riscv: cpufeature: extend riscv_cpufeature_patch_func to all ISA extensions

riscv_cpufeature_patch_func() currently only scans a limited set of
cpufeatures, explicitly defined with macros. Extend it to probe for all
ISA extensions.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230128172856.3814-5-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/errata_list.h

@@ -7,6 +7,7 @@
 
 #include <asm/alternative.h>
 #include <asm/csr.h>
+#include <asm/hwcap.h>
 #include <asm/vendorid_list.h>
 
 #ifdef CONFIG_ERRATA_SIFIVE
@@ -22,10 +23,6 @@
 #define	ERRATA_THEAD_NUMBER 3
 #endif
 
-#define	CPUFEATURE_SVPBMT 0
-#define	CPUFEATURE_ZICBOM 1
-#define	CPUFEATURE_NUMBER 2
-
 #ifdef __ASSEMBLY__
 
 #define ALT_INSN_FAULT(x)						\
@@ -55,7 +52,7 @@ asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID,	\
 #define ALT_SVPBMT(_val, prot)						\
 asm(ALTERNATIVE_2("li %0, 0\t\nnop",					\
 		  "li %0, %1\t\nslli %0,%0,%3", 0,			\
-			CPUFEATURE_SVPBMT, CONFIG_RISCV_ISA_SVPBMT,	\
+			RISCV_ISA_EXT_SVPBMT, CONFIG_RISCV_ISA_SVPBMT,	\
 		  "li %0, %2\t\nslli %0,%0,%4", THEAD_VENDOR_ID,	\
 			ERRATA_THEAD_PBMT, CONFIG_ERRATA_THEAD_PBMT)	\
 		: "=r"(_val)						\
@@ -129,7 +126,7 @@ asm volatile(ALTERNATIVE_2(						\
 	"add a0, a0, %0\n\t"						\
 	"2:\n\t"							\
 	"bltu a0, %2, 3b\n\t"						\
-	"nop", 0, CPUFEATURE_ZICBOM, CONFIG_RISCV_ISA_ZICBOM,		\
+	"nop", 0, RISCV_ISA_EXT_ZICBOM, CONFIG_RISCV_ISA_ZICBOM,	\
 	"mv a0, %1\n\t"							\
 	"j 2f\n\t"							\
 	"3:\n\t"							\

arch/riscv/kernel/cpufeature.c

@@ -276,59 +276,11 @@ void __init riscv_fill_hwcap(void)
 }
 
 #ifdef CONFIG_RISCV_ALTERNATIVE
-static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage)
-{
-	if (!IS_ENABLED(CONFIG_RISCV_ISA_SVPBMT))
-		return false;
-
-	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
-		return false;
-
-	return riscv_isa_extension_available(NULL, SVPBMT);
-}
-
-static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage)
-{
-	if (!IS_ENABLED(CONFIG_RISCV_ISA_ZICBOM))
-		return false;
-
-	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
-		return false;
-
-	if (!riscv_isa_extension_available(NULL, ZICBOM))
-		return false;
-
-	return true;
-}
-
-/*
- * Probe presence of individual extensions.
- *
- * This code may also be executed before kernel relocation, so we cannot use
- * addresses generated by the address-of operator as they won't be valid in
- * this context.
- * Tests, unless otherwise required, are to be added in alphabetical order.
- */
-static u32 __init_or_module cpufeature_probe(unsigned int stage)
-{
-	u32 cpu_req_feature = 0;
-
-	if (cpufeature_probe_svpbmt(stage))
-		cpu_req_feature |= BIT(CPUFEATURE_SVPBMT);
-
-	if (cpufeature_probe_zicbom(stage))
-		cpu_req_feature |= BIT(CPUFEATURE_ZICBOM);
-
-	return cpu_req_feature;
-}
-
 void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 						  struct alt_entry *end,
 						  unsigned int stage)
 {
-	u32 cpu_req_feature = cpufeature_probe(stage);
 	struct alt_entry *alt;
-	u32 tmp;
 
 	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
 		return;
@@ -336,18 +288,18 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 	for (alt = begin; alt < end; alt++) {
 		if (alt->vendor_id != 0)
 			continue;
-		if (alt->errata_id >= CPUFEATURE_NUMBER) {
+		if (alt->errata_id >= RISCV_ISA_EXT_MAX) {
-			WARN(1, "This feature id:%d is not in kernel cpufeature list",
+			WARN(1, "This extension id:%d is not in ISA extension list",
 				alt->errata_id);
 			continue;
 		}
 
-		tmp = (1U << alt->errata_id);
+		if (!__riscv_isa_extension_available(NULL, alt->errata_id))
-		if (cpu_req_feature & tmp) {
+			continue;
+
 		patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
 		riscv_alternative_fix_offsets(alt->old_ptr, alt->alt_len,
 					      alt->old_ptr - alt->alt_ptr);
 	}
-	}
 }
 #endif