/*
* Copyright (C) 2021, Alexandre Iooss <erdnaxe@crans.org>
*
* Log instruction execution with memory access.
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include <glib.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <qemu-plugin.h>
QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
/* Store last executed instruction on each vCPU as a GString */
static GPtrArray *last_exec;
static GMutex expand_array_lock;
static GPtrArray *imatches;
static GArray *amatches;
/*
* Expand last_exec array.
*
* As we could have multiple threads trying to do this we need to
* serialise the expansion under a lock. Threads accessing already
* created entries can continue without issue even if the ptr array
* gets reallocated during resize.
*/
static void expand_last_exec(int cpu_index)
{
g_mutex_lock(&expand_array_lock);
while (cpu_index >= last_exec->len) {
GString *s = g_string_new(NULL);
g_ptr_array_add(last_exec, s);
}
g_mutex_unlock(&expand_array_lock);
}
/**
* Add memory read or write information to current instruction log
*/
static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info,
uint64_t vaddr, void *udata)
{
GString *s;
/* Find vCPU in array */
g_assert(cpu_index < last_exec->len);
s = g_ptr_array_index(last_exec, cpu_index);
/* Indicate type of memory access */
if (qemu_plugin_mem_is_store(info)) {
g_string_append(s, ", store");
} else {
g_string_append(s, ", load");
}
/* If full system emulation log physical address and device name */
struct qemu_plugin_hwaddr *hwaddr = qemu_plugin_get_hwaddr(info, vaddr);
if (hwaddr) {
uint64_t addr = qemu_plugin_hwaddr_phys_addr(hwaddr);
const char *name = qemu_plugin_hwaddr_device_name(hwaddr);
g_string_append_printf(s, ", 0x%08"PRIx64", %s", addr, name);
} else {
g_string_append_printf(s, ", 0x%08"PRIx64, vaddr);
}
}
/**
* Log instruction execution
*/
static void vcpu_insn_exec(unsigned int cpu_index, void *udata)
{
GString *s;
/* Find or create vCPU in array */
if (cpu_index >= last_exec->len) {
expand_last_exec(cpu_index);
}
s = g_ptr_array_index(last_exec, cpu_index);
/* Print previous instruction in cache */
if (s->len) {
qemu_plugin_outs(s->str);
qemu_plugin_outs("\n");
}
/* Store new instruction in cache */
/* vcpu_mem will add memory access information to last_exec */
g_string_printf(s, "%u, ", cpu_index);
g_string_append(s, (char *)udata);
}
/**
* On translation block new translation
*
* QEMU convert code by translation block (TB). By hooking here we can then hook
* a callback on each instruction and memory access.
*/
static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
{
struct qemu_plugin_insn *insn;
bool skip = (imatches || amatches);
size_t n = qemu_plugin_tb_n_insns(tb);
for (size_t i = 0; i < n; i++) {
char *insn_disas;
uint64_t insn_vaddr;
/*
* `insn` is shared between translations in QEMU, copy needed data here.
* `output` is never freed as it might be used multiple times during
* the emulation lifetime.
* We only consider the first 32 bits of the instruction, this may be
* a limitation for CISC architectures.
*/
insn = qemu_plugin_tb_get_insn(tb, i);
insn_disas = qemu_plugin_insn_disas(insn);
insn_vaddr = qemu_plugin_insn_vaddr(insn);
/*
* If we are filtering we better check out if we have any
* hits. The skip "latches" so we can track memory accesses
* after the instruction we care about.
*/
if (skip && imatches) {
int j;
for (j = 0; j < imatches->len && skip; j++) {
char *m = g_ptr_array_index(imatches, j);
if (g_str_has_prefix(insn_disas, m)) {
skip = false;
}
}
}
if (skip && amatches) {
int j;
for (j = 0; j < amatches->len && skip; j++) {
uint64_t v = g_array_index(amatches, uint64_t, j);
if (v == insn_vaddr) {
skip = false;
}
}
}
if (skip) {
g_free(insn_disas);
} else {
uint32_t insn_opcode;
insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn));
char *output = g_strdup_printf("0x%"PRIx64", 0x%"PRIx32", \"%s\"",
insn_vaddr, insn_opcode, insn_disas);
/* Register callback on memory read or write */
qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem,
QEMU_PLUGIN_CB_NO_REGS,
QEMU_PLUGIN_MEM_RW, NULL);
/* Register callback on instruction */
qemu_plugin_register_vcpu_insn_exec_cb(insn, vcpu_insn_exec,
QEMU_PLUGIN_CB_NO_REGS, output);
/* reset skip */
skip = (imatches || amatches);
}
}
}
/**
* On plugin exit, print last instruction in cache
*/
static void plugin_exit(qemu_plugin_id_t id, void *p)
{
guint i;
GString *s;
for (i = 0; i < last_exec->len; i++) {
s = g_ptr_array_index(last_exec, i);
if (s->str) {
qemu_plugin_outs(s->str);
qemu_plugin_outs("\n");
}
}
}
/* Add a match to the array of matches */
static void parse_insn_match(char *match)
{
if (!imatches) {
imatches = g_ptr_array_new();
}
g_ptr_array_add(imatches, match);
}
static void parse_vaddr_match(char *match)
{
uint64_t v = g_ascii_strtoull(match, NULL, 16);
if (!amatches) {
amatches = g_array_new(false, true, sizeof(uint64_t));
}
g_array_append_val(amatches, v);
}
/**
* Install the plugin
*/
QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
const qemu_info_t *info, int argc,
char **argv)
{
/*
* Initialize dynamic array to cache vCPU instruction. In user mode
* we don't know the size before emulation.
*/
if (info->system_emulation) {
last_exec = g_ptr_array_sized_new(info->system.max_vcpus);
} else {
last_exec = g_ptr_array_new();
}
for (int i = 0; i < argc; i++) {
char *opt = argv[i];
g_autofree char **tokens = g_strsplit(opt, "=", 2);
if (g_strcmp0(tokens[0], "ifilter") == 0) {
parse_insn_match(tokens[1]);
} else if (g_strcmp0(tokens[0], "afilter") == 0) {
parse_vaddr_match(tokens[1]);
} else {
fprintf(stderr, "option parsing failed: %s\n", opt);
return -1;
}
}
/* Register translation block and exit callbacks */
qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
return 0;
}
