Received: by 2002:a05:6a10:f347:0:0:0:0 with SMTP id d7csp656890pxu; Wed, 6 Jan 2021 00:19:43 -0800 (PST) X-Google-Smtp-Source: ABdhPJzVBfdFSYzEtf1OrvnLlyUJdYeax6E2GUMMx5SzaT65DWAxA1bN/FTdwYBFuZAqYuf68vLs X-Received: by 2002:a05:6402:13d1:: with SMTP id a17mr3216471edx.202.1609921183210; Wed, 06 Jan 2021 00:19:43 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1609921183; cv=none; d=google.com; s=arc-20160816; b=W5As3NL7K+xxSwh5rmbEyCA7MUyQvanLg4xzAlaXzkD0lTBo3XkkLXpKqlOcUJVhEf ZTvwCEdxNs79VrxnXCTjNm+JJp9e7dlCGPrEojR0dVgbJrotg6CAYJxHTmXMBkQsy8sb anYEl0mt+CaEtmTMOrp6faITam0Hdw5qyI7wRmK84Wr9Gv9y4nRUsmCjSQD9mWhIkcce M2z8mlBhxcGzcvw15CPtri+IWq2jDxjfb1T5RGmodMW8ZwCKhczmYybWRgWo0+48oMfI FmE9n+oHiBZL0y+NMX2bqKkIKNcEaq9r1mbCxIf1e6qzCiUSPVKg3TsffQIA3Gu8SoI8 7qig== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject; bh=mRcLuT92WhfWI20yfkIoNYNbhU3S0YrHrIAmTdPPzAc=; b=V9oMvBZpeuvHcGzBTl69X9GLl8b8iu1/Vn4TKewpaKVB2eE9XaYd/PPyIJGFJkFBRw 867cfqlrQi6yD8TCvZ4/vJbwwBwbYUqv8G+YEo8fAc5AWama3fE1kCJNQ5fwqoPrxVvU WswxG6zhMw4CG6MfsPuEiqQayoowZNEWwnH/wBFnmdN+Or2jcwig0RySD9BXDO4EhoDI cOe271mbghayYy/TDD8vqMJQ2pD3NI9r6/DyRRw+3vxJrX6JoGAPe2XT4d+80GipYjPe MaU+VCZqJcWx3zGw4KBoxcdIIA7Zl3WHz4i24hdyLGaKNwBmVyX3abEb9/nT6mPQjH8V Rwbg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id nw24si689932ejb.647.2021.01.06.00.19.20; Wed, 06 Jan 2021 00:19:43 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726345AbhAFIRm (ORCPT + 99 others); Wed, 6 Jan 2021 03:17:42 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:33129 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726229AbhAFIRm (ORCPT ); Wed, 6 Jan 2021 03:17:42 -0500 X-Originating-IP: 82.65.183.113 Received: from [172.16.5.113] (82-65-183-113.subs.proxad.net [82.65.183.113]) (Authenticated sender: alex@ghiti.fr) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 1FF1860003; Wed, 6 Jan 2021 08:16:56 +0000 (UTC) Subject: Re: [RFC PATCH 01/12] riscv: Move kernel mapping outside of linear mapping To: Anup Patel Cc: Paul Walmsley , Palmer Dabbelt , Zong Li , Christoph Hellwig , Ard Biesheuvel , Arnd Bergmann , linux-efi , linux-arch@vger.kernel.org, linux-riscv , "linux-kernel@vger.kernel.org List" References: <20210104195840.1593-1-alex@ghiti.fr> <20210104195840.1593-2-alex@ghiti.fr> From: Alex Ghiti Message-ID: <148ccc89-a277-a1bb-7779-d1b1dea59e43@ghiti.fr> Date: Wed, 6 Jan 2021 03:16:56 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 1/6/21 à 1:44 AM, Anup Patel a écrit : > On Wed, Jan 6, 2021 at 12:06 PM Alex Ghiti wrote: >> >> Hi Anup, >> >> Le 1/5/21 à 6:40 AM, Anup Patel a écrit : >>> On Tue, Jan 5, 2021 at 1:29 AM Alexandre Ghiti wrote: >>>> >>>> This is a preparatory patch for relocatable kernel and sv48 support. >>>> >>>> The kernel used to be linked at PAGE_OFFSET address therefore we could use >>>> the linear mapping for the kernel mapping. But the relocated kernel base >>>> address will be different from PAGE_OFFSET and since in the linear mapping, >>>> two different virtual addresses cannot point to the same physical address, >>>> the kernel mapping needs to lie outside the linear mapping so that we don't >>>> have to copy it at the same physical offset. >>>> >>>> The kernel mapping is moved to the last 2GB of the address space and then >>>> BPF and modules are also pushed to the same range since they have to lie >>>> close to the kernel inside a 2GB window. >>>> >>>> Note then that KASLR implementation will simply have to move the kernel in >>>> this 2GB range and modify BPF/modules regions accordingly. >>>> >>>> In addition, by moving the kernel to the end of the address space, both >>>> sv39 and sv48 kernels will be exactly the same without needing to be >>>> relocated at runtime. >>> >>> Awesome ! This is a good approach with no performance impact. >>> >>>> >>>> Suggested-by: Arnd Bergmann >>>> Signed-off-by: Alexandre Ghiti >>>> --- >>>> arch/riscv/boot/loader.lds.S | 3 +- >>>> arch/riscv/include/asm/page.h | 10 ++++- >>>> arch/riscv/include/asm/pgtable.h | 39 +++++++++++++------ >>>> arch/riscv/kernel/head.S | 3 +- >>>> arch/riscv/kernel/module.c | 4 +- >>>> arch/riscv/kernel/vmlinux.lds.S | 3 +- >>>> arch/riscv/mm/init.c | 65 ++++++++++++++++++++++++-------- >>>> arch/riscv/mm/physaddr.c | 2 +- >>>> 8 files changed, 94 insertions(+), 35 deletions(-) >>>> >>>> diff --git a/arch/riscv/boot/loader.lds.S b/arch/riscv/boot/loader.lds.S >>>> index 47a5003c2e28..62d94696a19c 100644 >>>> --- a/arch/riscv/boot/loader.lds.S >>>> +++ b/arch/riscv/boot/loader.lds.S >>>> @@ -1,13 +1,14 @@ >>>> /* SPDX-License-Identifier: GPL-2.0 */ >>>> >>>> #include >>>> +#include >>>> >>>> OUTPUT_ARCH(riscv) >>>> ENTRY(_start) >>>> >>>> SECTIONS >>>> { >>>> - . = PAGE_OFFSET; >>>> + . = KERNEL_LINK_ADDR; >>>> >>>> .payload : { >>>> *(.payload) >>>> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h >>>> index 2d50f76efe48..98188e315e8d 100644 >>>> --- a/arch/riscv/include/asm/page.h >>>> +++ b/arch/riscv/include/asm/page.h >>>> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t; >>>> >>>> #ifdef CONFIG_MMU >>>> extern unsigned long va_pa_offset; >>>> +extern unsigned long va_kernel_pa_offset; >>>> extern unsigned long pfn_base; >>>> #define ARCH_PFN_OFFSET (pfn_base) >>>> #else >>>> #define va_pa_offset 0 >>>> +#define va_kernel_pa_offset 0 >>>> #define ARCH_PFN_OFFSET (PAGE_OFFSET >> PAGE_SHIFT) >>>> #endif /* CONFIG_MMU */ >>>> >>>> extern unsigned long max_low_pfn; >>>> extern unsigned long min_low_pfn; >>>> +extern unsigned long kernel_virt_addr; >>>> >>>> #define __pa_to_va_nodebug(x) ((void *)((unsigned long) (x) + va_pa_offset)) >>>> -#define __va_to_pa_nodebug(x) ((unsigned long)(x) - va_pa_offset) >>>> +#define linear_mapping_va_to_pa(x) ((unsigned long)(x) - va_pa_offset) >>>> +#define kernel_mapping_va_to_pa(x) \ >>>> + ((unsigned long)(x) - va_kernel_pa_offset) >>>> +#define __va_to_pa_nodebug(x) \ >>>> + (((x) < KERNEL_LINK_ADDR) ? \ >>>> + linear_mapping_va_to_pa(x) : kernel_mapping_va_to_pa(x)) >>>> >>>> #ifdef CONFIG_DEBUG_VIRTUAL >>>> extern phys_addr_t __virt_to_phys(unsigned long x); >>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h >>>> index 183f1f4b2ae6..102b728ca146 100644 >>>> --- a/arch/riscv/include/asm/pgtable.h >>>> +++ b/arch/riscv/include/asm/pgtable.h >>>> @@ -11,23 +11,32 @@ >>>> >>>> #include >>>> >>>> -#ifndef __ASSEMBLY__ >>>> - >>>> -/* Page Upper Directory not used in RISC-V */ >>>> -#include >>>> -#include >>>> -#include >>>> -#include >>>> +#ifndef CONFIG_MMU >>>> +#define KERNEL_VIRT_ADDR PAGE_OFFSET >>>> +#define KERNEL_LINK_ADDR PAGE_OFFSET >>>> +#else >>>> >>>> -#ifdef CONFIG_MMU >>>> +#define ADDRESS_SPACE_END (UL(-1)) >>>> +/* >>>> + * Leave 2GB for kernel, modules and BPF at the end of the address space >>>> + */ >>>> +#define KERNEL_VIRT_ADDR (ADDRESS_SPACE_END - SZ_2G + 1) >>>> +#define KERNEL_LINK_ADDR KERNEL_VIRT_ADDR >>>> >>>> #define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1) >>>> #define VMALLOC_END (PAGE_OFFSET - 1) >>>> #define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE) >>>> >>>> +/* KASLR should leave at least 128MB for BPF after the kernel */ >>>> #define BPF_JIT_REGION_SIZE (SZ_128M) >>>> -#define BPF_JIT_REGION_START (PAGE_OFFSET - BPF_JIT_REGION_SIZE) >>>> -#define BPF_JIT_REGION_END (VMALLOC_END) >>>> +#define BPF_JIT_REGION_START PFN_ALIGN((unsigned long)&_end) >>>> +#define BPF_JIT_REGION_END (BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE) >>>> + >>>> +/* Modules always live before the kernel */ >>>> +#ifdef CONFIG_64BIT >>>> +#define VMALLOC_MODULE_START (PFN_ALIGN((unsigned long)&_end) - SZ_2G) >>>> +#define VMALLOC_MODULE_END (PFN_ALIGN((unsigned long)&_start)) >>>> +#endif >>> >>> This does not look right or I am missing something. >>> >>> I think the VMALLOC_MODULE_START should be: >>> #define VMALLOC_MODULE_START (PFN_ALIGN((unsigned long)&_start) - SZ_2G) >>> >> >> I think the patch is correct: worst-case, we want the first address of >> the module area to be able to access the last address of the kernel, so >> we must use _end and not _start to guarantee that the difference between >> those 2 addresses is not greater than 2GB. > > Makes sense. Please add more detailed comment instead of single-line comment. > Ok I'll do that. I realize the naming is confusing, this area does not belong to vmalloc anymore, I'll change that too. Thanks again, >> >>>> >>>> /* >>>> * Roughly size the vmemmap space to be large enough to fit enough >>>> @@ -57,9 +66,16 @@ >>>> #define FIXADDR_SIZE PGDIR_SIZE >>>> #endif >>>> #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) >>>> - >>>> #endif >>>> >>>> +#ifndef __ASSEMBLY__ >>>> + >>>> +/* Page Upper Directory not used in RISC-V */ >>>> +#include >>>> +#include >>>> +#include >>>> +#include >>>> + >>>> #ifdef CONFIG_64BIT >>>> #include >>>> #else >>>> @@ -467,6 +483,7 @@ static inline void __kernel_map_pages(struct page *page, int numpages, int enabl >>>> >>>> #define kern_addr_valid(addr) (1) /* FIXME */ >>>> >>>> +extern char _start[]; >>>> extern void *dtb_early_va; >>>> extern uintptr_t dtb_early_pa; >>>> void setup_bootmem(void); >>>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S >>>> index 7e849797c9c3..66f40c49bf68 100644 >>>> --- a/arch/riscv/kernel/head.S >>>> +++ b/arch/riscv/kernel/head.S >>>> @@ -69,7 +69,8 @@ pe_head_start: >>>> #ifdef CONFIG_MMU >>>> relocate: >>>> /* Relocate return address */ >>>> - li a1, PAGE_OFFSET >>>> + la a1, kernel_virt_addr >>>> + REG_L a1, 0(a1) >>>> la a2, _start >>>> sub a1, a1, a2 >>>> add ra, ra, a1 >>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c >>>> index 104fba889cf7..75a0b9541266 100644 >>>> --- a/arch/riscv/kernel/module.c >>>> +++ b/arch/riscv/kernel/module.c >>>> @@ -408,12 +408,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, >>>> } >>>> >>>> #if defined(CONFIG_MMU) && defined(CONFIG_64BIT) >>>> -#define VMALLOC_MODULE_START \ >>>> - max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START) >>>> void *module_alloc(unsigned long size) >>>> { >>>> return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START, >>>> - VMALLOC_END, GFP_KERNEL, >>>> + VMALLOC_MODULE_END, GFP_KERNEL, >>>> PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, >>>> __builtin_return_address(0)); >>>> } >>>> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S >>>> index 3ffbd6cbdb86..c21dc46f41be 100644 >>>> --- a/arch/riscv/kernel/vmlinux.lds.S >>>> +++ b/arch/riscv/kernel/vmlinux.lds.S >>>> @@ -4,7 +4,8 @@ >>>> * Copyright (C) 2017 SiFive >>>> */ >>>> >>>> -#define LOAD_OFFSET PAGE_OFFSET >>>> +#include >>>> +#define LOAD_OFFSET KERNEL_LINK_ADDR >>>> #include >>>> #include >>>> #include >>>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c >>>> index 8e577f14f120..9d06ff0e015a 100644 >>>> --- a/arch/riscv/mm/init.c >>>> +++ b/arch/riscv/mm/init.c >>>> @@ -23,6 +23,9 @@ >>>> >>>> #include "../kernel/head.h" >>>> >>>> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR; >>>> +EXPORT_SYMBOL(kernel_virt_addr); >>>> + >>>> unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] >>>> __page_aligned_bss; >>>> EXPORT_SYMBOL(empty_zero_page); >>>> @@ -201,8 +204,12 @@ void __init setup_bootmem(void) >>>> #ifdef CONFIG_MMU >>>> static struct pt_alloc_ops pt_ops; >>>> >>>> +/* Offset between linear mapping virtual address and kernel load address */ >>>> unsigned long va_pa_offset; >>>> EXPORT_SYMBOL(va_pa_offset); >>>> +/* Offset between kernel mapping virtual address and kernel load address */ >>>> +unsigned long va_kernel_pa_offset; >>>> +EXPORT_SYMBOL(va_kernel_pa_offset); >>>> unsigned long pfn_base; >>>> EXPORT_SYMBOL(pfn_base); >>>> >>>> @@ -316,7 +323,7 @@ static phys_addr_t __init alloc_pmd_early(uintptr_t va) >>>> { >>>> uintptr_t pmd_num; >>>> >>>> - pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT; >>>> + pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT; >>>> BUG_ON(pmd_num >= NUM_EARLY_PMDS); >>>> return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD]; >>>> } >>>> @@ -431,17 +438,34 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size) >>>> #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing." >>>> #endif >>>> >>>> +static uintptr_t load_pa, load_sz; >>>> + >>>> +static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size) >>>> +{ >>>> + uintptr_t va, end_va; >>>> + >>>> + end_va = kernel_virt_addr + load_sz; >>>> + for (va = kernel_virt_addr; va < end_va; va += map_size) >>>> + create_pgd_mapping(pgdir, va, >>>> + load_pa + (va - kernel_virt_addr), >>>> + map_size, PAGE_KERNEL_EXEC); >>>> +} >>>> + >>>> asmlinkage void __init setup_vm(uintptr_t dtb_pa) >>>> { >>>> - uintptr_t va, pa, end_va; >>>> - uintptr_t load_pa = (uintptr_t)(&_start); >>>> - uintptr_t load_sz = (uintptr_t)(&_end) - load_pa; >>>> - uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE); >>>> + uintptr_t pa; >>>> + uintptr_t map_size; >>>> #ifndef __PAGETABLE_PMD_FOLDED >>>> pmd_t fix_bmap_spmd, fix_bmap_epmd; >>>> #endif >>>> >>>> + load_pa = (uintptr_t)(&_start); >>>> + load_sz = (uintptr_t)(&_end) - load_pa; >>>> + map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE); >>>> + >>>> va_pa_offset = PAGE_OFFSET - load_pa; >>>> + va_kernel_pa_offset = kernel_virt_addr - load_pa; >>>> + >>>> pfn_base = PFN_DOWN(load_pa); >>>> >>>> /* >>>> @@ -470,26 +494,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) >>>> create_pmd_mapping(fixmap_pmd, FIXADDR_START, >>>> (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE); >>>> /* Setup trampoline PGD and PMD */ >>>> - create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET, >>>> + create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr, >>>> (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE); >>>> - create_pmd_mapping(trampoline_pmd, PAGE_OFFSET, >>>> + create_pmd_mapping(trampoline_pmd, kernel_virt_addr, >>>> load_pa, PMD_SIZE, PAGE_KERNEL_EXEC); >>>> #else >>>> /* Setup trampoline PGD */ >>>> - create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET, >>>> + create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr, >>>> load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC); >>>> #endif >>>> >>>> /* >>>> - * Setup early PGD covering entire kernel which will allows >>>> + * Setup early PGD covering entire kernel which will allow >>>> * us to reach paging_init(). We map all memory banks later >>>> * in setup_vm_final() below. >>>> */ >>>> - end_va = PAGE_OFFSET + load_sz; >>>> - for (va = PAGE_OFFSET; va < end_va; va += map_size) >>>> - create_pgd_mapping(early_pg_dir, va, >>>> - load_pa + (va - PAGE_OFFSET), >>>> - map_size, PAGE_KERNEL_EXEC); >>>> + create_kernel_page_table(early_pg_dir, map_size); >>>> >>>> #ifndef __PAGETABLE_PMD_FOLDED >>>> /* Setup early PMD for DTB */ >>>> @@ -549,6 +569,7 @@ static void __init setup_vm_final(void) >>>> uintptr_t va, map_size; >>>> phys_addr_t pa, start, end; >>>> u64 i; >>>> + static struct vm_struct vm_kernel = { 0 }; >>>> >>>> /** >>>> * MMU is enabled at this point. But page table setup is not complete yet. >>>> @@ -565,7 +586,7 @@ static void __init setup_vm_final(void) >>>> __pa_symbol(fixmap_pgd_next), >>>> PGDIR_SIZE, PAGE_TABLE); >>>> >>>> - /* Map all memory banks */ >>>> + /* Map all memory banks in the linear mapping */ >>>> for_each_mem_range(i, &start, &end) { >>>> if (start >= end) >>>> break; >>>> @@ -577,10 +598,22 @@ static void __init setup_vm_final(void) >>>> for (pa = start; pa < end; pa += map_size) { >>>> va = (uintptr_t)__va(pa); >>>> create_pgd_mapping(swapper_pg_dir, va, pa, >>>> - map_size, PAGE_KERNEL_EXEC); >>>> + map_size, PAGE_KERNEL); >>>> } >>>> } >>>> >>>> + /* Map the kernel */ >>>> + create_kernel_page_table(swapper_pg_dir, PMD_SIZE); >>>> + >>>> + /* Reserve the vmalloc area occupied by the kernel */ >>>> + vm_kernel.addr = (void *)kernel_virt_addr; >>>> + vm_kernel.phys_addr = load_pa; >>>> + vm_kernel.size = (load_sz + PMD_SIZE - 1) & ~(PMD_SIZE - 1); >>>> + vm_kernel.flags = VM_MAP | VM_NO_GUARD; >>>> + vm_kernel.caller = __builtin_return_address(0); >>>> + >>>> + vm_area_add_early(&vm_kernel); >>>> + >>>> /* Clear fixmap PTE and PMD mappings */ >>>> clear_fixmap(FIX_PTE); >>>> clear_fixmap(FIX_PMD); >>>> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c >>>> index e8e4dcd39fed..35703d5ef5fd 100644 >>>> --- a/arch/riscv/mm/physaddr.c >>>> +++ b/arch/riscv/mm/physaddr.c >>>> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys); >>>> >>>> phys_addr_t __phys_addr_symbol(unsigned long x) >>>> { >>>> - unsigned long kernel_start = (unsigned long)PAGE_OFFSET; >>>> + unsigned long kernel_start = (unsigned long)kernel_virt_addr; >>>> unsigned long kernel_end = (unsigned long)_end; >>>> >>>> /* >>>> -- >>>> 2.20.1 >>>> >>> >>> Apart from the minor comment above, this looks good to me. >>> >>> Reviewed-by: Anup Patel >> >> Thanks for your time Anup, >> >>> >>> Regards, >>> Anup >>> >> >> Alex > > Regards, > Anup > Alex