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Subject: Re: [PATCH v5 1/3] riscv: Move kernel mapping outside of linear
 mapping
To:     Palmer Dabbelt <palmer@dabbelt.com>
Cc:     corbet@lwn.net, Paul Walmsley <paul.walmsley@sifive.com>,
        aou@eecs.berkeley.edu, Arnd Bergmann <arnd@arndb.de>,
        aryabinin@virtuozzo.com, glider@google.com, dvyukov@google.com,
        linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
        linux-arch@vger.kernel.org, linux-mm@kvack.org
References: <mhng-90fff6bd-5a70-4927-98c1-a515a7448e71@palmerdabbelt-glaptop>
From:   Alex Ghiti <alex@ghiti.fr>
Message-ID: <76353fc0-f734-db47-0d0c-f0f379763aa0@ghiti.fr>
Date:   Thu, 15 Apr 2021 00:54:25 -0400
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Le 4/15/21 à 12:20 AM, Palmer Dabbelt a écrit :
> On Sun, 11 Apr 2021 09:41:44 PDT (-0700), alex@ghiti.fr 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, BPF
>> is now always after the kernel and modules use the 2GB memory range right
>> before the kernel, so BPF and modules regions do not overlap. KASLR
>> implementation will simply have to move the kernel in the last 2GB range
>> and just take care of leaving enough space for BPF.
>>
>> 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.
>>
>> Suggested-by: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> ---
>>  arch/riscv/boot/loader.lds.S        |  3 +-
>>  arch/riscv/include/asm/page.h       | 17 +++++-
>>  arch/riscv/include/asm/pgtable.h    | 37 ++++++++----
>>  arch/riscv/include/asm/set_memory.h |  1 +
>>  arch/riscv/kernel/head.S            |  3 +-
>>  arch/riscv/kernel/module.c          |  6 +-
>>  arch/riscv/kernel/setup.c           |  5 ++
>>  arch/riscv/kernel/vmlinux.lds.S     |  3 +-
>>  arch/riscv/mm/fault.c               | 13 +++++
>>  arch/riscv/mm/init.c                | 87 ++++++++++++++++++++++-------
>>  arch/riscv/mm/kasan_init.c          |  9 +++
>>  arch/riscv/mm/physaddr.c            |  2 +-
>>  12 files changed, 146 insertions(+), 40 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 <asm/page.h>
>> +#include <asm/pgtable.h>
>>
>>  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 adc9d26f3d75..22cfb2be60dc 100644
>> --- a/arch/riscv/include/asm/page.h
>> +++ b/arch/riscv/include/asm/page.h
>> @@ -90,15 +90,28 @@ 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 */
>>
>> -#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)
>> +extern unsigned long kernel_virt_addr;
>> +
>> +#define linear_mapping_pa_to_va(x)    ((void *)((unsigned long)(x) + 
>> va_pa_offset))
>> +#define kernel_mapping_pa_to_va(x)    ((void *)((unsigned long)(x) + 
>> va_kernel_pa_offset))
>> +#define __pa_to_va_nodebug(x)        linear_mapping_pa_to_va(x)
>> +
>> +#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)    ({                        \
>> +    unsigned long _x = x;                            \
>> +    (_x < kernel_virt_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 ebf817c1bdf4..80e63a93e903 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -11,23 +11,30 @@
>>
>>  #include <asm/pgtable-bits.h>
>>
>> -#ifndef __ASSEMBLY__
>> -
>> -/* Page Upper Directory not used in RISC-V */
>> -#include <asm-generic/pgtable-nopud.h>
>> -#include <asm/page.h>
>> -#include <asm/tlbflush.h>
>> -#include <linux/mm_types.h>
>> +#ifndef CONFIG_MMU
>> +#define KERNEL_LINK_ADDR    PAGE_OFFSET
>> +#else
>>
>> -#ifdef CONFIG_MMU
>> +#define ADDRESS_SPACE_END    (UL(-1))
>> +/*
>> + * Leave 2GB for kernel and BPF at the end of the address space
>> + */
>> +#define KERNEL_LINK_ADDR    (ADDRESS_SPACE_END - SZ_2G + 1)
>>
>>  #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 MODULES_VADDR    (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
>> +#define MODULES_END    (PFN_ALIGN((unsigned long)&_start))
>> +#endif
>>
>>  /*
>>   * Roughly size the vmemmap space to be large enough to fit enough
>> @@ -57,9 +64,16 @@
>>  #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 <asm-generic/pgtable-nopud.h>
>> +#include <asm/page.h>
>> +#include <asm/tlbflush.h>
>> +#include <linux/mm_types.h>
>> +
>>  #ifdef CONFIG_64BIT
>>  #include <asm/pgtable-64.h>
>>  #else
>> @@ -484,6 +498,7 @@ static inline int ptep_clear_flush_young(struct 
>> vm_area_struct *vma,
>>
>>  #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/include/asm/set_memory.h 
>> b/arch/riscv/include/asm/set_memory.h
>> index 6887b3d9f371..a9c56776fa0e 100644
>> --- a/arch/riscv/include/asm/set_memory.h
>> +++ b/arch/riscv/include/asm/set_memory.h
>> @@ -17,6 +17,7 @@ int set_memory_x(unsigned long addr, int numpages);
>>  int set_memory_nx(unsigned long addr, int numpages);
>>  int set_memory_rw_nx(unsigned long addr, int numpages);
>>  void protect_kernel_text_data(void);
>> +void protect_kernel_linear_mapping_text_rodata(void);
>>  #else
>>  static inline int set_memory_ro(unsigned long addr, int numpages) { 
>> return 0; }
>>  static inline int set_memory_rw(unsigned long addr, int numpages) { 
>> return 0; }
>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>> index f5a9bad86e58..6cb05f22e52a 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..ce153771e5e9 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,
>> +    return __vmalloc_node_range(size, 1, MODULES_VADDR,
>> +                    MODULES_END, GFP_KERNEL,
>>                      PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
>>                      __builtin_return_address(0));
>>  }
>> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> index e85bacff1b50..30e4af0fd50c 100644
>> --- a/arch/riscv/kernel/setup.c
>> +++ b/arch/riscv/kernel/setup.c
>> @@ -265,6 +265,11 @@ void __init setup_arch(char **cmdline_p)
>>
>>      if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
>>          protect_kernel_text_data();
>> +
>> +#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
>> +    protect_kernel_linear_mapping_text_rodata();
>> +#endif
>> +
>>  #ifdef CONFIG_SWIOTLB
>>      swiotlb_init(1);
>>  #endif
>> diff --git a/arch/riscv/kernel/vmlinux.lds.S 
>> b/arch/riscv/kernel/vmlinux.lds.S
>> index de03cb22d0e9..0726c05e0336 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 <asm/pgtable.h>
>> +#define LOAD_OFFSET KERNEL_LINK_ADDR
>>  #include <asm/vmlinux.lds.h>
>>  #include <asm/page.h>
>>  #include <asm/cache.h>
>> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
>> index 8f17519208c7..1b14d523a95c 100644
>> --- a/arch/riscv/mm/fault.c
>> +++ b/arch/riscv/mm/fault.c
>> @@ -231,6 +231,19 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
>>          return;
>>      }
>>
>> +#ifdef CONFIG_64BIT
>> +    /*
>> +     * Modules in 64bit kernels lie in their own virtual region which 
>> is not
>> +     * in the vmalloc region, but dealing with page faults in this 
>> region
>> +     * or the vmalloc region amounts to doing the same thing: 
>> checking that
>> +     * the mapping exists in init_mm.pgd and updating user page 
>> table, so
>> +     * just use vmalloc_fault.
>> +     */
>> +    if (unlikely(addr >= MODULES_VADDR && addr < MODULES_END)) {
>> +        vmalloc_fault(regs, code, addr);
>> +        return;
>> +    }
>> +#endif
>>      /* Enable interrupts if they were enabled in the parent context. */
>>      if (likely(regs->status & SR_PIE))
>>          local_irq_enable();
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index 7f5036fbee8c..093f3a96ecfc 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
>> @@ -25,6 +25,9 @@
>>
>>  #include "../kernel/head.h"
>>
>> +unsigned long kernel_virt_addr = KERNEL_LINK_ADDR;
>> +EXPORT_SYMBOL(kernel_virt_addr);
>> +
>>  unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>>                              __page_aligned_bss;
>>  EXPORT_SYMBOL(empty_zero_page);
>> @@ -88,6 +91,8 @@ static void print_vm_layout(void)
>>            (unsigned long)VMALLOC_END);
>>      print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
>>            (unsigned long)high_memory);
>> +    print_mlm("kernel", (unsigned long)KERNEL_LINK_ADDR,
>> +          (unsigned long)ADDRESS_SPACE_END);
>>  }
>>  #else
>>  static void print_vm_layout(void) { }
>> @@ -116,8 +121,13 @@ void __init setup_bootmem(void)
>>      /* The maximal physical memory size is -PAGE_OFFSET. */
>>      memblock_enforce_memory_limit(-PAGE_OFFSET);
>>
>> -    /* Reserve from the start of the kernel to the end of the kernel */
>> -    memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
>> +    /*
>> +     * Reserve from the start of the kernel to the end of the kernel
>> +     * and make sure we align the reservation on PMD_SIZE since we will
>> +     * map the kernel in the linear mapping as read-only: we do not want
>> +     * any allocation to happen between _end and the next pmd aligned 
>> page.
>> +     */
>> +    memblock_reserve(vmlinux_start, (vmlinux_end - vmlinux_start + 
>> PMD_SIZE - 1) & PMD_MASK);
>>
>>      /*
>>       * memblock allocator is not aware of the fact that last 4K bytes of
>> @@ -152,8 +162,12 @@ 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);
>>
>> @@ -257,7 +271,7 @@ static pmd_t *get_pmd_virt_late(phys_addr_t pa)
>>
>>  static phys_addr_t __init alloc_pmd_early(uintptr_t va)
>>  {
>> -    BUG_ON((va - PAGE_OFFSET) >> PGDIR_SHIFT);
>> +    BUG_ON((va - kernel_virt_addr) >> PGDIR_SHIFT);
>>
>>      return (uintptr_t)early_pmd;
>>  }
>> @@ -372,17 +386,32 @@ 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
>>
>> +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 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;
>>
>>      va_pa_offset = PAGE_OFFSET - load_pa;
>> +    va_kernel_pa_offset = kernel_virt_addr - load_pa;
>> +
>>      pfn_base = PFN_DOWN(load_pa);
>>
>>      /*
>> @@ -410,26 +439,22 @@ 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 */
>> @@ -444,7 +469,12 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>                 pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
>>      dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 
>> 1));
>>  #else /* CONFIG_BUILTIN_DTB */
>> -    dtb_early_va = __va(dtb_pa);
>> +    /*
>> +     * __va can't be used since it would return a linear mapping address
>> +     * whereas dtb_early_va will be used before setup_vm_final installs
>> +     * the linear mapping.
>> +     */
>> +    dtb_early_va = kernel_mapping_pa_to_va(dtb_pa);
>>  #endif /* CONFIG_BUILTIN_DTB */
>>  #else
>>  #ifndef CONFIG_BUILTIN_DTB
>> @@ -456,7 +486,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>                 pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
>>      dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE 
>> - 1));
>>  #else /* CONFIG_BUILTIN_DTB */
>> -    dtb_early_va = __va(dtb_pa);
>> +    dtb_early_va = kernel_mapping_pa_to_va(dtb_pa);
>>  #endif /* CONFIG_BUILTIN_DTB */
>>  #endif
>>      dtb_early_pa = dtb_pa;
>> @@ -492,6 +522,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>  #endif
>>  }
>>
>> +#ifdef CONFIG_64BIT
>> +void protect_kernel_linear_mapping_text_rodata(void)
>> +{
>> +    unsigned long text_start = (unsigned long)lm_alias(_start);
>> +    unsigned long init_text_start = (unsigned 
>> long)lm_alias(__init_text_begin);
>> +    unsigned long rodata_start = (unsigned 
>> long)lm_alias(__start_rodata);
>> +    unsigned long data_start = (unsigned long)lm_alias(_data);
>> +
>> +    set_memory_ro(text_start, (init_text_start - text_start) >> 
>> PAGE_SHIFT);
>> +    set_memory_nx(text_start, (init_text_start - text_start) >> 
>> PAGE_SHIFT);
>> +
>> +    set_memory_ro(rodata_start, (data_start - rodata_start) >> 
>> PAGE_SHIFT);
>> +    set_memory_nx(rodata_start, (data_start - rodata_start) >> 
>> PAGE_SHIFT);
>> +}
>> +#endif
>> +
>>  static void __init setup_vm_final(void)
>>  {
>>      uintptr_t va, map_size;
>> @@ -513,7 +559,7 @@ 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;
>> @@ -525,10 +571,13 @@ 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);
>> +
>>      /* Clear fixmap PTE and PMD mappings */
>>      clear_fixmap(FIX_PTE);
>>      clear_fixmap(FIX_PMD);
>> diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
>> index 2c39f0386673..28f4d52cf17e 100644
>> --- a/arch/riscv/mm/kasan_init.c
>> +++ b/arch/riscv/mm/kasan_init.c
>> @@ -171,6 +171,10 @@ void __init kasan_init(void)
>>      phys_addr_t _start, _end;
>>      u64 i;
>>
>> +    /*
>> +     * Populate all kernel virtual address space with 
>> kasan_early_shadow_page
>> +     * except for the linear mapping and the modules/kernel/BPF mapping.
>> +     */
>>      kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
>>                      (void *)kasan_mem_to_shadow((void *)
>>                                  VMEMMAP_END));
>> @@ -183,6 +187,7 @@ void __init kasan_init(void)
>>              (void *)kasan_mem_to_shadow((void *)VMALLOC_START),
>>              (void *)kasan_mem_to_shadow((void *)VMALLOC_END));
>>
>> +    /* Populate the linear mapping */
>>      for_each_mem_range(i, &_start, &_end) {
>>          void *start = (void *)__va(_start);
>>          void *end = (void *)__va(_end);
>> @@ -193,6 +198,10 @@ void __init kasan_init(void)
>>          kasan_populate(kasan_mem_to_shadow(start), 
>> kasan_mem_to_shadow(end));
>>      };
>>
>> +    /* Populate kernel, BPF, modules mapping */
>> +    kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR),
>> +               kasan_mem_to_shadow((const void *)BPF_JIT_REGION_END));
>> +
>>      for (i = 0; i < PTRS_PER_PTE; i++)
>>          set_pte(&kasan_early_shadow_pte[i],
>>              mk_pte(virt_to_page(kasan_early_shadow_page),
>> 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;
>>
>>      /*
> 
> This is breaking boot for me with CONFIG_STRICT_KERNEL_RWX=n.  I'm not 
> even really convinced that's a useful config to support, but it's 
> currently optional and I'd prefer to avoid breaking it if possible.
> 
> I can't quite figure out what's going on here and I'm pretty much tired 
> out for tonight.  LMK if you don't have time to look at it and I'll try 
> to give it another shot.

I'm taking a look at that.

Thanks,

Alex