[PATCH v2] riscv: Add kprobes KUnit test
Alexandre Ghiti
alex at ghiti.fr
Wed May 14 01:22:03 PDT 2025
On 13/05/2025 17:16, Nam Cao wrote:
> Add KUnit test for riscv kprobes, mostly for simulated instructions. The
> test install kprobes into multiple sample functions, and check that these
> functions still return the expected magic value.
>
> This test can detect some kprobe bugs reported in the past (in Link:).
>
> Link: https://lore.kernel.org/linux-riscv/20241119111056.2554419-1-namcao@linutronix.de/
> Link: https://lore.kernel.org/stable/c7e463c0-8cad-4f4e-addd-195c06b7b6de@iscas.ac.cn/
> Link: https://lore.kernel.org/linux-riscv/20230829182500.61875-1-namcaov@gmail.com/
> Signed-off-by: Nam Cao <namcao at linutronix.de>
> ---
> v2: rewrite the auipc test so that clang can compile
>
> arch/riscv/kernel/tests/Kconfig.debug | 12 +
> arch/riscv/kernel/tests/Makefile | 1 +
> arch/riscv/kernel/tests/kprobes/Makefile | 1 +
> .../kernel/tests/kprobes/test-kprobes-asm.S | 229 ++++++++++++++++++
> .../riscv/kernel/tests/kprobes/test-kprobes.c | 56 +++++
> .../riscv/kernel/tests/kprobes/test-kprobes.h | 24 ++
> 6 files changed, 323 insertions(+)
> create mode 100644 arch/riscv/kernel/tests/kprobes/Makefile
> create mode 100644 arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> create mode 100644 arch/riscv/kernel/tests/kprobes/test-kprobes.c
> create mode 100644 arch/riscv/kernel/tests/kprobes/test-kprobes.h
>
> diff --git a/arch/riscv/kernel/tests/Kconfig.debug b/arch/riscv/kernel/tests/Kconfig.debug
> index 78cea5d2c270..5db4df44279e 100644
> --- a/arch/riscv/kernel/tests/Kconfig.debug
> +++ b/arch/riscv/kernel/tests/Kconfig.debug
> @@ -30,6 +30,18 @@ config RISCV_MODULE_LINKING_KUNIT
>
> If unsure, say N.
>
> +config RISCV_KPROBES_KUNIT
> + bool "KUnit test for riscv kprobes" if !KUNIT_ALL_TESTS
> + depends on KUNIT
> + depends on KPROBES
> + default KUNIT_ALL_TESTS
> + help
> + Enable testing for riscv kprobes. Useful for riscv and/or kprobes
> + development. The test verifies that kprobes do not change the behaviour
> + of some sample functions.
> +
> + If unsure, say N.
> +
> endif # RUNTIME_TESTING_MENU
>
> endmenu # "arch/riscv/kernel runtime Testing"
> diff --git a/arch/riscv/kernel/tests/Makefile b/arch/riscv/kernel/tests/Makefile
> index 7d6c76cffe20..407e7e6c28dc 100644
> --- a/arch/riscv/kernel/tests/Makefile
> +++ b/arch/riscv/kernel/tests/Makefile
> @@ -1 +1,2 @@
> obj-$(CONFIG_RISCV_MODULE_LINKING_KUNIT) += module_test/
> +obj-$(CONFIG_RISCV_KPROBES_KUNIT) += kprobes/
> diff --git a/arch/riscv/kernel/tests/kprobes/Makefile b/arch/riscv/kernel/tests/kprobes/Makefile
> new file mode 100644
> index 000000000000..4cb6c66a98e8
> --- /dev/null
> +++ b/arch/riscv/kernel/tests/kprobes/Makefile
> @@ -0,0 +1 @@
> +obj-y += test-kprobes.o test-kprobes-asm.o
> diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> new file mode 100644
> index 000000000000..b951d0f12482
> --- /dev/null
> +++ b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> @@ -0,0 +1,229 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +
> +#include <linux/linkage.h>
> +#include <asm/asm.h>
> +#include "test-kprobes.h"
> +
> +SYM_FUNC_START(test_kprobes_add)
> + li a1, KPROBE_TEST_MAGIC_UPPER
> + li a2, KPROBE_TEST_MAGIC_LOWER
> +test_kprobes_add_addr1:
> + add a1, a1, a2
> +test_kprobes_add_addr2:
> + add a0, a1, x0
> + ret
> +SYM_FUNC_END(test_kprobes_add)
> +
> +SYM_FUNC_START(test_kprobes_jal)
> + li a0, 0
> + mv a1, ra
> + .option push
> + .option norvc
> +test_kprobes_jal_addr1:
> + jal x0, 2f
> + ret
> + .option pop
> +1: li a0, KPROBE_TEST_MAGIC_UPPER
> + ret
> + .option push
> + .option norvc
> +test_kprobes_jal_addr2:
> +2: jal 1b
> + .option pop
> + li a2, KPROBE_TEST_MAGIC_LOWER
> + add a0, a0, a2
> + jr a1
> +SYM_FUNC_END(test_kprobes_jal)
> +
> +SYM_FUNC_START(test_kprobes_jalr)
> + la a0, 1f
> + mv a1, ra
> + .option push
> + .option norvc
> +test_kprobes_jalr_addr:
> + jalr a0
> + .option pop
> + li t0, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, t0
> + jr a1
> +1: li a0, KPROBE_TEST_MAGIC_LOWER
> + ret
> +SYM_FUNC_END(test_kprobes_jalr)
> +
> +SYM_FUNC_START(test_kprobes_auipc)
> +test_kprobes_auipc_addr:
> + auipc a0, KPROBE_TEST_MAGIC_LOWER
> + la a1, test_kprobes_auipc_addr
> + sub a0, a0, a1
> + srli a0, a0, 12
> + li a1, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, a1
> + ret
> +SYM_FUNC_END(test_kprobes_auipc)
> +
> +SYM_FUNC_START(test_kprobes_branch)
> + .option push
> + .option norvc
> + li a0, 0
> + li a1, 1
> + li a2, 2
> +test_kprobes_branch_addr1:
> + beqz a0, 1f
> + ret
> +1:
> +test_kprobes_branch_addr2:
> + beqz a1, 3f
> +test_kprobes_branch_addr3:
> + bnez a0, 3f
> +test_kprobes_branch_addr4:
> + bnez a2, 1f
> + ret
> +1:
> +test_kprobes_branch_addr5:
> + bge a1, a2, 3f
> +test_kprobes_branch_addr6:
> + bge a2, a1, 2f
> + ret
> +1:
> + li t0, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, t0
> + ret
> +2:
> +test_kprobes_branch_addr7:
> + blt a2, a1, 3f
> + li a0, KPROBE_TEST_MAGIC_LOWER
> +test_kprobes_branch_addr8:
> + blt a1, a2, 1b
> +3:
> + li a0, 0
> + ret
> + .option pop
> +SYM_FUNC_END(test_kprobes_branch)
> +
> +#ifdef CONFIG_RISCV_ISA_C
> +
> +SYM_FUNC_START(test_kprobes_c_j)
> + li a0, 0
> +test_kprobes_branch_c_j_addr1:
> + c.j 2f
> +1:
> + li a1, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, a1
> + ret
> +2: li a0, KPROBE_TEST_MAGIC_LOWER
> +test_kprobes_branch_c_j_addr2:
> + c.j 1b
> +SYM_FUNC_END(test_kprobes_c_j)
> +
> +SYM_FUNC_START(test_kprobes_c_jr)
> + la a0, 2f
> +test_kprobes_c_jr_addr1:
> + c.jr a0
> + ret
> +1: li a1, KPROBE_TEST_MAGIC_LOWER
> + add a0, a0, a1
> + ret
> +2:
> + li a0, KPROBE_TEST_MAGIC_UPPER
> + la a1, 1b
> +test_kprobes_c_jr_addr2:
> + c.jr a1
> +SYM_FUNC_END(test_kprobes_c_jr)
> +
> +SYM_FUNC_START(test_kprobes_c_jalr)
> + mv a1, ra
> + la a0, 1f
> +test_kprobes_c_jalr_addr:
> + c.jalr a0
> + li a2, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, a2
> + jr a1
> +1: li a0, KPROBE_TEST_MAGIC_LOWER
> + ret
> +SYM_FUNC_END(test_kprobes_c_jalr)
> +
> +SYM_FUNC_START(test_kprobes_c_beqz)
> + li a0, 0
> + li a1, 1
> +test_kprobes_c_beqz_addr1:
> + c.beqz a0, 2f
> + ret
> +1: li a1, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, a1
> + ret
> +test_kprobes_c_beqz_addr2:
> +2: c.beqz a1, 3f
> + li a0, KPROBE_TEST_MAGIC_LOWER
> + mv a1, x0
> +test_kprobes_c_beqz_addr3:
> + c.beqz a1, 1b
> +3: li a0, 0
> + ret
> +SYM_FUNC_END(test_kprobes_c_beqz)
> +
> +SYM_FUNC_START(test_kprobes_c_bnez)
> + li a0, 0
> + li a1, 1
> +test_kprobes_c_bnez_addr1:
> + c.bnez a1, 2f
> + ret
> +1: li a1, KPROBE_TEST_MAGIC_UPPER
> + add a0, a0, a1
> + ret
> +test_kprobes_c_bnez_addr2:
> +2: c.bnez a0, 3f
> + li a0, KPROBE_TEST_MAGIC_LOWER
> +test_kprobes_c_bnez_addr3:
> + c.bnez a0, 1b
> +3: li a0, 0
> + ret
> +SYM_FUNC_END(test_kprobes_c_bnez)
> +
> +#endif /* CONFIG_RISCV_ISA_C */
> +
> +SYM_DATA_START(test_kprobes_addresses)
> + RISCV_PTR test_kprobes_add_addr1
> + RISCV_PTR test_kprobes_add_addr2
> + RISCV_PTR test_kprobes_jal_addr1
> + RISCV_PTR test_kprobes_jal_addr2
> + RISCV_PTR test_kprobes_jalr_addr
> + RISCV_PTR test_kprobes_auipc_addr
> + RISCV_PTR test_kprobes_branch_addr1
> + RISCV_PTR test_kprobes_branch_addr2
> + RISCV_PTR test_kprobes_branch_addr3
> + RISCV_PTR test_kprobes_branch_addr4
> + RISCV_PTR test_kprobes_branch_addr5
> + RISCV_PTR test_kprobes_branch_addr6
> + RISCV_PTR test_kprobes_branch_addr7
> + RISCV_PTR test_kprobes_branch_addr8
> +#ifdef CONFIG_RISCV_ISA_C
> + RISCV_PTR test_kprobes_branch_c_j_addr1
> + RISCV_PTR test_kprobes_branch_c_j_addr2
> + RISCV_PTR test_kprobes_c_jr_addr1
> + RISCV_PTR test_kprobes_c_jr_addr2
> + RISCV_PTR test_kprobes_c_jalr_addr
> + RISCV_PTR test_kprobes_c_beqz_addr1
> + RISCV_PTR test_kprobes_c_beqz_addr2
> + RISCV_PTR test_kprobes_c_beqz_addr3
> + RISCV_PTR test_kprobes_c_bnez_addr1
> + RISCV_PTR test_kprobes_c_bnez_addr2
> + RISCV_PTR test_kprobes_c_bnez_addr3
> +#endif /* CONFIG_RISCV_ISA_C */
> + RISCV_PTR 0
> +SYM_DATA_END(test_kprobes_addresses)
> +
> +SYM_DATA_START(test_kprobes_functions)
> + RISCV_PTR test_kprobes_add
> + RISCV_PTR test_kprobes_jal
> + RISCV_PTR test_kprobes_jalr
> + RISCV_PTR test_kprobes_auipc
> + RISCV_PTR test_kprobes_branch
> +#ifdef CONFIG_RISCV_ISA_C
> + RISCV_PTR test_kprobes_c_j
> + RISCV_PTR test_kprobes_c_jr
> + RISCV_PTR test_kprobes_c_jalr
> + RISCV_PTR test_kprobes_c_beqz
> + RISCV_PTR test_kprobes_c_bnez
> +#endif /* CONFIG_RISCV_ISA_C */
> + RISCV_PTR 0
> +SYM_DATA_END(test_kprobes_functions)
> diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes.c b/arch/riscv/kernel/tests/kprobes/test-kprobes.c
> new file mode 100644
> index 000000000000..6f6cdfbf5a95
> --- /dev/null
> +++ b/arch/riscv/kernel/tests/kprobes/test-kprobes.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +#include <linux/kernel.h>
> +#include <linux/kprobes.h>
> +#include <kunit/test.h>
> +#include "test-kprobes.h"
> +
> +static int kprobe_dummy_handler(struct kprobe *kp, struct pt_regs *regs)
> +{
> + return 0;
> +}
> +
> +static void test_kprobe_riscv(struct kunit *test)
> +{
> + unsigned int num_kprobe = 0;
> + long (*func)(void);
> + struct kprobe *kp;
> + int i;
> +
> + while (test_kprobes_addresses[num_kprobe])
> + num_kprobe++;
> +
> + kp = kcalloc(num_kprobe, sizeof(*kp), GFP_KERNEL);
> + KUNIT_EXPECT_TRUE(test, kp);
> + if (!kp)
> + return;
> +
> + for (i = 0; i < num_kprobe; ++i) {
> + kp[i].addr = test_kprobes_addresses[i];
> + kp[i].pre_handler = kprobe_dummy_handler;
> + KUNIT_EXPECT_EQ(test, 0, register_kprobe(&kp[i]));
Will kp be freed if the test fails?
> + }
> +
> + for (i = 0;; ++i) {
> + func = test_kprobes_functions[i];
> + if (!func)
> + break;
> + KUNIT_EXPECT_EQ_MSG(test, KPROBE_TEST_MAGIC, func(), "function %d broken", i);
> + }
> +
> + for (i = 0; i < num_kprobe; ++i)
> + unregister_kprobe(&kp[i]);
> + kfree(kp);
> +}
> +
> +static struct kunit_case kprobes_testcases[] = {
> + KUNIT_CASE(test_kprobe_riscv),
> + {}
> +};
> +
> +static struct kunit_suite kprobes_test_suite = {
> + .name = "kprobes_test_riscv",
> + .test_cases = kprobes_testcases,
> +};
> +
> +kunit_test_suites(&kprobes_test_suite);
> diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes.h b/arch/riscv/kernel/tests/kprobes/test-kprobes.h
> new file mode 100644
> index 000000000000..3886ab491ecb
> --- /dev/null
> +++ b/arch/riscv/kernel/tests/kprobes/test-kprobes.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +#ifndef TEST_KPROBES_H
> +#define TEST_KPROBES_H
> +
> +/*
> + * The magic value that all the functions in the test_kprobes_functions array return. The test
> + * installs kprobes into these functions, and verify that the functions still correctly return this
> + * value.
> + */
> +#define KPROBE_TEST_MAGIC 0xcafebabe
> +#define KPROBE_TEST_MAGIC_LOWER 0x0000babe
> +#define KPROBE_TEST_MAGIC_UPPER 0xcafe0000
> +
> +#ifndef __ASSEMBLY__
> +
> +/* array of addresses to install kprobes */
> +extern void *test_kprobes_addresses[];
> +
> +/* array of functions that return KPROBE_TEST_MAGIC */
> +extern long (*test_kprobes_functions[])(void);
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* TEST_KPROBES_H */
Other than that, you can add:
Tested-by: Alexandre Ghiti <alexghiti at rivosinc.com>
I'll merge it for 6.16.
Thanks for adding new tests, KUnit tests do not run yet in the CI but
I'll add them soon!
Alex
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