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[v3,01/12] RISC-V: add helper function to read the vector VLEN

Message ID 20231205092801.1335-2-jerry.shih@sifive.com
State New
Headers show
Series RISC-V: provide some accelerated cryptography implementations using vector extensions | expand

Commit Message

Jerry Shih Dec. 5, 2023, 9:27 a.m. UTC 
From: Heiko Stuebner <heiko.stuebner@vrull.eu>

VLEN describes the length of each vector register and some instructions
need specific minimal VLENs to work correctly.

The vector code already includes a variable riscv_v_vsize that contains
the value of "32 vector registers with vlenb length" that gets filled
during boot. vlenb is the value contained in the CSR_VLENB register and
the value represents "VLEN / 8".

So add riscv_vector_vlen() to return the actual VLEN value for in-kernel
users when they need to check the available VLEN.

Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jerry Shih <jerry.shih@sifive.com>
---
 arch/riscv/include/asm/vector.h | 11 +++++++++++
 1 file changed, 11 insertions(+)
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Patch

diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index 9fb2dea66abd..1fd3e5510b64 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -244,4 +244,15 @@  void kernel_vector_allow_preemption(void);
 #define kernel_vector_allow_preemption()	do {} while (0)
 #endif
 
+/*
+ * Return the implementation's vlen value.
+ *
+ * riscv_v_vsize contains the value of "32 vector registers with vlenb length"
+ * so rebuild the vlen value in bits from it.
+ */
+static inline int riscv_vector_vlen(void)
+{
+	return riscv_v_vsize / 32 * 8;
+}
+
 #endif /* ! __ASM_RISCV_VECTOR_H */