Re: [PATCH] perf riscv: fix register name strings

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Mon, Jun 08, 2026 at 01:08:28PM -0700, Ian Rogers wrote:
> On Mon, Jun 8, 2026 at 12:27 PM Martin Kaiser <martin@kaiser.cx> wrote:
> >
> > On risc-v, pref probe generates an invalid syntax for a named register in
> > a kprobe.
> >
> > $ perf probe --debug verbose --add "n_tty_write tty"
> > ...
> > Writing event: p:probe/n_tty_write _text+8922528 tty=%"%a0":x64
> > Failed to write event: Invalid argument
> >
> > The problem is the combination of
> >
> >    #define REG_DWARFNUM_NAME(reg, idx) [idx] = "%" #reg
> >
> > and entries such as
> >
> >    REG_DWARFNUM_NAME("%a0", 10)
> >
> > where #reg will escape the quotes of the first macro parameter.
> >
> > Update the macro definition to produce the correct syntax for a named
> > register in a kprobe, i.e. the unquoted register name with only one
> > leading %.
> >
> > Fixes: a90c4519186d ("perf riscv: Remove dwarf-regs.c and add dwarf-regs-table.h")
> > Signed-off-by: Martin Kaiser <martin@kaiser.cx>
> 
> Reviewed-by: Ian Rogers <irogers@google.com>
> 
> Thanks for catching this! Sashiko is also green for this change:
> https://sashiko.dev/#/patchset/20260608192731.708606-1-martin%40kaiser.cx

Strange,

  LD      /tmp/build/perf-tools-next/tests/perf-test-in.o
  LD      /tmp/build/perf-tools-next/perf-test-in.o
In file included from util/dwarf-regs.c:23:
util/../arch/riscv/include/dwarf-regs-table.h:5:9: error: ‘REG_DWARFNUM_NAME’ redefined [-Werror]
    5 | #define REG_DWARFNUM_NAME(reg, idx)     [idx] = reg
      |         ^~~~~~~~~~~~~~~~~
In file included from util/dwarf-regs.c:22:
util/../arch/powerpc/include/dwarf-regs-table.h:10:9: note: this is the location of the previous definition
   10 | #define REG_DWARFNUM_NAME(reg, idx)     [idx] = "%" #reg
      |         ^~~~~~~~~~~~~~~~~
In file included from util/dwarf-regs.c:24:
util/../arch/s390/include/dwarf-regs-table.h:5:9: error: ‘REG_DWARFNUM_NAME’ redefined [-Werror]
    5 | #define REG_DWARFNUM_NAME(reg, idx)     [idx] = "%" #reg
      |         ^~~~~~~~~~~~~~~~~
util/../arch/riscv/include/dwarf-regs-table.h:5:9: note: this is the location of the previous definition
    5 | #define REG_DWARFNUM_NAME(reg, idx)     [idx] = reg
      |         ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[4]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:96: /tmp/build/perf-tools-next/util/dwarf-regs.o] Error 1


Trying to figure out why Sashiko is green on it but it doesn't buind
here...

- Arnaldo