On Sun, Feb 2, 2025 at 2:24 PM Sergio González Collado <sergio.collado@xxxxxxxxx> wrote: > > The longest length of a symbol (KSYM_NAME_LEN) was increased to 512 > in the reference [1]. This patch adds kunit test suite to check the longest > symbol length. These tests verify that the longest symbol length defined > is supported. > > This test can also help other efforts for longer symbol length, > like [2]. > > The test suite defines one symbol with the longest possible length. > > The first test verify that functions with names of the created > symbol, can be called or not. > > The second test, verify that the symbols are created (or > not) in the kernel symbol table. > > [1] https://lore.kernel.org/lkml/20220802015052.10452-6-ojeda@xxxxxxxxxx/ > [2] https://lore.kernel.org/lkml/20240605032120.3179157-1-song@xxxxxxxxxx/ > > Tested-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx> > Reviewed-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> > Reviewed-by: Rae Moar <rmoar@xxxxxxxxxx> > Signed-off-by: Sergio González Collado <sergio.collado@xxxxxxxxx> > Link: https://github.com/Rust-for-Linux/linux/issues/504 Hello! Thanks for fixing the typo and this new version! This patch still does not apply cleanly in the Makefile for me. Have you rebased it on the kselftest/kunit branch? I also have a few more questions that I just noticed. Thanks! -Rae > --- > V7 -> V8: typo fixed & rebased > --- > V6 -> V7: rebased > --- > V5 -> V6: remove tests with symbols of length KSYM_NAME_LEN+1 > --- > V4 -> V5: fixed typo, added improved description > --- > V3 -> V4: add x86 mantainers, add new reference. > --- > V2 -> V3: updated base and added MODULE_DESCRIPTION() and MODULE_AUTHOR() > --- > V1 -> V2: corrected CI tests. Added fix proposed at [3] > > [3] https://lore.kernel.org/lkml/Y9ES4UKl%2F+DtvAVS@xxxxxxxxx/T/#m3ef0e12bb834d01ed1ebdcae12ef5f2add342077 > > The test execution should result in something like: > ``` > [20:04:35] =============== longest-symbol (4 subtests) ================ > [20:04:35] [PASSED] test_longest_symbol > [20:04:35] [PASSED] test_longest_symbol_kallsyms > [20:04:35] ================= [PASSED] longest-symbol ================== > [20:04:35] ============================================================ > [20:04:35] Testing complete. Ran 4 tests: passed: 4 > ``` > --- > arch/x86/tools/insn_decoder_test.c | 3 +- > lib/Kconfig.debug | 9 ++++ > lib/Makefile | 2 + > lib/longest_symbol_kunit.c | 84 ++++++++++++++++++++++++++++++ > 4 files changed, 97 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..6c2986d2ad11 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/kallsyms.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) I'm not too familiar with this test. I believe this would potentially make a symbol with a length that exceeds the KSYM_NAME_LEN. What is the intention for this line? > > int main(int argc, char **argv) > { > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 1af972a92d06..62d43aa9e8f0 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2838,6 +2838,15 @@ 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 d5cfc7afbbb8..e8fec9defec2 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -393,6 +393,8 @@ obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o > obj-$(CONFIG_CRC_KUNIT_TEST) += crc_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 These are the lines that are causing the patch to not apply cleanly. The change list that applies cleanly for me is: 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_CRC16_KUNIT_TEST) += crc16_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..2a2dd1151097 > --- /dev/null > +++ b/lib/longest_symbol_kunit.c > @@ -0,0 +1,84 @@ > +// 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 --kconfig_add CONFIG_CFI_CLANG=n > + * --kconfig_add CONFIG_MITIGATION_RETPOLINE=n > + */ > + > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt I don't believe you use this macro. Could probably be deleted. > + > +#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) I don't think you use this anymore with the new changes. Can probably be deleted. > + > +/*Generate a symbol whose name length is 511 */ > +#define LONGEST_SYM_NAME DDDDDI(g1h2i3j4k5l6m7n) > + > +#define RETURN_LONGEST_SYM 0xAAAAA > + > +noinline int LONGEST_SYM_NAME(void); > +noinline int LONGEST_SYM_NAME(void) > +{ > + return RETURN_LONGEST_SYM; > +} > + > +_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))); Should this error return __stringify(KSYM_NAME_LEN) instead of __stringify(KSYM_NAME) to give the maximum length? Also, I get an error because the length of LONGEST_SYM_NAME is 512. The error is produced by this code: https://elixir.bootlin.com/linux/v6.13.1/source/scripts/kallsyms.c#L152 and alerts if the symbol length is >= to KSYM_NAME_LEN. That is fine as long as that is the intention of this test to produce a warning. Or should this warning change to be "> KSYM_NAME_LEN" if usage of symbols that are the maximum length is allowed? > + > +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 kallsyms: 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 struct kunit_case longest_symbol_test_cases[] = { > + KUNIT_CASE(test_longest_symbol), > + KUNIT_CASE(test_longest_symbol_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: a86bf2283d2c9769205407e2b54777c03d012939 > -- > 2.39.2 >
