From 61114e734ccb804bc12561ab4020745e02c468c2 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 16 May 2022 14:45:21 -0700 Subject: [PATCH] riscv: Move alternative length validation into subsection After commit 49b290e430d3 ("riscv: prevent compressed instructions in alternatives"), builds with LLVM's integrated assembler fail: In file included from arch/riscv/mm/init.c:10: In file included from ./include/linux/mm.h:29: In file included from ./include/linux/pgtable.h:6: In file included from ./arch/riscv/include/asm/pgtable.h:108: ./arch/riscv/include/asm/tlbflush.h:23:2: error: expected assembly-time absolute expression ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory")); ^ ./arch/riscv/include/asm/errata_list.h:33:5: note: expanded from macro 'ALT_FLUSH_TLB_PAGE' asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID, \ ^ ./arch/riscv/include/asm/alternative-macros.h:187:2: note: expanded from macro 'ALTERNATIVE' _ALTERNATIVE_CFG(old_content, new_content, vendor_id, errata_id, CONFIG_k) ^ ./arch/riscv/include/asm/alternative-macros.h:113:2: note: expanded from macro '_ALTERNATIVE_CFG' __ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, IS_ENABLED(CONFIG_k)) ^ ./arch/riscv/include/asm/alternative-macros.h:110:2: note: expanded from macro '__ALTERNATIVE_CFG' ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) ^ ./arch/riscv/include/asm/alternative-macros.h:99:3: note: expanded from macro 'ALT_NEW_CONTENT' ".org . - (889b - 888b) + (887b - 886b)\n" \ ^ :26:6: note: instantiated into assembly here .org . - (889b - 888b) + (887b - 886b) ^ This error happens because LLVM's integrated assembler has a one-pass design, which means it cannot figure out the instruction lengths when the .org directive is outside of the subsection that contains the instructions, which was changed by the .option directives added by the above change. Move the .org directives before the .previous directive so that these directives are always within the same subsection, which resolves the failures and does not introduce any new issues with GNU as. This was done for arm64 in commit 966a0acce2fc ("arm64/alternatives: move length validation inside the subsection") and commit 22315a2296f4 ("arm64: alternatives: Move length validation in alternative_{insn, endif}"). While there is no error from the assembly versions of the macro, they appear to have the same problem so just make the same change there as well so that there are no problems in the future. Link: https://github.com/ClangBuiltLinux/linux/issues/1640 Reported-by: kernel test robot Signed-off-by: Nathan Chancellor Reviewed-by: Heiko Stuebner Tested-by: Heiko Stuebner Link: https://lore.kernel.org/r/20220516214520.3252074-1-nathan@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/alternative-macros.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h index e13b1f6..ec2f3f1 100644 --- a/arch/riscv/include/asm/alternative-macros.h +++ b/arch/riscv/include/asm/alternative-macros.h @@ -27,9 +27,9 @@ \new_c .option pop 889 : - .previous .org . - (889b - 888b) + (887b - 886b) .org . - (887b - 886b) + (889b - 888b) + .previous .endif .endm @@ -94,9 +94,9 @@ new_c "\n" \ ".option pop\n" \ "889 :\n" \ - ".previous\n" \ ".org . - (887b - 886b) + (889b - 888b)\n" \ ".org . - (889b - 888b) + (887b - 886b)\n" \ + ".previous\n" \ ".endif\n" #define __ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, enable) \ -- 2.7.4