Hello,
Please consider this series for 6.1.y
This patch series backports two patches that implement a test to verify that a symbol with KSYM_NAME_LEN of 512 can be read.
The first patch implements the test. This commit also includes a fix for the test x86/insn_decoder_test. In the case a symbol exceeds the symbol length limit, an error will happen:
arch/x86/tools/insn_decoder_test: error: malformed line 1152000: tBb_+0xf2>
..which overflowed by 10 characters reading this line:
ffffffff81458193: 74 3d je ffffffff814581d2 <_RNvXse_NtNtNtCshGpAVYOtgW1_4core4iter8adapters7flattenINtB5_13FlattenCompatINtNtB7_3map3MapNtNtNtBb_3str4iter5CharsNtB1v_17CharEscapeDefaultENtNtBb_4char13EscapeDefaultENtNtBb_3fmt5Debug3fmtBb_+0xf2>
The fix was proposed in [1] and initially mentioned at [2].
The second patch fixes a warning when building with clang because there was a definition of unlikely from compiler.h in tools/include/linux, which conflicted with the one in the instruction decoder selftest.
[1] https://lore.kernel.org/lkml/Y9ES4UKl%2F+DtvAVS@gmail.com/ [2] https://lore.kernel.org/lkml/320c4dba-9919-404b-8a26-a8af16be1845@app.fastma...
Thanks, Sergio
Nathan Chancellor (1): x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c
Sergio González Collado (1): Kunit to check the longest symbol length
arch/x86/tools/insn_decoder_test.c | 5 +- lib/Kconfig.debug | 9 ++++ lib/Makefile | 2 + lib/longest_symbol_kunit.c | 82 ++++++++++++++++++++++++++++++ 4 files changed, 95 insertions(+), 3 deletions(-) create mode 100644 lib/longest_symbol_kunit.c
base-commit: 58485ff1a74f6c5be9e7c6aafb7293e4337348e7
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 e5fbae585e52..1220e8113dad 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2600,6 +2600,15 @@ 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 6f1611d053e6..6ae66e13f319 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -389,6 +389,8 @@ obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable) obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o +obj-$(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");
[ Sasha's backport helper bot ]
Hi,
Summary of potential issues: ⚠️ Found follow-up fixes in mainline
The upstream commit SHA1 provided is correct: c104c16073b7fdb3e4eae18f66f4009f6b073d6f
Status in newer kernel trees: 6.15.y | Present (exact SHA1) 6.12.y | Present (different SHA1: 6ad4997209cb) 6.6.y | Not found
Found fixes commits: f710202b2a45 x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c
Note: The patch differs from the upstream commit: --- 1: c104c16073b7f ! 1: 8591a0ffe2b52 Kunit to check the longest symbol length @@ Metadata ## Commit message ## Kunit to check the longest symbol length
+ 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 @@ lib/Kconfig.debug: config FORTIFY_KUNIT_TEST depends on HAVE_HW_BREAKPOINT
## lib/Makefile ## -@@ lib/Makefile: 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 +@@ lib/Makefile: obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o + CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable) + obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o + obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o +obj-$(CONFIG_LONGEST_SYM_KUNIT_TEST) += longest_symbol_kunit.o +CFLAGS_longest_symbol_kunit.o += $(call cc-disable-warning, missing-prototypes)
---
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.1.y | Success | Success |
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 Link: https://lore.kernel.org/r/20250318-x86-decoder-test-fix-unlikely-redef-v1-1-... --- 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>
[ Sasha's backport helper bot ]
Hi,
✅ All tests passed successfully. No issues detected. No action required from the submitter.
The upstream commit SHA1 provided is correct: f710202b2a45addea3dcdcd862770ecbaf6597ef
WARNING: Author mismatch between patch and upstream commit: Backport author: sergio.collado@gmail.com Commit author: Nathan Chancellornathan@kernel.org
Status in newer kernel trees: 6.15.y | Present (exact SHA1) 6.12.y | Present (different SHA1: 9614c82c0ba2) 6.6.y | Not found
Note: The patch differs from the upstream commit: --- 1: f710202b2a45a ! 1: ffa5674e5ea27 x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c @@ Metadata ## Commit message ## x86/tools: Drop duplicate unlikely() definition in insn_decoder_test.c
+ 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 ---
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.6.y | Success | Success |
On Sun, Jun 22, 2025 at 06:00:08PM +0200, Sergio González Collado wrote:
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 Link: https://lore.kernel.org/r/20250318-x86-decoder-test-fix-unlikely-redef-v1-1-...
arch/x86/tools/insn_decoder_test.c | 2 -- 1 file changed, 2 deletions(-)
You forgot to sign-off on this change :(
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