[v7,14/33] arm64: idreg-override: avoid strlen() to check for empty strings

Commit Message

Ard Biesheuvel Nov. 11, 2022, 5:11 p.m. UTC

strlen() is a costly way to decide whether a string is empty, as in that
case, the first character will be NUL so we can check for that directly.

Signed-off-by: Ard Biesheuvel <[e-mail]>
---
 arch/arm64/kernel/idreg-override.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index b3288e827a6bbec3..97ec832d87d44f64 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -196,7 +196,7 @@  static void __init match_options(const char *cmdline)
 		const struct ftr_set_desc *reg = offset_to_ptr(&regs[i]);
 		int f;
 
-		for (f = 0; strlen(reg->fields[f].name); f++) {
+		for (f = 0; reg->fields[f].name[0] != '\0'; f++) {
 			u64 shift = reg->fields[f].shift;
 			u64 width = reg->fields[f].width ?: 4;
 			u64 mask = GENMASK_ULL(shift + width - 1, shift);