linux-kernel - [PATCH RFC v2 03/16] RISC-V: add Zbc extension detection

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Date:   Tue, 28 Feb 2023 01:05:31 +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,
        Heiko Stuebner <heiko.stuebner@...ll.eu>
Subject: [PATCH RFC v2 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 179e52c7e531..471f0f42855d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -450,6 +450,28 @@ 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 TOOLCHAIN_HAS_ZICBOM
 	bool
 	default y
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index c8c69b49f0ad..8673c2146d20 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -60,6 +60,7 @@ enum riscv_isa_ext_id {
 	RISCV_ISA_EXT_SVINVAL,
 	RISCV_ISA_EXT_SVPBMT,
 	RISCV_ISA_EXT_ZBB,
+	RISCV_ISA_EXT_ZBC,
 	RISCV_ISA_EXT_ZICBOM,
 	RISCV_ISA_EXT_ZIHINTPAUSE,
 	RISCV_ISA_EXT_ID_MAX
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 af201b2b8933..696b39de7e09 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -234,6 +234,7 @@ 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