Re: [PATCH v4 05/23] perf dwarf-regs: Adapt get_dwarf_regnum() for arm64

On 2026/8/8 21:12, [email protected] wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The programmatic DWARF register lookup __get_dwarf_regnum_arm64() fails to support the standard AArch64 'lr' (link register) and 'fp' (frame pointer) aliases.
> --
> 
> --- Patch [5]: [PATCH v4 05/23] perf dwarf-regs: Adapt get_dwarf_regnum() for arm64 ---
> commit 7e82be98e18ee79f31ad73b727e21d33b0a6f30d
> Author: Tengda Wu <[email protected]>
> 
> perf dwarf-regs: Adapt get_dwarf_regnum() for arm64
> 
> This patch replaces the static string table lookup for arm64 DWARF registers
> with a programmatic implementation. This change allows resolving arm64
> register names directly into their corresponding DWARF register numbers
> during annotation parsing.
> 
>> diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-arm64.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-arm64.c
>> index 593ca7d4fccca..720c863d18696 100644
>> --- a/tools/perf/util/dwarf-regs-arch/dwarf-regs-arm64.c
>> +++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-arm64.c
> 
> [ ... ]
> 
>> @@ -10,3 +13,22 @@ int __get_dwarf_regnum_for_perf_regnum_arm64(int perf_regnum)
>>  
>>  	return perf_regnum;
>>  }
>> +
>> +int __get_dwarf_regnum_arm64(const char *name)
>> +{
>> +	int reg;
>> +
>> +	if (!strcmp(name, "sp"))
>> +		return 31;
>> +
>> +	if (*name != 'x' && *name != 'w')
>> +		return -ENOENT;
> 
> [Severity: Medium]
> Will this strict prefix check inadvertently reject standard AArch64 aliases
> like lr and fp?
> 
> These architectural aliases are frequently emitted by objdump and were
> previously handled by the old static table. When perf annotate attempts
> to look up lr or fp, this programmatic DWARF register lookup in
> __get_dwarf_regnum_arm64() will fail because the name does not start with
> x or w.
> 

Currently, I have not seen such aliases in AArch64 disassembly output,
nor are they documented in the manual. Therefore, I will not change this
and will keep it as-is.