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[v3,09/14] RISC-V: add U-type imm parsing to insn.h header

Message ID 20221130225614.1594256-10-heiko@sntech.de
State New
Headers show
Series Zbb string optimizations and call support in alternatives | expand

Commit Message

Heiko Stübner Nov. 30, 2022, 10:56 p.m. UTC 
From: Heiko Stuebner <heiko.stuebner@vrull.eu>

Similar to other existing types, allow extracting the immediate
for a U-type instruction.

U-type immediates are special in that regard, that the value
in the instruction in bits [31:12] already represents the same
bits of the immediate, so no shifting is required.

U-type immediates are for example used in the auipc instruction,
so these constants make it easier to parse such instructions.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
---
 arch/riscv/include/asm/insn.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
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Patch

diff --git a/arch/riscv/include/asm/insn.h b/arch/riscv/include/asm/insn.h
index 50c899cf4de5..21ec817abec1 100644
--- a/arch/riscv/include/asm/insn.h
+++ b/arch/riscv/include/asm/insn.h
@@ -34,6 +34,15 @@ 
 #define RV_J_IMM_11_MASK	GENMASK(0, 0)
 #define RV_J_IMM_19_12_MASK	GENMASK(7, 0)
 
+/*
+ * U-type IMMs contain the upper 20bits [31:20] of an immediate with
+ * the rest filled in by zeros, so no shifting required. Similarly,
+ * bit31 contains the signed state, so no sign extension necessary.
+ */
+#define RV_U_IMM_SIGN_OPOFF	31
+#define RV_U_IMM_31_12_OPOFF	0
+#define RV_U_IMM_31_12_MASK	GENMASK(31, 12)
+
 /* The bit field of immediate value in B-type instruction */
 #define RV_B_IMM_SIGN_OPOFF	31
 #define RV_B_IMM_10_5_OPOFF	25
@@ -235,6 +244,10 @@  static __always_inline bool riscv_insn_is_branch(u32 code)
 #define RV_X(X, s, mask)  (((X) >> (s)) & (mask))
 #define RVC_X(X, s, mask) RV_X(X, s, mask)
 
+#define RV_EXTRACT_UTYPE_IMM(x) \
+	({typeof(x) x_ = (x); \
+	(RV_X(x_, RV_U_IMM_31_12_OPOFF, RV_U_IMM_31_12_MASK)); })
+
 #define RV_EXTRACT_JTYPE_IMM(x) \
 	({typeof(x) x_ = (x); \
 	(RV_X(x_, RV_J_IMM_10_1_OPOFF, RV_J_IMM_10_1_MASK) << RV_J_IMM_10_1_OFF) | \