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Message-ID: <631f8b5e-2bd2-4419-885f-34be07012b29@intel.com>
Date: Tue, 6 Feb 2024 12:33:10 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Changbin Du <changbin.du@...wei.com>,
Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
Thomas Richter <tmricht@...ux.ibm.com>, changbin.du@...il.com
Subject: Re: [PATCH v6 2/5] perf: util: use capstone disasm engine to show
assembly instructions
On 6/02/24 04:14, Changbin Du wrote:
> Currently, the instructions of samples are shown as raw hex strings
> which are hard to read. x86 has a special option '--xed' to disassemble
> the hex string via intel XED tool.
>
> Here we use capstone as our disassembler engine to give more friendly
> instructions. We select libcapstone because capstone can provide more
> insn details. Perf will fallback to raw instructions if libcapstone is
> not available.
>
> The advantages compared to XED tool:
> * Support arm, arm64, x86-32, x86_64 (more could be supported),
> xed only for x86_64.
> * Immediate address operands are shown as symbol+offs.
>
> Signed-off-by: Changbin Du <changbin.du@...wei.com>
>
> ---
> v3:
> - show warning msg if libcapstone is not available.
> v2:
> - line up the output by preceding two tabs. (Adrian Hunter)
> - removed the tailing space. (Adrian Hunter)
> - forward declaration for perf_sample, thread, machine. (Adrian Hunter)
> - other trivial fixes (Adrian Hunter)
> ---
> tools/perf/builtin-script.c | 8 +--
> tools/perf/util/Build | 1 +
> tools/perf/util/print_insn.c | 134 +++++++++++++++++++++++++++++++++++
> tools/perf/util/print_insn.h | 16 +++++
> 4 files changed, 154 insertions(+), 5 deletions(-)
> create mode 100644 tools/perf/util/print_insn.c
> create mode 100644 tools/perf/util/print_insn.h
>
> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> index b1f57401ff23..4817a37f16e2 100644
> --- a/tools/perf/builtin-script.c
> +++ b/tools/perf/builtin-script.c
> @@ -34,6 +34,7 @@
> #include "util/event.h"
> #include "ui/ui.h"
> #include "print_binary.h"
> +#include "print_insn.h"
> #include "archinsn.h"
> #include <linux/bitmap.h>
> #include <linux/kernel.h>
> @@ -1511,11 +1512,8 @@ static int perf_sample__fprintf_insn(struct perf_sample *sample,
> if (PRINT_FIELD(INSNLEN))
> printed += fprintf(fp, " ilen: %d", sample->insn_len);
> if (PRINT_FIELD(INSN) && sample->insn_len) {
> - int i;
> -
> - printed += fprintf(fp, " insn:");
> - for (i = 0; i < sample->insn_len; i++)
> - printed += fprintf(fp, " %02x", (unsigned char)sample->insn[i]);
> + printed += fprintf(fp, " insn: ");
> + printed += sample__fprintf_insn_raw(sample, fp);
> }
> if (PRINT_FIELD(BRSTACKINSN) || PRINT_FIELD(BRSTACKINSNLEN))
> printed += perf_sample__fprintf_brstackinsn(sample, thread, attr, machine, fp);
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index 8027f450fa3e..2cbeeb79b6ef 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -32,6 +32,7 @@ perf-y += perf_regs.o
> perf-y += perf-regs-arch/
> perf-y += path.o
> perf-y += print_binary.o
> +perf-y += print_insn.o
> perf-y += rlimit.o
> perf-y += argv_split.o
> perf-y += rbtree.o
> diff --git a/tools/perf/util/print_insn.c b/tools/perf/util/print_insn.c
> new file mode 100644
> index 000000000000..163307a02274
> --- /dev/null
> +++ b/tools/perf/util/print_insn.c
> @@ -0,0 +1,134 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Instruction binary disassembler based on capstone.
> + *
> + * Author(s): Changbin Du <changbin.du@...wei.com>
> + */
> +#include <string.h>
> +#include <stdbool.h>
> +#include "debug.h"
> +#include "event.h"
> +#include "symbol.h"
> +#include "machine.h"
> +#include "thread.h"
> +#include "print_insn.h"
> +
> +size_t sample__fprintf_insn_raw(struct perf_sample *sample, FILE *fp)
> +{
> + int printed = 0;
> +
> + for (int i = 0; i < sample->insn_len; i++) {
> + printed += fprintf(fp, "%02x ", (unsigned char)sample->insn[i]);
Same as last time, there are 2 spaces between bytes
instead of 1. It needs:
"%02x " -> "%02x"
> + if (sample->insn_len - i > 1)
> + printed += fprintf(fp, " ");
> + }
> + return printed;
> +}
> +
> +#ifdef HAVE_LIBCAPSTONE_SUPPORT
> +#include <capstone/capstone.h>
> +
> +static int capstone_init(struct machine *machine, csh *cs_handle)
> +{
> + cs_arch arch;
> + cs_mode mode;
> +
> + if (machine__is(machine, "x86_64")) {
> + arch = CS_ARCH_X86;
> + mode = CS_MODE_64;
> + } else if (machine__normalized_is(machine, "x86")) {
> + arch = CS_ARCH_X86;
> + mode = CS_MODE_32;
> + } else if (machine__normalized_is(machine, "arm64")) {
> + arch = CS_ARCH_ARM64;
> + mode = CS_MODE_ARM;
> + } else if (machine__normalized_is(machine, "arm")) {
> + arch = CS_ARCH_ARM;
> + mode = CS_MODE_ARM + CS_MODE_V8;
> + } else if (machine__normalized_is(machine, "s390")) {
> + arch = CS_ARCH_SYSZ;
> + mode = CS_MODE_BIG_ENDIAN;
> + } else {
> + return -1;
> + }
> +
> + if (cs_open(arch, mode, cs_handle) != CS_ERR_OK) {
> + pr_warning_once("cs_open failed\n");
> + return -1;
> + }
> +
> + if (machine__normalized_is(machine, "x86")) {
> + cs_option(*cs_handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT);
> + /*
> + * Resolving address operands to symbols is implemented
> + * on x86 by investigating instruction details.
> + */
> + cs_option(*cs_handle, CS_OPT_DETAIL, CS_OPT_ON);
> + }
> +
> + return 0;
> +}
> +
> +static size_t print_insn_x86(struct perf_sample *sample, struct thread *thread,
> + cs_insn *insn, FILE *fp)
> +{
> + struct addr_location al;
> + size_t printed = 0;
> +
> + if (insn->detail && insn->detail->x86.op_count == 1) {
> + cs_x86_op *op = &insn->detail->x86.operands[0];
> +
> + addr_location__init(&al);
> + if (op->type == X86_OP_IMM &&
> + thread__find_symbol(thread, sample->cpumode, op->imm, &al)) {
> + printed += fprintf(fp, "%s ", insn[0].mnemonic);
> + printed += symbol__fprintf_symname_offs(al.sym, &al, fp);
> + addr_location__exit(&al);
> + return printed;
> + }
> + addr_location__exit(&al);
> + }
> +
> + printed += fprintf(fp, "%s %s", insn[0].mnemonic, insn[0].op_str);
> + return printed;
> +}
> +
> +size_t sample__fprintf_insn(struct perf_sample *sample, struct thread *thread,
> + struct machine *machine, FILE *fp)
> +{
> + csh cs_handle;
> + cs_insn *insn;
> + size_t count;
> + size_t printed = 0;
> + int ret;
> +
> + /* TODO: Try to initiate capstone only once but need a proper place. */
> + ret = capstone_init(machine, &cs_handle);
> + if (ret < 0) {
> + /* fallback */
> + return sample__fprintf_insn_raw(sample, fp);
> + }
> +
> + count = cs_disasm(cs_handle, (uint8_t *)sample->insn, sample->insn_len,
> + sample->ip, 1, &insn);
> + if (count > 0) {
> + if (machine__normalized_is(machine, "x86"))
> + printed += print_insn_x86(sample, thread, &insn[0], fp);
> + else
> + printed += fprintf(fp, "%s %s", insn[0].mnemonic, insn[0].op_str);
> + cs_free(insn, count);
> + } else {
> + printed += fprintf(fp, "illegal instruction");
> + }
> +
> + cs_close(&cs_handle);
> + return printed;
> +}
> +#else
> +size_t sample__fprintf_insn(struct perf_sample *sample, struct thread *thread __maybe_unused,
> + struct machine *machine __maybe_unused, FILE *fp)
> +{
> + pr_warning_once("perf needs to be built with libcapstone support to disassemble instructions\n");
> + return sample__fprintf_insn_raw(sample, fp);
The validation stops this being called so could just leave
out the 2 lines above, and add __maybe_unused as necessary.
> +}
> +#endif
> diff --git a/tools/perf/util/print_insn.h b/tools/perf/util/print_insn.h
> new file mode 100644
> index 000000000000..80dda6da7c60
> --- /dev/null
> +++ b/tools/perf/util/print_insn.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef PERF_PRINT_INSN_H
> +#define PERF_PRINT_INSN_H
> +
> +#include <stddef.h>
> +#include <stdio.h>
> +
> +struct perf_sample;
> +struct thread;
> +struct machine;
> +
> +size_t sample__fprintf_insn(struct perf_sample *sample, struct thread *thread,
> + struct machine *machine, FILE *fp);
> +size_t sample__fprintf_insn_raw(struct perf_sample *sample, FILE *fp);
> +
> +#endif /* PERF_PRINT_INSN_H */
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