On 9/24/24 11:23, Sergio González Collado wrote:
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.
This test can also help other efforts for longer symbol lenght,
Spelling - length
Can you explain what kind of tests does it run and how it is useful?
Include test output in the change log.
like [2].
[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>
Signed-off-by: Sergio González Collado <sergio.collado@xxxxxxxxx>
---
V1 -> V2: corrected CI tests. Added fix proposed at [3]
[3] https://lore.kernel.org/lkml/Y9ES4UKl%2F+DtvAVS@xxxxxxxxx/T/#m3ef0e12bb834d01ed1ebdcae12ef5f2add342077
---
V2 -> V3: updated base and added MODULE_DESCRIPTION() and MODULE_AUTHOR()
---
V3 -> V4: add x86 mantainers, add new reference.
---
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 bc8faa4509e1..09015e7e07f3 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2805,6 +2805,15 @@ 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
Can you add more detail why one would want to enable this test?
+
+ 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 773adf88af41..fc878e716825 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -389,6 +389,8 @@ 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: abf2050f51fdca0fd146388f83cddd95a57a008d
thanks,
-- Shuah
