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![Kees Cook](/assets/img/avatar_default.png)
Convert stackinit unit tests to KUnit, for better integration into the kernel self test framework. Includes a rename of test_stackinit.c to stackinit_kunit.c, and CONFIG_TEST_STACKINIT to CONFIG_STACKINIT_KUNIT_TEST. Adjust expected test results based on which stack initialization method was chosen: $ CMD="./tools/testing/kunit/kunit.py run stackinit --raw_output \ --arch=x86_64 --kconfig_add" $ $CMD | grep stackinit: # stackinit: pass:36 fail:0 skip:29 total:65 $ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_USER=y | grep stackinit: # stackinit: pass:37 fail:0 skip:28 total:65 $ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF=y | grep stackinit: # stackinit: pass:55 fail:0 skip:10 total:65 $ $CMD CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL=y | grep stackinit: # stackinit: pass:62 fail:0 skip:3 total:65 $ $CMD CONFIG_INIT_STACK_ALL_PATTERN=y --make_option LLVM=1 | grep stackinit: # stackinit: pass:60 fail:0 skip:5 total:65 $ $CMD CONFIG_INIT_STACK_ALL_ZERO=y --make_option LLVM=1 | grep stackinit: # stackinit: pass:60 fail:0 skip:5 total:65 Temporarily remove the userspace-build mode, which will be restored in a later patch. Expand the size of the pre-case switch variable so it doesn't get accidentally cleared. Cc: David Gow <davidgow@google.com> Cc: Daniel Latypov <dlatypov@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Kees Cook <keescook@chromium.org> --- v1: https://lore.kernel.org/lkml/20220224055145.1853657-1-keescook@chromium.org v2: - split "userspace KUnit stub" into separate header and patch (Daniel) - Improve commit log and comments (David) - Provide mapping of expected XFAIL tests to CONFIGs (David)
461 lines
14 KiB
C
461 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Test cases for compiler-based stack variable zeroing via
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* -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
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* For example, see:
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* https://www.kernel.org/doc/html/latest/dev-tools/kunit/kunit-tool.html#configuring-building-and-running-tests
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* ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
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* --make_option LLVM=1 \
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* --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <kunit/test.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/string.h>
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/* Exfiltration buffer. */
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#define MAX_VAR_SIZE 128
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static u8 check_buf[MAX_VAR_SIZE];
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/* Character array to trigger stack protector in all functions. */
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#define VAR_BUFFER 32
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/* Volatile mask to convince compiler to copy memory with 0xff. */
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static volatile u8 forced_mask = 0xff;
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/* Location and size tracking to validate fill and test are colocated. */
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static void *fill_start, *target_start;
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static size_t fill_size, target_size;
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static bool range_contains(char *haystack_start, size_t haystack_size,
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char *needle_start, size_t needle_size)
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{
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if (needle_start >= haystack_start &&
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needle_start + needle_size <= haystack_start + haystack_size)
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return true;
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return false;
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}
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/* Whether the test is expected to fail. */
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#define WANT_SUCCESS 0
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#define XFAIL 1
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#define DO_NOTHING_TYPE_SCALAR(var_type) var_type
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#define DO_NOTHING_TYPE_STRING(var_type) void
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#define DO_NOTHING_TYPE_STRUCT(var_type) void
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#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)
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#define DO_NOTHING_RETURN_STRING(ptr) /**/
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#define DO_NOTHING_RETURN_STRUCT(ptr) /**/
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#define DO_NOTHING_CALL_SCALAR(var, name) \
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(var) = do_nothing_ ## name(&(var))
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#define DO_NOTHING_CALL_STRING(var, name) \
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do_nothing_ ## name(var)
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#define DO_NOTHING_CALL_STRUCT(var, name) \
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do_nothing_ ## name(&(var))
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#define FETCH_ARG_SCALAR(var) &var
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#define FETCH_ARG_STRING(var) var
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#define FETCH_ARG_STRUCT(var) &var
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#define FILL_SIZE_STRING 16
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#define INIT_CLONE_SCALAR /**/
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#define INIT_CLONE_STRING [FILL_SIZE_STRING]
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#define INIT_CLONE_STRUCT /**/
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#define ZERO_CLONE_SCALAR(zero) memset(&(zero), 0x00, sizeof(zero))
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#define ZERO_CLONE_STRING(zero) memset(&(zero), 0x00, sizeof(zero))
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/*
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* For the struct, intentionally poison padding to see if it gets
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* copied out in direct assignments.
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* */
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#define ZERO_CLONE_STRUCT(zero) \
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do { \
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memset(&(zero), 0xFF, sizeof(zero)); \
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zero.one = 0; \
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zero.two = 0; \
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zero.three = 0; \
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zero.four = 0; \
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} while (0)
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#define INIT_SCALAR_none(var_type) /**/
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#define INIT_SCALAR_zero(var_type) = 0
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#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/
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#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { }
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#define INIT_STRUCT_none(var_type) /**/
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#define INIT_STRUCT_zero(var_type) = { }
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#define __static_partial { .two = 0, }
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#define __static_all { .one = 0, \
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.two = 0, \
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.three = 0, \
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.four = 0, \
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}
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#define __dynamic_partial { .two = arg->two, }
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#define __dynamic_all { .one = arg->one, \
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.two = arg->two, \
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.three = arg->three, \
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.four = arg->four, \
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}
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#define __runtime_partial var.two = 0
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#define __runtime_all var.one = 0; \
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var.two = 0; \
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var.three = 0; \
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var.four = 0
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#define INIT_STRUCT_static_partial(var_type) \
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= __static_partial
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#define INIT_STRUCT_static_all(var_type) \
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= __static_all
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#define INIT_STRUCT_dynamic_partial(var_type) \
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= __dynamic_partial
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#define INIT_STRUCT_dynamic_all(var_type) \
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= __dynamic_all
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#define INIT_STRUCT_runtime_partial(var_type) \
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; __runtime_partial
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#define INIT_STRUCT_runtime_all(var_type) \
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; __runtime_all
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#define INIT_STRUCT_assigned_static_partial(var_type) \
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; var = (var_type)__static_partial
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#define INIT_STRUCT_assigned_static_all(var_type) \
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; var = (var_type)__static_all
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#define INIT_STRUCT_assigned_dynamic_partial(var_type) \
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; var = (var_type)__dynamic_partial
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#define INIT_STRUCT_assigned_dynamic_all(var_type) \
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; var = (var_type)__dynamic_all
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#define INIT_STRUCT_assigned_copy(var_type) \
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; var = *(arg)
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/*
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* @name: unique string name for the test
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* @var_type: type to be tested for zeroing initialization
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* @which: is this a SCALAR, STRING, or STRUCT type?
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* @init_level: what kind of initialization is performed
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* @xfail: is this test expected to fail?
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*/
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#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \
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/* Returns 0 on success, 1 on failure. */ \
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static noinline void test_ ## name (struct kunit *test) \
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{ \
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var_type zero INIT_CLONE_ ## which; \
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int ignored; \
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u8 sum = 0, i; \
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\
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/* Notice when a new test is larger than expected. */ \
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BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \
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\
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/* Fill clone type with zero for per-field init. */ \
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ZERO_CLONE_ ## which(zero); \
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/* Clear entire check buffer for 0xFF overlap test. */ \
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memset(check_buf, 0x00, sizeof(check_buf)); \
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/* Fill stack with 0xFF. */ \
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ignored = leaf_ ##name((unsigned long)&ignored, 1, \
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FETCH_ARG_ ## which(zero)); \
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/* Verify all bytes overwritten with 0xFF. */ \
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for (sum = 0, i = 0; i < target_size; i++) \
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sum += (check_buf[i] != 0xFF); \
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KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
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"leaf fill was not 0xFF!?\n"); \
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/* Clear entire check buffer for later bit tests. */ \
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memset(check_buf, 0x00, sizeof(check_buf)); \
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/* Extract stack-defined variable contents. */ \
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ignored = leaf_ ##name((unsigned long)&ignored, 0, \
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FETCH_ARG_ ## which(zero)); \
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\
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/* Validate that compiler lined up fill and target. */ \
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KUNIT_ASSERT_TRUE_MSG(test, \
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range_contains(fill_start, fill_size, \
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target_start, target_size), \
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"stack fill missed target!? " \
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"(fill %zu wide, target offset by %d)\n", \
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fill_size, \
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(int)((ssize_t)(uintptr_t)fill_start - \
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(ssize_t)(uintptr_t)target_start)); \
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\
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/* Look for any bytes still 0xFF in check region. */ \
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for (sum = 0, i = 0; i < target_size; i++) \
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sum += (check_buf[i] == 0xFF); \
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\
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if (sum != 0 && xfail) \
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kunit_skip(test, \
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"XFAIL uninit bytes: %d\n", \
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sum); \
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KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
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"uninit bytes: %d\n", sum); \
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}
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#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
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/* no-op to force compiler into ignoring "uninitialized" vars */\
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static noinline DO_NOTHING_TYPE_ ## which(var_type) \
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do_nothing_ ## name(var_type *ptr) \
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{ \
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/* Will always be true, but compiler doesn't know. */ \
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if ((unsigned long)ptr > 0x2) \
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return DO_NOTHING_RETURN_ ## which(ptr); \
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else \
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return DO_NOTHING_RETURN_ ## which(ptr + 1); \
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} \
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static noinline int leaf_ ## name(unsigned long sp, bool fill, \
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var_type *arg) \
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{ \
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char buf[VAR_BUFFER]; \
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var_type var \
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INIT_ ## which ## _ ## init_level(var_type); \
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\
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target_start = &var; \
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target_size = sizeof(var); \
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/* \
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* Keep this buffer around to make sure we've got a \
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* stack frame of SOME kind... \
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*/ \
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memset(buf, (char)(sp & 0xff), sizeof(buf)); \
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/* Fill variable with 0xFF. */ \
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if (fill) { \
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fill_start = &var; \
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fill_size = sizeof(var); \
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memset(fill_start, \
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(char)((sp & 0xff) | forced_mask), \
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fill_size); \
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} \
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\
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/* Silence "never initialized" warnings. */ \
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DO_NOTHING_CALL_ ## which(var, name); \
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\
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/* Exfiltrate "var". */ \
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memcpy(check_buf, target_start, target_size); \
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\
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return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \
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} \
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DEFINE_TEST_DRIVER(name, var_type, which, xfail)
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/* Structure with no padding. */
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struct test_packed {
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unsigned long one;
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unsigned long two;
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unsigned long three;
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unsigned long four;
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};
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/* Simple structure with padding likely to be covered by compiler. */
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struct test_small_hole {
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size_t one;
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char two;
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/* 3 byte padding hole here. */
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int three;
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unsigned long four;
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};
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/* Trigger unhandled padding in a structure. */
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struct test_big_hole {
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u8 one;
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u8 two;
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u8 three;
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/* 61 byte padding hole here. */
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u8 four __aligned(64);
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} __aligned(64);
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struct test_trailing_hole {
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char *one;
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char *two;
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char *three;
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char four;
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/* "sizeof(unsigned long) - 1" byte padding hole here. */
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};
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/* Test if STRUCTLEAK is clearing structs with __user fields. */
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struct test_user {
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u8 one;
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unsigned long two;
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char __user *three;
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unsigned long four;
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};
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#define ALWAYS_PASS WANT_SUCCESS
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#define ALWAYS_FAIL XFAIL
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#ifdef CONFIG_INIT_STACK_NONE
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# define USER_PASS XFAIL
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# define BYREF_PASS XFAIL
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# define STRONG_PASS XFAIL
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#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER)
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# define USER_PASS WANT_SUCCESS
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# define BYREF_PASS XFAIL
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# define STRONG_PASS XFAIL
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#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF)
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# define USER_PASS WANT_SUCCESS
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# define BYREF_PASS WANT_SUCCESS
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# define STRONG_PASS XFAIL
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#else
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# define USER_PASS WANT_SUCCESS
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# define BYREF_PASS WANT_SUCCESS
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# define STRONG_PASS WANT_SUCCESS
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#endif
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#define DEFINE_SCALAR_TEST(name, init, xfail) \
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DEFINE_TEST(name ## _ ## init, name, SCALAR, \
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init, xfail)
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#define DEFINE_SCALAR_TESTS(init, xfail) \
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DEFINE_SCALAR_TEST(u8, init, xfail); \
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DEFINE_SCALAR_TEST(u16, init, xfail); \
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DEFINE_SCALAR_TEST(u32, init, xfail); \
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DEFINE_SCALAR_TEST(u64, init, xfail); \
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DEFINE_TEST(char_array_ ## init, unsigned char, \
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STRING, init, xfail)
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#define DEFINE_STRUCT_TEST(name, init, xfail) \
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DEFINE_TEST(name ## _ ## init, \
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struct test_ ## name, STRUCT, init, \
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xfail)
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#define DEFINE_STRUCT_TESTS(init, xfail) \
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DEFINE_STRUCT_TEST(small_hole, init, xfail); \
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DEFINE_STRUCT_TEST(big_hole, init, xfail); \
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DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
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DEFINE_STRUCT_TEST(packed, init, xfail)
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#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail) \
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DEFINE_STRUCT_TESTS(base ## _ ## partial, \
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xfail); \
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DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)
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/* These should be fully initialized all the time! */
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DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
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DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
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/* Struct initializers: padding may be left uninitialized. */
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DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
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DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
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DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
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DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
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DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
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DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
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/* No initialization without compiler instrumentation. */
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DEFINE_SCALAR_TESTS(none, STRONG_PASS);
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DEFINE_STRUCT_TESTS(none, BYREF_PASS);
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/* Initialization of members with __user attribute. */
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DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);
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/*
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* Check two uses through a variable declaration outside either path,
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* which was noticed as a special case in porting earlier stack init
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* compiler logic.
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*/
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static int noinline __leaf_switch_none(int path, bool fill)
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{
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switch (path) {
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/*
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* This is intentionally unreachable. To silence the
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* warning, build with -Wno-switch-unreachable
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*/
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uint64_t var[10];
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case 1:
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target_start = &var;
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target_size = sizeof(var);
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if (fill) {
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fill_start = &var;
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fill_size = sizeof(var);
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memset(fill_start, forced_mask | 0x55, fill_size);
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}
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memcpy(check_buf, target_start, target_size);
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break;
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case 2:
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target_start = &var;
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target_size = sizeof(var);
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if (fill) {
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fill_start = &var;
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fill_size = sizeof(var);
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memset(fill_start, forced_mask | 0xaa, fill_size);
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}
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memcpy(check_buf, target_start, target_size);
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break;
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default:
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var[1] = 5;
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return var[1] & forced_mask;
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}
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return 0;
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}
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static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
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uint64_t *arg)
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{
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return __leaf_switch_none(1, fill);
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}
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static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
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uint64_t *arg)
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{
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return __leaf_switch_none(2, fill);
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}
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/*
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* These are expected to fail for most configurations because neither
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* GCC nor Clang have a way to perform initialization of variables in
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* non-code areas (i.e. in a switch statement before the first "case").
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* https://bugs.llvm.org/show_bug.cgi?id=44916
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*/
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DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
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DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
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#define KUNIT_test_scalars(init) \
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KUNIT_CASE(test_u8_ ## init), \
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KUNIT_CASE(test_u16_ ## init), \
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KUNIT_CASE(test_u32_ ## init), \
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KUNIT_CASE(test_u64_ ## init), \
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KUNIT_CASE(test_char_array_ ## init)
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#define KUNIT_test_structs(init) \
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KUNIT_CASE(test_small_hole_ ## init), \
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KUNIT_CASE(test_big_hole_ ## init), \
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KUNIT_CASE(test_trailing_hole_ ## init),\
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KUNIT_CASE(test_packed_ ## init) \
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static struct kunit_case stackinit_test_cases[] = {
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/* These are explicitly initialized and should always pass. */
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KUNIT_test_scalars(zero),
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KUNIT_test_structs(zero),
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/* Padding here appears to be accidentally always initialized? */
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KUNIT_test_structs(dynamic_partial),
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KUNIT_test_structs(assigned_dynamic_partial),
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/* Padding initialization depends on compiler behaviors. */
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KUNIT_test_structs(static_partial),
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KUNIT_test_structs(static_all),
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KUNIT_test_structs(dynamic_all),
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KUNIT_test_structs(runtime_partial),
|
|
KUNIT_test_structs(runtime_all),
|
|
KUNIT_test_structs(assigned_static_partial),
|
|
KUNIT_test_structs(assigned_static_all),
|
|
KUNIT_test_structs(assigned_dynamic_all),
|
|
/* Everything fails this since it effectively performs a memcpy(). */
|
|
KUNIT_test_structs(assigned_copy),
|
|
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
|
|
KUNIT_test_scalars(none),
|
|
KUNIT_CASE(test_switch_1_none),
|
|
KUNIT_CASE(test_switch_2_none),
|
|
/* STRUCTLEAK_BYREF should cover from here down. */
|
|
KUNIT_test_structs(none),
|
|
/* STRUCTLEAK will only cover this. */
|
|
KUNIT_CASE(test_user),
|
|
{}
|
|
};
|
|
|
|
static struct kunit_suite stackinit_test_suite = {
|
|
.name = "stackinit",
|
|
.test_cases = stackinit_test_cases,
|
|
};
|
|
|
|
kunit_test_suites(&stackinit_test_suite);
|
|
|
|
MODULE_LICENSE("GPL");
|