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Date: Sat, 8 Jun 2024 08:58:16 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Namhyung Kim <namhyung@...nel.org>, Athira Rajeev
<atrajeev@...ux.vnet.ibm.com>
CC: "acme@...nel.org" <acme@...nel.org>, "jolsa@...nel.org"
<jolsa@...nel.org>, "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"irogers@...gle.com" <irogers@...gle.com>, "segher@...nel.crashing.org"
<segher@...nel.crashing.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "linux-perf-users@...r.kernel.org"
<linux-perf-users@...r.kernel.org>, "linuxppc-dev@...ts.ozlabs.org"
<linuxppc-dev@...ts.ozlabs.org>, "akanksha@...ux.ibm.com"
<akanksha@...ux.ibm.com>, "maddy@...ux.ibm.com" <maddy@...ux.ibm.com>,
"kjain@...ux.ibm.com" <kjain@...ux.ibm.com>, "disgoel@...ux.vnet.ibm.com"
<disgoel@...ux.vnet.ibm.com>
Subject: Re: [PATCH V3 05/14] tools/perf: Add disasm_line__parse to parse raw
instruction for powerpc
Le 06/06/2024 à 08:33, Namhyung Kim a écrit :
> Hello,
>
> On Sat, Jun 01, 2024 at 11:39:32AM +0530, Athira Rajeev wrote:
>> Currently, the perf tool infrastructure disasm_line__parse function to
>> parse disassembled line.
>>
>> Example snippet from objdump:
>> objdump --start-address=<address> --stop-address=<address> -d --no-show-raw-insn -C <vmlinux>
>>
>> c0000000010224b4: lwz r10,0(r9)
>>
>> This line "lwz r10,0(r9)" is parsed to extract instruction name,
>> registers names and offset. In powerpc, the approach for data type
>> profiling uses raw instruction instead of result from objdump to identify
>> the instruction category and extract the source/target registers.
>>
>> Example: 38 01 81 e8 ld r4,312(r1)
>>
>> Here "38 01 81 e8" is the raw instruction representation. Add function
>> "disasm_line__parse_powerpc" to handle parsing of raw instruction. Also
>> update "struct ins" and "struct ins_operands" to save "opcode" and
>> binary code. With the change, function captures:
>>
>> line -> "38 01 81 e8 ld r4,312(r1)"
>> opcode and raw instruction "38 01 81 e8"
>>
>> Raw instruction is used later to extract the reg/offset fields. Macros
>> are added to extract opcode and register fields. "struct ins_operands"
>> and "struct ins" is updated to carry opcode and raw instruction binary
>> code (raw_insn). Function "disasm_line__parse_powerpc fills the raw
>> instruction hex value and opcode in newly added fields. There is no
>> changes in existing code paths, which parses the disassembled code.
>> The architecture using the instruction name and present approach is
>> not altered. Since this approach targets powerpc, the macro
>> implementation is added for powerpc as of now.
>>
>> Since the disasm_line__parse is used in other cases (perf annotate) and
>> not only data tye profiling, the powerpc callback includes changes to
>> work with binary code as well as mneumonic representation. Also in case
>> if the DSO read fails and libcapstone is not supported, the approach
>> fallback to use objdump as option. Hence as option, patch has changes to
>> ensure objdump option also works well.
>>
>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
>> ---
>> tools/include/linux/string.h | 2 +
>> tools/lib/string.c | 13 ++++
>> .../perf/arch/powerpc/annotate/instructions.c | 1 +
>> tools/perf/arch/powerpc/util/dwarf-regs.c | 9 +++
>> tools/perf/util/disasm.c | 63 ++++++++++++++++++-
>> tools/perf/util/disasm.h | 7 +++
>> 6 files changed, 94 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
>> index db5c99318c79..0acb1fc14e19 100644
>> --- a/tools/include/linux/string.h
>> +++ b/tools/include/linux/string.h
>> @@ -46,5 +46,7 @@ extern char * __must_check skip_spaces(const char *);
>>
>> extern char *strim(char *);
>>
>> +extern void remove_spaces(char *s);
>> +
>> extern void *memchr_inv(const void *start, int c, size_t bytes);
>> #endif /* _TOOLS_LINUX_STRING_H_ */
>> diff --git a/tools/lib/string.c b/tools/lib/string.c
>> index 8b6892f959ab..3126d2cff716 100644
>> --- a/tools/lib/string.c
>> +++ b/tools/lib/string.c
>> @@ -153,6 +153,19 @@ char *strim(char *s)
>> return skip_spaces(s);
>> }
>>
>> +/*
>> + * remove_spaces - Removes whitespaces from @s
>> + */
>> +void remove_spaces(char *s)
>> +{
>> + char *d = s;
>> +
>> + do {
>> + while (*d == ' ')
>> + ++d;
>> + } while ((*s++ = *d++));
>> +}
>> +
>> /**
>> * strreplace - Replace all occurrences of character in string.
>> * @s: The string to operate on.
>> diff --git a/tools/perf/arch/powerpc/annotate/instructions.c b/tools/perf/arch/powerpc/annotate/instructions.c
>> index a3f423c27cae..d57fd023ef9c 100644
>> --- a/tools/perf/arch/powerpc/annotate/instructions.c
>> +++ b/tools/perf/arch/powerpc/annotate/instructions.c
>> @@ -55,6 +55,7 @@ static int powerpc__annotate_init(struct arch *arch, char *cpuid __maybe_unused)
>> arch->initialized = true;
>> arch->associate_instruction_ops = powerpc__associate_instruction_ops;
>> arch->objdump.comment_char = '#';
>> + annotate_opts.show_asm_raw = true;
>> }
>>
>> return 0;
>> diff --git a/tools/perf/arch/powerpc/util/dwarf-regs.c b/tools/perf/arch/powerpc/util/dwarf-regs.c
>> index 0c4f4caf53ac..430623ca5612 100644
>> --- a/tools/perf/arch/powerpc/util/dwarf-regs.c
>> +++ b/tools/perf/arch/powerpc/util/dwarf-regs.c
>> @@ -98,3 +98,12 @@ int regs_query_register_offset(const char *name)
>> return roff->ptregs_offset;
>> return -EINVAL;
>> }
>> +
>> +#define PPC_OP(op) (((op) >> 26) & 0x3F)
>> +#define PPC_RA(a) (((a) >> 16) & 0x1f)
>> +#define PPC_RT(t) (((t) >> 21) & 0x1f)
>> +#define PPC_RB(b) (((b) >> 11) & 0x1f)
>> +#define PPC_D(D) ((D) & 0xfffe)
>> +#define PPC_DS(DS) ((DS) & 0xfffc)
>> +#define OP_LD 58
>> +#define OP_STD 62
>> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
>> index 3cd187f08193..61f0f1656f82 100644
>> --- a/tools/perf/util/disasm.c
>> +++ b/tools/perf/util/disasm.c
>> @@ -45,6 +45,7 @@ static int call__scnprintf(struct ins *ins, char *bf, size_t size,
>>
>> static void ins__sort(struct arch *arch);
>> static int disasm_line__parse(char *line, const char **namep, char **rawp);
>> +static int disasm_line__parse_powerpc(struct disasm_line *dl);
>>
>> static __attribute__((constructor)) void symbol__init_regexpr(void)
>> {
>> @@ -844,6 +845,63 @@ static int disasm_line__parse(char *line, const char **namep, char **rawp)
>> return -1;
>> }
>>
>> +/*
>> + * Parses the result captured from symbol__disassemble_*
>> + * Example, line read from DSO file in powerpc:
>> + * line: 38 01 81 e8
>> + * opcode: fetched from arch specific get_opcode_insn
>> + * rawp_insn: e8810138
>> + *
>> + * rawp_insn is used later to extract the reg/offset fields
>> + */
>> +#define PPC_OP(op) (((op) >> 26) & 0x3F)
>> +
>> +static int disasm_line__parse_powerpc(struct disasm_line *dl)
>> +{
>> + char *line = dl->al.line;
>> + const char **namep = &dl->ins.name;
>> + char **rawp = &dl->ops.raw;
>> + char tmp, *tmp_opcode, *name_opcode = skip_spaces(line);
>> + char *name = skip_spaces(name_opcode + 11);
>> + int objdump = 0;
>> +
>> + if (strlen(line) > 11)
>> + objdump = 1;
>> +
>> + if (name_opcode[0] == '\0')
>> + return -1;
>> +
>> + if (objdump) {
>> + *rawp = name + 1;
>> + while ((*rawp)[0] != '\0' && !isspace((*rawp)[0]))
>> + ++*rawp;
>> + tmp = (*rawp)[0];
>> + (*rawp)[0] = '\0';
>> +
>> + *namep = strdup(name);
>> + if (*namep == NULL)
>> + return -1;
>> +
>> + (*rawp)[0] = tmp;
>> + *rawp = strim(*rawp);
>> + } else
>> + *namep = "";
>> +
>> + tmp_opcode = strdup(name_opcode);
>> + tmp_opcode[11] = '\0';
>> + remove_spaces(tmp_opcode);
>> +
>> + dl->ins.opcode = PPC_OP(strtol(tmp_opcode, NULL, 16));
>> + if (objdump)
>> + dl->ins.opcode = PPC_OP(be32_to_cpu(strtol(tmp_opcode, NULL, 16)));
>> + dl->ops.opcode = dl->ins.opcode;
>> +
>> + dl->ops.raw_insn = strtol(tmp_opcode, NULL, 16);
>> + if (objdump)
>> + dl->ops.raw_insn = be32_to_cpu(strtol(tmp_opcode, NULL, 16));
>> + return 0;
>> +}
>> +
>> static void annotation_line__init(struct annotation_line *al,
>> struct annotate_args *args,
>> int nr)
>> @@ -897,7 +955,10 @@ struct disasm_line *disasm_line__new(struct annotate_args *args)
>> goto out_delete;
>>
>> if (args->offset != -1) {
>> - if (disasm_line__parse(dl->al.line, &dl->ins.name, &dl->ops.raw) < 0)
>> + if (arch__is(args->arch, "powerpc")) {
>> + if (disasm_line__parse_powerpc(dl) < 0)
>> + goto out_free_line;
>> + } else if (disasm_line__parse(dl->al.line, &dl->ins.name, &dl->ops.raw) < 0)
>> goto out_free_line;
>>
>> disasm_line__init_ins(dl, args->arch, &args->ms);
>> diff --git a/tools/perf/util/disasm.h b/tools/perf/util/disasm.h
>> index 718177fa4775..a391e1bb81f7 100644
>> --- a/tools/perf/util/disasm.h
>> +++ b/tools/perf/util/disasm.h
>> @@ -43,14 +43,19 @@ struct arch {
>>
>> struct ins {
>> const char *name;
>> + int opcode;
>
> I don't think this is the right place as 'ins' can be shared for
> different opcodes. IIUC it's like a class and disasm_line should
> have a pointer instead of a copy of the arch instructions. So I'd
> like to keep a single instance if they behave in the same way. But
> this is a separate change.
>
> I guess we can move it to struct disasm_line and use helper macros when
> we need to access the opcode. This will be helpful for other arches.
>
> struct disasm_line {
> struct ins *ins;
> struct ins_operands ops;
> union {
> u8 bytes[4];
> u32 opcode;
> } raw;
> struct annotation_line al;
> };
>
> #define PPC_OP(dl) (((dl)->raw.bytes[0] >> 2) & 0x3F)
We already have a definition for PPC_OP(), see arch/powerpc/xmon/ppc.h:
/* A macro to extract the major opcode from an instruction. */
#define PPC_OP(i) (((i) >> 26) & 0x3f)
By the way why do you want to split off instructions in bytes ? On
powerpc an instruction is one (sometimes two) u32, nothing else, and if
you start breaking that into bytes you will likely unnecessarily
increase complexity when a param has bits on different bytes, and maybe
also with the byte order depending whether you are running on a little
or big endian PPC.
See for instance arch_decode_instruction() in
tools/objtool/arch/powerpc/decode.c
By the way, why are we spreading different decoding functions in
different tools ? Wouldn't it make sense to try and share decoding
functions between objtool and perf for instance ?
Christophe
>
> Thanks,
> Namhyung
>
>>
>> struct ins_ops *ops;
>> };
>>
>> struct ins_operands {
>> char *raw;
>> + int raw_insn;
>> + int opcode;
>> struct {
>> char *raw;
>> char *name;
>> + int opcode;
>> + int raw_insn;
>> struct symbol *sym;
>> u64 addr;
>> s64 offset;
>> @@ -62,6 +67,8 @@ struct ins_operands {
>> struct {
>> char *raw;
>> char *name;
>> + int opcode;
>> + int raw_insn;
>> u64 addr;
>> bool multi_regs;
>> } source;
>> --
>> 2.43.0
>>
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