[RFC PATCH 1/3] riscv: Correctly print supported extensions

Tsukasa OI research_trasio at irq.a4lg.com
Sat Nov 20 00:53:50 PST 2021


This commit replaces BITS_PER_LONG with magic number 26.

Current ISA pretty-printing code expects extension 'a' (bit 0) through
'z' (bit 25).  Although bit 26 and higher is not currently used (thus never
cause an issue in practice), it will be an annoying problem if we start to
use those in the future.

This commit disables printing high bits for now.

Signed-off-by: Tsukasa OI <research_trasio at irq.a4lg.com>
---
 arch/riscv/kernel/cpufeature.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index d959d207a40d..6f2bf6ae4ae2 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -63,7 +63,7 @@ void __init riscv_fill_hwcap(void)
 {
 	struct device_node *node;
 	const char *isa;
-	char print_str[BITS_PER_LONG + 1];
+	char print_str[26 + 1];
 	size_t i, j, isa_len;
 	static unsigned long isa2hwcap[256] = {0};
 
@@ -133,13 +133,13 @@ void __init riscv_fill_hwcap(void)
 	}
 
 	memset(print_str, 0, sizeof(print_str));
-	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+	for (i = 0, j = 0; i < 26; i++)
 		if (riscv_isa[0] & BIT_MASK(i))
 			print_str[j++] = (char)('a' + i);
 	pr_info("riscv: ISA extensions %s\n", print_str);
 
 	memset(print_str, 0, sizeof(print_str));
-	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+	for (i = 0, j = 0; i < 26; i++)
 		if (elf_hwcap & BIT_MASK(i))
 			print_str[j++] = (char)('a' + i);
 	pr_info("riscv: ELF capabilities %s\n", print_str);
-- 
2.32.0




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