linux-kernel - [PATCH RFC v3 03/16] RISC-V: add Zbc extension detection

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Message-Id: <20230313191302.580787-4-heiko.stuebner@vrull.eu>
Date:   Mon, 13 Mar 2023 20:12:49 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     palmer@...osinc.com
Cc:     greentime.hu@...ive.com, conor@...nel.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        christoph.muellner@...ll.eu, heiko@...ech.de
Subject: [PATCH RFC v3 03/16] RISC-V: add Zbc extension detection

From: Heiko Stuebner <heiko.stuebner@...ll.eu>

Add handling for Zbc extension.

Zbc provides instruction for carry-less multiplication.

Signed-off-by: Heiko Stuebner <heiko.stuebner@...ll.eu>
---
 arch/riscv/Kconfig             | 22 ++++++++++++++++++++++
 arch/riscv/include/asm/hwcap.h |  1 +
 arch/riscv/kernel/cpu.c        |  1 +
 arch/riscv/kernel/cpufeature.c |  1 +
 4 files changed, 25 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index eb691dd8ee4f..8d83935f77d2 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -459,6 +459,28 @@ config RISCV_ISA_ZBB
 
 	   If you don't know what to do here, say Y.
 
+config TOOLCHAIN_HAS_ZBC
+	bool
+	default y
+	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbc)
+	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
+	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on AS_IS_GNU
+
+config RISCV_ISA_ZBC
+	bool "Zbc extension support for bit manipulation instructions"
+	depends on TOOLCHAIN_HAS_ZBC
+	depends on !XIP_KERNEL && MMU
+	default y
+	help
+	   Adds support to dynamically detect the presence of the ZBC
+	   extension (carry-less multiplication) and enable its usage.
+
+	   The Zbc extension provides instructions clmul, clmulh and clmulr
+	   to accelerate carry-less multiplications.
+
+	   If you don't know what to do here, say Y.
+
 config RISCV_ISA_ZICBOM
 	bool "Zicbom extension support for non-coherent DMA operation"
 	depends on !XIP_KERNEL && MMU
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index ee73341bb1d4..92f234c6cb4c 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -43,6 +43,7 @@
 #define RISCV_ISA_EXT_ZBB		30
 #define RISCV_ISA_EXT_ZICBOM		31
 #define RISCV_ISA_EXT_ZIHINTPAUSE	32
+#define RISCV_ISA_EXT_ZBC		33
 
 #define RISCV_ISA_EXT_MAX		64
 #define RISCV_ISA_EXT_NAME_LEN_MAX	32
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 8400f0cc9704..5d47a0c75c69 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -188,6 +188,7 @@ static struct riscv_isa_ext_data isa_ext_arr[] = {
 	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
 	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
+	__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
 	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index e6d53e2e672b..c9099694b5bb 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -228,6 +228,7 @@ void __init riscv_fill_hwcap(void)
 				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
 				SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB);
+				SET_ISA_EXT_MAP("zbc", RISCV_ISA_EXT_ZBC);
 				SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
 				SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
 			}
-- 
2.39.0