Re: [PATCH v5 1/3] riscv: Move kernel mapping outside of linear mapping

[Alex Ghiti]

Hi Palmer,

Le 4/15/21 à 2:00 PM, Alex Ghiti a écrit :
> Le 4/15/21 à 12:54 AM, Alex Ghiti a écrit :
> > Le 4/15/21 à 12:20 AM, Palmer Dabbelt a écrit :
> > > On Sun, 11 Apr 2021 09:41:44 PDT (-0700), alex@xxxxxxxx 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@xxxxxxxx>
> > > > Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
> > > > ---
> > > >  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 ownvirtual 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 inthe 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 onPMD_SIZE since we will
> > > > +     * map the kernel in the linear mapping as read-only: we do not 
> > > > want
> > > > +     * any allocation to happen between _end andthe 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 spacewith 
> > > > 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.
>
> Just to make sure you don't miss it, I fixed this issue in 
> https://patchwork.kernel.org/project/linux-riscv/patch/20210415110426.2238-1-alex@xxxxxxxx/

Guenter reported that this patchset broke 32b kernel build: I had 
neglected it. So I pushed 2 other fixes for this where I added Fixes tag 
and that can be squashed in case you want to squash them.

To sum up, there are 3 patches that fix this series:

https://patchwork.kernel.org/project/linux-riscv/patch/20210415110426.2238-1-alex@xxxxxxxx/

https://patchwork.kernel.org/project/linux-riscv/patch/20210417172159.32085-1-alex@xxxxxxxx/

https://patchwork.kernel.org/project/linux-riscv/patch/20210418112856.15078-1-alex@xxxxxxxx/

Sorry for that,

Thanks,

Alex

> Thanks,
>
> Alex
>
> > Thanks,
> >
> > Alex
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-riscv