Add ability to dump /tmp/perf-.map and jit-.dump.
The first one allows the perf tool to map samples to each individual
translation block. The second one adds the ability to resolve symbol
names, line numbers and inspect JITed code.
Example of use:
perf record qemu-x86_64 -perfmap ./a.out
perf report
or
perf record -k 1 qemu-x86_64 -jitdump ./a.out
DEBUGINFOD_URLS= perf inject -j -i perf.data -o perf.data.jitted
perf report -i perf.data.jitted
Co-developed-by: Vanderson M. do Rosario
Co-developed-by: Alex Bennée
Signed-off-by: Ilya Leoshkevich
---
accel/tcg/meson.build | 1 +
accel/tcg/perf.c | 366 ++
accel/tcg/perf.h | 49 +
accel/tcg/translate-all.c | 8 +
docs/devel/tcg.rst| 23 +++
linux-user/exit.c | 2 +
linux-user/main.c | 15 ++
qemu-options.hx | 20 +++
softmmu/vl.c | 11 ++
tcg/tcg.c | 2 +
10 files changed, 497 insertions(+)
create mode 100644 accel/tcg/perf.c
create mode 100644 accel/tcg/perf.h
diff --git a/accel/tcg/meson.build b/accel/tcg/meson.build
index 55b3b4dd7e3..77740b1a0d7 100644
--- a/accel/tcg/meson.build
+++ b/accel/tcg/meson.build
@@ -13,6 +13,7 @@ tcg_ss.add(when: 'CONFIG_USER_ONLY', if_true:
files('user-exec.c'))
tcg_ss.add(when: 'CONFIG_SOFTMMU', if_false: files('user-exec-stub.c'))
tcg_ss.add(when: 'CONFIG_PLUGIN', if_true: [files('plugin-gen.c')])
tcg_ss.add(when: libdw, if_true: files('debuginfo.c'))
+tcg_ss.add(when: 'CONFIG_LINUX', if_true: files('perf.c'))
specific_ss.add_all(when: 'CONFIG_TCG', if_true: tcg_ss)
specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: files(
diff --git a/accel/tcg/perf.c b/accel/tcg/perf.c
new file mode 100644
index 000..427ccbe80e1
--- /dev/null
+++ b/accel/tcg/perf.c
@@ -0,0 +1,366 @@
+/*
+ * Linux perf perf-.map and jit-.dump integration.
+ *
+ * The jitdump spec can be found at [1].
+ *
+ * [1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/tools/perf/Documentation/jitdump-specification.txt
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "elf.h"
+#include "qemu/timer.h"
+#include "tcg/tcg.h"
+
+#include "debuginfo.h"
+#include "perf.h"
+
+static FILE *safe_fopen_w(const char *path)
+{
+int saved_errno;
+FILE *f;
+int fd;
+
+/* Delete the old file, if any. */
+unlink(path);
+
+/* Avoid symlink attacks by using O_CREAT | O_EXCL. */
+fd = open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
+if (fd == -1) {
+return NULL;
+}
+
+/* Convert fd to FILE*. */
+f = fdopen(fd, "w");
+if (f == NULL) {
+saved_errno = errno;
+close(fd);
+errno = saved_errno;
+return NULL;
+}
+
+return f;
+}
+
+static FILE *perfmap;
+
+void perf_enable_perfmap(void)
+{
+char map_file[32];
+
+snprintf(map_file, sizeof(map_file), "/tmp/perf-%d.map", getpid());
+perfmap = safe_fopen_w(map_file);
+if (perfmap == NULL) {
+warn_report("Could not open %s: %s, proceeding without perfmap",
+map_file, strerror(errno));
+}
+}
+
+/* Get PC and size of code JITed for guest instruction #INSN. */
+static void get_host_pc_size(uintptr_t *host_pc, uint16_t *host_size,
+ const void *start, size_t insn)
+{
+uint16_t start_off = insn ? tcg_ctx->gen_insn_end_off[insn - 1] : 0;
+
+if (host_pc) {
+*host_pc = (uintptr_t)start + start_off;
+}
+if (host_size) {
+*host_size = tcg_ctx->gen_insn_end_off[insn] - start_off;
+}
+}
+
+static const char *pretty_symbol(const struct debuginfo_query *q, size_t *len)
+{
+static __thread char buf[64];
+int tmp;
+
+if (!q->symbol) {
+tmp = snprintf(buf, sizeof(buf), "guest-0x%llx", q->address);
+if (len) {
+*len = MIN(tmp + 1, sizeof(buf));
+}
+return buf;
+}
+
+if (!q->offset) {
+if (len) {
+*len = strlen(q->symbol) + 1;
+}
+return q->symbol;
+}
+
+tmp = snprintf(buf, sizeof(buf), "%s+0x%llx", q->symbol, q->offset);
+if (len) {
+*len = MIN(tmp + 1, sizeof(buf));
+}
+return buf;
+}
+
+static void write_perfmap_entry(const void *start, size_t insn,
+const struct debuginfo_query *q)
+{
+uint16_t host_size;
+uintptr_t host_pc;
+
+get_host_pc_size(_pc, _size, start, insn);
+fprintf(perfmap, "%"PRIxPTR" %"PRIx16" %s\n",
+host_pc, host_size, pretty_symbol(q, NULL));
+}
+
+static FILE *jitdump;
+
+#define JITHEADER_MAGIC 0x4A695444
+#define JITHEADER_VERSION 1
+
+struct jitheader {
+uint32_t magic;
+uint32_t version;
+uint32_t total_size;
+uint32_t elf_mach;
+uint32_t pad1;
+uint32_t pid;
+uint64_t timestamp;
+uint64_t flags;
+};
+
+enum jit_record_type {
+JIT_CODE_LOAD =
