linux-kernel - Re: [PATCH V2 7/9] tools/perf: Update instruction tracking with add instruction

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Date: Thu, 23 May 2024 19:25:55 +0530
From: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>
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>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "segher@...nel.crashing.org" <segher@...nel.crashing.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "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>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akanksha@...ux.ibm.com" <akanksha@...ux.ibm.com>
Subject: Re: [PATCH V2 7/9] tools/perf: Update instruction tracking with add
 instruction



> On 7 May 2024, at 3:28 PM, Christophe Leroy <christophe.leroy@...roup.eu> wrote:
> 
> 
> 
> Le 06/05/2024 à 14:19, Athira Rajeev a écrit :
>> Update instruction tracking with add instruction. Apart from "mr"
>> instruction, the register state is carried on by other insns, ie,
>> "add, addi, addis". Since these are not memory instructions and doesn't
>> fall in the range of (32 to 63), add these as part of nmemonic table.
>> For now, add* instructions are added. There is possibility of getting
>> more added here. But to extract regs, still the binary code will be
>> used. So associate this with "load_store_ops" itself and no other
>> changes required.
> 
> Looks fragile.
> 
> How do you handle addc, adde, addic ?
> And also addme, addze, which only have two operands instead of 3 ?

Hi Christophe,

Thanks for pointing these cases. Will address these cases in next version

Thanks
Athira
> 
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
>> ---
>>  .../perf/arch/powerpc/annotate/instructions.c | 21 +++++++++++++++++++
>>  tools/perf/util/disasm.c                      |  1 +
>>  2 files changed, 22 insertions(+)
>> 
>> diff --git a/tools/perf/arch/powerpc/annotate/instructions.c b/tools/perf/arch/powerpc/annotate/instructions.c
>> index cce7023951fe..1f35d8a65bb4 100644
>> --- a/tools/perf/arch/powerpc/annotate/instructions.c
>> +++ b/tools/perf/arch/powerpc/annotate/instructions.c
>> @@ -1,6 +1,17 @@
>>  // SPDX-License-Identifier: GPL-2.0
>>  #include <linux/compiler.h>
>> 
>> +/*
>> + * powerpc instruction nmemonic table to associate load/store instructions with
>> + * move_ops. mov_ops is used to identify add/mr to do instruction tracking.
>> + */
>> +static struct ins powerpc__instructions[] = {
>> + { .name = "mr",         .ops = &load_store_ops,  },
>> + { .name = "addi",       .ops = &load_store_ops,   },
>> + { .name = "addis",      .ops = &load_store_ops,  },
>> + { .name = "add",        .ops = &load_store_ops,  },
>> +};
>> +
>>  static struct ins_ops *powerpc__associate_instruction_ops(struct arch *arch, const char *name)
>>  {
>>   int i;
>> @@ -75,6 +86,9 @@ static void update_insn_state_powerpc(struct type_state *state,
>>   if (annotate_get_insn_location(dloc->arch, dl, &loc) < 0)
>>   return;
>> 
>> + if (!strncmp(dl->ins.name, "add", 3))
>> + goto regs_check;
>> +
>>   if (strncmp(dl->ins.name, "mr", 2))
>>   return;
>> 
>> @@ -85,6 +99,7 @@ static void update_insn_state_powerpc(struct type_state *state,
>>   dst->reg1 = src_reg;
>>   }
>> 
>> +regs_check:
>>   if (!has_reg_type(state, dst->reg1))
>>   return;
>> 
>> @@ -115,6 +130,12 @@ static void update_insn_state_powerpc(struct type_state *state __maybe_unused, s
>>  static int powerpc__annotate_init(struct arch *arch, char *cpuid __maybe_unused)
>>  {
>>   if (!arch->initialized) {
>> + arch->nr_instructions = ARRAY_SIZE(powerpc__instructions);
>> + arch->instructions = calloc(arch->nr_instructions, sizeof(struct ins));
>> + if (!arch->instructions)
>> + return -ENOMEM;
>> + memcpy(arch->instructions, powerpc__instructions, sizeof(struct ins) * arch->nr_instructions);
>> + arch->nr_instructions_allocated = arch->nr_instructions;
>>   arch->initialized = true;
>>   arch->associate_instruction_ops = powerpc__associate_instruction_ops;
>>   arch->objdump.comment_char      = '#';
>> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
>> index ac6b8b8da38a..32cf506a9010 100644
>> --- a/tools/perf/util/disasm.c
>> +++ b/tools/perf/util/disasm.c
>> @@ -36,6 +36,7 @@ static struct ins_ops mov_ops;
>>  static struct ins_ops nop_ops;
>>  static struct ins_ops lock_ops;
>>  static struct ins_ops ret_ops;
>> +static struct ins_ops load_store_ops;
>> 
>>  static int jump__scnprintf(struct ins *ins, char *bf, size_t size,
>>     struct ins_operands *ops, int max_ins_name);