Re: [PATCH 4/4] perf annotate: Use libcapstone to disassemble

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

Hi, Namhyung,
On Thu, Mar 28, 2024 at 04:20:09PM -0700, Namhyung Kim wrote:
> Now it can use the capstone library to disassemble the instructions.
> Let's use that (if available) for perf annotate to speed up.  Currently
> it only supports x86 architecture.  With this change I can see ~3x speed
> up in data type profiling.
>
> But note that capstone cannot give the source file and line number info.
> For now, users should use the external objdump for that by specifying
> the --objdump option explicitly.
>
> Cc: Changbin Du <changbin.du@huawei.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/util/disasm.c | 153 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 153 insertions(+)
>
> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> index 59ac37723990..c58ea6d822ed 100644
> --- a/tools/perf/util/disasm.c
> +++ b/tools/perf/util/disasm.c
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  #include <ctype.h>
>  #include <errno.h>
> +#include <fcntl.h>
>  #include <inttypes.h>
>  #include <libgen.h>
>  #include <regex.h>
> @@ -18,6 +19,7 @@
>  #include "evsel.h"
>  #include "map.h"
>  #include "maps.h"
> +#include "namespaces.h"
>  #include "srcline.h"
>  #include "symbol.h"
>
> @@ -1341,6 +1343,151 @@ symbol__disassemble_bpf_image(struct symbol *sym,
>       return 0;
>  }
>
> +#ifdef HAVE_LIBCAPSTONE_SUPPORT
> +#include <capstone/capstone.h>
> +
> +static int open_capstone_handle(struct annotate_args *args, bool is_64bit,
> +                             csh *handle)
> +{
> +     struct annotation_options *opt = args->options;
> +     cs_mode mode = is_64bit ? CS_MODE_64 : CS_MODE_32;
> +
> +     /* TODO: support more architectures */
> +     if (!arch__is(args->arch, "x86"))
> +             return -1;
> +
> +     if (cs_open(CS_ARCH_X86, mode, handle) != CS_ERR_OK)
> +             return -1;
> +
> +     if (!opt->disassembler_style ||
> +         !strcmp(opt->disassembler_style, "att"))
> +             cs_option(*handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT);
> +
> +     /*
> +      * Resolving address operands to symbols is implemented
> +      * on x86 by investigating instruction details.
> +      */
> +     cs_option(*handle, CS_OPT_DETAIL, CS_OPT_ON);
Enabling CS_OPT_DETAIL is to symbolize branch target address. You can refer to
print_insn_x86() in print_insn.c.

> +
> +     return 0;
> +}
> +

--
Cheers,
Changbin Du