The longest length of a symbol (KSYM_NAME_LEN) was increased to 512 in the reference [1]. This patch adds a kunit test to check the longest symbol length.

[1] https://lore.kernel.org/lkml/20220802015052.10452-6-ojeda@kernel.org/

Tested-by: Martin Rodriguez Reboredo yakoyoku@gmail.com Signed-off-by: Sergio González Collado sergio.collado@gmail.com --- V1 -> V2: corrected CI tests. Added fix proposed at [2]

[2] https://lore.kernel.org/lkml/Y9ES4UKl%2F+DtvAVS@gmail.com/T/#m3ef0e12bb834d0... --- V2 -> V3: updated base and added MODULE_DESCRIPTION() and MODULE_AUTHOR() --- arch/x86/tools/insn_decoder_test.c | 3 +- lib/Kconfig.debug | 9 +++ lib/Makefile | 2 + lib/longest_symbol_kunit.c | 124 +++++++++++++++++++++++++++++ 4 files changed, 137 insertions(+), 1 deletion(-) create mode 100644 lib/longest_symbol_kunit.c

diff --git a/arch/x86/tools/insn_decoder_test.c b/arch/x86/tools/insn_decoder_test.c index 472540aeabc2..3bde35ea4188 100644 --- a/arch/x86/tools/insn_decoder_test.c +++ b/arch/x86/tools/insn_decoder_test.c @@ -10,6 +10,7 @@ #include <assert.h> #include <unistd.h> #include <stdarg.h> +#include <linux/kallsysms.h>

#define unlikely(cond) (cond)

@@ -106,7 +107,7 @@ static void parse_args(int argc, char **argv) } }

-#define BUFSIZE 256 +#define BUFSIZE (256 + KSYM_NAME_LEN)

int main(int argc, char **argv) { diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index a30c03a66172..4587466f7d07 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2783,6 +2783,15 @@ config FORTIFY_KUNIT_TEST by the str*() and mem*() family of functions. For testing runtime traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.

+config LONGEST_SYM_KUNIT_TEST + tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS + depends on KUNIT && KPROBES + default KUNIT_ALL_TESTS + help + Tests the longest symbol possible + + If unsure, say N. + config HW_BREAKPOINT_KUNIT_TEST bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS depends on HAVE_HW_BREAKPOINT diff --git a/lib/Makefile b/lib/Makefile index 322bb127b4dc..4241807025b8 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -388,6 +388,8 @@ CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN) obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o +obj-$(CONFIG_LONGEST_SYM_KUNIT_TEST) += longest_symbol_kunit.o +CFLAGS_longest_symbol_kunit.o += $(call cc-disable-warning, missing-prototypes)

obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o

diff --git a/lib/longest_symbol_kunit.c b/lib/longest_symbol_kunit.c new file mode 100644 index 000000000000..557ad6eae56c --- /dev/null +++ b/lib/longest_symbol_kunit.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test the longest symbol length. Execute with: + * ./tools/testing/kunit/kunit.py run longest-symbol + * --arch=x86_64 --kconfig_add CONFIG_KPROBES=y --kconfig_add CONFIG_MODULES=y + * --kconfig_add CONFIG_RETPOLINE=n + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <kunit/test.h> +#include <linux/stringify.h> +#include <linux/kprobes.h> +#include <linux/kallsyms.h> + +#define DI(name) s##name##name +#define DDI(name) DI(n##name##name) +#define DDDI(name) DDI(n##name##name) +#define DDDDI(name) DDDI(n##name##name) +#define DDDDDI(name) DDDDI(n##name##name) + +#define PLUS1(name) __PASTE(name, e) + +/*Generate a symbol whose name length is 511 */ +#define LONGEST_SYM_NAME DDDDDI(g1h2i3j4k5l6m7n) + +/*Generate a symbol whose name length is 512 */ +#define LONGEST_SYM_NAME_PLUS1 PLUS1(LONGEST_SYM_NAME) + +#define RETURN_LONGEST_SYM 0xAAAAA +#define RETURN_LONGEST_SYM_PLUS1 0x55555 + +noinline int LONGEST_SYM_NAME(void); +noinline int LONGEST_SYM_NAME(void) +{ + return RETURN_LONGEST_SYM; +} + +noinline int LONGEST_SYM_NAME_PLUS1(void); +noinline int LONGEST_SYM_NAME_PLUS1(void) +{ + return RETURN_LONGEST_SYM_PLUS1; +} + +_Static_assert(sizeof(__stringify(LONGEST_SYM_NAME)) == KSYM_NAME_LEN, +"Incorrect symbol length found. Expected KSYM_NAME_LEN: " +__stringify(KSYM_NAME) ", but found: " +__stringify(sizeof(LONGEST_SYM_NAME))); + +static void test_longest_symbol(struct kunit *test) +{ + KUNIT_EXPECT_EQ(test, RETURN_LONGEST_SYM, LONGEST_SYM_NAME()); +}; + +static void test_longest_symbol_kallsyms(struct kunit *test) +{ + unsigned long (*kallsyms_lookup_name)(const char *name); + static int (*longest_sym)(void); + + struct kprobe kp = { + .symbol_name = "kallsyms_lookup_name", + }; + + if (register_kprobe(&kp) < 0) { + pr_info("%s: kprobe not registered\n", __func__); + KUNIT_FAIL(test, "test_longest_symbol kallsysms: kprobe not registered\n"); + return; + } + + kunit_warn(test, "test_longest_symbol kallsyms: kprobe registered\n"); + kallsyms_lookup_name = (unsigned long (*)(const char *name))kp.addr; + unregister_kprobe(&kp); + + longest_sym = + (void *) kallsyms_lookup_name(__stringify(LONGEST_SYM_NAME)); + KUNIT_EXPECT_EQ(test, RETURN_LONGEST_SYM, longest_sym()); +}; + +static void test_longest_symbol_plus1(struct kunit *test) +{ + KUNIT_EXPECT_EQ(test, RETURN_LONGEST_SYM_PLUS1, LONGEST_SYM_NAME_PLUS1()); +}; + +static void test_longest_symbol_plus1_kallsyms(struct kunit *test) +{ + unsigned long (*kallsyms_lookup_name)(const char *name); + static int (*longest_sym_plus1)(void); + + struct kprobe kp = { + .symbol_name = "kallsyms_lookup_name", + }; + + if (register_kprobe(&kp) < 0) { + pr_info("%s: kprobe not registered\n", __func__); + KUNIT_FAIL(test, "test_longest_symbol kallsysms: kprobe not registered\n"); + return; + } + + kunit_warn(test, "test_longest_symbol_plus1 kallsyms: kprobe registered\n"); + kallsyms_lookup_name = (unsigned long (*)(const char *name))kp.addr; + unregister_kprobe(&kp); + + longest_sym_plus1 = + (void *) kallsyms_lookup_name(__stringify(LONGEST_SYM_NAME_PLUS1)); + KUNIT_EXPECT_NULL(test, longest_sym_plus1); +}; + +static struct kunit_case longest_symbol_test_cases[] = { + KUNIT_CASE(test_longest_symbol), + KUNIT_CASE(test_longest_symbol_kallsyms), + KUNIT_CASE(test_longest_symbol_plus1), + KUNIT_CASE(test_longest_symbol_plus1_kallsyms), + {} +}; + +static struct kunit_suite longest_symbol_test_suite = { + .name = "longest-symbol", + .test_cases = longest_symbol_test_cases, +}; +kunit_test_suite(longest_symbol_test_suite); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Test the longest symbol length"); +MODULE_AUTHOR("Sergio González Collado");

base-commit: de9c2c66ad8e787abec7c9d7eff4f8c3cdd28aed