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

[Andi Kleen <ak@linux.intel.com>]

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