[PATCH] riscv: kprobes: Add test case for c.jal instruction simulation

[PATCH] riscv: kprobes: Add test case for c.jal instruction simulation

[Nam Cao]

Add test validating that kprobes correctly simulate the c.jal
instruction.

Signed-off-by: Nam Cao <namcao@linutronix.de>
---
the test fails without c.jal simulation patch:
https://lore.kernel.org/linux-riscv/20260627001939.3847-1-xiaofengmian@163.com/
---
 .../kernel/tests/kprobes/test-kprobes-asm.S   | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
index f16deee9e091..15e50934bbd7 100644
--- a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
+++ b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
@@ -179,6 +179,23 @@ test_kprobes_c_bnez_addr3:
 	ret
 SYM_FUNC_END(test_kprobes_c_bnez)
 
+#ifdef CONFIG_32BIT
+SYM_FUNC_START(test_kprobes_c_jal)
+	li a0, 0
+	mv a1, ra
+test_kprobes_c_jal_addr1:
+	c.jal 2f
+	ret
+1:	li a0, KPROBE_TEST_MAGIC_UPPER
+	ret
+test_kprobes_c_jal_addr2:
+2:	c.jal 1b
+	li a2, KPROBE_TEST_MAGIC_LOWER
+	add a0, a0, a2
+	jr a1
+SYM_FUNC_END(test_kprobes_c_jal)
+#endif
+
 #endif /* CONFIG_RISCV_ISA_C */
 
 .section .rodata
@@ -209,6 +226,10 @@ SYM_DATA_START(test_kprobes_addresses)
 	RISCV_PTR test_kprobes_c_bnez_addr1
 	RISCV_PTR test_kprobes_c_bnez_addr2
 	RISCV_PTR test_kprobes_c_bnez_addr3
+#ifdef CONFIG_32BIT
+	RISCV_PTR test_kprobes_c_jal_addr1
+	RISCV_PTR test_kprobes_c_jal_addr2
+#endif
 #endif /* CONFIG_RISCV_ISA_C */
 	RISCV_PTR 0
 SYM_DATA_END(test_kprobes_addresses)
@@ -226,6 +247,9 @@ SYM_DATA_START(test_kprobes_functions)
 	RISCV_PTR test_kprobes_c_jalr
 	RISCV_PTR test_kprobes_c_beqz
 	RISCV_PTR test_kprobes_c_bnez
+#ifdef CONFIG_32BIT
+	RISCV_PTR test_kprobes_c_jal
+#endif
 #endif /* CONFIG_RISCV_ISA_C */
 	RISCV_PTR 0
 SYM_DATA_END(test_kprobes_functions)
-- 
2.47.3

[PATCH] riscv: kprobes: Add test case for c.jal instruction simulation

[Nam Cao]

Add test validating that kprobes correctly simulate the c.jal
instruction.

Signed-off-by: Nam Cao <namcao@linutronix.de>
---
the test fails without c.jal simulation patch:
https://lore.kernel.org/linux-riscv/20260627001939.3847-1-xiaofengmian@163.com/
---
 .../kernel/tests/kprobes/test-kprobes-asm.S   | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
index f16deee9e091..15e50934bbd7 100644
--- a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
+++ b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
@@ -179,6 +179,23 @@ test_kprobes_c_bnez_addr3:
 	ret
 SYM_FUNC_END(test_kprobes_c_bnez)
 
+#ifdef CONFIG_32BIT
+SYM_FUNC_START(test_kprobes_c_jal)
+	li a0, 0
+	mv a1, ra
+test_kprobes_c_jal_addr1:
+	c.jal 2f
+	ret
+1:	li a0, KPROBE_TEST_MAGIC_UPPER
+	ret
+test_kprobes_c_jal_addr2:
+2:	c.jal 1b
+	li a2, KPROBE_TEST_MAGIC_LOWER
+	add a0, a0, a2
+	jr a1
+SYM_FUNC_END(test_kprobes_c_jal)
+#endif
+
 #endif /* CONFIG_RISCV_ISA_C */
 
 .section .rodata
@@ -209,6 +226,10 @@ SYM_DATA_START(test_kprobes_addresses)
 	RISCV_PTR test_kprobes_c_bnez_addr1
 	RISCV_PTR test_kprobes_c_bnez_addr2
 	RISCV_PTR test_kprobes_c_bnez_addr3
+#ifdef CONFIG_32BIT
+	RISCV_PTR test_kprobes_c_jal_addr1
+	RISCV_PTR test_kprobes_c_jal_addr2
+#endif
 #endif /* CONFIG_RISCV_ISA_C */
 	RISCV_PTR 0
 SYM_DATA_END(test_kprobes_addresses)
@@ -226,6 +247,9 @@ SYM_DATA_START(test_kprobes_functions)
 	RISCV_PTR test_kprobes_c_jalr
 	RISCV_PTR test_kprobes_c_beqz
 	RISCV_PTR test_kprobes_c_bnez
+#ifdef CONFIG_32BIT
+	RISCV_PTR test_kprobes_c_jal
+#endif
 #endif /* CONFIG_RISCV_ISA_C */
 	RISCV_PTR 0
 SYM_DATA_END(test_kprobes_functions)
-- 
2.47.3


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Re: [PATCH] riscv: kprobes: Add test case for c.jal instruction simulation

[Xiaofeng Yuan]

Hi Nam,

Thanks for the test case. Since c.jal is RV32-only, I haven't been able
to run it on real hardware. I tried running the full kprobes KUNIT test
suite under QEMU riscv32, but the test appears to hang before
completing -- even without the c.jal test case included.

I suspect this may be a QEMU emulation speed issue or a pre-existing
limitation of the test framework in an emulated environment.

Did you run this test on real hardware or in QEMU? If QEMU, any tips
on how to get it to complete?

Best regards,
Xiaofeng


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Re: [PATCH] riscv: kprobes: Add test case for c.jal instruction simulation

[Nam Cao]

Xiaofeng Yuan <xiaofengmian@163.com> writes:
> Thanks for the test case. Since c.jal is RV32-only, I haven't been able
> to run it on real hardware. I tried running the full kprobes KUNIT test
> suite under QEMU riscv32, but the test appears to hang before
> completing -- even without the c.jal test case included.

That is not supposed to happen.

> I suspect this may be a QEMU emulation speed issue or a pre-existing
> limitation of the test framework in an emulated environment.
>
> Did you run this test on real hardware or in QEMU? If QEMU, any tips
> on how to get it to complete?

I mostly run on QEMU, but I did run on real hardware a few times. I
never observed a problem.

If you want me to look into it, please share your qemu command and
kernel config file.

Nam

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