From nobody Fri Dec 19 16:10:46 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E1A3C6FA8F for ; Wed, 30 Aug 2023 18:53:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245386AbjH3SwN (ORCPT ); Wed, 30 Aug 2023 14:52:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239047AbjH3GfD (ORCPT ); Wed, 30 Aug 2023 02:35:03 -0400 Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.154.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10C7D107 for ; Tue, 29 Aug 2023 23:34:57 -0700 (PDT) X-QQ-mid: bizesmtp72t1693377284t20dyyw5 Received: from localhost.localdomain ( [221.226.144.218]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 30 Aug 2023 14:34:42 +0800 (CST) X-QQ-SSF: 01200000000000B0B000000A0000000 X-QQ-FEAT: I8hG9CuxGDLVX4zYenMnZzfme72U6h6VUyCmh7+o/2/nV1SicSheCqLWUS/6f 6UBdxSE+5weyB8T4IXrP/HkOLySS94hUiIsCzTvD5UBUakxSArtJyUcT73pGsZfVR2aAx0u X0NTTXxVE8YaME/T4o2p69r3PUsGs8E+PX+KlZWNJ/aCopGnPy+twcWgkdCRkQpOrGtxObS t92LfKJyicKmsjEyxI21m68yYxHg416+39bO+IFEE4HEKtqI6EJqhBzGEPTuID98pPHXO/1 LQFFbENG8KfWdMSZD/8Yz9zNVHUAzjpcW4PKTXPvbaQx1JrNVtCamJ1z0lr1rby48BJ9pXB L9dc0jYTFpe1jkv8MAvQrXdmPa4760QS2i6adCK X-QQ-GoodBg: 0 X-BIZMAIL-ID: 10736640701935298722 From: Song Shuai To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, mick@ics.forth.gr, alex@ghiti.fr Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Song Shuai Subject: [PATCH] riscv: kexec: Cleanup riscv_kexec_relocate Date: Wed, 30 Aug 2023 14:34:35 +0800 Message-Id: <20230830063435.1105726-1-songshuaishuai@tinylab.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:tinylab.org:qybglogicsvrsz:qybglogicsvrsz4a-0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" For readability and simplicity, cleanup the riscv_kexec_relocate code: - Re-sort the first 4 `mv` instructions against `riscv_kexec_method()` - Eliminate registers for debugging (s9,s10,s11) and storing const-value (s= 5,s6) - Replace `jalr` with `jr` for no-link jump I tested this on Qemu virt machine and works as it was. Signed-off-by: Song Shuai --- arch/riscv/kernel/kexec_relocate.S | 52 +++++++++++++----------------- 1 file changed, 23 insertions(+), 29 deletions(-) diff --git a/arch/riscv/kernel/kexec_relocate.S b/arch/riscv/kernel/kexec_r= elocate.S index 059c5e216ae7..de0a4b35d01e 100644 --- a/arch/riscv/kernel/kexec_relocate.S +++ b/arch/riscv/kernel/kexec_relocate.S @@ -17,27 +17,17 @@ SYM_CODE_START(riscv_kexec_relocate) * s1: (const) Phys address to jump to after relocation * s2: (const) Phys address of the FDT image * s3: (const) The hartid of the current hart - * s4: Pointer to the destination address for the relocation - * s5: (const) Number of words per page - * s6: (const) 1, used for subtraction - * s7: (const) kernel_map.va_pa_offset, used when switching MMU off - * s8: (const) Physical address of the main loop - * s9: (debug) indirection page counter - * s10: (debug) entry counter - * s11: (debug) copied words counter + * s4: (const) kernel_map.va_pa_offset, used when switching MMU off + * s5: Pointer to the destination address for the relocation + * s6: (const) Physical address of the main loop */ mv s0, a0 mv s1, a1 mv s2, a2 mv s3, a3 - mv s4, zero - li s5, (PAGE_SIZE / RISCV_SZPTR) - li s6, 1 - mv s7, a4 - mv s8, zero - mv s9, zero - mv s10, zero - mv s11, zero + mv s4, a4 + mv s5, zero + mv s6, zero =20 /* Disable / cleanup interrupts */ csrw CSR_SIE, zero @@ -52,21 +42,27 @@ SYM_CODE_START(riscv_kexec_relocate) * the start of the loop below so that we jump there in * any case. */ - la s8, 1f - sub s8, s8, s7 - csrw CSR_STVEC, s8 + la s6, 1f + sub s6, s6, s4 + csrw CSR_STVEC, s6 + + /* + * With C-extension, here we get 42 Bytes and the next + * .align directive would pad zeros here up to 44 Bytes. + * So manually put a nop here to avoid zeros padding. + */ + nop =20 /* Process entries in a loop */ .align 2 1: - addi s10, s10, 1 REG_L t0, 0(s0) /* t0 =3D *image->entry */ addi s0, s0, RISCV_SZPTR /* image->entry++ */ =20 /* IND_DESTINATION entry ? -> save destination address */ andi t1, t0, 0x1 beqz t1, 2f - andi s4, t0, ~0x1 + andi s5, t0, ~0x1 j 1b =20 2: @@ -74,9 +70,8 @@ SYM_CODE_START(riscv_kexec_relocate) andi t1, t0, 0x2 beqz t1, 2f andi s0, t0, ~0x2 - addi s9, s9, 1 csrw CSR_SATP, zero - jalr zero, s8, 0 + jr s6 =20 2: /* IND_DONE entry ? -> jump to done label */ @@ -92,14 +87,13 @@ SYM_CODE_START(riscv_kexec_relocate) andi t1, t0, 0x8 beqz t1, 1b /* Unknown entry type, ignore it */ andi t0, t0, ~0x8 - mv t3, s5 /* i =3D num words per page */ + li t3, (PAGE_SIZE / RISCV_SZPTR) /* i =3D num words per page */ 3: /* copy loop */ REG_L t1, (t0) /* t1 =3D *src_ptr */ - REG_S t1, (s4) /* *dst_ptr =3D *src_ptr */ + REG_S t1, (s5) /* *dst_ptr =3D *src_ptr */ addi t0, t0, RISCV_SZPTR /* stc_ptr++ */ - addi s4, s4, RISCV_SZPTR /* dst_ptr++ */ - sub t3, t3, s6 /* i-- */ - addi s11, s11, 1 /* c++ */ + addi s5, s5, RISCV_SZPTR /* dst_ptr++ */ + addi t3, t3, -0x1 /* i-- */ beqz t3, 1b /* copy done ? */ j 3b =20 @@ -146,7 +140,7 @@ SYM_CODE_START(riscv_kexec_relocate) */ fence.i =20 - jalr zero, a2, 0 + jr a2 =20 SYM_CODE_END(riscv_kexec_relocate) riscv_kexec_relocate_end: --=20 2.20.1