On Sun, 11 Sep 2022 05:28:04 +0800 David Gow davidgow@google.com wrote:
+++ b/lib/kunit/ftrace_stub.c @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <kunit/test.h>
+#include <linux/typecheck.h>
+#include <linux/ftrace.h> +#include <linux/sched.h>
+struct kunit_ftrace_stub_ctx {
- struct kunit *test;
- unsigned long real_fn_addr; /* used as a key to lookup the stub */
- unsigned long replacement_addr;
- struct ftrace_ops ops; /* a copy of kunit_stub_base_ops with .private set */
+};
+static void kunit_stub_trampoline(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops,struct ftrace_regs *fregs)+{
- struct kunit_ftrace_stub_ctx *ctx = ops->private;
- int lock_bit;
- if (current->kunit_test != ctx->test)
return;- lock_bit = ftrace_test_recursion_trylock(ip, parent_ip);
- KUNIT_ASSERT_GE(ctx->test, lock_bit, 0);
- ftrace_instruction_pointer_set(fregs, ctx->replacement_addr);
- ftrace_test_recursion_unlock(lock_bit);
+}
+static struct ftrace_ops kunit_stub_base_ops = {
- .func = &kunit_stub_trampoline,
- .flags = FTRACE_OPS_FL_IPMODIFY |
+#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
FTRACE_OPS_FL_SAVE_REGS |+#endif
FTRACE_OPS_FL_DYNAMIC+};
+static void __kunit_ftrace_stub_resource_free(struct kunit_resource *res) +{
- struct kunit_ftrace_stub_ctx *ctx = res->data;
- unregister_ftrace_function(&ctx->ops);
- kfree(ctx);
+}
+/* Matching function for kunit_find_resource(). match_data is real_fn_addr. */ +static bool __kunit_ftrace_stub_resource_match(struct kunit *test,
struct kunit_resource *res,void *match_real_fn_addr)+{
- /* This pointer is only valid if res is a static stub resource. */
- struct kunit_ftrace_stub_ctx *ctx = res->data;
- /* Make sure the resource is a static stub resource. */
- if (res->free != &__kunit_ftrace_stub_resource_free)
return false;- return ctx->real_fn_addr == (unsigned long)match_real_fn_addr;
+}
+void kunit_deactivate_ftrace_stub(struct kunit *test, void *real_fn_addr) +{
- struct kunit_resource *res;
- KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL,
"Tried to deactivate a NULL stub.");- /* Look up the existing stub for this function. */
- res = kunit_find_resource(test,
__kunit_ftrace_stub_resource_match,real_fn_addr);- /* Error out if the stub doesn't exist. */
- KUNIT_ASSERT_PTR_NE_MSG(test, res, NULL,
"Tried to deactivate a nonexistent stub.");- /* Free the stub. We 'put' twice, as we got a reference
* from kunit_find_resource(). The free function will deactivate the* ftrace stub.*/- kunit_remove_resource(test, res);
- kunit_put_resource(res);
+} +EXPORT_SYMBOL_GPL(kunit_deactivate_ftrace_stub);
+void __kunit_activate_ftrace_stub(struct kunit *test,
const char *name,void *real_fn_addr,void *replacement_addr)+{
- unsigned long ftrace_ip;
- struct kunit_ftrace_stub_ctx *ctx;
- int ret;
- ftrace_ip = ftrace_location((unsigned long)real_fn_addr);
- if (!ftrace_ip)
KUNIT_ASSERT_FAILURE(test, "%s ip is invalid: not a function, or is marked notrace or inline", name);- /* Allocate the stub context, which contains pointers to the replacement
* function and the test object. It's also registered as a KUnit* resource which can be looked up by address (to deactivate manually)* and is destroyed automatically on test exit.*/- ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
- KUNIT_ASSERT_NOT_ERR_OR_NULL_MSG(test, ctx, "failed to allocate kunit stub for %s", name);
- ctx->test = test;
- ctx->ops = kunit_stub_base_ops;
- ctx->ops.private = ctx;
- ctx->real_fn_addr = (unsigned long)real_fn_addr;
- ctx->replacement_addr = (unsigned long)replacement_addr;
- ret = ftrace_set_filter_ip(&ctx->ops, ftrace_ip, 0, 0);
- if (ret) {
kfree(ctx);KUNIT_ASSERT_FAILURE(test, "failed to set filter ip for %s: %d", name, ret);
I don't know the KUNIT_ASSERT content, but I'm guessing that any failure is just to crash the kernel or something where you do not need to bail out of the function?
- }
- ret = register_ftrace_function(&ctx->ops);
- if (ret) {
kfree(ctx);if (ret == -EBUSY)KUNIT_ASSERT_FAILURE(test, "failed to register stub (-EBUSY) for %s, likely due to already stubbing it?", name);KUNIT_ASSERT_FAILURE(test, "failed to register stub for %s: %d", name, ret);- }
- /* Register the stub as a resource with a cleanup function */
- kunit_alloc_resource(test, NULL,
__kunit_ftrace_stub_resource_free,GFP_KERNEL, ctx);
And I'm also guessing that there's no race concern with registering the free resource after enabling the function code?
Other than that, looks good to me.
Reviewed-by: Steven Rostedt (Google) rostedt@goodmis.org
-- Steve
+}