perf script: Fix script_fetch_insn for more than just x86

The script_fetch_insn code was only supported on natively running x86.

Implement a crude elf_machine_max_instruction_length function and use to
give an instruction length on more than just x86.

Use the ELF machine to determine the length to use to support
cross-architecture development.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shimin Guo <shimin.guo@skydio.com>
Cc: Yujie Liu <yujie.liu@intel.com>
[ Conditionally define EM_CSKY and EM_LOONGARCH for older distros ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/util/Build

@@ -14,6 +14,5 @@ perf-util-y += iostat.o
 perf-util-$(CONFIG_LOCAL_LIBUNWIND)    += unwind-libunwind.o
 
 perf-util-y += auxtrace.o
-perf-util-y += archinsn.o
 perf-util-y += intel-pt.o
 perf-util-y += intel-bts.o

tools/perf/arch/x86/util/archinsn.c

@@ -1,27 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include "archinsn.h"
-#include "event.h"
-#include "machine.h"
-#include "thread.h"
-#include "symbol.h"
-#include "../../../../arch/x86/include/asm/insn.h"
-
-void arch_fetch_insn(struct perf_sample *sample,
-		     struct thread *thread,
-		     struct machine *machine)
-{
-	struct insn insn;
-	int len, ret;
-	bool is64bit = false;
-
-	if (!sample->ip)
-		return;
-	len = thread__memcpy(thread, machine, sample->insn, sample->ip, sizeof(sample->insn), &is64bit);
-	if (len <= 0)
-		return;
-
-	ret = insn_decode(&insn, sample->insn, len,
-			  is64bit ? INSN_MODE_64 : INSN_MODE_32);
-	if (ret >= 0 && insn.length <= len)
-		sample->insn_len = insn.length;
-}

tools/perf/builtin-script.c

@@ -37,7 +37,6 @@
 #include "ui/ui.h"
 #include "print_binary.h"
 #include "print_insn.h"
-#include "archinsn.h"
 #include <linux/bitmap.h>
 #include <linux/compiler.h>
 #include <linux/kernel.h>
@@ -90,7 +89,6 @@ static bool			print_flags;
 static const char		*cpu_list;
 static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
 static int			max_blocks;
-static bool			native_arch;
 static struct dlfilter		*dlfilter;
 static int			dlargc;
 static char			**dlargv;
@@ -1627,7 +1625,7 @@ static int perf_sample__fprintf_insn(struct perf_sample *sample,
 {
 	int printed = 0;
 
-	script_fetch_insn(sample, thread, machine, native_arch);
+	perf_sample__fetch_insn(sample, thread, machine);
 
 	if (PRINT_FIELD(INSNLEN))
 		printed += fprintf(fp, " ilen: %d", sample->insn_len);
@@ -4034,7 +4032,6 @@ int cmd_script(int argc, const char **argv)
 		.set = false,
 		.default_no_sample = true,
 	};
-	struct utsname uts;
 	char *script_path = NULL;
 	const char *dlfilter_file = NULL;
 	const char **__argv;
@@ -4456,17 +4453,6 @@ script_found:
 	if (symbol__init(env) < 0)
 		goto out_delete;
 
-	uname(&uts);
-	if (data.is_pipe) { /* Assume pipe_mode indicates native_arch */
-		native_arch = true;
-	} else if (env->arch) {
-		if (!strcmp(uts.machine, env->arch))
-			native_arch = true;
-		else if (!strcmp(uts.machine, "x86_64") &&
-			 !strcmp(env->arch, "i386"))
-			native_arch = true;
-	}
-
 	script.session = session;
 	script__setup_sample_type(&script);
 

tools/perf/scripts/python/Perf-Trace-Util/Context.c

@@ -93,7 +93,7 @@ static PyObject *perf_sample_insn(PyObject *obj, PyObject *args)
 	if (c->sample->ip && !c->sample->insn_len && thread__maps(c->al->thread)) {
 		struct machine *machine =  maps__machine(thread__maps(c->al->thread));
 
-		script_fetch_insn(c->sample, c->al->thread, machine, /*native_arch=*/true);
+		perf_sample__fetch_insn(c->sample, c->al->thread, machine);
 	}
 	if (!c->sample->insn_len)
 		Py_RETURN_NONE; /* N.B. This is a return statement */

tools/perf/tests/dlfilter-test.c

@@ -30,7 +30,6 @@
 #include "symbol.h"
 #include "synthetic-events.h"
 #include "util.h"
-#include "archinsn.h"
 #include "dlfilter.h"
 #include "tests.h"
 #include "util/sample.h"

tools/perf/util/archinsn.h

@@ -1,12 +0,0 @@
-#ifndef INSN_H
-#define INSN_H 1
-
-struct perf_sample;
-struct machine;
-struct thread;
-
-void arch_fetch_insn(struct perf_sample *sample,
-		     struct thread *thread,
-		     struct machine *machine);
-
-#endif

tools/perf/util/dlfilter.c

@@ -234,8 +234,7 @@ static const __u8 *dlfilter__insn(void *ctx, __u32 *len)
 			struct machine *machine = maps__machine(thread__maps(al->thread));
 
 			if (machine)
-				script_fetch_insn(d->sample, al->thread, machine,
-						  /*native_arch=*/true);
+				perf_sample__fetch_insn(d->sample, al->thread, machine);
 		}
 	}
 

tools/perf/util/sample.c

@@ -1,9 +1,18 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include "sample.h"
 #include "debug.h"
+#include "thread.h"
+#include <elf.h>
+#ifndef EM_CSKY
+#define EM_CSKY		252
+#endif
+#ifndef EM_LOONGARCH
+#define EM_LOONGARCH	258
+#endif
 #include <linux/zalloc.h>
 #include <stdlib.h>
 #include <string.h>
+#include "../../arch/x86/include/asm/insn.h"
 
 void perf_sample__init(struct perf_sample *sample, bool all)
 {
@@ -41,3 +50,71 @@ struct regs_dump *perf_sample__intr_regs(struct perf_sample *sample)
 	}
 	return sample->intr_regs;
 }
+
+static int elf_machine_max_instruction_length(uint16_t e_machine)
+{
+	switch (e_machine) {
+	/* Fixed 4-byte (32-bit) architectures */
+	case EM_AARCH64:
+	case EM_PPC:
+	case EM_PPC64:
+	case EM_MIPS:
+	case EM_SPARC:
+	case EM_SPARCV9:
+	case EM_ALPHA:
+	case EM_LOONGARCH:
+	case EM_PARISC:
+	case EM_SH:
+		return 4;
+
+	/* Variable length or mixed-mode architectures */
+	case EM_ARM:    /* Variable due to Thumb/Thumb-2 */
+	case EM_RISCV:  /* Variable due to Compressed (C) extension */
+	case EM_CSKY:   /* Variable (16 or 32 bit) */
+	case EM_ARC:    /* Variable (ARCompact) */
+		return 4;
+	case EM_S390:   /* Variable (2, 4, or 6 bytes) */
+		return 6;
+	case EM_68K:
+		return 10;
+	case EM_386:
+	case EM_X86_64:
+		return 15;
+	case EM_XTENSA: /* Variable (FLIX) */
+		return 16;
+	default:
+		return MAX_INSN;
+	}
+}
+
+void perf_sample__fetch_insn(struct perf_sample *sample,
+			     struct thread *thread,
+			     struct machine *machine)
+{
+	int ret, len;
+	bool is64bit = false;
+	uint16_t e_machine;
+
+	if (!sample->ip || sample->insn_len != 0)
+		return;
+
+	e_machine = thread__e_machine(thread, machine);
+	len = elf_machine_max_instruction_length(e_machine);
+	len = thread__memcpy(thread, machine, sample->insn,
+			     sample->ip, len,
+			     &is64bit);
+	if (len <= 0)
+		return;
+
+	sample->insn_len = len;
+
+	if (e_machine == EM_386 || e_machine == EM_X86_64) {
+		/* Refine the x86 instruction length with the decoder. */
+		struct insn insn;
+
+		ret = insn_decode(&insn, sample->insn, len,
+				  is64bit ? INSN_MODE_64 : INSN_MODE_32);
+		if (ret >= 0 && insn.length <= len)
+			sample->insn_len = insn.length;
+	}
+}

tools/perf/util/sample.h

@@ -5,6 +5,9 @@
 #include <linux/perf_event.h>
 #include <linux/types.h>
 
+struct machine;
+struct thread;
+
 /* number of register is bound by the number of bits in regs_dump::mask (64) */
 #define PERF_SAMPLE_REGS_CACHE_SIZE (8 * sizeof(u64))
 
@@ -127,6 +130,10 @@ void perf_sample__exit(struct perf_sample *sample);
 struct regs_dump *perf_sample__user_regs(struct perf_sample *sample);
 struct regs_dump *perf_sample__intr_regs(struct perf_sample *sample);
 
+void perf_sample__fetch_insn(struct perf_sample *sample,
+			     struct thread *thread,
+			     struct machine *machine);
+
 /*
  * raw_data is always 4 bytes from an 8-byte boundary, so subtract 4 to get
  * 8-byte alignment.

tools/perf/util/trace-event-scripting.c

@@ -13,7 +13,6 @@
 #include <event-parse.h>
 #endif
 
-#include "archinsn.h"
 #include "debug.h"
 #include "event.h"
 #include "trace-event.h"
@@ -274,21 +273,6 @@ void setup_perl_scripting(void)
 #endif
 #endif
 
-#if !defined(__i386__) && !defined(__x86_64__)
-void arch_fetch_insn(struct perf_sample *sample __maybe_unused,
-		     struct thread *thread __maybe_unused,
-		     struct machine *machine __maybe_unused)
-{
-}
-#endif
-
-void script_fetch_insn(struct perf_sample *sample, struct thread *thread,
-		       struct machine *machine, bool native_arch)
-{
-	if (sample->insn_len == 0 && native_arch)
-		arch_fetch_insn(sample, thread, machine);
-}
-
 static const struct {
 	u32 flags;
 	const char *name;

tools/perf/util/trace-event.h

@@ -116,9 +116,6 @@ extern unsigned int scripting_max_stack;
 struct scripting_ops *script_spec__lookup(const char *spec);
 int script_spec__for_each(int (*cb)(struct scripting_ops *ops, const char *spec));
 
-void script_fetch_insn(struct perf_sample *sample, struct thread *thread,
-		       struct machine *machine, bool native_arch);
-
 void setup_perl_scripting(void);
 void setup_python_scripting(void);