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This patch adds a plugin that exercises the virtual and hardware memory read-write API functions added in a previous patch. The plugin takes a target and patch byte sequence, and will overwrite any instruction matching the target byte sequence with the patch. Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> Signed-off-by: Rowan Hart <rowanbhart@gmail.com> Message-ID: <20250624175351.440780-8-rowanbhart@gmail.com> [AJB: tweak Makefile, use uintptr_t for pointer stuffing] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Message-ID: <20250627112512.1880708-12-alex.bennee@linaro.org>pull/292/head
Rowan Hart
9 months ago
committed by
Alex Bennée
Alex Bennée
6 changed files with 328 additions and 2 deletions
@ -0,0 +1,251 @@ |
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/*
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* SPDX-License-Identifier: GPL-2.0-or-later |
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* |
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* This plugin patches instructions matching a pattern to a different |
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* instruction as they execute |
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* |
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*/ |
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#include "glib.h" |
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#include "glibconfig.h" |
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#include <qemu-plugin.h> |
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#include <string.h> |
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#include <stdio.h> |
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QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION; |
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static bool use_hwaddr; |
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static GByteArray *target_data; |
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static GByteArray *patch_data; |
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/**
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* Parse a string of hexadecimal digits into a GByteArray. The string must be |
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* even length |
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*/ |
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static GByteArray *str_to_bytes(const char *str) |
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{ |
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size_t len = strlen(str); |
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if (len == 0 || len % 2 != 0) { |
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return NULL; |
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} |
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GByteArray *bytes = g_byte_array_new(); |
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char byte[3] = {0}; |
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guint8 value = 0; |
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for (size_t i = 0; i < len; i += 2) { |
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byte[0] = str[i]; |
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byte[1] = str[i + 1]; |
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value = (guint8)g_ascii_strtoull(byte, NULL, 16); |
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g_byte_array_append(bytes, &value, 1); |
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} |
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return bytes; |
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} |
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static void patch_hwaddr(unsigned int vcpu_index, void *userdata) |
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{ |
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uintptr_t addr = (uintptr_t) userdata; |
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g_autoptr(GString) str = g_string_new(NULL); |
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g_string_printf(str, "patching: @0x%" |
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PRIxPTR "\n", |
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addr); |
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qemu_plugin_outs(str->str); |
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enum qemu_plugin_hwaddr_operation_result result = |
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qemu_plugin_write_memory_hwaddr(addr, patch_data); |
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if (result != QEMU_PLUGIN_HWADDR_OPERATION_OK) { |
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g_autoptr(GString) errmsg = g_string_new(NULL); |
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g_string_printf(errmsg, "Failed to write memory: %d\n", result); |
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qemu_plugin_outs(errmsg->str); |
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return; |
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} |
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GByteArray *read_data = g_byte_array_new(); |
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result = qemu_plugin_read_memory_hwaddr(addr, read_data, |
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patch_data->len); |
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qemu_plugin_outs("Reading memory...\n"); |
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if (result != QEMU_PLUGIN_HWADDR_OPERATION_OK) { |
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g_autoptr(GString) errmsg = g_string_new(NULL); |
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g_string_printf(errmsg, "Failed to read memory: %d\n", result); |
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qemu_plugin_outs(errmsg->str); |
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return; |
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} |
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if (memcmp(patch_data->data, read_data->data, patch_data->len) != 0) { |
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qemu_plugin_outs("Failed to read back written data\n"); |
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} |
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qemu_plugin_outs("Success!\n"); |
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return; |
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} |
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static void patch_vaddr(unsigned int vcpu_index, void *userdata) |
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{ |
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uintptr_t addr = (uintptr_t) userdata; |
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uint64_t hwaddr = 0; |
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if (!qemu_plugin_translate_vaddr(addr, &hwaddr)) { |
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qemu_plugin_outs("Failed to translate vaddr\n"); |
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return; |
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} |
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g_autoptr(GString) str = g_string_new(NULL); |
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g_string_printf(str, "patching: @0x%" |
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PRIxPTR " hw: @0x%" PRIx64 "\n", |
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addr, hwaddr); |
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qemu_plugin_outs(str->str); |
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qemu_plugin_outs("Writing memory (vaddr)...\n"); |
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if (!qemu_plugin_write_memory_vaddr(addr, patch_data)) { |
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qemu_plugin_outs("Failed to write memory\n"); |
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return; |
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} |
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qemu_plugin_outs("Reading memory (vaddr)...\n"); |
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g_autoptr(GByteArray) read_data = g_byte_array_new(); |
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if (!qemu_plugin_read_memory_vaddr(addr, read_data, patch_data->len)) { |
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qemu_plugin_outs("Failed to read memory\n"); |
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return; |
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} |
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if (memcmp(patch_data->data, read_data->data, patch_data->len) != 0) { |
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qemu_plugin_outs("Failed to read back written data\n"); |
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} |
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qemu_plugin_outs("Success!\n"); |
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return; |
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} |
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/*
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* Callback on translation of a translation block. |
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*/ |
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static void vcpu_tb_trans_cb(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) |
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{ |
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g_autoptr(GByteArray) insn_data = g_byte_array_new(); |
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uintptr_t addr = 0; |
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for (size_t i = 0; i < qemu_plugin_tb_n_insns(tb); i++) { |
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struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i); |
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uint64_t vaddr = qemu_plugin_insn_vaddr(insn); |
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if (use_hwaddr) { |
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uint64_t hwaddr = 0; |
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if (!qemu_plugin_translate_vaddr(vaddr, &hwaddr)) { |
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qemu_plugin_outs("Failed to translate vaddr\n"); |
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continue; |
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} |
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/*
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* As we cannot emulate 64 bit systems on 32 bit hosts we |
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* should never see the top bits set, hence we can safely |
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* cast to uintptr_t. |
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*/ |
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g_assert(hwaddr <= UINTPTR_MAX); |
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addr = (uintptr_t) hwaddr; |
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} else { |
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g_assert(vaddr <= UINTPTR_MAX); |
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addr = (uintptr_t) vaddr; |
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} |
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g_byte_array_set_size(insn_data, qemu_plugin_insn_size(insn)); |
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qemu_plugin_insn_data(insn, insn_data->data, insn_data->len); |
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if (insn_data->len >= target_data->len && |
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!memcmp(insn_data->data, target_data->data, |
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MIN(target_data->len, insn_data->len))) { |
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if (use_hwaddr) { |
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qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_hwaddr, |
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QEMU_PLUGIN_CB_NO_REGS, |
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(void *) addr); |
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} else { |
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qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_vaddr, |
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QEMU_PLUGIN_CB_NO_REGS, |
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(void *) addr); |
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} |
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} |
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} |
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} |
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static void usage(void) |
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{ |
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fprintf(stderr, "Usage: <lib>,target=<bytes>,patch=<new_bytes>" |
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"[,use_hwaddr=true|false]"); |
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} |
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/*
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* Called when the plugin is installed |
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*/ |
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QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, |
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const qemu_info_t *info, int argc, |
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char **argv) |
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{ |
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use_hwaddr = true; |
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target_data = NULL; |
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patch_data = NULL; |
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if (argc > 4) { |
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usage(); |
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return -1; |
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} |
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for (size_t i = 0; i < argc; i++) { |
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char *opt = argv[i]; |
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g_auto(GStrv) tokens = g_strsplit(opt, "=", 2); |
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if (g_strcmp0(tokens[0], "use_hwaddr") == 0) { |
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if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &use_hwaddr)) { |
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fprintf(stderr, |
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"Failed to parse boolean argument use_hwaddr\n"); |
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return -1; |
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} |
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} else if (g_strcmp0(tokens[0], "target") == 0) { |
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target_data = str_to_bytes(tokens[1]); |
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if (!target_data) { |
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fprintf(stderr, |
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"Failed to parse target bytes.\n"); |
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return -1; |
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} |
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} else if (g_strcmp0(tokens[0], "patch") == 0) { |
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patch_data = str_to_bytes(tokens[1]); |
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if (!patch_data) { |
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fprintf(stderr, "Failed to parse patch bytes.\n"); |
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return -1; |
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} |
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} else { |
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fprintf(stderr, "Unknown argument: %s\n", tokens[0]); |
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usage(); |
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return -1; |
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} |
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} |
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if (!target_data) { |
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fprintf(stderr, "target argument is required\n"); |
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usage(); |
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return -1; |
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} |
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if (!patch_data) { |
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fprintf(stderr, "patch argument is required\n"); |
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usage(); |
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return -1; |
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} |
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if (target_data->len != patch_data->len) { |
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fprintf(stderr, "Target and patch data must be the same length\n"); |
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return -1; |
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} |
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qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans_cb); |
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return 0; |
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} |
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@ -0,0 +1,22 @@ |
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/*
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* SPDX-License-Identifier: GPL-2.0-or-later |
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* |
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* This test target increments a value 100 times. The patcher converts the |
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* inc instruction to a nop, so it only increments the value once. |
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* |
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*/ |
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#include <minilib.h> |
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int main(void) |
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{ |
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ml_printf("Running test...\n"); |
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unsigned int x = 0; |
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for (int i = 0; i < 100; i++) { |
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asm volatile ( |
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"inc %[x]" |
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: [x] "+a" (x) |
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); |
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} |
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ml_printf("Value: %d\n", x); |
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return 0; |
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} |
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@ -0,0 +1,39 @@ |
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#!/usr/bin/env python3 |
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# |
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# validate-patch.py: check the patch applies |
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# |
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# This program takes two inputs: |
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# - the plugin output |
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# - the binary output |
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# |
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# Copyright (C) 2024 |
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# |
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# SPDX-License-Identifier: GPL-2.0-or-later |
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import sys |
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from argparse import ArgumentParser |
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def main() -> None: |
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""" |
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Process the arguments, injest the program and plugin out and |
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verify they match up and report if they do not. |
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""" |
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parser = ArgumentParser(description="Validate patch") |
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parser.add_argument('test_output', |
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help="The output from the test itself") |
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parser.add_argument('plugin_output', |
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help="The output from plugin") |
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args = parser.parse_args() |
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with open(args.test_output, 'r') as f: |
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test_data = f.read() |
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with open(args.plugin_output, 'r') as f: |
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plugin_data = f.read() |
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if "Value: 1" in test_data: |
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sys.exit(0) |
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else: |
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sys.exit(1) |
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if __name__ == "__main__": |
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main() |
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