* [PATCH v2 6.6.y 1/2] Kunit to check the longest symbol length
2025-06-24 17:04 [PATCH v2 6.6.y 0/2] Kunit to check the longest symbol length Sergio González Collado
@ 2025-06-24 17:04 ` Sergio González Collado
2025-06-25 9:25 ` Miguel Ojeda
2025-06-25 14:07 ` Sasha Levin
2025-06-24 17:04 ` [PATCH v2 6.6.y 2/2] x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c Sergio González Collado
1 sibling, 2 replies; 6+ messages in thread
From: Sergio González Collado @ 2025-06-24 17:04 UTC (permalink / raw)
To: stable, Greg KH, Sasha Levin
Cc: Miguel Ojeda, Sergio González Collado,
Martin Rodriguez Reboredo, Shuah Khan, Rae Moar, David Gow,
Shuah Khan
commit c104c16073b7fdb3e4eae18f66f4009f6b073d6f upstream.
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@kernel.org/
[2] https://lore.kernel.org/lkml/20240605032120.3179157-1-song@kernel.org/
Link: https://lore.kernel.org/r/20250302221518.76874-1-sergio.collado@gmail.com
Tested-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Sergio González Collado <sergio.collado@gmail.com>
Link: https://github.com/Rust-for-Linux/linux/issues/504
Reviewed-by: Rae Moar <rmoar@google.com>
Acked-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <shuah@kernel.org>
---
arch/x86/tools/insn_decoder_test.c | 3 +-
lib/Kconfig.debug | 9 ++++
lib/Makefile | 2 +
lib/longest_symbol_kunit.c | 82 ++++++++++++++++++++++++++++++
4 files changed, 95 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)
int main(int argc, char **argv)
{
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e809b6d8bc53..1aae81c57b2c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2747,6 +2747,15 @@ 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 740109b6e2c8..b9d2577fbbe1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -402,6 +402,8 @@ obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
obj-$(CONFIG_STRCAT_KUNIT_TEST) += strcat_kunit.o
obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o
obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_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..e3c28ff1807f
--- /dev/null
+++ b/lib/longest_symbol_kunit.c
@@ -0,0 +1,82 @@
+// 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
+
+#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)
+
+/*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_LEN) ", 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", __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");
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 6.6.y 2/2] x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c
2025-06-24 17:04 [PATCH v2 6.6.y 0/2] Kunit to check the longest symbol length Sergio González Collado
2025-06-24 17:04 ` [PATCH v2 6.6.y 1/2] " Sergio González Collado
@ 2025-06-24 17:04 ` Sergio González Collado
2025-06-25 14:09 ` Sasha Levin
1 sibling, 1 reply; 6+ messages in thread
From: Sergio González Collado @ 2025-06-24 17:04 UTC (permalink / raw)
To: stable, Greg KH, Sasha Levin
Cc: Miguel Ojeda, Nathan Chancellor, Ingo Molnar, Shuah Khan,
Sergio González Collado
From: Nathan Chancellor <nathan@kernel.org>
commit f710202b2a45addea3dcdcd862770ecbaf6597ef upstream.
After commit c104c16073b7 ("Kunit to check the longest symbol length"),
there is a warning when building with clang because there is now a
definition of unlikely from compiler.h in tools/include/linux, which
conflicts with the one in the instruction decoder selftest:
arch/x86/tools/insn_decoder_test.c:15:9: warning: 'unlikely' macro redefined [-Wmacro-redefined]
Remove the second unlikely() definition, as it is no longer necessary,
clearing up the warning.
Fixes: c104c16073b7 ("Kunit to check the longest symbol length")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sergio González Collado <sergio.collado@gmail.com>
Link: https://lore.kernel.org/r/20250318-x86-decoder-test-fix-unlikely-redef-v1-1-74c84a7bf05b@kernel.org
---
arch/x86/tools/insn_decoder_test.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/tools/insn_decoder_test.c b/arch/x86/tools/insn_decoder_test.c
index 6c2986d2ad11..08cd913cbd4e 100644
--- a/arch/x86/tools/insn_decoder_test.c
+++ b/arch/x86/tools/insn_decoder_test.c
@@ -12,8 +12,6 @@
#include <stdarg.h>
#include <linux/kallsyms.h>
-#define unlikely(cond) (cond)
-
#include <asm/insn.h>
#include <inat.c>
#include <insn.c>
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread