perf thread: Generalize function to copy from thread addr space from intel-bts code

Add a utility function to fetch executable code. Convert one
user over to it. There are more places doing that, but they
do significantly different actions, so they are not
easy to fit into a single library function.

Committer changes:

. No need to cast around, make 'buf' be a void pointer.

. Rename it to thread__memcpy() to reflect the fact it is about copying
  a chunk of memory from a thread, i.e. from its address space.

. No need to have it in a separate object file, move it to thread.[ch]

. Check the return of map__load(), the original code didn't do it, but
  since we're moving this around, check that as well.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/r/20190305144758.12397-2-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/intel-bts.c

@@ -328,35 +328,19 @@ static int intel_bts_get_next_insn(struct intel_bts_queue *btsq, u64 ip)
 {
 	struct machine *machine = btsq->bts->machine;
 	struct thread *thread;
-	struct addr_location al;
 	unsigned char buf[INTEL_PT_INSN_BUF_SZ];
 	ssize_t len;
-	int x86_64;
-	uint8_t cpumode;
+	bool x86_64;
 	int err = -1;
 
-	if (machine__kernel_ip(machine, ip))
-		cpumode = PERF_RECORD_MISC_KERNEL;
-	else
-		cpumode = PERF_RECORD_MISC_USER;
-
 	thread = machine__find_thread(machine, -1, btsq->tid);
 	if (!thread)
 		return -1;
 
-	if (!thread__find_map(thread, cpumode, ip, &al) || !al.map->dso)
-		goto out_put;
-
-	len = dso__data_read_addr(al.map->dso, al.map, machine, ip, buf,
-				  INTEL_PT_INSN_BUF_SZ);
+	len = thread__memcpy(thread, machine, buf, ip, INTEL_PT_INSN_BUF_SZ, &x86_64);
 	if (len <= 0)
 		goto out_put;
 
-	/* Load maps to ensure dso->is_64_bit has been updated */
-	map__load(al.map);
-
-	x86_64 = al.map->dso->is_64_bit;
-
 	if (intel_pt_get_insn(buf, len, x86_64, &btsq->intel_pt_insn))
 		goto out_put;
 

tools/perf/util/thread.c

@@ -12,6 +12,7 @@
 #include "debug.h"
 #include "namespaces.h"
 #include "comm.h"
+#include "map.h"
 #include "symbol.h"
 #include "unwind.h"
 
@@ -393,3 +394,25 @@ struct thread *thread__main_thread(struct machine *machine, struct thread *threa
 
 	return machine__find_thread(machine, thread->pid_, thread->pid_);
 }
+
+int thread__memcpy(struct thread *thread, struct machine *machine,
+		   void *buf, u64 ip, int len, bool *is64bit)
+{
+       u8 cpumode = PERF_RECORD_MISC_USER;
+       struct addr_location al;
+       long offset;
+
+       if (machine__kernel_ip(machine, ip))
+               cpumode = PERF_RECORD_MISC_KERNEL;
+
+       if (!thread__find_map(thread, cpumode, ip, &al) || !al.map->dso ||
+	   al.map->dso->data.status == DSO_DATA_STATUS_ERROR ||
+	   map__load(al.map) < 0)
+               return -1;
+
+       offset = al.map->map_ip(al.map, ip);
+       if (is64bit)
+               *is64bit = al.map->dso->is_64_bit;
+
+       return dso__data_read_offset(al.map->dso, machine, offset, buf, len);
+}

tools/perf/util/thread.h

@@ -113,6 +113,9 @@ struct symbol *thread__find_symbol_fb(struct thread *thread, u8 cpumode,
 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
 					struct addr_location *al);
 
+int thread__memcpy(struct thread *thread, struct machine *machine,
+		   void *buf, u64 ip, int len, bool *is64bit);
+
 static inline void *thread__priv(struct thread *thread)
 {
 	return thread->priv;