[PATCH v2 8/8] RISC-V: always report presence of extenstions formerly part of the base ISA

[Conor Dooley]

From: Conor Dooley <conor.dooley at microchip.com>

These four extensions were part of the base ISA when the port was written
and are required by the kernel. There's not much that userspace can do
with this extra information, but there is no harm in reporting an ISA
string that closer resembles the current versions of the ISA
specifications either.

Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
---
Intentionally avoided your conditional tag here Drew.
---
 arch/riscv/include/asm/hwcap.h |  4 ++++
 arch/riscv/kernel/cpu.c        |  4 ++++
 arch/riscv/kernel/cpufeature.c | 10 ++++++++++
 3 files changed, 18 insertions(+)

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 9af793970855..302f06191056 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -44,6 +44,10 @@
 #define RISCV_ISA_EXT_ZIHINTPAUSE	32
 #define RISCV_ISA_EXT_SVNAPOT		33
 #define RISCV_ISA_EXT_ZICBOZ		34
+#define RISCV_ISA_EXT_ZICNTR		35
+#define RISCV_ISA_EXT_ZICSR		36
+#define RISCV_ISA_EXT_ZIFENCEI		37
+#define RISCV_ISA_EXT_ZIHPM		38
 
 #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 b0c3ec0f2f5b..958073bd3451 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -206,7 +206,11 @@ arch_initcall(riscv_cpuinfo_init);
 static struct riscv_isa_ext_data isa_ext_arr[] = {
 	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
 	__RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
+	__RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
+	__RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
+	__RISCV_ISA_EXT_DATA(zifencei, RISCV_ISA_EXT_ZIFENCEI),
 	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
+	__RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
 	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index bbf3cd203fad..1b43d1fb31e4 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -291,6 +291,16 @@ void __init riscv_fill_hwcap(void)
 #undef SET_ISA_EXT_MAP
 		}
 
+		/*
+		 * Linux requires the following extensions, as they were part of
+		 * the base ISA when the port & dt-bindings were upstreamed, so
+		 * we may as well always set them.
+		 */
+		set_bit(RISCV_ISA_EXT_ZICNTR, this_isa);
+		set_bit(RISCV_ISA_EXT_ZICSR, this_isa);
+		set_bit(RISCV_ISA_EXT_ZIFENCEI, this_isa);
+		set_bit(RISCV_ISA_EXT_ZIHPM, this_isa);
+
 		/*
 		 * All "okay" hart should have same isa. Set HWCAP based on
 		 * common capabilities of every "okay" hart, in case they don't
-- 
2.39.2