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SubjectRe: [PATCH 06/10] perf probe: Check if dwarf_getlocations() is available
On Thu, 12 May 2016 17:03:51 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> If not, tell the user that:
>
> config/Makefile:273: Old libdw.h, finding variables at given 'perf probe' point will not work, install elfutils-devel/libdw-dev >= 0.157
>
> And return -ENOTSUPP in die_get_var_range(), failing features that
> need it, like the one pointed out above.
>
> This fixes the build on older systems, such as Ubuntu 12.04.5.
>

Hmm, would we better to use similar technique for dwarf_cfi_addrframe?
the commit 7752f1b096e1
("perf probe: Don't compile CFI related code if elfutils is old")
uses _ELFUTILS_PREREQ() macro for checking the elfutils version directly.

Anyway, this looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

> 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: Vinson Lee <vlee@freedesktop.org>
> Cc: Wang Nan <wangnan0@huawei.com>
> Link: http://lkml.kernel.org/n/tip-9l7luqkq4gfnx7vrklkq4obs@git.kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/build/Makefile.feature | 2 ++
> tools/build/feature/Makefile | 4 ++++
> tools/build/feature/test-all.c | 5 +++++
> tools/build/feature/test-dwarf_getlocations.c | 12 ++++++++++++
> tools/perf/config/Makefile | 6 ++++++
> tools/perf/util/dwarf-aux.c | 9 +++++++++
> 6 files changed, 38 insertions(+)
> create mode 100644 tools/build/feature/test-dwarf_getlocations.c
>
> diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
> index 6b7707270aa3..9f878619077a 100644
> --- a/tools/build/Makefile.feature
> +++ b/tools/build/Makefile.feature
> @@ -30,6 +30,7 @@ endef
> FEATURE_TESTS_BASIC := \
> backtrace \
> dwarf \
> + dwarf_getlocations \
> fortify-source \
> sync-compare-and-swap \
> glibc \
> @@ -78,6 +79,7 @@ endif
>
> FEATURE_DISPLAY ?= \
> dwarf \
> + dwarf_getlocations \
> glibc \
> gtk2 \
> libaudit \
> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> index c5f4c417428d..4ae94dbfdab9 100644
> --- a/tools/build/feature/Makefile
> +++ b/tools/build/feature/Makefile
> @@ -3,6 +3,7 @@ FILES= \
> test-backtrace.bin \
> test-bionic.bin \
> test-dwarf.bin \
> + test-dwarf_getlocations.bin \
> test-fortify-source.bin \
> test-sync-compare-and-swap.bin \
> test-glibc.bin \
> @@ -82,6 +83,9 @@ endif
> $(OUTPUT)test-dwarf.bin:
> $(BUILD) $(DWARFLIBS)
>
> +$(OUTPUT)test-dwarf_getlocations.bin:
> + $(BUILD) $(DWARFLIBS)
> +
> $(OUTPUT)test-libelf-mmap.bin:
> $(BUILD) -lelf
>
> diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
> index e499a36c1e4a..a282e8cb84f3 100644
> --- a/tools/build/feature/test-all.c
> +++ b/tools/build/feature/test-all.c
> @@ -41,6 +41,10 @@
> # include "test-dwarf.c"
> #undef main
>
> +#define main main_test_dwarf_getlocations
> +# include "test-dwarf_getlocations.c"
> +#undef main
> +
> #define main main_test_libelf_getphdrnum
> # include "test-libelf-getphdrnum.c"
> #undef main
> @@ -143,6 +147,7 @@ int main(int argc, char *argv[])
> main_test_libelf_mmap();
> main_test_glibc();
> main_test_dwarf();
> + main_test_dwarf_getlocations();
> main_test_libelf_getphdrnum();
> main_test_libunwind();
> main_test_libaudit();
> diff --git a/tools/build/feature/test-dwarf_getlocations.c b/tools/build/feature/test-dwarf_getlocations.c
> new file mode 100644
> index 000000000000..70162699dd43
> --- /dev/null
> +++ b/tools/build/feature/test-dwarf_getlocations.c
> @@ -0,0 +1,12 @@
> +#include <stdlib.h>
> +#include <elfutils/libdw.h>
> +
> +int main(void)
> +{
> + Dwarf_Addr base, start, end;
> + Dwarf_Attribute attr;
> + Dwarf_Op *op;
> + size_t nops;
> + ptrdiff_t offset = 0;
> + return (int)dwarf_getlocations(&attr, offset, &base, &start, &end, &op, &nops);
> +}
> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> index f7d7f5a1cad5..6f8f6430f2bf 100644
> --- a/tools/perf/config/Makefile
> +++ b/tools/perf/config/Makefile
> @@ -268,6 +268,12 @@ else
> ifneq ($(feature-dwarf), 1)
> msg := $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.138, disables dwarf support. Please install new elfutils-devel/libdw-dev);
> NO_DWARF := 1
> + else
> + ifneq ($(feature-dwarf_getlocations), 1)
> + msg := $(warning Old libdw.h, finding variables at given 'perf probe' point will not work, install elfutils-devel/libdw-dev >= 0.157);
> + else
> + CFLAGS += -DHAVE_DWARF_GETLOCATIONS
> + endif # dwarf_getlocations
> endif # Dwarf support
> endif # libelf support
> endif # NO_LIBELF
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 577e600c8eb1..aea189b41cc8 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -959,6 +959,7 @@ int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
> return 0;
> }
>
> +#ifdef HAVE_DWARF_GETLOCATIONS
> /**
> * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
> * @sp_die: a subprogram DIE
> @@ -1080,3 +1081,11 @@ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
>
> return ret;
> }
> +#else
> +int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
> + Dwarf_Die *vr_die __maybe_unused,
> + struct strbuf *buf __maybe_unused)
> +{
> + return -ENOTSUP;
> +}
> +#endif
> --
> 2.5.5
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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