114 lines
3.6 KiB
C
114 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* KUnit function redirection (static stubbing) API.
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*
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* Copyright (C) 2022, Google LLC.
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* Author: David Gow <davidgow@google.com>
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*/
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#ifndef _KUNIT_STATIC_STUB_H
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#define _KUNIT_STATIC_STUB_H
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#if !IS_ENABLED(CONFIG_KUNIT)
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/* If CONFIG_KUNIT is not enabled, these stubs quietly disappear. */
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#define KUNIT_STATIC_STUB_REDIRECT(real_fn_name, args...) do {} while (0)
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#else
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#include <kunit/test.h>
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#include <kunit/test-bug.h>
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#include <linux/compiler.h> /* for {un,}likely() */
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#include <linux/sched.h> /* for task_struct */
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/**
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* KUNIT_STATIC_STUB_REDIRECT() - call a replacement 'static stub' if one exists
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* @real_fn_name: The name of this function (as an identifier, not a string)
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* @args: All of the arguments passed to this function
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*
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* This is a function prologue which is used to allow calls to the current
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* function to be redirected by a KUnit test. KUnit tests can call
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* kunit_activate_static_stub() to pass a replacement function in. The
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* replacement function will be called by KUNIT_STATIC_STUB_REDIRECT(), which
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* will then return from the function. If the caller is not in a KUnit context,
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* the function will continue execution as normal.
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*
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* Example:
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*
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* .. code-block:: c
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*
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* int real_func(int n)
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* {
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* KUNIT_STATIC_STUB_REDIRECT(real_func, n);
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* return 0;
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* }
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*
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* int replacement_func(int n)
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* {
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* return 42;
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* }
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*
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* void example_test(struct kunit *test)
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* {
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* kunit_activate_static_stub(test, real_func, replacement_func);
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* KUNIT_EXPECT_EQ(test, real_func(1), 42);
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* }
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*
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*/
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#define KUNIT_STATIC_STUB_REDIRECT(real_fn_name, args...) \
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do { \
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typeof(&real_fn_name) replacement; \
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struct kunit *current_test = kunit_get_current_test(); \
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\
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if (likely(!current_test)) \
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break; \
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\
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replacement = kunit_hooks.get_static_stub_address(current_test, \
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&real_fn_name); \
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\
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if (unlikely(replacement)) \
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return replacement(args); \
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} while (0)
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/* Helper function for kunit_activate_static_stub(). The macro does
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* typechecking, so use it instead.
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*/
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void __kunit_activate_static_stub(struct kunit *test,
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void *real_fn_addr,
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void *replacement_addr);
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/**
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* kunit_activate_static_stub() - replace a function using static stubs.
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* @test: A pointer to the 'struct kunit' test context for the current test.
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* @real_fn_addr: The address of the function to replace.
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* @replacement_addr: The address of the function to replace it with.
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*
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* When activated, calls to real_fn_addr from within this test (even if called
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* indirectly) will instead call replacement_addr. The function pointed to by
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* real_fn_addr must begin with the static stub prologue in
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* KUNIT_STATIC_STUB_REDIRECT() for this to work. real_fn_addr and
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* replacement_addr must have the same type.
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*
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* The redirection can be disabled again with kunit_deactivate_static_stub().
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*/
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#define kunit_activate_static_stub(test, real_fn_addr, replacement_addr) do { \
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typecheck_fn(typeof(&replacement_addr), real_fn_addr); \
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__kunit_activate_static_stub(test, real_fn_addr, replacement_addr); \
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} while (0)
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/**
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* kunit_deactivate_static_stub() - disable a function redirection
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* @test: A pointer to the 'struct kunit' test context for the current test.
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* @real_fn_addr: The address of the function to no-longer redirect
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*
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* Deactivates a redirection configured with kunit_activate_static_stub(). After
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* this function returns, calls to real_fn_addr() will execute the original
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* real_fn, not any previously-configured replacement.
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*/
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void kunit_deactivate_static_stub(struct kunit *test, void *real_fn_addr);
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#endif
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#endif
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