Re: [PATCH v5 07/26] perf dwarf-regs: Adapt get_dwarf_regnum() for arm64

[Namhyung Kim <namhyung@kernel.org>]

On Tue, Sep 08, 2026 at 01:21:51PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Missing 'lr' (link register) support in arm64 DWARF register programmatic lookup.
> --
> 
> commit 5d023c42589d9bd9061d9468194dc470f5cdc273
> Author: Tengda Wu <wutengda@huaweicloud.com>
> 
> perf dwarf-regs: Adapt get_dwarf_regnum() for arm64
> 
> This commit replaces the static table lookup for arm64 DWARF registers with a
> programmatic parser in __get_dwarf_regnum_arm64(). This allows resolving
> arm64 register names directly into their corresponding DWARF register numbers
> for perf annotate.
> 
> > 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]
> Does this code inadvertently drop support for the link register ('lr')?
> 
> If perf annotate processes an instruction containing 'lr' (e.g.,
> stp x29, lr, [sp, #-16]!), arch__dwarf_regnum() extracts "lr" and calls
> this programmatic logic. Since "lr" does not start with 'x' or 'w' and is not
> "sp", it will return -ENOENT. This seems like it will prevent data type
> tracking for the link register, which was previously supported when mapping
> to DWARF register 30.

I think we agreed to ignore 'lr' for now.

Reviewed-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung
> 
> > +
> > +	name++;
> > +	if (!isdigit(*name))
> > +		return -ENOENT;
> > +
> > +	reg = strtol(name, NULL, 10);
> > +
> > +	return reg >= 0 && reg <= 30 ? reg : -ENOENT;
> > +}
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/cover.1788872630.git.wutengda@huaweicloud.com?part=7