Re: [PATCH v2 02/16] perf capstone: Fix arm64 jump/adrp disassembly mismatch with objdump

[Tengda Wu]

On 2026/4/7 14:43, Namhyung Kim wrote:
> On Fri, Apr 03, 2026 at 09:47:46AM +0000, Tengda Wu wrote:
>> The jump and adrp instructions parsed by libcapstone currently lack
>> symbolic representation and use a '#' prefix for addresses. This
>> format is inconsistent with objdump's output, which causes subsequent
>> parsing in jump__parse() and arm64_mov__parse() to fail.
>>
>> Example mismatch:
>>   Current: b #0xffff8000800114c8
>>   Fix:     b ffff8000800114c8 <el0t_64_sync+0x108>
>>
>>   Current: adrp x18, #0xffff800081f5f000
>>   Fix:     adrp x18, ffff800081f5f000 <this_cpu_vector>
>>
>> Fix this by implementing extended formatting for these arm64
>> instructions during symbol__disassemble_capstone(). This ensures
>> the output matches objdump's expected style, including the raw
>> address and the associated <symbol+offset> suffix.
>>
>> Signed-off-by: Tengda Wu <wutengda@xxxxxxxxxxxxxxx>
>> ---
>>  tools/perf/util/capstone.c | 107 ++++++++++++++++++++++++++++++++-----
>>  tools/perf/util/disasm.c   |   5 ++
>>  tools/perf/util/disasm.h   |   1 +
>>  3 files changed, 101 insertions(+), 12 deletions(-)
>>
>> diff --git a/tools/perf/util/capstone.c b/tools/perf/util/capstone.c
>> index 25cf6e15ec27..1d8421d2d98c 100644
>> --- a/tools/perf/util/capstone.c
>> +++ b/tools/perf/util/capstone.c
>> @@ -255,10 +255,6 @@ static void print_capstone_detail(struct cs_insn *insn, char *buf, size_t len,
>>  	struct map *map = args->ms->map;
>>  	struct symbol *sym;
>>  
>> -	/* TODO: support more architectures */
>> -	if (!arch__is_x86(args->arch))
>> -		return;
>> -
>>  	if (insn->detail == NULL)
>>  		return;
>>  
>> @@ -305,6 +301,98 @@ static void print_capstone_detail(struct cs_insn *insn, char *buf, size_t len,
>>  	}
>>  }
>>  
>> +static void format_capstone_insn_x86(struct cs_insn *insn, char *buf,
>> +				     size_t len, struct annotate_args *args,
>> +				     u64 addr)
>> +{
>> +	int printed;
>> +
>> +	printed = scnprintf(buf, len, "       %-7s %s",
>> +			    insn->mnemonic, insn->op_str);
>> +	buf += printed;
>> +	len -= printed;
>> +
>> +	print_capstone_detail(insn, buf, len, args, addr);
>> +}
>> +
>> +static void format_capstone_insn_arm64(struct cs_insn *insn, char *buf,
>> +				       size_t len, struct annotate_args *args,
>> +				       u64 addr)
>> +{
>> +	struct map *map = args->ms->map;
>> +	struct symbol *sym;
>> +	char *last_imm, *endptr;
>> +	u64 orig_addr;
>> +
>> +	scnprintf(buf, len, "       %-7s %s",
>> +		  insn->mnemonic, insn->op_str);
>> +	/*
>> +	 * Adjust instructions to keep the existing behavior with objdump.
>> +	 *
>> +	 * Example conversion:
>> +	 * From: b #0xffff8000800114c8
>> +	 * To:   b ffff8000800114c8 <el0t_64_sync+0x108>
>> +	 */
>> +	switch (insn->id) {
>> +	case ARM64_INS_B:
>> +	case ARM64_INS_BL:
>> +	case ARM64_INS_CBNZ:
>> +	case ARM64_INS_CBZ:
>> +	case ARM64_INS_TBNZ:
>> +	case ARM64_INS_TBZ:
>> +	case ARM64_INS_ADRP:
>> +		/* Extract last immediate value as address */
>> +		last_imm = strrchr(buf, '#');
>> +		if (!last_imm)
>> +			return;
>> +
>> +		orig_addr = strtoull(last_imm + 1, &endptr, 16);
>> +		if (endptr == last_imm + 1)
>> +			return;
>> +
>> +		/* Relocate map that contains the address */
>> +		if (dso__kernel(map__dso(map))) {
>> +			map = maps__find(map__kmaps(map), orig_addr);
>> +			if (map == NULL)
>> +				return;
> 
> I know you copied the logic from x86, but I've realized that it leaks a
> refcount for the new kernel map returned from maps__find().  This needs
> to be fixed separately.
> 
> Thanks,
> Namhyung
> 

Oh, right.
I will send a separate patch to fix this issue in the existing x86 logic and
will make sure the arm64 implementation follows the fix.

-- Tengda

> 
>> +		}
>> +
>> +		/* Convert it to map-relative address for search */
>> +		addr = map__map_ip(map, orig_addr);
>> +
>> +		sym = map__find_symbol(map, addr);
>> +		if (sym == NULL)
>> +			return;
>> +
>> +		/* Symbolize the resolved address */
>> +		len = len - (last_imm - buf);
>> +		if (addr == sym->start) {
>> +			scnprintf(last_imm, len, "%"PRIx64" <%s>",
>> +				  orig_addr, sym->name);
>> +		} else {
>> +			scnprintf(last_imm, len, "%"PRIx64" <%s+%#"PRIx64">",
>> +				  orig_addr, sym->name, addr - sym->start);
>> +		}
>> +		break;
>> +	default:
>> +		break;
>> +	}
>> +}
>> +
>> +static void format_capstone_insn(struct cs_insn *insn, char *buf, size_t len,
>> +				 struct annotate_args *args, u64 addr)
>> +{
>> +	/* TODO: support more architectures */
>> +	if (arch__is_x86(args->arch))
>> +		format_capstone_insn_x86(insn, buf, len, args, addr);
>> +	else if (arch__is_arm64(args->arch))
>> +		format_capstone_insn_arm64(insn, buf, len, args, addr);
>> +	else {
>> +		scnprintf(buf, len, "       %-7s %s",
>> +			  insn->mnemonic, insn->op_str);
>> +	}
>> +}
>> +
>>  struct find_file_offset_data {
>>  	u64 ip;
>>  	u64 offset;
>> @@ -381,14 +469,9 @@ int symbol__disassemble_capstone(const char *filename __maybe_unused,
>>  
>>  	free_count = count = perf_cs_disasm(handle, buf, buf_len, start, buf_len, &insn);
>>  	for (i = 0, offset = 0; i < count; i++) {
>> -		int printed;
>> -
>> -		printed = scnprintf(disasm_buf, sizeof(disasm_buf),
>> -				    "       %-7s %s",
>> -				    insn[i].mnemonic, insn[i].op_str);
>> -		print_capstone_detail(&insn[i], disasm_buf + printed,
>> -				      sizeof(disasm_buf) - printed, args,
>> -				      start + offset);
>> +		format_capstone_insn(&insn[i], disasm_buf,
>> +				     sizeof(disasm_buf), args,
>> +				     start + offset);
>>  
>>  		args->offset = offset;
>>  		args->line = disasm_buf;
>> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
>> index 40fcaed5d0b1..988b2b748e11 100644
>> --- a/tools/perf/util/disasm.c
>> +++ b/tools/perf/util/disasm.c
>> @@ -202,6 +202,11 @@ bool arch__is_powerpc(const struct arch *arch)
>>  	return arch->id.e_machine == EM_PPC || arch->id.e_machine == EM_PPC64;
>>  }
>>  
>> +bool arch__is_arm64(const struct arch *arch)
>> +{
>> +	return arch->id.e_machine == EM_AARCH64;
>> +}
>> +
>>  static void ins_ops__delete(struct ins_operands *ops)
>>  {
>>  	if (ops == NULL)
>> diff --git a/tools/perf/util/disasm.h b/tools/perf/util/disasm.h
>> index a6e478caf61a..d3730ed86dba 100644
>> --- a/tools/perf/util/disasm.h
>> +++ b/tools/perf/util/disasm.h
>> @@ -111,6 +111,7 @@ struct annotate_args {
>>  const struct arch *arch__find(uint16_t e_machine, uint32_t e_flags, const char *cpuid);
>>  bool arch__is_x86(const struct arch *arch);
>>  bool arch__is_powerpc(const struct arch *arch);
>> +bool arch__is_arm64(const struct arch *arch);
>>  
>>  extern const struct ins_ops call_ops;
>>  extern const struct ins_ops dec_ops;
>> -- 
>> 2.34.1
>>