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Subject[RFC PATCH V3 07/11] riscv: Reset vector register
Date
From: Guo Ren <guoren@linux.alibaba.com>

Reset vector registers at boot-time and disable vector instructions
execution for kernel mode.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
arch/riscv/kernel/entry.S | 2 +-
arch/riscv/kernel/head.S | 49 +++++++++++++++++++++++++++++++++++++--
2 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index bad4d85b5e91..449e0a7ef115 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -76,7 +76,7 @@ _save_context:
* Disable the FPU to detect illegal usage of floating point in kernel
* space.
*/
- li t0, SR_SUM | SR_FS
+ li t0, SR_SUM | SR_FS | SR_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 271860fc2c3f..b40d8ec7ad5d 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -72,10 +72,10 @@ _start_kernel:
.option pop

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

#ifdef CONFIG_SMP
@@ -290,6 +290,51 @@ ENTRY(reset_regs)
csrw fcsr, 0
/* note that the caller must clear SR_FS */
#endif /* CONFIG_FPU */
+
+#ifdef CONFIG_VECTOR
+ csrr t0, CSR_MISA
+ li t1, (COMPAT_HWCAP_ISA_V >> 16)
+ slli t1, t1, 16
+ and t0, t0, t1
+ beqz t0, .Lreset_regs_done
+
+ li t1, SR_VS
+ csrs CSR_STATUS, t1
+ vmv.v.i v0, 0
+ vmv.v.i v1, 0
+ vmv.v.i v2, 0
+ vmv.v.i v3, 0
+ vmv.v.i v4, 0
+ vmv.v.i v5, 0
+ vmv.v.i v6, 0
+ vmv.v.i v7, 0
+ vmv.v.i v8, 0
+ vmv.v.i v9, 0
+ vmv.v.i v10, 0
+ vmv.v.i v11, 0
+ vmv.v.i v12, 0
+ vmv.v.i v13, 0
+ vmv.v.i v14, 0
+ vmv.v.i v15, 0
+ vmv.v.i v16, 0
+ vmv.v.i v17, 0
+ vmv.v.i v18, 0
+ vmv.v.i v19, 0
+ vmv.v.i v20, 0
+ vmv.v.i v21, 0
+ vmv.v.i v22, 0
+ vmv.v.i v23, 0
+ vmv.v.i v24, 0
+ vmv.v.i v25, 0
+ vmv.v.i v26, 0
+ vmv.v.i v27, 0
+ vmv.v.i v28, 0
+ vmv.v.i v29, 0
+ vmv.v.i v30, 0
+ vmv.v.i v31, 0
+ /* note that the caller must clear SR_VS */
+#endif /* CONFIG_VECTOR */
+
.Lreset_regs_done:
ret
END(reset_regs)
--
2.17.0
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