tests/tcg/plugins: test register accesses
The additional plugin tests register accesses, specifically both for read-only and read-write registers. Writing to a read-only register is currently not tested, as this would trigger an assertion and fail the test. Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> Signed-off-by: Florian Hofhammer <florian.hofhammer@epfl.ch> Link: https://lore.kernel.org/qemu-devel/20260305-setpc-v5-v7-8-4c3adba52403@epfl.ch Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Florian Hofhammer committed
Mar 5, 2026 at 11:06 UTC
9fb1f82794fd61c2bb4d0d933ab03495f43af691
2 files changed
+80
tests/tcg/plugins/meson.build
+1
@@ -6,6 +6,7 @@ test_plugins = [
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'insn.c',
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'mem.c',
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'patch.c',
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+'registers.c',
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'reset.c',
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'setpc.c',
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'syscall.c',
tests/tcg/plugins/registers.c
new
+79
@@ -0,0 +1,79 @@
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+/*
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ *
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+ * Copyright (C) 2026, Florian Hofhammer <florian.hofhammer@epfl.ch>
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+ */
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+#include "glib.h"
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+#include <inttypes.h>
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+#include <assert.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <unistd.h>
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+#include <stdio.h>
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+
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+#include <qemu-plugin.h>
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+
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+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
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+
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+/*
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+ * This plugin tests whether we can read and write registers via the plugin
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+ * API. We try to just read/write a single register, as some architectures have
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+ * registers that cannot be written to, which would fail the test.
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+ * See: https://lists.gnu.org/archive/html/qemu-devel/2026-02/msg07025.html
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+ */
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+static void vcpu_init_cb(qemu_plugin_id_t id, unsigned int vcpu_index)
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+{
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+ g_autoptr(GArray) regs = qemu_plugin_get_registers();
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+ g_assert(regs != NULL);
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+ g_autoptr(GByteArray) buf = g_byte_array_sized_new(0);
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+ qemu_plugin_reg_descriptor *reg_desc = NULL;
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+ bool success = false;
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+
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+ /* Make sure we can read and write a register not marked as readonly */
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+ for (size_t i = 0; i < regs->len; i++) {
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+ reg_desc = &g_array_index(regs, qemu_plugin_reg_descriptor, i);
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+ if (!reg_desc->is_readonly) {
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+ g_byte_array_set_size(buf, 0);
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+ success = qemu_plugin_read_register(reg_desc->handle, buf);
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+ g_assert(success);
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+ g_assert(buf->len > 0);
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+ success = qemu_plugin_write_register(reg_desc->handle, buf);
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+ g_assert(success);
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+ break;
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+ } else {
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+ reg_desc = NULL;
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+ }
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+ }
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+ g_assert(regs->len == 0 || reg_desc != NULL);
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+
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+ /*
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+ * Check whether we can still read a read-only register. On each
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+ * architecture, at least the PC should be read-only because it's only
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+ * supposed to be modified via the qemu_plugin_set_pc() function.
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+ */
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+ for (size_t i = 0; i < regs->len; i++) {
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+ reg_desc = &g_array_index(regs, qemu_plugin_reg_descriptor, i);
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+ if (reg_desc->is_readonly) {
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+ g_byte_array_set_size(buf, 0);
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+ success = qemu_plugin_read_register(reg_desc->handle, buf);
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+ g_assert(success);
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+ g_assert(buf->len > 0);
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+ break;
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+ } else {
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+ reg_desc = NULL;
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+ }
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+ }
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+ g_assert(regs->len == 0 || reg_desc != NULL);
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+ /*
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+ * Note: we currently do not test whether the read-only register can be
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+ * written to, because doing so would throw an assert in the plugin API.
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+ */
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+}
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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,
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+ int argc, char **argv)
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+{
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+ qemu_plugin_register_vcpu_init_cb(id, vcpu_init_cb);
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+ return 0;
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+}