Message-ID: <e3463435-b879-4d72-9cab-c4bf951b9084@intel.com>
Date: Fri, 19 Jan 2024 20:39:19 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Changbin Du <changbin.du@...wei.com>
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,
 Peter Zijlstra <peterz@...radead.org>,
 Arnaldo Carvalho de Melo <acme@...nel.org>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v4 2/5] perf: util: use capstone disasm engine to show
 assembly instructions

On 19/01/24 12:48, 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>
> ---
>  tools/perf/builtin-script.c  |   8 +--
>  tools/perf/util/Build        |   1 +
>  tools/perf/util/print_insn.c | 122 +++++++++++++++++++++++++++++++++++
>  tools/perf/util/print_insn.h |  14 ++++
>  4 files changed, 140 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: ");

"insn:" seems unnecessary.  Also xed prints 2 tabs, which
helps line up the output.  Perhaps 1 tab and 2 spaces is
enough.

> +		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 988473bf907a..c33aab53d8dd 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..162be4856f79
> --- /dev/null
> +++ b/tools/perf/util/print_insn.c
> @@ -0,0 +1,122 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Instruction binary disassembler based on capstone.
> + *
> + * Author(s): Changbin Du <changbin.du@...wei.com>
> + */
> +#include "print_insn.h"

Please put with the other non-system includes

> +#include <stdlib.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include "util/debug.h"

util/ not needed

> +#include "util/symbol.h"

util/ not needed

> +#include "machine.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]);

Why change this to put a space on the end?

> +	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;
> +	}
> +
> +	cs_option(*cs_handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT);

That's only needed for x86 isn't it

> +	if (machine__normalized_is(machine, "x86"))
> +		cs_option(*cs_handle, CS_OPT_DETAIL, CS_OPT_ON);

Why? Could use a comment.

> +
> +	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);

Missing addr_location__exit()

> +
> +		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);
> +			return printed;
> +		}
> +	}
> +
> +	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)
> +{
> +	static csh cs_handle;

Why static?

> +	cs_insn *insn;
> +	size_t count;
> +	size_t printed = 0;
> +	int ret;
> +
> +	ret = capstone_init(machine, &cs_handle);

Does this really need to be done every time?

> +	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)
> +{
> +	return sample__fprintf_insn_raw(sample, fp);
> +}
> +#endif
> diff --git a/tools/perf/util/print_insn.h b/tools/perf/util/print_insn.h
> new file mode 100644
> index 000000000000..af8fa5d01fb7
> --- /dev/null
> +++ b/tools/perf/util/print_insn.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef PERF_PRINT_ISNS_H

Here and elsewhere

ISNS -> INSN

> +#define PERF_PRINT_ISNS_H
> +
> +#include <stddef.h>
> +#include <stdio.h>
> +#include "event.h"
> +#include "util/thread.h"

Instead of including event.h and thread.h, just forward declare:

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_ISNS_H */

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