linux-kernel - Re: [PATCH V2] tools/perf: Add basic support for LoongArch

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Message-ID: <CAAhV-H5EMaobTNrCX5FthD6zPLwZB6c46M0Y=kTqEUetRpwo3w@mail.gmail.com>
Date:   Tue, 18 Apr 2023 09:14:51 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Youling Tang <tangyouling@...ngson.cn>
Cc:     Huacai Chen <chenhuacai@...ngson.cn>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>, loongarch@...ts.linux.dev,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Xuerui Wang <kernel@...0n.name>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org,
        loongson-kernel@...ts.loongnix.cn,
        Ming Wang <wangming01@...ngson.cn>
Subject: Re: [PATCH V2] tools/perf: Add basic support for LoongArch

On Mon, Apr 17, 2023 at 5:22 PM Youling Tang <tangyouling@...ngson.cn> wrote:
>
> /* snip */
>
> >>>> --- /dev/null
> >>>> +++ b/tools/perf/arch/loongarch/util/dwarf-regs.c
> >>>> @@ -0,0 +1,44 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0
> >>>> +/*
> >>>> + * dwarf-regs.c : Mapping of DWARF debug register numbers into
> >>>> register names.
> >>>> + *
> >>>> + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
> >>>> + */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +#include <errno.h> /* for EINVAL */
> >>>> +#include <string.h> /* for strcmp */
> >>>> +#include <dwarf-regs.h>
> >>>> +
> >>>> +struct pt_regs_dwarfnum {
> >>>> +     const char *name;
> >>>> +     unsigned int dwarfnum;
> >>>> +};
> >>>> +
> >>>> +static struct pt_regs_dwarfnum loongarch_gpr_table[] = {
> >>>> +     {"$0", 0}, {"$1", 1}, {"$2", 2}, {"$3", 3},
> >>>> +     {"$4", 4}, {"$5", 5}, {"$6", 6}, {"$7", 7},
> >>>> +     {"$8", 8}, {"$9", 9}, {"$10", 10}, {"$11", 11},
> >>>> +     {"$12", 12}, {"$13", 13}, {"$14", 14}, {"$15", 15},
> >>>> +     {"$16", 16}, {"$17", 17}, {"$18", 18}, {"$19", 19},
> >>>> +     {"$20", 20}, {"$21", 21}, {"$22", 22}, {"$23", 23},
> >>>> +     {"$24", 24}, {"$25", 25}, {"$26", 26}, {"$27", 27},
> >>>> +     {"$28", 28}, {"$29", 29}, {"$30", 30}, {"$31", 31},
> >>>> +     {NULL, 0}
> >>>> +};
> >>> Do you need to change it to the following:
> >>>
> >>> #define GPR_DWARFNUM_NAME(num) {.name = __stringify($r##num), .dwarfnum
> >>> = num}
> >>> #define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0}
> >>>
> >>> static const struct pt_regs_dwarfnum regdwarfnum_table[] = {
> >>>          GPR_DWARFNUM_NAME(0),
> >>>          GPR_DWARFNUM_NAME(1),
> >>>          GPR_DWARFNUM_NAME(2),
> >>>          GPR_DWARFNUM_NAME(3),
> >>>          GPR_DWARFNUM_NAME(4),
> >>>          GPR_DWARFNUM_NAME(5),
> >>>          GPR_DWARFNUM_NAME(6),
> >>>          GPR_DWARFNUM_NAME(7),
> >>>          GPR_DWARFNUM_NAME(8),
> >>>          GPR_DWARFNUM_NAME(9),
> >>>          GPR_DWARFNUM_NAME(10),
> >>>          GPR_DWARFNUM_NAME(11),
> >>>          GPR_DWARFNUM_NAME(12),
> >>>          GPR_DWARFNUM_NAME(13),
> >>>          GPR_DWARFNUM_NAME(14),
> >>>          GPR_DWARFNUM_NAME(15),
> >>>          GPR_DWARFNUM_NAME(16),
> >>>          GPR_DWARFNUM_NAME(17),
> >>>          GPR_DWARFNUM_NAME(18),
> >>>          GPR_DWARFNUM_NAME(19),
> >>>          GPR_DWARFNUM_NAME(20),
> >>>          GPR_DWARFNUM_NAME(21),
> >>>          GPR_DWARFNUM_NAME(22),
> >>>          GPR_DWARFNUM_NAME(23),
> >>>          GPR_DWARFNUM_NAME(24),
> >>>          GPR_DWARFNUM_NAME(25),
> >>>          GPR_DWARFNUM_NAME(26),
> >>>          GPR_DWARFNUM_NAME(27),
> >>>          GPR_DWARFNUM_NAME(28),
> >>>          GPR_DWARFNUM_NAME(29),
> >>>          REG_DWARFNUM_NAME(30),
> >>>          REG_DWARFNUM_NAME(31),
> >>>          REG_DWARFNUM_END,
> >>> };
> >>>
> >>> At the same time, "$rx" is used in __perf_reg_name_loongarch and
> >>> loongarch_regstr_tbl, which is consistent with assembly.
> >> OK, I will use the "$rx" format, but I don't want to use macros.
> > Use the "rx" format to make regs_query_register_offset consistent with
> > arch/loongarch/kernel/ptrace.c (that is, the names in
> > loongarch_gpr_table and regoffset_table are consistent)
>
> If we want to be consistent with the usage of `trace probe`, we should
> use "%rx".
OK, make sense.

Huacai
>
> eg:
>     # echo "p:myuprobe /tmp/test:0x4194 %r4 %r5" > uprobe_events
>
> parse_probe_arg()
>           case '%': regs_query_register_offset()
>
> Youling.
> >
> > Youling.
> >>
> >> Huacai
> >>>
> >>>> +
> >>>> +const char *get_arch_regstr(unsigned int n)
> >>>> +{
> >>>> +     n %= 32;
> >>>> +     return loongarch_gpr_table[n].name;
> >>>> +}
> >>>> +
> >>>> +int regs_query_register_offset(const char *name)
> >>>> +{
> >>>> +     const struct pt_regs_dwarfnum *roff;
> >>>> +
> >>>> +     for (roff = loongarch_gpr_table; roff->name != NULL; roff++)
> >>>> +             if (!strcmp(roff->name, name))
> >>>> +                     return roff->dwarfnum;
> >>>> +     return -EINVAL;
> >>>> +}
> >
>
>