RISC-V: add single letter extensions to riscv_isa_ext

So that riscv_fill_hwcap() can use riscv_isa_ext to probe for single
letter extensions, add them to it.
As a result, what gets spat out in /proc/cpuinfo will become borked, as
single letter extensions will be printed as part of the base extensions
and while printing from riscv_isa_arr. Take the opportunity to unify the
printing of the isa string, using the new member of riscv_isa_ext_data
in the process.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-despite-bright-de00ac888cc7@wendySigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/kernel/cpu.c

@@ -164,41 +164,26 @@ arch_initcall(riscv_cpuinfo_init);
 
 #ifdef CONFIG_PROC_FS
 
-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->id))
-			continue;
-
-		seq_printf(f, "_%s", edata->name);
-	}
-}
-
-/*
- * These are the only valid base (single letter) ISA extensions as per the spec.
- * It also specifies the canonical order in which it appears in the spec.
- * Some of the extension may just be a place holder for now (B, K, P, J).
- * This should be updated once corresponding extensions are ratified.
- */
-static const char base_riscv_exts[13] = "imafdqcbkjpvh";
-
 static void print_isa(struct seq_file *f)
 {
-	int i;
-
 	seq_puts(f, "isa\t\t: ");
+
 	if (IS_ENABLED(CONFIG_32BIT))
 		seq_write(f, "rv32", 4);
 	else
 		seq_write(f, "rv64", 4);
 
-	for (i = 0; i < sizeof(base_riscv_exts); i++) {
-		if (__riscv_isa_extension_available(NULL, base_riscv_exts[i] - 'a'))
-			/* Print only enabled the base ISA extensions */
-			seq_write(f, &base_riscv_exts[i], 1);
+	for (int i = 0; i < riscv_isa_ext_count; i++) {
+		if (!__riscv_isa_extension_available(NULL, riscv_isa_ext[i].id))
+			continue;
+
+		/* Only multi-letter extensions are split by underscores */
+		if (strnlen(riscv_isa_ext[i].name, 2) != 1)
+			seq_puts(f, "_");
+
+		seq_printf(f, "%s", riscv_isa_ext[i].name);
 	}
-	print_isa_ext(f);
+
 	seq_puts(f, "\n");
 }
 

arch/riscv/kernel/cpufeature.c

@@ -144,6 +144,19 @@ static bool riscv_isa_extension_check(int id)
  * New entries to this struct should follow the ordering rules described above.
  */
 const struct riscv_isa_ext_data riscv_isa_ext[] = {
+	__RISCV_ISA_EXT_DATA(i, RISCV_ISA_EXT_i),
+	__RISCV_ISA_EXT_DATA(m, RISCV_ISA_EXT_m),
+	__RISCV_ISA_EXT_DATA(a, RISCV_ISA_EXT_a),
+	__RISCV_ISA_EXT_DATA(f, RISCV_ISA_EXT_f),
+	__RISCV_ISA_EXT_DATA(d, RISCV_ISA_EXT_d),
+	__RISCV_ISA_EXT_DATA(q, RISCV_ISA_EXT_q),
+	__RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c),
+	__RISCV_ISA_EXT_DATA(b, RISCV_ISA_EXT_b),
+	__RISCV_ISA_EXT_DATA(k, RISCV_ISA_EXT_k),
+	__RISCV_ISA_EXT_DATA(j, RISCV_ISA_EXT_j),
+	__RISCV_ISA_EXT_DATA(p, RISCV_ISA_EXT_p),
+	__RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v),
+	__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
 	__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),