Re: [PATCH v3 06/18] perf capstone: Support for dlopen-ing libcapstone.so

[Namhyung Kim <namhyung@kernel.org>]

On Fri, Jan 24, 2025 at 09:20:15PM -0800, Ian Rogers wrote:
> On Fri, Jan 24, 2025 at 2:22 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > On Wed, Jan 22, 2025 at 09:42:56AM -0800, Ian Rogers wrote:
> > > If perf wasn't built against libcapstone, no HAVE_LIBCAPSTONE_SUPPORT,
> > > support dlopen-ing libcapstone.so and then calling the necessary
> > > functions by looking them up using dlsym. Reverse engineer the types
> > > in the API using pahole, adding only what's used in the perf code or
> > > necessary for the sake of struct size and alignment.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/util/capstone.c | 287 ++++++++++++++++++++++++++++++++-----
> > >  1 file changed, 248 insertions(+), 39 deletions(-)
> > >
> > > diff --git a/tools/perf/util/capstone.c b/tools/perf/util/capstone.c
> > > index c9845e4d8781..8d65c7a55a8b 100644
> > > --- a/tools/perf/util/capstone.c
> > > +++ b/tools/perf/util/capstone.c
> > > @@ -11,19 +11,249 @@
> > >  #include "print_insn.h"
> > >  #include "symbol.h"
> > >  #include "thread.h"
> > > +#include <dlfcn.h>
> > >  #include <fcntl.h>
> > > +#include <inttypes.h>
> >
> > These two can go under #else (!HAVE_LIBCAPSTONE_SUPPORT).
> 
> Ack.
> 
> > >  #include <string.h>
> > >
> > >  #ifdef HAVE_LIBCAPSTONE_SUPPORT
> > >  #include <capstone/capstone.h>
> > > +#else
> > > +typedef size_t csh;
> > > +enum cs_arch {
> > > +     CS_ARCH_ARM = 0,
> > > +     CS_ARCH_ARM64 = 1,
> > > +     CS_ARCH_X86 = 3,
> > > +     CS_ARCH_SYSZ = 6,
> > > +};
> > > +enum cs_mode {
> > > +     CS_MODE_ARM = 0,
> > > +     CS_MODE_32 = 1 << 2,
> > > +     CS_MODE_64 = 1 << 3,
> > > +     CS_MODE_V8 = 1 << 6,
> > > +     CS_MODE_BIG_ENDIAN = 1 << 31,
> > > +};
> > > +enum cs_opt_type {
> > > +     CS_OPT_SYNTAX = 1,
> > > +     CS_OPT_DETAIL = 2,
> > > +};
> > > +enum cs_opt_value {
> > > +     CS_OPT_SYNTAX_ATT = 2,
> > > +     CS_OPT_ON = 3,
> > > +};
> > > +enum cs_err {
> > > +     CS_ERR_OK = 0,
> > > +     CS_ERR_HANDLE = 3,
> > > +};
> > > +enum x86_op_type {
> > > +     X86_OP_IMM = 2,
> > > +     X86_OP_MEM = 3,
> > > +};
> > > +enum x86_reg {
> > > +     X86_REG_RIP = 41,
> > > +};
> > > +typedef int32_t x86_avx_bcast;
> > > +struct x86_op_mem {
> > > +     enum x86_reg segment;
> > > +     enum x86_reg base;
> > > +     enum x86_reg index;
> > > +     int scale;
> > > +     int64_t disp;
> > > +};
> > > +
> > > +struct cs_x86_op {
> > > +     enum x86_op_type type;
> > > +     union {
> > > +             enum x86_reg  reg;
> > > +             int64_t imm;
> > > +             struct x86_op_mem mem;
> > > +     };
> > > +     uint8_t size;
> > > +     uint8_t access;
> > > +     x86_avx_bcast avx_bcast;
> > > +     bool avx_zero_opmask;
> > > +};
> > > +struct cs_x86_encoding {
> > > +     uint8_t modrm_offset;
> > > +     uint8_t disp_offset;
> > > +     uint8_t disp_size;
> > > +     uint8_t imm_offset;
> > > +     uint8_t imm_size;
> > > +};
> > > +typedef int32_t  x86_xop_cc;
> > > +typedef int32_t  x86_sse_cc;
> > > +typedef int32_t  x86_avx_cc;
> > > +typedef int32_t  x86_avx_rm;
> > > +struct cs_x86 {
> > > +     uint8_t prefix[4];
> > > +     uint8_t opcode[4];
> > > +     uint8_t rex;
> > > +     uint8_t addr_size;
> > > +     uint8_t modrm;
> > > +     uint8_t sib;
> > > +     int64_t disp;
> > > +     enum x86_reg sib_index;
> > > +     int8_t sib_scale;
> > > +     enum x86_reg sib_base;
> > > +     x86_xop_cc xop_cc;
> > > +     x86_sse_cc sse_cc;
> > > +     x86_avx_cc avx_cc;
> > > +     bool avx_sae;
> > > +     x86_avx_rm avx_rm;
> > > +     union {
> > > +             uint64_t eflags;
> > > +             uint64_t fpu_flags;
> > > +     };
> > > +     uint8_t op_count;
> > > +     struct cs_x86_op operands[8];
> > > +     struct cs_x86_encoding encoding;
> > > +};
> > > +struct cs_detail {
> > > +     uint16_t regs_read[12];
> > > +     uint8_t regs_read_count;
> > > +     uint16_t regs_write[20];
> > > +     uint8_t regs_write_count;
> > > +     uint8_t groups[8];
> > > +     uint8_t groups_count;
> > > +
> > > +     union {
> > > +             struct cs_x86 x86;
> > > +     };
> > > +};
> >
> > As discussed, let's remove the detail part.
> 
> I kind of feel there should be a #warning in that case. I'd rather
> leave it as is and not have a build warning.

What kind of build warning are you talking about?

Thanks,
Namhyung