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Date:   Mon, 13 Jun 2022 02:47:31 +0800
From:   "Hongren (Zenithal) Zheng" <i@zenithal.me>
To:     Palmer Dabbelt <palmer@rivosinc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>
Cc:     Atish Patra <atishp@rivosinc.com>,
        Anup Patel <anup@brainfault.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>, linux-mm@kvack.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        linux-man@vger.kernel.org, Jiatai He <jiatai2021@iscas.ac.cn>,
        Heiko Stuebner <heiko@sntech.de>, Conor.Dooley@microchip.com
Subject: [PATCH v3 3/3] RISC-V: HWCAP: parse Bitmanip/Scalar Crypto HWCAP
 from DT
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One viable way to detect Zb/Zk HWCAP is from the DT binding.
No matter how the "M" mode things change, this way can
always be an auxiliary way to detect it.

Note that QEMU currently has "zba/zbb/zbc/zbs" in their device tree
riscv,isa

This also fixes the isa2hwcap way as using unsigned char
for long extension is not viable. Note that the tolower function
ensures functionality. For other no-hwcap extension (e.g. h, s, u),
or ("|") with 0 has no effect on hwcap.

Tested-by: Jiatai He <jiatai2021@iscas.ac.cn>
Signed-off-by: Hongren (Zenithal) Zheng <i@zenithal.me>
---
 arch/riscv/include/asm/elf.h   |  2 ++
 arch/riscv/include/asm/hwcap.h |  2 ++
 arch/riscv/kernel/cpufeature.c | 48 ++++++++++++++++++++++++++--------
 3 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index 14fc7342490b..cbf70c5ac1a4 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -65,7 +65,9 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
  * but it's not easy, and we've already done it here.
  */
 #define ELF_HWCAP	(elf_hwcap)
+#define ELF_HWCAP2	(elf_hwcap2)
 extern unsigned long elf_hwcap;
+extern unsigned long elf_hwcap2;
 
 /*
  * This yields a string that ld.so will use to load implementation
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 02c454a12683..ef0349c5d303 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -17,12 +17,14 @@
  * instruction set this cpu supports.
  */
 #define ELF_HWCAP		(elf_hwcap)
+#define ELF_HWCAP2		(elf_hwcap2)
 
 enum {
 	CAP_HWCAP = 1,
 };
 
 extern unsigned long elf_hwcap;
+extern unsigned long elf_hwcap2;
 
 #define RISCV_ISA_EXT_a		('a' - 'a')
 #define RISCV_ISA_EXT_c		('c' - 'a')
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 0c2638365ec2..40a5ab3962f0 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -23,6 +23,7 @@
 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
 
 unsigned long elf_hwcap __read_mostly;
+unsigned long elf_hwcap2 __read_mostly;
 
 /* Host ISA bitmap */
 static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
@@ -74,21 +75,39 @@ void __init riscv_fill_hwcap(void)
 	const char *isa;
 	char print_str[NUM_ALPHA_EXTS + 1];
 	int i, j;
-	static unsigned long isa2hwcap[256] = {0};
-
-	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
-	isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
-	isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
-	isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
-	isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
-	isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
+	static unsigned long isa2hwcap[RISCV_ISA_EXT_MAX] = {0};
+
+	/* HWCAP */
+	isa2hwcap[RISCV_ISA_EXT_i] = COMPAT_HWCAP_ISA_I;
+	isa2hwcap[RISCV_ISA_EXT_m] = COMPAT_HWCAP_ISA_M;
+	isa2hwcap[RISCV_ISA_EXT_a] = COMPAT_HWCAP_ISA_A;
+	isa2hwcap[RISCV_ISA_EXT_f] = COMPAT_HWCAP_ISA_F;
+	isa2hwcap[RISCV_ISA_EXT_d] = COMPAT_HWCAP_ISA_D;
+	isa2hwcap[RISCV_ISA_EXT_c] = COMPAT_HWCAP_ISA_C;
+	/* HWCAP2 */
+	isa2hwcap[RISCV_ISA_EXT_ZBA] = COMPAT_HWCAP2_ISA_ZBA;
+	isa2hwcap[RISCV_ISA_EXT_ZBB] = COMPAT_HWCAP2_ISA_ZBB;
+	isa2hwcap[RISCV_ISA_EXT_ZBC] = COMPAT_HWCAP2_ISA_ZBC;
+	isa2hwcap[RISCV_ISA_EXT_ZBS] = COMPAT_HWCAP2_ISA_ZBS;
+	isa2hwcap[RISCV_ISA_EXT_ZBKB] = COMPAT_HWCAP2_ISA_ZBKB;
+	isa2hwcap[RISCV_ISA_EXT_ZBKC] = COMPAT_HWCAP2_ISA_ZBKC;
+	isa2hwcap[RISCV_ISA_EXT_ZBKX] = COMPAT_HWCAP2_ISA_ZBKX;
+	isa2hwcap[RISCV_ISA_EXT_ZKNE] = COMPAT_HWCAP2_ISA_ZKND;
+	isa2hwcap[RISCV_ISA_EXT_ZKND] = COMPAT_HWCAP2_ISA_ZKNE;
+	isa2hwcap[RISCV_ISA_EXT_ZKNH] = COMPAT_HWCAP2_ISA_ZKNH;
+	isa2hwcap[RISCV_ISA_EXT_ZKSED] = COMPAT_HWCAP2_ISA_ZKSED;
+	isa2hwcap[RISCV_ISA_EXT_ZKSH] = COMPAT_HWCAP2_ISA_ZKSH;
+	isa2hwcap[RISCV_ISA_EXT_ZKR] = COMPAT_HWCAP2_ISA_ZKR;
+	isa2hwcap[RISCV_ISA_EXT_ZKT] = COMPAT_HWCAP2_ISA_ZKT;
 
 	elf_hwcap = 0;
+	elf_hwcap2 = 0;
 
 	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
 
 	for_each_of_cpu_node(node) {
 		unsigned long this_hwcap = 0;
+		unsigned long this_hwcap2 = 0;
 		DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
 		const char *temp;
 
@@ -187,15 +206,17 @@ void __init riscv_fill_hwcap(void)
 #define SET_ISA_EXT_MAP(name, bit)						\
 			do {							\
 				if ((ext_end - ext == sizeof(name) - 1) &&	\
-				     !memcmp(ext, name, sizeof(name) - 1))	\
+				     !memcmp(ext, name, sizeof(name) - 1)) {	\
+					this_hwcap2 |= isa2hwcap[bit];		\
 					set_bit(bit, this_isa);			\
+				}						\
 			} while (false)						\
 
 			if (unlikely(ext_err))
 				continue;
 			if (!ext_long) {
-				this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
-				set_bit(*ext - 'a', this_isa);
+				this_hwcap |= isa2hwcap[tolower(*ext) - 'a'];
+				set_bit(tolower(*ext) - 'a', this_isa);
 			} else {
 				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
@@ -246,6 +267,11 @@ void __init riscv_fill_hwcap(void)
 		else
 			elf_hwcap = this_hwcap;
 
+		if (elf_hwcap2)
+			elf_hwcap2 &= this_hwcap2;
+		else
+			elf_hwcap2 = this_hwcap2;
+
 		if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
 			bitmap_copy(riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
 		else
-- 
2.35.1