From nobody Sun Apr 5 13:24:56 2026 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B2113F65EB for ; Tue, 24 Mar 2026 11:45:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774352751; cv=none; b=eDR4Jdvh1m8Gc/JHkpPe6lDE8YX9WXxwDfIJYExtg2KmjDH3i6udI3NYWPUSla1pIlSo6XjGt3FAy6uYSOM9PZBbkzx1lLNpBJ998MjHMGjWjmL3Q6JbmVaugCaLjBcNOCnNvu+qvLTnw/Zhm1aYepk5uCQRMlB0OOq28CNW2cY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774352751; c=relaxed/simple; bh=wZRqnfDZn0H0D2XdXK1rrl/nAmou2a718Iss63kB8O0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ppqq6WfoRkrX6FwMqXbOzqCdW+GcAHbv1FHmrhUWg73DrEi/tM3q/S6ZfEGXEz0l+f1XbM854ddh/WIYPRUjsCb0r8epy7PaVCsbkkAM7cbHa3Uwo0OYQDcVT0c8wdK5BnHV7QRDQdqJMM2rrF/huaPxP6FyKpu+Zn8a+GSCSAo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=DSItUImd; arc=none smtp.client-ip=115.124.30.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="DSItUImd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1774352738; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=5u8vaxNzmtFsbfL7LvvEbSUs+WLXyb+uBK2uxrcg2Kc=; b=DSItUImd/GrwOVb+BVohtcBmdN2MZD+8kQJYVMnmd4xyV8iY9t0ZW43VQSAQIzV99s3l+tRh7++Vj7qAqjE+v03XmyU9Z2iRdxqf7o9vqmRVN9gmt/lFYzudPb0V5rx0chvZt0YaO/OdKeebSQze05V7lGBV7pGzyOSpaqyOZuQ= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037009110;MF=fangyu.yu@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0X.eWVFq_1774352736; Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0X.eWVFq_1774352736 cluster:ay36) by smtp.aliyun-inc.com; Tue, 24 Mar 2026 19:45:37 +0800 From: fangyu.yu@linux.alibaba.com To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, songshuaishuai@tinylab.org, bjorn@rivosinc.com, ardb@kernel.org, arnd@arndb.de, bhelgaas@google.com, richard.lyu@suse.com, tzimmermann@suse.de, nathan@kernel.org Cc: guoren@kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Fangyu Yu Subject: [PATCH 3/4] riscv: kexec: Build trampoline page tables for crash kernel entry Date: Tue, 24 Mar 2026 19:45:26 +0800 Message-Id: <20260324114527.91494-4-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260324114527.91494-1-fangyu.yu@linux.alibaba.com> References: <20260324114527.91494-1-fangyu.yu@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Fangyu Yu Crash kexec uses riscv_kexec_norelocate as a trampoline to jump into the crashkernel. Add a small helper to build dedicated 4KB page tables that map the trampoline page as executable. Two mappings are installed: - VA(__kexec_tramp_text_start) -> PA(__kexec_tramp_text_start) - PA(__kexec_tramp_text_start) -> PA(__kexec_tramp_text_start) This allows the trampoline to run regardless of whether it is entered via its linked virtual address or its physical address. Signed-off-by: Fangyu Yu --- arch/riscv/kernel/machine_kexec.c | 103 +++++++++++++++++++++++++++++- 1 file changed, 102 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_= kexec.c index 2306ce3e5f22..4e522a64a614 100644 --- a/arch/riscv/kernel/machine_kexec.c +++ b/arch/riscv/kernel/machine_kexec.c @@ -18,6 +18,98 @@ #include #include =20 +static pgd_t kexec_tramp_pgd[PTRS_PER_PGD] __aligned(PAGE_SIZE); +static p4d_t kexec_tramp_p4d[PTRS_PER_P4D] __aligned(PAGE_SIZE); +static pud_t kexec_tramp_pud[PTRS_PER_PUD] __aligned(PAGE_SIZE); +static pmd_t kexec_tramp_pmd[PTRS_PER_PMD] __aligned(PAGE_SIZE); +static pte_t kexec_tramp_pte[PTRS_PER_PTE] __aligned(PAGE_SIZE); +static p4d_t kexec_tramp_p4d2[PTRS_PER_P4D] __aligned(PAGE_SIZE); +static pud_t kexec_tramp_pud2[PTRS_PER_PUD] __aligned(PAGE_SIZE); +static pmd_t kexec_tramp_pmd2[PTRS_PER_PMD] __aligned(PAGE_SIZE); +static pte_t kexec_tramp_pte2[PTRS_PER_PTE] __aligned(PAGE_SIZE); + +static void riscv_kexec_build_tramp(unsigned long va, unsigned long pa) +{ + pgd_t *pgd; + pud_t *pud; + p4d_t *p4d; + pmd_t *pmd; + pte_t *pte; + int index; + + index =3D pgd_index(va); + pgd =3D (pgd_t *)kexec_tramp_pgd + index; + if (pgtable_l5_enabled) + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa_symbol(kexec_tramp_p4d)), + PAGE_TABLE)); + else + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa_symbol(kexec_tramp_pud)), + PAGE_TABLE)); + + if (pgtable_l5_enabled) { + index =3D p4d_index(va); + p4d =3D (p4d_t *)kexec_tramp_p4d + index; + if (pgtable_l4_enabled) + set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa_symbol(kexec_tramp_pud)), + PAGE_TABLE)); + else + set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa_symbol(kexec_tramp_pmd)), + PAGE_TABLE)); + } + + if (pgtable_l4_enabled) { + index =3D pud_index(va); + pud =3D (pud_t *)kexec_tramp_pud + index; + set_pud(pud, pfn_pud(PFN_DOWN(__pa_symbol(kexec_tramp_pmd)), PAGE_TABLE)= ); + } + + index =3D pmd_index(va); + if (pgtable_l4_enabled) + pmd =3D (pmd_t *)kexec_tramp_pmd + index; + else + pmd =3D (pmd_t *)kexec_tramp_pud + index; + set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa_symbol(kexec_tramp_pte)), PAGE_TABLE)); + + index =3D pte_index(va); + pte =3D (pte_t *)kexec_tramp_pte + index; + set_pte(pte, pfn_pte(PFN_DOWN(pa), PAGE_KERNEL_EXEC)); + + index =3D pgd_index(pa); + pgd =3D (pgd_t *)kexec_tramp_pgd + index; + if (pgtable_l5_enabled) + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa_symbol(kexec_tramp_p4d2)), PAGE_TABLE= )); + else + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa_symbol(kexec_tramp_pud2)), PAGE_TABLE= )); + + if (pgtable_l5_enabled) { + index =3D p4d_index(pa); + p4d =3D (p4d_t *)kexec_tramp_p4d2 + index; + if (pgtable_l4_enabled) + set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa_symbol(kexec_tramp_pud2)), + PAGE_TABLE)); + else + set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa_symbol(kexec_tramp_pmd2)), + PAGE_TABLE)); + } + + if (pgtable_l4_enabled) { + index =3D pud_index(pa); + pud =3D (pud_t *)kexec_tramp_pud2 + index; + set_pud(pud, pfn_pud(PFN_DOWN(__pa_symbol(kexec_tramp_pmd2)), PAGE_TABLE= )); + } + + index =3D pmd_index(pa); + if (pgtable_l4_enabled) + pmd =3D (pmd_t *)kexec_tramp_pmd2 + index; + else + pmd =3D (pmd_t *)kexec_tramp_pud2 + index; + set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa_symbol(kexec_tramp_pte2)), PAGE_TABLE)= ); + + index =3D pte_index(pa); + pte =3D (pte_t *)kexec_tramp_pte2 + index; + set_pte(pte, pfn_pte(PFN_DOWN(pa), PAGE_KERNEL_EXEC)); +} + /* * machine_kexec_prepare - Initialize kexec * @@ -164,8 +256,17 @@ machine_kexec(struct kimage *image) =20 if (image->type !=3D KEXEC_TYPE_CRASH) kexec_method =3D control_code_buffer; - else + else { kexec_method =3D (riscv_kexec_method) &riscv_kexec_norelocate; + /* + * Build two 4KB identity-mapping page tables for the + * trampoline page: + * - VA(__kexec_tramp_text_start) -> PA(__kexec_tramp_text_start) + * - PA(__kexec_tramp_text_start) -> PA(__kexec_tramp_text_start) + */ + riscv_kexec_build_tramp((unsigned long)__kexec_tramp_text_start, + __pa_symbol(__kexec_tramp_text_start)); + } =20 pr_notice("Will call new kernel at %08lx from hart id %lx\n", jump_addr, this_hart_id); --=20 2.50.1