accel/tcg: Unmap perf_marker

Coverity complains that perf_marker is never unmapped.
Fix by unmapping it in perf_exit().

Fixes: Coverity CID 1507929
Fixes: 5584e2db ("tcg: add perfmap and jitdump")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230605114134.1169974-1-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

accel/tcg/perf.c

@@ -111,6 +111,8 @@ static void write_perfmap_entry(const void *start, size_t insn,
 }
 
 static FILE *jitdump;
+static size_t perf_marker_size;
+static void *perf_marker = MAP_FAILED;
 
 #define JITHEADER_MAGIC 0x4A695444
 #define JITHEADER_VERSION 1
@@ -190,7 +192,6 @@ void perf_enable_jitdump(void)
 {
     struct jitheader header;
     char jitdump_file[32];
-    void *perf_marker;
 
     if (!use_rt_clock) {
         warn_report("CLOCK_MONOTONIC is not available, proceeding without jitdump");
@@ -210,7 +211,8 @@ void perf_enable_jitdump(void)
      * PERF_RECORD_MMAP or PERF_RECORD_MMAP2 event is of the form jit-%d.dump
      * and will process it as a jitdump file.
      */
-    perf_marker = mmap(NULL, qemu_real_host_page_size(), PROT_READ | PROT_EXEC,
+    perf_marker_size = qemu_real_host_page_size();
+    perf_marker = mmap(NULL, perf_marker_size, PROT_READ | PROT_EXEC,
                        MAP_PRIVATE, fileno(jitdump), 0);
     if (perf_marker == MAP_FAILED) {
         warn_report("Could not map %s: %s, proceeding without jitdump",
@@ -372,6 +374,11 @@ void perf_exit(void)
         perfmap = NULL;
     }
 
+    if (perf_marker != MAP_FAILED) {
+        munmap(perf_marker, perf_marker_size);
+        perf_marker = MAP_FAILED;
+    }
+
     if (jitdump) {
         fclose(jitdump);
         jitdump = NULL;