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

From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Brown <broonie@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>
Subject: [PATCH v7 14/33] arm64: idreg-override: avoid strlen() to check for empty strings
Date: Fri, 11 Nov 2022 18:11:42 +0100	[thread overview]
Message-ID: <20221111171201.2088501-15-ardb@kernel.org> (raw)
In-Reply-To: <20221111171201.2088501-1-ardb@kernel.org>

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 <ardb@kernel.org>
---
 arch/arm64/kernel/idreg-override.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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);
-- 
2.35.1


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