1 files changed, 110 insertions, 4 deletions

diff --git a/contrib/plugins/uftrace.c b/contrib/plugins/uftrace.c
index 4af0130b15..d060513446 100644
--- a/contrib/plugins/uftrace.c
+++ b/contrib/plugins/uftrace.c
@@ -11,14 +11,94 @@
 
 #include <qemu-plugin.h>
 #include <glib.h>
+#include <stdio.h>
 
 QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
 
+typedef struct Cpu Cpu;
+
+typedef struct {
+    void (*init)(Cpu *cpu);
+    void (*end)(Cpu *cpu);
+    uint64_t (*get_frame_pointer)(Cpu *cpu);
+    bool (*does_insn_modify_frame_pointer)(const char *disas);
+} CpuOps;
+
 typedef struct Cpu {
     GByteArray *buf;
+    CpuOps ops;
+    void *arch;
 } Cpu;
 
+typedef struct {
+    struct qemu_plugin_register *reg_fp;
+} Aarch64Cpu;
+
 static struct qemu_plugin_scoreboard *score;
+static CpuOps arch_ops;
+
+static uint64_t cpu_read_register64(Cpu *cpu, struct qemu_plugin_register *reg)
+{
+    GByteArray *buf = cpu->buf;
+    g_byte_array_set_size(buf, 0);
+    size_t sz = qemu_plugin_read_register(reg, buf);
+    g_assert(sz == 8);
+    g_assert(buf->len == 8);
+    return *((uint64_t *) buf->data);
+}
+
+static struct qemu_plugin_register *plugin_find_register(const char *name)
+{
+    g_autoptr(GArray) regs = qemu_plugin_get_registers();
+    for (int i = 0; i < regs->len; ++i) {
+        qemu_plugin_reg_descriptor *reg;
+        reg = &g_array_index(regs, qemu_plugin_reg_descriptor, i);
+        if (!strcmp(reg->name, name)) {
+            return reg->handle;
+        }
+    }
+    return NULL;
+}
+
+static uint64_t aarch64_get_frame_pointer(Cpu *cpu_)
+{
+    Aarch64Cpu *cpu = cpu_->arch;
+    return cpu_read_register64(cpu_, cpu->reg_fp);
+}
+
+static void aarch64_init(Cpu *cpu_)
+{
+    Aarch64Cpu *cpu = g_new0(Aarch64Cpu, 1);
+    cpu_->arch = cpu;
+    cpu->reg_fp = plugin_find_register("x29");
+    if (!cpu->reg_fp) {
+        fprintf(stderr, "uftrace plugin: frame pointer register (x29) is not "
+                        "available. Please use an AArch64 cpu (or -cpu max).\n");
+        g_abort();
+    }
+}
+
+static void aarch64_end(Cpu *cpu)
+{
+    g_free(cpu->arch);
+}
+
+static bool aarch64_does_insn_modify_frame_pointer(const char *disas)
+{
+    /*
+     * Check if current instruction concerns fp register "x29".
+     * We add a prefix space to make sure we don't match addresses dump
+     * in disassembly.
+     */
+    return strstr(disas, " x29");
+}
+
+static CpuOps aarch64_ops = {
+    .init = aarch64_init,
+    .end = aarch64_end,
+    .get_frame_pointer = aarch64_get_frame_pointer,
+    .does_insn_modify_frame_pointer = aarch64_does_insn_modify_frame_pointer,
+};
 
 static void track_callstack(unsigned int cpu_index, void *udata)
 {
@@ -28,19 +108,37 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
 {
     size_t n_insns = qemu_plugin_tb_n_insns(tb);
 
+    /*
+     * Callbacks and inline instrumentation are inserted before an instruction.
+     * Thus, to see instruction effect, we need to wait for next one.
+     * Potentially, the last instruction of a block could modify the frame
+     * pointer. Thus, we need to always instrument first instruction in a tb.
+     */
+    bool instrument_insn = true;
     for (size_t i = 0; i < n_insns; i++) {
         struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
 
-        uintptr_t pc = qemu_plugin_insn_vaddr(insn);
-        qemu_plugin_register_vcpu_insn_exec_cb(insn, track_callstack,
-                                               QEMU_PLUGIN_CB_R_REGS,
-                                               (void *) pc);
+        if (instrument_insn) {
+            uintptr_t pc = qemu_plugin_insn_vaddr(insn);
+            qemu_plugin_register_vcpu_insn_exec_cb(insn, track_callstack,
+                                                   QEMU_PLUGIN_CB_R_REGS,
+                                                   (void *) pc);
+            instrument_insn = false;
+        }
+
+        char *disas = qemu_plugin_insn_disas(insn);
+        if (arch_ops.does_insn_modify_frame_pointer(disas)) {
+            instrument_insn = true;
+        }
     }
 }
 
 static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index)
 {
     Cpu *cpu = qemu_plugin_scoreboard_find(score, vcpu_index);
+    cpu->ops = arch_ops;
+
+    cpu->ops.init(cpu);
     cpu->buf = g_byte_array_new();
 }
 
@@ -64,6 +162,14 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
                                            const qemu_info_t *info,
                                            int argc, char **argv)
 {
+    if (!strcmp(info->target_name, "aarch64")) {
+        arch_ops = aarch64_ops;
+    } else {
+        fprintf(stderr, "plugin uftrace: %s target is not supported\n",
+                info->target_name);
+        return 1;
+    }
+
     score = qemu_plugin_scoreboard_new(sizeof(Cpu));
     qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
     qemu_plugin_register_atexit_cb(id, at_exit, NULL);