[PATCH v1 1/2] perf build: Allow C++ demangle without libelf

[PATCH v1 1/2] perf build: Allow C++ demangle without libelf

[Ian Rogers]

The cxa demangle support isn't dependent on libelf and so we no longer
need to disable demangling if libelf isn't present.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Makefile.config | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 236d763181c5..dd203f0a2b7e 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -412,7 +412,6 @@ endif
 
 ifdef NO_LIBELF
   NO_DWARF := 1
-  NO_DEMANGLE := 1
   NO_LIBUNWIND := 1
   NO_LIBDW_DWARF_UNWIND := 1
   NO_LIBBPF := 1
-- 
2.40.0.348.gf938b09366-goog

[PATCH v1 2/2] perf build: Warn for BPF skeletons if endian mismatches

[Ian Rogers]

Done as a warning as I'm not fully confident of the test's robustness
of comparing the macro definition of __BYTE_ORDER__.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Makefile.config | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index dd203f0a2b7e..4be817ea4a59 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -659,14 +659,17 @@ ifndef NO_BPF_SKEL
   $(call feature_check,clang-bpf-co-re)
   ifeq ($(feature-clang-bpf-co-re), 0)
     dummy := $(error: ERROR: BPF skeletons unsupported. clang too old/not installed or build with NO_BPF_SKEL=1.)
-  else
-    ifeq ($(filter -DHAVE_LIBBPF_SUPPORT, $(CFLAGS)),)
-      dummy := $(error: ERROR: BPF skeletons unsupported. BPF skeleton support requires libbpf or build with NO_BPF_SKEL=1.)
-    else
-      $(call detected,CONFIG_PERF_BPF_SKEL)
-      CFLAGS += -DHAVE_BPF_SKEL
-    endif
   endif
+  ifeq ($(filter -DHAVE_LIBBPF_SUPPORT, $(CFLAGS)),)
+    dummy := $(error: ERROR: BPF skeletons unsupported. BPF skeleton support requires libbpf or build with NO_BPF_SKEL=1.)
+  endif
+  host_byte_order=$(echo ""|$(HOSTCC) -dM -E -|grep __BYTE_ORDER__)
+  target_byte_order=$(echo ""|$(CC) -dM -E -|grep __BYTE_ORDER__)
+  ifneq ($(host_byte_order), $(target_byte_order))
+    $(warning Possibly mismatched host and target endianness may break BPF skeletons)
+  endif
+  $(call detected,CONFIG_PERF_BPF_SKEL)
+  CFLAGS += -DHAVE_BPF_SKEL
 endif
 
 dwarf-post-unwind := 1
-- 
2.40.0.348.gf938b09366-goog

Re: [PATCH v1 1/2] perf build: Allow C++ demangle without libelf

[Arnaldo Carvalho de Melo]

Em Mon, Apr 03, 2023 at 02:10:20PM -0700, Ian Rogers escreveu:
> The cxa demangle support isn't dependent on libelf and so we no longer
> need to disable demangling if libelf isn't present.

Thanks, applied.

- Arnaldo

 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/Makefile.config | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 236d763181c5..dd203f0a2b7e 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -412,7 +412,6 @@ endif
>  
>  ifdef NO_LIBELF
>    NO_DWARF := 1
> -  NO_DEMANGLE := 1
>    NO_LIBUNWIND := 1
>    NO_LIBDW_DWARF_UNWIND := 1
>    NO_LIBBPF := 1
> -- 
> 2.40.0.348.gf938b09366-goog
> 

-- 

- Arnaldo