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Tue, 12 Sep 2023 07:17:55 -0700 (PDT) Date: Tue, 12 Sep 2023 14:16:07 +0000 In-Reply-To: <20230912141549.278777-63-ardb@google.com> Mime-Version: 1.0 References: <20230912141549.278777-63-ardb@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=924; i=ardb@kernel.org; h=from:subject; bh=7dwN4994wU2RkOX6xb0W36D2zJFK5xDHZIUcogKBXeY=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIZWhaHm48O8Maf/Vf5q17pVe+yT/kD+rbX5QejqPYWVcn bJf3uWOUhYGMQ4GWTFFFoHZf9/tPD1RqtZ5lizMHFYmkCEMXJwCMJGYXkaGY8q5T3g2fKtfYlbo Zz+f0TS42qHlWs0Gm6fZ/okLj+nHMPxTerTw7VeVLIPp670Uf7zqYso6p/UxZ72XZsDJQNZUES8 mAA== X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog Message-ID: <20230912141549.278777-80-ardb@google.com> Subject: [PATCH v4 17/61] arm64: idreg-override: avoid strlen() to check for empty strings From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Ryan Roberts , Anshuman Khandual , Kees Cook , Joey Gouly X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230912_071757_669030_93D2B550 X-CRM114-Status: GOOD ( 14.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Ard Biesheuvel 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 --- 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 cb4de31071d4..96fec5b7a65e 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -241,7 +241,7 @@ static void __init match_options(const char *cmdline) override = prel64_to_pointer(®->override_prel); - 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);