diff options
| -rw-r--r-- | include/kunit/static_stub.h | 113 | ||||
| -rw-r--r-- | include/kunit/test-bug.h | 1 | ||||
| -rw-r--r-- | lib/kunit/Makefile | 1 | ||||
| -rw-r--r-- | lib/kunit/hooks-impl.h | 2 | ||||
| -rw-r--r-- | lib/kunit/kunit-example-test.c | 38 | ||||
| -rw-r--r-- | lib/kunit/static_stub.c | 123 |
6 files changed, 278 insertions, 0 deletions
diff --git a/include/kunit/static_stub.h b/include/kunit/static_stub.h new file mode 100644 index 000000000000..9b80150a5d62 --- /dev/null +++ b/include/kunit/static_stub.h @@ -0,0 +1,113 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KUnit function redirection (static stubbing) API. + * + * Copyright (C) 2022, Google LLC. + * Author: David Gow <davidgow@google.com> + */ +#ifndef _KUNIT_STATIC_STUB_H +#define _KUNIT_STATIC_STUB_H + +#if !IS_ENABLED(CONFIG_KUNIT) + +/* If CONFIG_KUNIT is not enabled, these stubs quietly disappear. */ +#define KUNIT_TRIGGER_STATIC_STUB(real_fn_name, args...) do {} while (0) + +#else + +#include <kunit/test.h> +#include <kunit/test-bug.h> + +#include <linux/compiler.h> /* for {un,}likely() */ +#include <linux/sched.h> /* for task_struct */ + + +/** + * KUNIT_STATIC_STUB_REDIRECT() - call a replacement 'static stub' if one exists + * @real_fn_name: The name of this function (as an identifier, not a string) + * @args: All of the arguments passed to this function + * + * This is a function prologue which is used to allow calls to the current + * function to be redirected by a KUnit test. KUnit tests can call + * kunit_activate_static_stub() to pass a replacement function in. The + * replacement function will be called by KUNIT_TRIGGER_STATIC_STUB(), which + * will then return from the function. If the caller is not in a KUnit context, + * the function will continue execution as normal. + * + * Example: + * + * .. code-block:: c + * + * int real_func(int n) + * { + * KUNIT_STATIC_STUB_REDIRECT(real_func, n); + * return 0; + * } + * + * int replacement_func(int n) + * { + * return 42; + * } + * + * void example_test(struct kunit *test) + * { + * kunit_activate_static_stub(test, real_func, replacement_func); + * KUNIT_EXPECT_EQ(test, real_func(1), 42); + * } + * + */ +#define KUNIT_STATIC_STUB_REDIRECT(real_fn_name, args...) \ +do { \ + typeof(&real_fn_name) replacement; \ + struct kunit *current_test = kunit_get_current_test(); \ + \ + if (likely(!current_test)) \ + break; \ + \ + replacement = kunit_hooks.get_static_stub_address(current_test, \ + &real_fn_name); \ + \ + if (unlikely(replacement)) \ + return replacement(args); \ +} while (0) + +/* Helper function for kunit_activate_static_stub(). The macro does + * typechecking, so use it instead. + */ +void __kunit_activate_static_stub(struct kunit *test, + void *real_fn_addr, + void *replacement_addr); + +/** + * kunit_activate_static_stub() - replace a function using static stubs. + * @test: A pointer to the 'struct kunit' test context for the current test. + * @real_fn_addr: The address of the function to replace. + * @replacement_addr: The address of the function to replace it with. + * + * When activated, calls to real_fn_addr from within this test (even if called + * indirectly) will instead call replacement_addr. The function pointed to by + * real_fn_addr must begin with the static stub prologue in + * KUNIT_TRIGGER_STATIC_STUB() for this to work. real_fn_addr and + * replacement_addr must have the same type. + * + * The redirection can be disabled again with kunit_deactivate_static_stub(). + */ +#define kunit_activate_static_stub(test, real_fn_addr, replacement_addr) do { \ + typecheck_fn(typeof(&real_fn_addr), replacement_addr); \ + __kunit_activate_static_stub(test, real_fn_addr, replacement_addr); \ +} while (0) + + +/** + * kunit_deactivate_static_stub() - disable a function redirection + * @test: A pointer to the 'struct kunit' test context for the current test. + * @real_fn_addr: The address of the function to no-longer redirect + * + * Deactivates a redirection configured with kunit_activate_static_stub(). After + * this function returns, calls to real_fn_addr() will execute the original + * real_fn, not any previously-configured replacement. + */ +void kunit_deactivate_static_stub(struct kunit *test, void *real_fn_addr); + +#endif +#endif diff --git a/include/kunit/test-bug.h b/include/kunit/test-bug.h index 2b505a95b641..30ca541b6ff2 100644 --- a/include/kunit/test-bug.h +++ b/include/kunit/test-bug.h @@ -20,6 +20,7 @@ DECLARE_STATIC_KEY_FALSE(kunit_running); /* Hooks table: a table of function pointers filled in when kunit loads */ extern struct kunit_hooks_table { __printf(3, 4) void (*fail_current_test)(const char*, int, const char*, ...); + void *(*get_static_stub_address)(struct kunit *test, void *real_fn_addr); } kunit_hooks; /** diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index deeb46cc879b..da665cd4ea12 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -2,6 +2,7 @@ obj-$(CONFIG_KUNIT) += kunit.o kunit-objs += test.o \ resource.o \ + static_stub.o \ string-stream.o \ assert.o \ try-catch.o \ diff --git a/lib/kunit/hooks-impl.h b/lib/kunit/hooks-impl.h index d911f40f76db..ec745a39832c 100644 --- a/lib/kunit/hooks-impl.h +++ b/lib/kunit/hooks-impl.h @@ -16,12 +16,14 @@ /* List of declarations. */ void __kunit_fail_current_test_impl(const char *file, int line, const char *fmt, ...); +void *__kunit_get_static_stub_address_impl(struct kunit *test, void *real_fn_addr); /* Code to set all of the function pointers. */ static inline void kunit_install_hooks(void) { /* Install the KUnit hook functions. */ kunit_hooks.fail_current_test = __kunit_fail_current_test_impl; + kunit_hooks.get_static_stub_address = __kunit_get_static_stub_address_impl; } #endif /* _KUNIT_HOOKS_IMPL_H */ diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c index 66cc4e2365ec..cd8b7e51d02b 100644 --- a/lib/kunit/kunit-example-test.c +++ b/lib/kunit/kunit-example-test.c @@ -7,6 +7,7 @@ */ #include <kunit/test.h> +#include <kunit/static_stub.h> /* * This is the most fundamental element of KUnit, the test case. A test case @@ -130,6 +131,42 @@ static void example_all_expect_macros_test(struct kunit *test) KUNIT_ASSERT_GT_MSG(test, sizeof(int), 0, "Your ints are 0-bit?!"); } +/* This is a function we'll replace with static stubs. */ +static int add_one(int i) +{ + /* This will trigger the stub if active. */ + KUNIT_STATIC_STUB_REDIRECT(add_one, i); + + return i + 1; +} + +/* This is used as a replacement for the above function. */ +static int subtract_one(int i) +{ + /* We don't need to trigger the stub from the replacement. */ + + return i - 1; +} + +/* + * This test shows the use of static stubs. + */ +static void example_static_stub_test(struct kunit *test) +{ + /* By default, function is not stubbed. */ + KUNIT_EXPECT_EQ(test, add_one(1), 2); + + /* Replace add_one() with subtract_one(). */ + kunit_activate_static_stub(test, add_one, subtract_one); + + /* add_one() is now replaced. */ + KUNIT_EXPECT_EQ(test, add_one(1), 0); + + /* Return add_one() to normal. */ + kunit_deactivate_static_stub(test, add_one); + KUNIT_EXPECT_EQ(test, add_one(1), 2); +} + /* * Here we make a list of all the test cases we want to add to the test suite * below. @@ -145,6 +182,7 @@ static struct kunit_case example_test_cases[] = { KUNIT_CASE(example_skip_test), KUNIT_CASE(example_mark_skipped_test), KUNIT_CASE(example_all_expect_macros_test), + KUNIT_CASE(example_static_stub_test), {} }; diff --git a/lib/kunit/static_stub.c b/lib/kunit/static_stub.c new file mode 100644 index 000000000000..92b2cccd5e76 --- /dev/null +++ b/lib/kunit/static_stub.c @@ -0,0 +1,123 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit function redirection (static stubbing) API. + * + * Copyright (C) 2022, Google LLC. + * Author: David Gow <davidgow@google.com> + */ + +#include <kunit/test.h> +#include <kunit/static_stub.h> +#include "hooks-impl.h" + + +/* Context for a static stub. This is stored in the resource data. */ +struct kunit_static_stub_ctx { + void *real_fn_addr; + void *replacement_addr; +}; + +static void __kunit_static_stub_resource_free(struct kunit_resource *res) +{ + kfree(res->data); +} + +/* Matching function for kunit_find_resource(). match_data is real_fn_addr. */ +static bool __kunit_static_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_static_stub_ctx *ctx = res->data; + + /* Make sure the resource is a static stub resource. */ + if (res->free != &__kunit_static_stub_resource_free) + return false; + + return ctx->real_fn_addr == match_real_fn_addr; +} + +/* Hook to return the address of the replacement function. */ +void *__kunit_get_static_stub_address_impl(struct kunit *test, void *real_fn_addr) +{ + struct kunit_resource *res; + struct kunit_static_stub_ctx *ctx; + void *replacement_addr; + + res = kunit_find_resource(test, + __kunit_static_stub_resource_match, + real_fn_addr); + + if (!res) + return NULL; + + ctx = res->data; + replacement_addr = ctx->replacement_addr; + kunit_put_resource(res); + return replacement_addr; +} + +void kunit_deactivate_static_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_static_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() + */ + kunit_remove_resource(test, res); + kunit_put_resource(res); +} +EXPORT_SYMBOL_GPL(kunit_deactivate_static_stub); + +/* Helper function for kunit_activate_static_stub(). The macro does + * typechecking, so use it instead. + */ +void __kunit_activate_static_stub(struct kunit *test, + void *real_fn_addr, + void *replacement_addr) +{ + struct kunit_static_stub_ctx *ctx; + struct kunit_resource *res; + + KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL, + "Tried to activate a stub for function NULL"); + + /* If the replacement address is NULL, deactivate the stub. */ + if (!replacement_addr) { + kunit_deactivate_static_stub(test, replacement_addr); + return; + } + + /* Look up any existing stubs for this function, and replace them. */ + res = kunit_find_resource(test, + __kunit_static_stub_resource_match, + real_fn_addr); + if (res) { + ctx = res->data; + ctx->replacement_addr = replacement_addr; + + /* We got an extra reference from find_resource(), so put it. */ + kunit_put_resource(res); + } else { + ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx); + ctx->real_fn_addr = real_fn_addr; + ctx->replacement_addr = replacement_addr; + res = kunit_alloc_resource(test, NULL, + &__kunit_static_stub_resource_free, + GFP_KERNEL, ctx); + } +} +EXPORT_SYMBOL_GPL(__kunit_activate_static_stub); |