Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934179AbbGVLVV (ORCPT ); Wed, 22 Jul 2015 07:21:21 -0400 Received: from mail-wi0-f182.google.com ([209.85.212.182]:33190 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933841AbbGVLVS (ORCPT ); Wed, 22 Jul 2015 07:21:18 -0400 From: Daniel Thompson To: Catalin Marinas , Will Deacon Cc: Daniel Thompson , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, patches@linaro.org, linaro-kernel@lists.linaro.org, John Stultz , Sumit Semwal , Christoffer Dall , Marc Zyngier , Andre Przywara Subject: [PATCH v3 1/5] arm64: alternative: Provide if/else/endif assembler macros Date: Wed, 22 Jul 2015 12:21:01 +0100 Message-Id: <1437564065-4356-2-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1437564065-4356-1-git-send-email-daniel.thompson@linaro.org> References: <1436536130-31438-1-git-send-email-daniel.thompson@linaro.org> <1437564065-4356-1-git-send-email-daniel.thompson@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2402 Lines: 76 The existing alternative_insn macro has some limitations that make it hard to work with. In particular the fact it takes instructions from it own macro arguments means it doesn't play very nicely with C pre-processor macros because the macro arguments look like a string to the C pre-processor. Workarounds are (probably) possible but things start to look ugly. Introduce an alternative set of macros that allows instructions to be presented to the assembler as normal and switch everything over to the new macros. Signed-off-by: Daniel Thompson --- arch/arm64/include/asm/alternative.h | 41 ++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index c385a0c4057f..e86681ad0931 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -77,6 +77,47 @@ void free_alternatives_memory(void); .org . - (662b-661b) + (664b-663b) .endm +/* + * Begin an alternative code sequence. + * + * The code that follows this macro will be assembled and linked as + * normal. There are no restrictions on this code. + */ +.macro alternative_if_not cap + .pushsection .altinstructions, "a" + altinstruction_entry 661f, 663f, \cap, 662f-661f, 664f-663f + .popsection +661: +.endm + +/* + * Provide the alternative code sequence. + * + * The code that follows this macro is assembled into a special + * section to be used for dynamic patching. Code that follows this + * macro must: + * + * 1. Be exactly the same length (in bytes) as the default code + * sequence. + * + * 2. Not contain a branch target that is used outside of the + * alternative sequence it is defined in (branches into an + * alternative sequence are not fixed up). + */ +.macro alternative_else +662: .pushsection .altinstr_replacement, "ax" +663: +.endm + +/* + * Complete an alternative code sequence. + */ +.macro alternative_endif +664: .popsection + .org . - (664b-663b) + (662b-661b) + .org . - (662b-661b) + (664b-663b) +.endm + #endif /* __ASSEMBLY__ */ #endif /* __ASM_ALTERNATIVE_H */ -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/