Re: [PATCH V3 11/14] tools/perf: Add support to use libcapstone in powerpc

Athira Rajeev
2024-06-10T12:21:23Z

> On 3 Jun 2024, at 10:28 PM, Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 3/06/24 19:30, Ian Rogers wrote:
>> On Fri, May 31, 2024 at 11:10 PM Athira Rajeev
>> <atrajeev@linux.vnet.ibm.com> wrote:
>>>
>>> Now perf uses the capstone library to disassemble the instructions in
>>> x86. capstone is used (if available) for perf annotate to speed up.
>>> Currently it only supports x86 architecture. Patch includes changes to
>>> enable this in powerpc. For now, only for data type sort keys, this
>>> method is used and only binary code (raw instruction) is read. This is
>>> because powerpc approach to understand instructions and reg fields uses
>>> raw instruction. The "cs_disasm" is currently not enabled. While
>>> attempting to do cs_disasm, observation is that some of the instructions
>>> were not identified (ex: extswsli, maddld) and it had to fallback to use
>>> objdump. Hence enabling "cs_disasm" is added in comment section as a
>>> TODO for powerpc.
>>>
>>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
>>> ---
>>> tools/perf/util/disasm.c | 148 ++++++++++++++++++++++++++++++++++++++-
>>> 1 file changed, 146 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
>>> index d8b357055302..915508d2e197 100644
>>> --- a/tools/perf/util/disasm.c
>>> +++ b/tools/perf/util/disasm.c
>>> @@ -1540,12 +1540,18 @@ static int open_capstone_handle(struct annotate_args *args, bool is_64bit,
>>> {
>>> struct annotation_options *opt = args->options;
>>> cs_mode mode = is_64bit ? CS_MODE_64 : CS_MODE_32;
>>> + int ret;
>>>
>>> /* TODO: support more architectures */
>>> - if (!arch__is(args->arch, "x86"))
>>> + if ((!arch__is(args->arch, "x86")) && (!arch__is(args->arch, "powerpc")))
>>> return -1;
>>>
>>> - if (cs_open(CS_ARCH_X86, mode, handle) != CS_ERR_OK)
>>> + if (arch__is(args->arch, "x86"))
>>> + ret = cs_open(CS_ARCH_X86, mode, handle);
>>> + else
>>> + ret = cs_open(CS_ARCH_PPC, mode, handle);
>>> +
>>> + if (ret != CS_ERR_OK)
>>> return -1;
>>
>> There looks to be a pretty/more robust capstone_init function in
>> print_insn.c, should we factor this code out and recycle:
>> https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/print_insn.c?h=perf-tools-next#n40
>
> On a slightly related note, there is a compile error
> been around for a while in util/disasm.c on Ubuntu 22.04
>
> In file included from /usr/include/capstone/capstone.h:279,
> from util/disasm.c:1354:
> /usr/include/capstone/bpf.h:94:14: error: ‘bpf_insn’ defined as wrong
> kind of tag
> 94 | typedef enum bpf_insn {
> | ^~~~~~~~
>

Hi Adrian

I tried compilation on Ubuntu 22.04, but didn’t face this issue.
The libcapstone version I have is libcapstone4 which doesn’t have the include for “bpf.h”
What is the version of libcapstone in the setup where you are seeing this issue ?

Thanks
Athira
>>
>> Thanks,
>> Ian
>>
>>> if (!opt->disassembler_style ||
>>> @@ -1635,6 +1641,139 @@ static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
>>> }
>>> }
>>>
>>> +static int symbol__disassemble_capstone_powerpc(char *filename, struct symbol *sym,
>>> + struct annotate_args *args)
>>> +{
>>> + struct annotation *notes = symbol__annotation(sym);
>>> + struct map *map = args->ms.map;
>>> + struct dso *dso = map__dso(map);
>>> + struct nscookie nsc;
>>> + u64 start = map__rip_2objdump(map, sym->start);
>>> + u64 end = map__rip_2objdump(map, sym->end);
>>> + u64 len = end - start;
>>> + u64 offset;
>>> + int i, fd, count;
>>> + bool is_64bit = false;
>>> + bool needs_cs_close = false;
>>> + u8 *buf = NULL;
>>> + struct find_file_offset_data data = {
>>> + .ip = start,
>>> + };
>>> + csh handle;
>>> + char disasm_buf[512];
>>> + struct disasm_line *dl;
>>> + u32 *line;
>>> +
>>> + if (args->options->objdump_path)
>>> + return -1;
>>> +
>>> + nsinfo__mountns_enter(dso->nsinfo, &nsc);
>>> + fd = open(filename, O_RDONLY);
>>> + nsinfo__mountns_exit(&nsc);
>>> + if (fd < 0)
>>> + return -1;
>>> +
>>> + if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data,
>>> + &is_64bit) == 0)
>>> + goto err;
>>> +
>>> + if (open_capstone_handle(args, is_64bit, &handle) < 0)
>>> + goto err;
>>> +
>>> + needs_cs_close = true;
>>> +
>>> + buf = malloc(len);
>>> + if (buf == NULL)
>>> + goto err;
>>> +
>>> + count = pread(fd, buf, len, data.offset);
>>> + close(fd);
>>> + fd = -1;
>>> +
>>> + if ((u64)count != len)
>>> + goto err;
>>> +
>>> + line = (u32 *)buf;
>>> +
>>> + /* add the function address and name */
>>> + scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
>>> + start, sym->name);
>>> +
>>> + args->offset = -1;
>>> + args->line = disasm_buf;
>>> + args->line_nr = 0;
>>> + args->fileloc = NULL;
>>> + args->ms.sym = sym;
>>> +
>>> + dl = disasm_line__new(args);
>>> + if (dl == NULL)
>>> + goto err;
>>> +
>>> + annotation_line__add(&dl->al, &notes->src->source);
>>> +
>>> + /*
>>> + * TODO: enable disassm for powerpc
>>> + * count = cs_disasm(handle, buf, len, start, len, &insn);
>>> + *
>>> + * For now, only binary code is saved in disassembled line
>>> + * to be used in "type" and "typeoff" sort keys. Each raw code
>>> + * is 32 bit instruction. So use "len/4" to get the number of
>>> + * entries.
>>> + */
>>> + count = len/4;
>>> +
>>> + for (i = 0, offset = 0; i < count; i++) {
>>> + args->offset = offset;
>>> + sprintf(args->line, "%x", line[i]);
>>> +
>>> + dl = disasm_line__new(args);
>>> + if (dl == NULL)
>>> + goto err;
>>> +
>>> + annotation_line__add(&dl->al, &notes->src->source);
>>> +
>>> + offset += 4;
>>> + }
>>> +
>>> + /* It failed in the middle */
>>> + if (offset != len) {
>>> + struct list_head *list = &notes->src->source;
>>> +
>>> + /* Discard all lines and fallback to objdump */
>>> + while (!list_empty(list)) {
>>> + dl = list_first_entry(list, struct disasm_line, al.node);
>>> +
>>> + list_del_init(&dl->al.node);
>>> + disasm_line__free(dl);
>>> + }
>>> + count = -1;
>>> + }
>>> +
>>> +out:
>>> + if (needs_cs_close)
>>> + cs_close(&handle);
>>> + free(buf);
>>> + return count < 0 ? count : 0;
>>> +
>>> +err:
>>> + if (fd >= 0)
>>> + close(fd);
>>> + if (needs_cs_close) {
>>> + struct disasm_line *tmp;
>>> +
>>> + /*
>>> + * It probably failed in the middle of the above loop.
>>> + * Release any resources it might add.
>>> + */
>>> + list_for_each_entry_safe(dl, tmp, &notes->src->source, al.node) {
>>> + list_del(&dl->al.node);
>>> + free(dl);
>>> + }
>>> + }
>>> + count = -1;
>>> + goto out;
>>> +}
>>> +
>>> static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
>>> struct annotate_args *args)
>>> {
>>> @@ -1987,6 +2126,11 @@ int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
>>> err = symbol__disassemble_dso(symfs_filename, sym, args);
>>> if (err == 0)
>>> goto out_remove_tmp;
>>> +#ifdef HAVE_LIBCAPSTONE_SUPPORT
>>> + err = symbol__disassemble_capstone_powerpc(symfs_filename, sym, args);
>>> + if (err == 0)
>>> + goto out_remove_tmp;
>>> +#endif
>>> }
>>> }
>>>
>>> --
>>> 2.43.0