Re: [PATCH -next v19 06/24] riscv: Disable Vector Instructions for kernel itself

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On Tue, 09 May 2023 03:30:15 PDT (-0700), andy.chiu@xxxxxxxxxx wrote:
From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

Disable vector instructions execution for kernel mode at its entrances.
This helps find illegal uses of vector in the kernel space, which is
similar to the fpu.

Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Co-developed-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
Signed-off-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
Co-developed-by: Han-Kuan Chen <hankuan.chen@xxxxxxxxxx>
Signed-off-by: Han-Kuan Chen <hankuan.chen@xxxxxxxxxx>
Co-developed-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
Signed-off-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
Signed-off-by: Vineet Gupta <vineetg@xxxxxxxxxxxx>
Signed-off-by: Andy Chiu <andy.chiu@xxxxxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Heiko Stuebner <heiko.stuebner@xxxxxxxx>
Tested-by: Heiko Stuebner <heiko.stuebner@xxxxxxxx>
---
Changelog V19:
 - Add description in commit msg (Heiko's suggestion on v17)

 arch/riscv/kernel/entry.S |  6 +++---
 arch/riscv/kernel/head.S  | 12 ++++++------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 3fbb100bc9e4..e9ae284a55c1 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -48,10 +48,10 @@ _save_context:
 	 * Disable user-mode memory access as it should only be set in the
 	 * actual user copy routines.
 	 *
-	 * Disable the FPU to detect illegal usage of floating point in kernel
-	 * space.
+	 * Disable the FPU/Vector to detect illegal usage of floating point
+	 * or vector in kernel space.
 	 */
-	li t0, SR_SUM | SR_FS
+	li t0, SR_SUM | SR_FS_VS

 	REG_L s0, TASK_TI_USER_SP(tp)
 	csrrc s1, CSR_STATUS, t0
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 3fd6a4bd9c3e..e16bb2185d55 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -140,10 +140,10 @@ secondary_start_sbi:
 	.option pop

 	/*
-	 * Disable FPU to detect illegal usage of
-	 * floating point in kernel space
+	 * Disable FPU & VECTOR to detect illegal usage of
+	 * floating point or vector in kernel space
 	 */
-	li t0, SR_FS
+	li t0, SR_FS_VS
 	csrc CSR_STATUS, t0

 	/* Set trap vector to spin forever to help debug */
@@ -234,10 +234,10 @@ pmp_done:
 .option pop

 	/*
-	 * Disable FPU to detect illegal usage of
-	 * floating point in kernel space
+	 * Disable FPU & VECTOR to detect illegal usage of
+	 * floating point or vector in kernel space
 	 */
-	li t0, SR_FS
+	li t0, SR_FS_VS
 	csrc CSR_STATUS, t0

 #ifdef CONFIG_RISCV_BOOT_SPINWAIT

Reviewed-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>



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