From nobody Sat Feb 7 15:09:40 2026 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 9E6BEEB64DC for ; Mon, 10 Jul 2023 05:40:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229514AbjGJFkw (ORCPT ); Mon, 10 Jul 2023 01:40:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229458AbjGJFku (ORCPT ); Mon, 10 Jul 2023 01:40:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43C14A8; Sun, 9 Jul 2023 22:40:49 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D630560DFE; Mon, 10 Jul 2023 05:40:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DF2DC433C7; Mon, 10 Jul 2023 05:40:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688967648; bh=vTePZySJwROm5kopsmfpT+96m9V/ekc/sUd11srBFsU=; h=From:To:Cc:Subject:Date:From; b=YWmXKZSqljsSEjQnsy1OYiCfCaPh2j1hzxcY/ZLIkpotGxHgoJM5wkIKD7Go1IcRV cfJwcsPsQdTbXlFiDpUYgfj3lpAMuZRUEQqBuj6dOlB5Ev14XeXsfd6fsd88lLIDCm cVmu5BCSMYaRKXqdXfCsPmrsT+g1inMmhTyQ13so+6W6hZrMCgRHwQlhxdSnKdwCjh v++6Z0GP66TwoQmjwWQgAwwkbE/fiJBu7Jr0NtV5pPhs2Mdw8CFlTbC2KBA0GYIIRu FWGX3u0fURZZj9hQuSpEjDYgYryvisP1XPwyVJnJ3fYmI+r1vS22O/2vb/VAdUNN73 jPXdeZ53PuEMQ== From: guoren@kernel.org To: guoren@kernel.org, palmer@rivosinc.com, paul.walmsley@sifive.com, zong.li@sifive.com, atishp@atishpatra.org, alex@ghiti.fr, jszhang@kernel.org, bjorn@kernel.org Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Guo Ren Subject: [PATCH V2] riscv: kexec: Fixup synchronization problem between init_mm and active_mm Date: Mon, 10 Jul 2023 01:40:29 -0400 Message-Id: <20230710054029.2026124-1-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Guo Ren The machine_kexec() uses set_memory_x to modify the direct mapping attributes from RW to RWX. But set_memory_x only changes the init_mm's attributes, not current->active_mm, so when kexec jumps into control_buffer, the instruction page fault happens, and there is no minor_pagefault for it, then panic. The bug is found on an MMU_sv39 machine, and the direct mapping used a 1GB PUD, the pgd entries. Here is the bug output: kexec_core: Starting new kernel Will call new kernel at 00300000 from hart id 0 FDT image at 747c7000 Bye... Unable to handle kernel paging request at virtual address ffffffda23b0d000 Oops [#1] Modules linked in: CPU: 0 PID: 53 Comm: uinit Not tainted 6.4.0-rc6 #15 Hardware name: Sophgo Mango (DT) epc : 0xffffffda23b0d000 ra : machine_kexec+0xa6/0xb0 epc : ffffffda23b0d000 ra : ffffffff80008272 sp : ffffffc80c173d10 gp : ffffffff8150e1e0 tp : ffffffd9073d2c40 t0 : 0000000000000000 t1 : 0000000000000042 t2 : 6567616d69205444 s0 : ffffffc80c173d50 s1 : ffffffd9076c4800 a0 : ffffffd9076c4800 a1 : 0000000000300000 a2 : 00000000747c7000 a3 : 0000000000000000 a4 : ffffffd800000000 a5 : 0000000000000000 a6 : ffffffd903619c40 a7 : ffffffffffffffff s2 : ffffffda23b0d000 s3 : 0000000000300000 s4 : 00000000747c7000 s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000 s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000 s11: 0000003f940001a0 t3 : ffffffff815351af t4 : ffffffff815351af t5 : ffffffff815351b0 t6 : ffffffc80c173b50 status: 0000000200000100 badaddr: ffffffda23b0d000 cause: 000000000000000c The solution is to fix machine_kexec() to remap control code page outside the linear mapping. Fixes: 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear mapping") Signed-off-by: Guo Ren Signed-off-by: Guo Ren Cc: Alexandre Ghiti Reviewed-by: Alexandre Ghiti --- Changelog: V2: - Use vm_map_ram instead of modifying set_memory_x - Correct Fixes tag --- arch/riscv/include/asm/kexec.h | 1 + arch/riscv/kernel/machine_kexec.c | 14 ++++++++++---- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h index 2b56769cb530..17456e91476e 100644 --- a/arch/riscv/include/asm/kexec.h +++ b/arch/riscv/include/asm/kexec.h @@ -41,6 +41,7 @@ crash_setup_regs(struct pt_regs *newregs, struct kimage_arch { void *fdt; /* For CONFIG_KEXEC_FILE */ unsigned long fdt_addr; + void *control_code_buffer; }; =20 extern const unsigned char riscv_kexec_relocate[]; diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_= kexec.c index 2d139b724bc8..eeb209775107 100644 --- a/arch/riscv/kernel/machine_kexec.c +++ b/arch/riscv/kernel/machine_kexec.c @@ -86,7 +86,14 @@ machine_kexec_prepare(struct kimage *image) =20 /* Copy the assembler code for relocation to the control page */ if (image->type !=3D KEXEC_TYPE_CRASH) { - control_code_buffer =3D page_address(image->control_code_page); + control_code_buffer =3D vm_map_ram(&image->control_code_page, + KEXEC_CONTROL_PAGE_SIZE/PAGE_SIZE, + NUMA_NO_NODE); + if (control_code_buffer =3D=3D NULL) { + pr_err("Failed to vm_map control page\n"); + return -ENOMEM; + } + control_code_buffer_sz =3D page_size(image->control_code_page); =20 if (unlikely(riscv_kexec_relocate_size > control_code_buffer_sz)) { @@ -97,8 +104,7 @@ machine_kexec_prepare(struct kimage *image) memcpy(control_code_buffer, riscv_kexec_relocate, riscv_kexec_relocate_size); =20 - /* Mark the control page executable */ - set_memory_x((unsigned long) control_code_buffer, 1); + internal->control_code_buffer =3D control_code_buffer; } =20 return 0; @@ -211,7 +217,7 @@ machine_kexec(struct kimage *image) unsigned long this_cpu_id =3D __smp_processor_id(); unsigned long this_hart_id =3D cpuid_to_hartid_map(this_cpu_id); unsigned long fdt_addr =3D internal->fdt_addr; - void *control_code_buffer =3D page_address(image->control_code_page); + void *control_code_buffer =3D internal->control_code_buffer; riscv_kexec_method kexec_method =3D NULL; =20 #ifdef CONFIG_SMP --=20 2.36.1