From patchwork Wed Apr 6 04:01:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 1613687 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=112.213.38.117; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4KY9nb02SMz9sFk for ; Wed, 6 Apr 2022 14:02:09 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KY9nX3Gfwz3bZN for ; Wed, 6 Apr 2022 14:02:08 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.ru (client-ip=107.174.27.60; helo=ozlabs.ru; envelope-from=aik@ozlabs.ru; receiver=) Received: from ozlabs.ru (ozlabs.ru [107.174.27.60]) by lists.ozlabs.org (Postfix) with ESMTP id 4KY9nL3RXxz2xjY for ; Wed, 6 Apr 2022 14:01:56 +1000 (AEST) Received: from fstn1-p1.ozlabs.ibm.com. (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id 13F81804AA; Wed, 6 Apr 2022 00:01:50 -0400 (EDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH kernel v2] powerpc/boot: Stop using RELACOUNT Date: Wed, 6 Apr 2022 14:01:48 +1000 Message-Id: <20220406040148.3608400-1-aik@ozlabs.ru> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , llvm@lists.linux.dev, Nick Desaulniers , Nathan Chancellor Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" So far the RELACOUNT tag from the ELF header was containing the exact number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's recent change [1] make it equal-or-less than the actual number which makes it useless. This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT. The vmlinux relocation code is fixed in commit d79976918852 ("powerpc/64: Add UADDR64 relocation support"). To make it more future proof, this walks through the entire .rela.dyn section instead of assuming that the section is sorter by a relocation type. Unlike d79976918852, this does not add unaligned UADDR/UADDR64 relocations as we are likely not to see those in practice - the zImage is small and very arch specific so there is a smaller chance that some generic feature (such as PRINK_INDEX) triggers unaligned relocations. [1] https://github.com/llvm/llvm-project/commit/da0e5b885b25cf4 Signed-off-by: Alexey Kardashevskiy --- Changes: v2: * s/divd/divwu/ for ppc32 * updated the commit log * named all new labels instead of numbering them (s/101f/.Lcheck_for_relaent/ and so on) --- arch/powerpc/boot/crt0.S | 45 ++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S index feadee18e271..e9306d862f8d 100644 --- a/arch/powerpc/boot/crt0.S +++ b/arch/powerpc/boot/crt0.S @@ -8,7 +8,8 @@ #include "ppc_asm.h" RELA = 7 -RELACOUNT = 0x6ffffff9 +RELASZ = 8 +RELAENT = 9 .data /* A procedure descriptor used when booting this as a COFF file. @@ -75,34 +76,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */ bne 11f lwz r9,4(r12) /* get RELA pointer in r9 */ b 12f -11: addis r8,r8,(-RELACOUNT)@ha - cmpwi r8,RELACOUNT@l +11: cmpwi r8,RELASZ + bne .Lcheck_for_relaent + lwz r0,4(r12) /* get RELASZ value in r0 */ + b 12f +.Lcheck_for_relaent: + cmpwi r8,RELAENT bne 12f - lwz r0,4(r12) /* get RELACOUNT value in r0 */ + lwz r14,4(r12) /* get RELAENT value in r14 */ 12: addi r12,r12,8 b 9b /* The relocation section contains a list of relocations. * We now do the R_PPC_RELATIVE ones, which point to words - * which need to be initialized with addend + offset. - * The R_PPC_RELATIVE ones come first and there are RELACOUNT - * of them. */ + * which need to be initialized with addend + offset */ 10: /* skip relocation if we don't have both */ cmpwi r0,0 beq 3f cmpwi r9,0 beq 3f + cmpwi r14,0 + beq 3f add r9,r9,r11 /* Relocate RELA pointer */ + divwu r0,r0,r14 /* RELASZ / RELAENT */ mtctr r0 2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */ cmpwi r0,22 /* R_PPC_RELATIVE */ - bne 3f + bne .Lnext lwz r12,0(r9) /* reloc->r_offset */ lwz r0,8(r9) /* reloc->r_addend */ add r0,r0,r11 stwx r0,r11,r12 - addi r9,r9,12 +.Lnext: add r9,r9,r14 bdnz 2b /* Do a cache flush for our text, in case the loader didn't */ @@ -160,32 +166,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */ bne 10f ld r13,8(r11) /* get RELA pointer in r13 */ b 11f -10: addis r12,r12,(-RELACOUNT)@ha - cmpdi r12,RELACOUNT@l - bne 11f - ld r8,8(r11) /* get RELACOUNT value in r8 */ +10: cmpwi r12,RELASZ + bne .Lcheck_for_relaent + lwz r8,8(r11) /* get RELASZ pointer in r8 */ + b 11f +.Lcheck_for_relaent: + cmpwi r12,RELAENT + bne 11f + lwz r14,8(r11) /* get RELAENT pointer in r14 */ 11: addi r11,r11,16 b 9b 12: - cmpdi r13,0 /* check we have both RELA and RELACOUNT */ + cmpdi r13,0 /* check we have both RELA, RELASZ, RELAENT*/ cmpdi cr1,r8,0 beq 3f beq cr1,3f + cmpdi r14,0 + beq 3f /* Calcuate the runtime offset. */ subf r13,r13,r9 /* Run through the list of relocations and process the * R_PPC64_RELATIVE ones. */ + divd r8,r8,r14 /* RELASZ / RELAENT */ mtctr r8 13: ld r0,8(r9) /* ELF64_R_TYPE(reloc->r_info) */ cmpdi r0,22 /* R_PPC64_RELATIVE */ - bne 3f + bne .Lnext ld r12,0(r9) /* reloc->r_offset */ ld r0,16(r9) /* reloc->r_addend */ add r0,r0,r13 stdx r0,r13,r12 - addi r9,r9,24 +.Lnext: add r9,r9,r14 bdnz 13b /* Do a cache flush for our text, in case the loader didn't */