Re: [PATCH 1/1] perf build: Fix up broken capstone feature detection fast path

[duchangbin <changbin.du@huawei.com>]

Hi, Arnaldo,

How about workaround it by rename the 'bpf_insn' in capstione?

Change test-libcapstone.c as:

#define bpf_insn capstone_bpf_insn
#include <capstone/capstone.h>
#undef bpf_insn

I haven't tried it but seems feasible.

On Wed, Aug 14, 2024 at 10:44:17AM -0300, Arnaldo Carvalho de Melo wrote:
> The capstone devel headers define 'struct bpf_insn' in a way that clashes with
> what is in the libbpf devel headers, so we so far need to avoid including both.
> 
> This is happening on the tools/build/feature/test-all.c file, where we try
> building all the expected set of libraries to be normally available on a
> system:
> 
>   ⬢[acme@toolbox perf-tools-next]$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   In file included from test-bpf.c:3,
>                    from test-all.c:150:
>   /home/acme/git/perf-tools-next/tools/include/uapi/linux/bpf.h:77:8: error: ‘bpf_insn’ defined as wrong kind of tag
>      77 | struct bpf_insn {
>         |        ^~~~~~~~
>   ⬢[acme@toolbox perf-tools-next]$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
> 
> When doing so there is a trick where we define main to be
> main_test_libcapstone, then include the individual
> tools/build/feture/test-libcapstone.c capability query test, and then we undef
> 'main' because we'll do it all over again with the next expected library to
> be tested (at this time 'lzma').
> 
> To complete this mechanism we need to, in test-all.c 'main' routine, to
> call main_test_libcapstone(), which isn't being done, so the effect of
> adding references to capstone in test-all.c are not achieved.
> 
> The only thing that is happening is that test-all.c is failing to build and thus
> all the tests will have to be done individually, which nullifies the test-all.c
> single build speedup.
> 
> So lets remove references to capstone from test-all.c to see if this makes it
> build again so that we get faster builds or go on fixing up whatever is
> preventing us to get that benefit.
> 
> Nothing: after this fix we get a clean test-all.c build and get the build speedup back:
> 
>   ⬢[acme@toolbox perf-tools-next]$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   ⬢[acme@toolbox perf-tools-next]$ cat /tmp/build/perf-tools-next/feature/test-all.
>   test-all.bin          test-all.d            test-all.make.output
>   ⬢[acme@toolbox perf-tools-next]$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   ⬢[acme@toolbox perf-tools-next]$ ldd /tmp/build/perf-tools-next/feature/test-all.bin
>   	linux-vdso.so.1 (0x00007f13277a1000)
>   	libpython3.12.so.1.0 => /lib64/libpython3.12.so.1.0 (0x00007f1326e00000)
>   	libm.so.6 => /lib64/libm.so.6 (0x00007f13274be000)
>   	libtraceevent.so.1 => /lib64/libtraceevent.so.1 (0x00007f1327496000)
>   	libtracefs.so.1 => /lib64/libtracefs.so.1 (0x00007f132746f000)
>   	libcrypto.so.3 => /lib64/libcrypto.so.3 (0x00007f1326800000)
>   	libunwind-x86_64.so.8 => /lib64/libunwind-x86_64.so.8 (0x00007f1327452000)
>   	libunwind.so.8 => /lib64/libunwind.so.8 (0x00007f1327436000)
>   	liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f1327403000)
>   	libdw.so.1 => /lib64/libdw.so.1 (0x00007f1326d6f000)
>   	libz.so.1 => /lib64/libz.so.1 (0x00007f13273e2000)
>   	libelf.so.1 => /lib64/libelf.so.1 (0x00007f1326d53000)
>   	libnuma.so.1 => /lib64/libnuma.so.1 (0x00007f13273d4000)
>   	libslang.so.2 => /lib64/libslang.so.2 (0x00007f1326400000)
>   	libperl.so.5.38 => /lib64/libperl.so.5.38 (0x00007f1326000000)
>   	libc.so.6 => /lib64/libc.so.6 (0x00007f1325e0f000)
>   	libzstd.so.1 => /lib64/libzstd.so.1 (0x00007f1326741000)
>   	/lib64/ld-linux-x86-64.so.2 (0x00007f13277a3000)
>   	libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f1326d3f000)
>   	libcrypt.so.2 => /lib64/libcrypt.so.2 (0x00007f1326d07000)
>   ⬢[acme@toolbox perf-tools-next]$
> 
> And when having capstone-devel installed we get it detected and linked with
> perf, allowing us to benefit from the features that it enables:
> 
>   ⬢[acme@toolbox perf-tools-next]$ rpm -q capstone-devel
>   capstone-devel-5.0.1-3.fc40.x86_64
>   ⬢[acme@toolbox perf-tools-next]$ ldd /tmp/build/perf-tools-next/perf | grep capstone
>   	libcapstone.so.5 => /lib64/libcapstone.so.5 (0x00007fe6a5c00000)
>   ⬢[acme@toolbox perf-tools-next]$ /tmp/build/perf-tools-next/perf -vv | grep cap
>              libcapstone: [ on  ]  # HAVE_LIBCAPSTONE_SUPPORT
>   ⬢[acme@toolbox perf-tools-next]$
> 
> Fixes: 8b767db3309595a2 ("perf: build: introduce the libcapstone")
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Andi Kleen <andi@firstfloor.org>
> Cc: Changbin Du <changbin.du@huawei.com>
> Cc: Ian Rogers <irogers@google.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  tools/build/feature/test-all.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
> index dd0a18c2ef8fc080..6f4bf386a3b5c4b0 100644
> --- a/tools/build/feature/test-all.c
> +++ b/tools/build/feature/test-all.c
> @@ -134,10 +134,6 @@
>  #undef main
>  #endif
>  
> -#define main main_test_libcapstone
> -# include "test-libcapstone.c"
> -#undef main
> -
>  #define main main_test_lzma
>  # include "test-lzma.c"
>  #undef main
> -- 
> 2.45.2
> 
> 

-- 
Cheers,
Changbin Du