritten to use it.
    
    Committer note:
    
    Running it:
    
      [root@zoo wb]# perf test -v LLVM
      35: Test LLVM searching and compiling                        :
      --- start ---
      test child forked, pid 17740
      Kernel build dir is set to /lib/modules/4.3.0-rc1+/build
      set env: KBUILD_DIR=/lib/modules/4.3.0-rc1+/build
      unset env: KBUILD_OPTS
      include option is set to  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated  -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h
      set env: NR_CPUS=4
      set env: LINUX_VERSION_CODE=0x40300
      set env: CLANG_EXEC=/usr/libexec/icecc/bin/clang
      set env: CLANG_OPTIONS=-xc
      set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated  -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h
      set env: WORKING_DIR=/lib/modules/4.3.0-rc1+/build
      set env: CLANG_SOURCE=-
      llvm compiling command template: echo '/*
       * bpf-script-example.c
       * Test basic LLVM building
       */
      #ifndef LINUX_VERSION_CODE
      # error Need LINUX_VERSION_CODE
      # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
      #endif
      #define BPF_ANY 0
      #define BPF_MAP_TYPE_ARRAY 2
      #define BPF_FUNC_map_lookup_elem 1
      #define BPF_FUNC_map_update_elem 2
    
      static void *(*bpf_map_lookup_elem)(void *map, void *key) =
    	  (void *) BPF_FUNC_map_lookup_elem;
      static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
    	  (void *) BPF_FUNC_map_update_elem;
    
      struct bpf_map_def {
    	  unsigned int type;
    	  unsigned int key_size;
    	  unsigned int value_size;
    	  unsigned int max_entries;
      };
    
      #define SEC(NAME) __attribute__((section(NAME), used))
      struct bpf_map_def SEC("maps") flip_table = {
    	  .type = BPF_MAP_TYPE_ARRAY,
    	  .key_size = sizeof(int),
    	  .value_size = sizeof(int),
    	  .max_entries = 1,
      };
    
      SEC("func=sys_epoll_pwait")
      int bpf_func__sys_epoll_pwait(void *ctx)
      {
    	  int ind =0;
    	  int *flag = bpf_map_lookup_elem(&flip_table, &ind);
    	  int new_flag;
    	  if (!flag)
    		  return 0;
    	  /* flip flag and store back */
    	  new_flag = !*flag;
    	  bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
    	  return new_flag;
      }
      char _license[] SEC("license") = "GPL";
      int _version SEC("version") = LINUX_VERSION_CODE;
      ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o -
      test child finished with 0
      ---- end ----
      Test LLVM searching and compiling: Ok
      [root@zoo wb]#
    Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
    Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Zefan Li <lizefan@huawei.com>
    Cc: pi3orama@163.com
    Link: http://lkml.kernel.org/r/1446817783-86722-6-git-send-email-wangnan0@huawei.comSigned-off-by: default avatarHe Kuang <hekuang@huawei.com>
    Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    b31de018
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