linux-kernel - [PATCH v5 1/4] RISC-V: add Zbc extension detection

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Message-Id: <20230612210442.1805962-2-heiko.stuebner@vrull.eu>
Date:   Mon, 12 Jun 2023 23:04:39 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     palmer@...belt.com, paul.walmsley@...ive.com
Cc:     heiko@...ech.de, aou@...s.berkeley.edu,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        conor.dooley@...rochip.com, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        christoph.muellner@...ll.eu,
        Heiko Stuebner <heiko.stuebner@...ll.eu>
Subject: [PATCH v5 1/4] 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 a3d54cd14fca..754cd154eca5 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -523,6 +523,28 @@ 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 MMU
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index e6c288ac4581..e48ac52b9174 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -47,6 +47,7 @@
 #define RISCV_ISA_EXT_ZICBOZ		34
 #define RISCV_ISA_EXT_SMAIA		35
 #define RISCV_ISA_EXT_SSAIA		36
+#define RISCV_ISA_EXT_ZBC		37
 
 #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 637263f9a7b9..bbff98d4712a 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(zicboz, RISCV_ISA_EXT_ZICBOZ),
 	__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(smaia, RISCV_ISA_EXT_SMAIA),
 	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index de2d16300f69..f46281f1e439 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -261,6 +261,7 @@ void __init riscv_fill_hwcap(void)
 				SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
 				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("zicboz", RISCV_ISA_EXT_ZICBOZ);
 				SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
-- 
2.39.0