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Message-ID: <CAM9d7ci=AZFpcYy4=qwTYTTVhWd6g6HHHUuV2B53hS-t8SOCag@mail.gmail.com>
Date: Mon, 6 May 2024 21:39:40 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc: acme@...nel.org, jolsa@...nel.org, adrian.hunter@...el.com,
irogers@...gle.com, segher@...nel.crashing.org, christophe.leroy@...roup.eu,
linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
maddy@...ux.ibm.com, kjain@...ux.ibm.com, disgoel@...ux.vnet.ibm.com,
linux-kernel@...r.kernel.org, akanksha@...ux.ibm.com
Subject: Re: [PATCH V2 0/9] Add data type profiling support for powerpc
Hello,
On Mon, May 6, 2024 at 5:19 AM Athira Rajeev
<atrajeev@...ux.vnet.ibm.com> wrote:
>
> The patchset from Namhyung added support for data type profiling
> in perf tool. This enabled support to associate PMU samples to data
> types they refer using DWARF debug information. With the upstream
> perf, currently it possible to run perf report or perf annotate to
> view the data type information on x86.
>
> Initial patchset posted here had changes need to enable data type
> profiling support for powerpc.
>
> https://lore.kernel.org/all/6e09dc28-4a2e-49d8-a2b5-ffb3396a9952@csgroup.eu/T/
>
> Main change were:
> 1. powerpc instruction nmemonic table to associate load/store
> instructions with move_ops which is use to identify if instruction
> is a memory access one.
> 2. To get register number and access offset from the given
> instruction, code uses fields from "struct arch" -> objump.
> Added entry for powerpc here.
> 3. A get_arch_regnum to return register number from the
> register name string.
>
> But the apporach used in the initial patchset used parsing of
> disassembled code which the current perf tool implementation does.
>
> Example: lwz r10,0(r9)
>
> This line "lwz r10,0(r9)" is parsed to extract instruction name,
> registers names and offset. Also to find whether there is a memory
> reference in the operands, "memory_ref_char" field of objdump is used.
> For x86, "(" is used as memory_ref_char to tackle instructions of the
> form "mov (%rax), %rcx".
>
> In case of powerpc, not all instructions using "(" are the only memory
> instructions. Example, above instruction can also be of extended form (X
> form) "lwzx r10,0,r19". Inorder to easy identify the instruction category
> and extract the source/target registers, this patchset adds support to use
> raw instruction. With raw instruction, macros are added to extract opcode
> and register fields.
>
> Example representation using --show-raw-insn in objdump gives result:
>
> 38 01 81 e8 ld r4,312(r1)
>
> Here "38 01 81 e8" is the raw instruction representation. In powerpc,
> this translates to instruction form: "ld RT,DS(RA)" and binary code
> as:
> _____________________________________
> | 58 | RT | RA | DS | |
> -------------------------------------
> 0 6 11 16 30 31
>
> Patchset adds support to pick the opcode and reg fields from this
> raw/binary instruction code. This approach came in from review comment
> by Segher Boessenkool for the initial patchset.
>
> Apart from that, instruction tracking is enabled for powerpc and
> support function is added to find variables defined as registers
> Example, in powerpc, two registers are
> defined to represent variable:
> 1. r13: represents local_paca
> register struct paca_struct *local_paca asm("r13");
>
> 2. r1: represents stack_pointer
> register void *__stack_pointer asm("r1");
>
> These are handled in this patchset.
>
> - Patch 1 is to rearrange register state type structures to header file
> so that it can referred from other arch specific files
> - Patch 2 is to make instruction tracking as a callback to"struct arch"
> so that it can be implemented by other archs easily and defined in arch
> specific files
> - Patch 3 is to fix a small comment
> - Patch 4 adds support to capture and parse raw instruction in objdump
> by keeping existing approach intact.
> - Patch 5 update parameters for reg extract functions to use raw
> instruction on powerpc
> - Patch 6 and patch 7 handles instruction tracking for powerpc.
> - Patch 8 and Patch 8 handles support to find global register variables
>
> With the current patchset:
>
> ./perf record -a -e mem-loads sleep 1
> ./perf report -s type,typeoff --hierarchy --group --stdio
> ./perf annotate --data-type --insn-stat
>
> perf annotate logs:
>
> Annotate Instruction stats
> total 562, ok 441 (78.5%), bad 121 (21.5%)
>
> Name : Good Bad
> -----------------------------------------------------------
> ld : 313 54
> lwz : 51 32
> lbz : 31 5
> ldx : 6 21
> lhz : 23 0
> lwa : 4 3
> lwarx : 5 0
> lwzx : 2 2
> ldarx : 3 0
> lwzu : 2 0
> stdcx. : 0 1
> nop : 0 1
> ldu : 1 0
> lbzx : 0 1
> lwax : 0 1
>
> perf report logs:
>
> # Samples: 1K of event 'mem-loads'
> # Event count (approx.): 937238
> #
> # Overhead Data Type Data Type Offset
> # ........ ......... ................
> #
> 48.81% (unknown) (unknown) +0 (no field)
> 12.85% long unsigned int long unsigned int +0 (current_stack_pointer)
> 4.68% struct paca_struct struct paca_struct +2312 (__current)
> 4.57% struct paca_struct struct paca_struct +2354 (irq_soft_mask)
> 2.68% struct paca_struct struct paca_struct +8 (paca_index)
> 2.64% struct paca_struct struct paca_struct +2808 (canary)
> 2.24% struct paca_struct struct paca_struct +48 (data_offset)
> 1.41% struct vm_fault struct vm_fault +0 (vma)
> 1.29% struct task_struct struct task_struct +276 (flags)
> 1.03% struct pt_regs struct pt_regs +264 (user_regs.msr)
> 1.00% struct menu_device struct menu_device +4 (tick_wakeup)
> 0.90% struct security_hook_list struct security_hook_list +0 (listnext)
> 0.76% struct irq_desc struct irq_desc +304 (irq_data.chip)
> 0.76% struct rq struct rq +2856 (cpu)
Looks great! I'm glad it worked on powerpc too.
We still need to verify the returned type is properly annotated.
But overall it looks really good, I will leave comments in reply.
Thanks,
Namhyung
>
> Thanks
> Athira Rajeev
>
> Changelog:
> From v1->v2:
> - Addressed suggestion from Christophe Leroy and Segher Boessenkool
> to use the binary code (raw insn) to fetch opcode, register and
> offset fields.
> - Added support for instruction tracking in powerpc
> - Find the register defined variables (r13 and r1 which points to
> local_paca and current_stack_pointer in powerpc)
>
> Athira Rajeev (9):
> tools/perf: Move the data structures related to register type to
> header file
> tools/perf: Add "update_insn_state" callback function to handle arch
> specific instruction tracking
> tools/perf: Fix a comment about multi_regs in extract_reg_offset
> function
> tools/perf: Add support to capture and parse raw instruction in
> objdump
> tools/perf: Update parameters for reg extract functions to use raw
> instruction on powerpc
> tools/perf: Update instruction tracking for powerpc
> tools/perf: Update instruction tracking with add instruction
> tools/perf: Add support to find global register variables using
> find_data_type_global_reg
> tools/perf: Add support for global_die to capture name of variable in
> case of register defined variable
>
> tools/include/linux/string.h | 2 +
> tools/lib/string.c | 13 +
> .../perf/arch/powerpc/annotate/instructions.c | 84 +++
> tools/perf/arch/powerpc/util/dwarf-regs.c | 52 ++
> tools/perf/arch/x86/annotate/instructions.c | 383 +++++++++++++
> tools/perf/util/annotate-data.c | 519 +++---------------
> tools/perf/util/annotate-data.h | 78 +++
> tools/perf/util/annotate.c | 32 +-
> tools/perf/util/annotate.h | 1 +
> tools/perf/util/disasm.c | 109 +++-
> tools/perf/util/disasm.h | 17 +-
> tools/perf/util/dwarf-aux.c | 1 +
> tools/perf/util/dwarf-aux.h | 1 +
> tools/perf/util/include/dwarf-regs.h | 12 +
> tools/perf/util/sort.c | 7 +-
> 15 files changed, 854 insertions(+), 457 deletions(-)
>
> --
> 2.43.0
>
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