Re: [PATCH -next v13 05/19] riscv: Disable Vector Instructions for kernel itself

Conor Dooley
2023-01-25T21:52:23Z

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On Wed, Jan 25, 2023 at 02:20:42PM +0000, Andy Chiu wrote:
> Disable vector instructions execution for kernel mode at its entrances.
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Co-developed-by: Vincent Chen <vincent.chen@sifive.com>
> Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
> Co-developed-by: Han-Kuan Chen <hankuan.chen@sifive.com>
> Signed-off-by: Han-Kuan Chen <hankuan.chen@sifive.com>
> Co-developed-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>
> [vineetg: split off vecreg file clearing]
> Signed-off-by: Andy Chiu <andy.chiu@sifive.com>

That's a hilarious co-developed-by list for adding "| foo".
I can only assume that this is mostly related to the asm that was
removed by Vineet?

Either way:
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

> ---
> 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 99d38fdf8b18..e38676d9a0d6 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -77,10 +77,10 @@ _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 ea803c96eeff..7cc975ce619d 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
> --
> 2.17.1
>

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