[Qemu-devel] [PATCH v1 1/2] accel/tcg: adding integration with linux perf

[vandersonmr <vandersonmr2@gmail.com>]

This commit adds support to Linux Perf in order
to be able to analyze qemu jitted code and
also to able to see the TBs PC in it.

Signed-off-by: Vanderson M. do Rosario <vandersonmr2@gmail.com>
---
 accel/tcg/Makefile.objs      |   1 +
 accel/tcg/perf/Makefile.objs |   1 +
 accel/tcg/perf/jitdump.c     | 180 +++++++++++++++++++++++++++++++++++
 accel/tcg/perf/jitdump.h     |  19 ++++
 accel/tcg/translate-all.c    |  12 +++
 include/qemu-common.h        |   3 +
 linux-user/main.c            |   7 ++
 qemu-options.hx              |  12 +++
 8 files changed, 235 insertions(+)
 create mode 100644 accel/tcg/perf/Makefile.objs
 create mode 100644 accel/tcg/perf/jitdump.c
 create mode 100644 accel/tcg/perf/jitdump.h

diff --git a/accel/tcg/Makefile.objs b/accel/tcg/Makefile.objs
index d381a02f34..f393a7438f 100644
--- a/accel/tcg/Makefile.objs
+++ b/accel/tcg/Makefile.objs
@@ -3,6 +3,7 @@ obj-$(CONFIG_SOFTMMU) += cputlb.o
 obj-y += tcg-runtime.o tcg-runtime-gvec.o
 obj-y += cpu-exec.o cpu-exec-common.o translate-all.o
 obj-y += translator.o
+obj-y += perf/
 
 obj-$(CONFIG_USER_ONLY) += user-exec.o
 obj-$(call lnot,$(CONFIG_SOFTMMU)) += user-exec-stub.o
diff --git a/accel/tcg/perf/Makefile.objs b/accel/tcg/perf/Makefile.objs
new file mode 100644
index 0000000000..f82fba35e5
--- /dev/null
+++ b/accel/tcg/perf/Makefile.objs
@@ -0,0 +1 @@
+obj-y += jitdump.o
diff --git a/accel/tcg/perf/jitdump.c b/accel/tcg/perf/jitdump.c
new file mode 100644
index 0000000000..6f4c0911c2
--- /dev/null
+++ b/accel/tcg/perf/jitdump.c
@@ -0,0 +1,180 @@
+#ifdef __linux__
+
+#include <stdint.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/syscall.h>
+#include <elf.h>
+
+#include "jitdump.h"
+#include "qemu-common.h"
+
+struct jitheader {
+    uint32_t magic;     /* characters "jItD" */
+    uint32_t version;   /* header version */
+    uint32_t total_size;/* total size of header */
+    uint32_t elf_mach;  /* elf mach target */
+    uint32_t pad1;      /* reserved */
+    uint32_t pid;       /* JIT process id */
+    uint64_t timestamp; /* timestamp */
+    uint64_t flags;     /* flags */
+};
+
+enum jit_record_type {
+    JIT_CODE_LOAD       = 0,
+    JIT_CODE_MOVE       = 1,
+    JIT_CODE_DEBUG_INFO = 2,
+    JIT_CODE_CLOSE      = 3,
+
+    JIT_CODE_MAX,
+};
+
+/* record prefix (mandatory in each record) */
+struct jr_prefix {
+    uint32_t id;
+    uint32_t total_size;
+    uint64_t timestamp;
+};
+
+struct jr_code_load {
+    struct jr_prefix p;
+
+    uint32_t pid;
+    uint32_t tid;
+    uint64_t vma;
+    uint64_t code_addr;
+    uint64_t code_size;
+    uint64_t code_index;
+};
+
+struct jr_code_close {
+    struct jr_prefix p;
+};
+
+struct jr_code_move {
+    struct jr_prefix p;
+
+    uint32_t pid;
+    uint32_t tid;
+    uint64_t vma;
+    uint64_t old_code_addr;
+    uint64_t new_code_addr;
+    uint64_t code_size;
+    uint64_t code_index;
+};
+
+FILE *dumpfile;
+void *perf_marker;
+
+static uint64_t get_timestamp(void)
+{
+    struct timespec ts;
+    if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
+        fprintf(stderr, "No support for CLOCK_MONOTONIC! -perf cannot be used!\n");
+        exit(1);
+    }
+    return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
+}
+
+static uint32_t get_e_machine(void)
+{
+    uint32_t e_machine = EM_NONE;
+    Elf64_Ehdr elf_header;
+    FILE *exe = fopen("/proc/self/exe", "r");
+
+    if (exe == NULL) {
+        return e_machine;
+    }
+
+    if (fread(&elf_header, sizeof(Elf64_Ehdr), 1, exe) != 1) {
+        goto end;
+    }
+
+    e_machine = elf_header.e_machine;
+
+end:
+    fclose(exe);
+    return e_machine;
+}
+
+void start_jitdump_file(void)
+{
+    GString *dumpfile_name = g_string_new(NULL);;
+    g_string_printf(dumpfile_name, "./jit-%d.dump", getpid());
+    dumpfile = fopen(dumpfile_name->str, "w+");
+
+    perf_marker = mmap(NULL, sysconf(_SC_PAGESIZE),
+                          PROT_READ | PROT_EXEC,
+                          MAP_PRIVATE,
+                          fileno(dumpfile), 0);
+
+    if (perf_marker == MAP_FAILED) {
+        printf("Failed to create mmap marker file for perf %d\n", fileno(dumpfile));
+        fclose(dumpfile);
+        return;
+    }
+
+    g_string_free(dumpfile_name, TRUE);
+
+    struct jitheader *header = g_new0(struct jitheader, 1);
+    header->magic = 0x4A695444;
+    header->version = 1;
+    header->elf_mach = get_e_machine();
+    header->total_size = sizeof(struct jitheader);
+    header->pid = getpid();
+    header->timestamp = get_timestamp();
+
+    fwrite(header, header->total_size, 1, dumpfile);
+
+    free(header);
+    fflush(dumpfile);
+}
+
+void append_load_in_jitdump_file(TranslationBlock *tb)
+{
+    GString *func_name = g_string_new(NULL);
+    g_string_printf(func_name, "TB virt:0x"TARGET_FMT_lx"%c", tb->pc, '\0');
+
+    struct jr_code_load *load_event = g_new0(struct jr_code_load, 1);
+    load_event->p.id = JIT_CODE_LOAD;
+    load_event->p.total_size = sizeof(struct jr_code_load) + func_name->len + tb->tc.size;
+    load_event->p.timestamp = get_timestamp();
+    load_event->pid = getpid();
+    load_event->tid = syscall(SYS_gettid);
+    load_event->vma = tb->pc;
+    load_event->code_addr = (uint64_t) tb->tc.ptr;
+    load_event->code_size = tb->tc.size;
+    load_event->code_index = tb->pc;
+
+    fwrite(load_event, sizeof(struct jr_code_load), 1, dumpfile);
+    fwrite(func_name->str, func_name->len, 1, dumpfile);
+    fwrite(tb->tc.ptr, tb->tc.size, 1, dumpfile);
+
+    g_string_free(func_name, TRUE);
+    free(load_event);
+    fflush(dumpfile);
+}
+
+void close_jitdump_file(void)
+{
+    fclose(dumpfile);
+    if (perf_marker != MAP_FAILED) {
+        munmap(perf_marker, sysconf(_SC_PAGESIZE));
+    }
+}
+
+bool is_jitdump_enabled;
+
+void jitdump_enable(void)
+{
+    is_jitdump_enabled = true;
+}
+
+bool jitdump_enabled(void)
+{
+    return is_jitdump_enabled;
+}
+
+#endif
diff --git a/accel/tcg/perf/jitdump.h b/accel/tcg/perf/jitdump.h
new file mode 100644
index 0000000000..12c0991b04
--- /dev/null
+++ b/accel/tcg/perf/jitdump.h
@@ -0,0 +1,19 @@
+#ifdef __linux__
+#ifndef JITDUMP_H
+#define JITDUMP_H
+
+#include "qemu/osdep.h"
+
+#include "disas/disas.h"
+#include "exec/exec-all.h"
+
+void start_jitdump_file(void);
+
+void append_load_in_jitdump_file(TranslationBlock *tb);
+void append_move_in_jitdump_file(TranslationBlock *tb);
+
+void close_jitdump_file(void);
+
+#endif
+
+#endif
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 5d1e08b169..0a4211d3d2 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -58,6 +58,8 @@
 #include "sysemu/cpus.h"
 #include "sysemu/tcg.h"
 
+#include "perf/jitdump.h"
+
 /* #define DEBUG_TB_INVALIDATE */
 /* #define DEBUG_TB_FLUSH */
 /* make various TB consistency checks */
@@ -1148,6 +1150,11 @@ void tcg_exec_init(unsigned long tb_size)
     cpu_gen_init();
     page_init();
     tb_htable_init();
+#ifdef __linux__
+    if (jitdump_enabled()) {
+        start_jitdump_file();
+    }
+#endif
     code_gen_alloc(tb_size);
 #if defined(CONFIG_SOFTMMU)
     /* There's no guest base to take into account, so go ahead and
@@ -1877,6 +1884,11 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
         return existing_tb;
     }
     tcg_tb_insert(tb);
+#ifdef __linux__
+    if (jitdump_enabled()) {
+        append_load_in_jitdump_file(tb);
+    }
+#endif
     return tb;
 }
 
diff --git a/include/qemu-common.h b/include/qemu-common.h
index 0235cd3b91..bd564a9e5c 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -130,4 +130,7 @@ void page_size_init(void);
  * returned. */
 bool dump_in_progress(void);
 
+void jitdump_enable(void);
+bool jitdump_enabled(void);
+
 #endif
diff --git a/linux-user/main.c b/linux-user/main.c
index 8ffc525195..6521cf0c68 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -378,6 +378,11 @@ static void handle_arg_strace(const char *arg)
     do_strace = 1;
 }
 
+static void handle_arg_perf(const char *arg)
+{
+    jitdump_enable();
+}
+
 static void handle_arg_version(const char *arg)
 {
     printf("qemu-" TARGET_NAME " version " QEMU_FULL_VERSION
@@ -443,6 +448,8 @@ static const struct qemu_argument arg_table[] = {
      "",           "Seed for pseudo-random number generator"},
     {"trace",      "QEMU_TRACE",       true,  handle_arg_trace,
      "",           "[[enable=]<pattern>][,events=<file>][,file=<file>]"},
+    {"perf",      "QEMU_PERF",         false, handle_arg_perf,
+     "",           "dump jitdump files to help linux perf JIT code visualization"},
     {"version",    "QEMU_VERSION",     false, handle_arg_version,
      "",           "display version information and exit"},
     {NULL, NULL, false, NULL, NULL, NULL}
diff --git a/qemu-options.hx b/qemu-options.hx
index 9621e934c0..1c26eeeb9c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4147,6 +4147,18 @@ STEXI
 Enable FIPS 140-2 compliance mode.
 ETEXI
 
+#ifdef __linux__
+DEF("perf", 0, QEMU_OPTION_perf,
+    "-perf    dump jitdump files to help linux perf JIT code visualization\n",
+    QEMU_ARCH_ALL)
+#endif
+STEXI
+@item -perf
+@findex -perf
+Dumps jitdump files to help linux perf JIT code visualization
+ETEXI
+
+
 HXCOMM Deprecated by -machine accel=tcg property
 DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)
 
-- 
2.22.0