RISC-V: repurpose riscv_isa_ext array in riscv_fill_hwcap()

In riscv_fill_hwcap() riscv_isa_ext array can be looped over, rather
than duplicating the list of extensions with individual
SET_ISA_EXT_MAP() usage. While at it, drop the statement-of-the-obvious
comments from the struct, rename uprop to something more suitable for
its new use & constify the members.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-dastardly-affiliate-4cf819dccde2@wendySigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/hwcap.h

@@ -55,7 +55,6 @@
 #define RISCV_ISA_EXT_ZIHPM		42
 
 #define RISCV_ISA_EXT_MAX		64
-#define RISCV_ISA_EXT_NAME_LEN_MAX	32
 
 #ifdef CONFIG_RISCV_M_MODE
 #define RISCV_ISA_EXT_SxAIA		RISCV_ISA_EXT_SMAIA
@@ -70,10 +69,8 @@
 unsigned long riscv_get_elf_hwcap(void);
 
 struct riscv_isa_ext_data {
-	/* Name of the extension displayed to userspace via /proc/cpuinfo */
-	char uprop[RISCV_ISA_EXT_NAME_LEN_MAX];
-	/* The logical ISA extension ID */
-	unsigned int isa_ext_id;
+	const unsigned int id;
+	const char *name;
 };
 
 extern const struct riscv_isa_ext_data riscv_isa_ext[];

arch/riscv/kernel/cpu.c

@@ -168,9 +168,10 @@ static void print_isa_ext(struct seq_file *f)
 {
 	for (int i = 0; i < riscv_isa_ext_count; i++) {
 		const struct riscv_isa_ext_data *edata = &riscv_isa_ext[i];
-		if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))
+		if (!__riscv_isa_extension_available(NULL, edata->id))
 			continue;
-		seq_printf(f, "_%s", edata->uprop);
+
+		seq_printf(f, "_%s", edata->name);
 	}
 }
 

arch/riscv/kernel/cpufeature.c

@@ -99,11 +99,10 @@ static bool riscv_isa_extension_check(int id)
 	return true;
 }
 
-#define __RISCV_ISA_EXT_DATA(UPROP, EXTID) \
-	{							\
-		.uprop = #UPROP,				\
-		.isa_ext_id = EXTID,				\
-	}
+#define __RISCV_ISA_EXT_DATA(_name, _id) {	\
+	.name = #_name,				\
+	.id = _id,				\
+}
 
 /*
  * The canonical order of ISA extension names in the ISA string is defined in
@@ -350,8 +349,8 @@ void __init riscv_fill_hwcap(void)
 
 #define SET_ISA_EXT_MAP(name, bit)							\
 			do {								\
-				if ((ext_end - ext == sizeof(name) - 1) &&		\
-				     !strncasecmp(ext, name, sizeof(name) - 1) &&	\
+				if ((ext_end - ext == strlen(name)) &&			\
+				     !strncasecmp(ext, name, strlen(name)) &&		\
 				     riscv_isa_extension_check(bit))			\
 					set_bit(bit, isainfo->isa);			\
 			} while (false)							\
@@ -366,20 +365,9 @@ void __init riscv_fill_hwcap(void)
 					set_bit(nr, isainfo->isa);
 				}
 			} else {
-				/* sorted alphabetically */
-				SET_ISA_EXT_MAP("smaia", RISCV_ISA_EXT_SMAIA);
-				SET_ISA_EXT_MAP("ssaia", RISCV_ISA_EXT_SSAIA);
-				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
-				SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
-				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
-				SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
-				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
-				SET_ISA_EXT_MAP("zba", RISCV_ISA_EXT_ZBA);
-				SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB);
-				SET_ISA_EXT_MAP("zbs", RISCV_ISA_EXT_ZBS);
-				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);
+				for (int i = 0; i < riscv_isa_ext_count; i++)
+					SET_ISA_EXT_MAP(riscv_isa_ext[i].name,
+							riscv_isa_ext[i].id);
 			}
 #undef SET_ISA_EXT_MAP
 		}