[PATCH v2 1/2] perf, capstone: Support 32bit code under 64bit OS

* [PATCH v2 1/2] perf, capstone: Support 32bit code under 64bit OS
@ 2024-02-29  1:38 Andi Kleen
  2024-02-29  1:38 ` [PATCH v2 2/2] perf, script, capstone: Add support for -F +brstackdisasm Andi Kleen
  2024-02-29  8:19 ` [PATCH v2 1/2] perf, capstone: Support 32bit code under 64bit OS Adrian Hunter
  0 siblings, 2 replies; 3+ messages in thread
From: Andi Kleen @ 2024-02-29  1:38 UTC (permalink / raw)
  To: linux-perf-users; +Cc: changbin.du, adrian.hunter, Andi Kleen

Use the DSO to resolve whether an IP is 32bit or 64bit and use that to
configure capstone to the correct mode. This allows to correctly
disassemble 32bit code under a 64bit OS.

% cat > loop.c
volatile int var;
int main(void)
{
	int i;
	for (i = 0; i < 100000; i++)
		var++;
}
% gcc -m32 -o loop loop.c
% perf record -e cycles:u ./loop
% perf script -F +disasm
            loop   82665 1833176.618023:          1 cycles:u:          f7eed500 _start+0x0 (/usr/lib/ld-linux.so.2)             movl %esp, %eax
            loop   82665 1833176.618029:          1 cycles:u:          f7eed500 _start+0x0 (/usr/lib/ld-linux.so.2)             movl %esp, %eax
            loop   82665 1833176.618031:          7 cycles:u:          f7eed500 _start+0x0 (/usr/lib/ld-linux.so.2)             movl %esp, %eax
            loop   82665 1833176.618034:         91 cycles:u:          f7eed500 _start+0x0 (/usr/lib/ld-linux.so.2)             movl %esp, %eax
            loop   82665 1833176.618036:       1242 cycles:u:          f7eed500 _start+0x0 (/usr/lib/ld-linux.so.2)             movl %esp, %eax

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---

v2: Factor out DSO lookup into separate function
---
 tools/perf/util/print_insn.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/print_insn.c b/tools/perf/util/print_insn.c
index 459e0e93d7b1..eca20dded45f 100644
--- a/tools/perf/util/print_insn.c
+++ b/tools/perf/util/print_insn.c
@@ -12,6 +12,8 @@
 #include "machine.h"
 #include "thread.h"
 #include "print_insn.h"
+#include "map.h"
+#include "dso.h"
 
 size_t sample__fprintf_insn_raw(struct perf_sample *sample, FILE *fp)
 {
@@ -28,12 +30,12 @@ size_t sample__fprintf_insn_raw(struct perf_sample *sample, FILE *fp)
 #ifdef HAVE_LIBCAPSTONE_SUPPORT
 #include <capstone/capstone.h>
 
-static int capstone_init(struct machine *machine, csh *cs_handle)
+static int capstone_init(struct machine *machine, csh *cs_handle, bool is64)
 {
 	cs_arch arch;
 	cs_mode mode;
 
-	if (machine__is(machine, "x86_64")) {
+	if (machine__is(machine, "x86_64") && is64) {
 		arch = CS_ARCH_X86;
 		mode = CS_MODE_64;
 	} else if (machine__normalized_is(machine, "x86")) {
@@ -93,6 +95,24 @@ static size_t print_insn_x86(struct perf_sample *sample, struct thread *thread,
 	return printed;
 }
 
+static bool is64bitip(struct perf_sample *sample, struct thread *thread,
+		      struct machine *machine,uint64_t ip)
+{
+	bool is64bit = machine__is(machine, "x86_64");
+	struct dso *dso;
+	struct addr_location al;
+
+	addr_location__init(&al);
+	if (thread__find_map(thread, sample->cpumode, ip, &al) &&
+		(dso = map__dso(al.map)) != NULL &&
+		(dso->data.status != DSO_DATA_STATUS_ERROR)) {
+		map__load(al.map);
+		is64bit = dso->is_64_bit;
+	}
+	addr_location__exit(&al);
+	return is64bit;
+}
+
 size_t sample__fprintf_insn_asm(struct perf_sample *sample, struct thread *thread,
 				struct machine *machine, FILE *fp)
 {
@@ -101,9 +121,10 @@ size_t sample__fprintf_insn_asm(struct perf_sample *sample, struct thread *threa
 	size_t count;
 	size_t printed = 0;
 	int ret;
+	bool is64bit = is64bitip(sample, thread, machine, sample->ip);
 
 	/* TODO: Try to initiate capstone only once but need a proper place. */
-	ret = capstone_init(machine, &cs_handle);
+	ret = capstone_init(machine, &cs_handle, is64bit);
 	if (ret < 0) {
 		/* fallback */
 		return sample__fprintf_insn_raw(sample, fp);
-- 
2.43.0


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