[PATCH v8] RISC-V: enable XIP

Palmer Dabbelt palmer at dabbelt.com
Mon Apr 26 16:32:48 BST 2021


On Fri, 23 Apr 2021 14:27:26 PDT (-0700), vitaly.wool at konsulko.com wrote:
> Hi Palmer,
>
> On Fri, Apr 23, 2021 at 6:22 AM Palmer Dabbelt <palmer at dabbelt.com> wrote:
>>
>> On Mon, 12 Apr 2021 23:35:14 PDT (-0700), alex at ghiti.fr wrote:
>> > From: Vitaly Wool <vitaly.wool at konsulko.com>
>> >
>> > Introduce XIP (eXecute In Place) support for RISC-V platforms.
>> > It allows code to be executed directly from non-volatile storage
>> > directly addressable by the CPU, such as QSPI NOR flash which can
>> > be found on many RISC-V platforms. This makes way for significant
>> > optimization of RAM footprint. The XIP kernel is not compressed
>> > since it has to run directly from flash, so it will occupy more
>> > space on the non-volatile storage. The physical flash address used
>> > to link the kernel object files and for storing it has to be known
>> > at compile time and is represented by a Kconfig option.
>> >
>> > XIP on RISC-V will for the time being only work on MMU-enabled
>> > kernels.
>> >
>> > Signed-off-by: Alexandre Ghiti <alex at ghiti.fr> [ Rebase on top of "Move
>> > kernel mapping outside the linear mapping" ]
>> > Signed-off-by: Vitaly Wool <vitaly.wool at konsulko.com>
>
> I'm currently looking at this patch in for-next
> [https://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git/commit/?h=for-next&id=2fd9503070f7e52cc8397845beb27ece2bcfe410]
> and see unresolved rejects, i. e. in '@@ -451,8 +547,13 @@ asmlinkage
> void __init setup_vm(uintptr_t dtb_pa)' chunk. Am I looking at the
> wrong place? I thought I'd flag it anyway just in case.

Sorry about that, they should be fixed now.

>
> Best regards,
>    Vitaly
>
>> > ---
>> >  arch/riscv/Kconfig                  |  55 +++++++++++-
>> >  arch/riscv/Makefile                 |   8 +-
>> >  arch/riscv/boot/Makefile            |  13 +++
>> >  arch/riscv/include/asm/page.h       |  21 +++++
>> >  arch/riscv/include/asm/pgtable.h    |  25 +++++-
>> >  arch/riscv/kernel/head.S            |  46 +++++++++-
>> >  arch/riscv/kernel/head.h            |   3 +
>> >  arch/riscv/kernel/setup.c           |  10 ++-
>> >  arch/riscv/kernel/vmlinux-xip.lds.S | 133 ++++++++++++++++++++++++++++
>> >  arch/riscv/kernel/vmlinux.lds.S     |   6 ++
>> >  arch/riscv/mm/init.c                | 115 ++++++++++++++++++++++--
>> >  11 files changed, 418 insertions(+), 17 deletions(-)
>> >  create mode 100644 arch/riscv/kernel/vmlinux-xip.lds.S
>> >
>> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> > index 8ea60a0a19ae..7c7efdd67a10 100644
>> > --- a/arch/riscv/Kconfig
>> > +++ b/arch/riscv/Kconfig
>> > @@ -28,7 +28,7 @@ config RISCV
>> >       select ARCH_HAS_PTE_SPECIAL
>> >       select ARCH_HAS_SET_DIRECT_MAP
>> >       select ARCH_HAS_SET_MEMORY
>> > -     select ARCH_HAS_STRICT_KERNEL_RWX if MMU
>> > +     select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
>>
>> We now also have STRICT_MODULE_RWX, which causes a merge conflict.  I've
>> added both as !XIP_KERNEL, though TBH I'm not even sure thot modules
>> make any sense with XIP.
>>
>> >       select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
>> >       select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
>> >       select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
>> > @@ -441,7 +441,7 @@ config EFI_STUB
>> >
>> >  config EFI
>> >       bool "UEFI runtime support"
>> > -     depends on OF
>> > +     depends on OF && !XIP_KERNEL
>> >       select LIBFDT
>> >       select UCS2_STRING
>> >       select EFI_PARAMS_FROM_FDT
>> > @@ -465,11 +465,60 @@ config STACKPROTECTOR_PER_TASK
>> >       def_bool y
>> >       depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
>> >
>> > +config PHYS_RAM_BASE_FIXED
>> > +     bool "Explicitly specified physical RAM address"
>> > +     default n
>> > +
>> > +config PHYS_RAM_BASE
>> > +     hex "Platform Physical RAM address"
>> > +     depends on PHYS_RAM_BASE_FIXED
>> > +     default "0x80000000"
>> > +     help
>> > +       This is the physical address of RAM in the system. It has to be
>> > +       explicitly specified to run early relocations of read-write data
>> > +       from flash to RAM.
>> > +
>> > +config XIP_KERNEL
>> > +     bool "Kernel Execute-In-Place from ROM"
>> > +     depends on MMU && SPARSEMEM
>> > +     select PHYS_RAM_BASE_FIXED
>> > +     help
>> > +       Execute-In-Place allows the kernel to run from non-volatile storage
>> > +       directly addressable by the CPU, such as NOR flash. This saves RAM
>> > +       space since the text section of the kernel is not loaded from flash
>> > +       to RAM.  Read-write sections, such as the data section and stack,
>> > +       are still copied to RAM.  The XIP kernel is not compressed since
>> > +       it has to run directly from flash, so it will take more space to
>> > +       store it.  The flash address used to link the kernel object files,
>> > +       and for storing it, is configuration dependent. Therefore, if you
>> > +       say Y here, you must know the proper physical address where to
>> > +       store the kernel image depending on your own flash memory usage.
>> > +
>> > +       Also note that the make target becomes "make xipImage" rather than
>> > +       "make zImage" or "make Image".  The final kernel binary to put in
>> > +       ROM memory will be arch/riscv/boot/xipImage.
>> > +
>> > +       SPARSEMEM is required because the kernel text and rodata that are
>> > +       flash resident are not backed by memmap, then any attempt to get
>> > +       a struct page on those regions will trigger a fault.
>> > +
>> > +       If unsure, say N.
>> > +
>> > +config XIP_PHYS_ADDR
>> > +     hex "XIP Kernel Physical Location"
>> > +     depends on XIP_KERNEL
>> > +     default "0x21000000"
>> > +     help
>> > +       This is the physical address in your flash memory the kernel will
>> > +       be linked for and stored to.  This address is dependent on your
>> > +       own flash usage.
>> > +
>> >  endmenu
>> >
>> >  config BUILTIN_DTB
>> > -     def_bool n
>> > +     bool
>> >       depends on OF
>> > +     default y if XIP_KERNEL
>> >
>> >  menu "Power management options"
>> >
>> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
>> > index 1368d943f1f3..8fcbec03974d 100644
>> > --- a/arch/riscv/Makefile
>> > +++ b/arch/riscv/Makefile
>> > @@ -82,7 +82,11 @@ CHECKFLAGS += -D__riscv -D__riscv_xlen=$(BITS)
>> >
>> >  # Default target when executing plain make
>> >  boot         := arch/riscv/boot
>> > +ifeq ($(CONFIG_XIP_KERNEL),y)
>> > +KBUILD_IMAGE := $(boot)/xipImage
>> > +else
>> >  KBUILD_IMAGE := $(boot)/Image.gz
>> > +endif
>> >
>> >  head-y := arch/riscv/kernel/head.o
>> >
>> > @@ -95,12 +99,14 @@ PHONY += vdso_install
>> >  vdso_install:
>> >       $(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
>> >
>> > +ifneq ($(CONFIG_XIP_KERNEL),y)
>> >  ifeq ($(CONFIG_RISCV_M_MODE)$(CONFIG_SOC_CANAAN),yy)
>> >  KBUILD_IMAGE := $(boot)/loader.bin
>> >  else
>> >  KBUILD_IMAGE := $(boot)/Image.gz
>> >  endif
>> > -BOOT_TARGETS := Image Image.gz loader loader.bin
>> > +endif
>> > +BOOT_TARGETS := Image Image.gz loader loader.bin xipImage
>> >
>> >  all: $(notdir $(KBUILD_IMAGE))
>> >
>> > diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
>> > index 03404c84f971..6bf299f70c27 100644
>> > --- a/arch/riscv/boot/Makefile
>> > +++ b/arch/riscv/boot/Makefile
>> > @@ -17,8 +17,21 @@
>> >  KCOV_INSTRUMENT := n
>> >
>> >  OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
>> > +OBJCOPYFLAGS_xipImage :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
>> >
>> >  targets := Image Image.* loader loader.o loader.lds loader.bin
>> > +targets := Image Image.* loader loader.o loader.lds loader.bin xipImage
>> > +
>> > +ifeq ($(CONFIG_XIP_KERNEL),y)
>> > +
>> > +quiet_cmd_mkxip = $(quiet_cmd_objcopy)
>> > +cmd_mkxip = $(cmd_objcopy)
>> > +
>> > +$(obj)/xipImage: vmlinux FORCE
>> > +     $(call if_changed,mkxip)
>> > +     @$(kecho) '  Physical Address of xipImage: $(CONFIG_XIP_PHYS_ADDR)'
>> > +
>> > +endif
>> >
>> >  $(obj)/Image: vmlinux FORCE
>> >       $(call if_changed,objcopy)
>> > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
>> > index 22cfb2be60dc..635c6b486806 100644
>> > --- a/arch/riscv/include/asm/page.h
>> > +++ b/arch/riscv/include/asm/page.h
>> > @@ -91,6 +91,9 @@ typedef struct page *pgtable_t;
>> >  #ifdef CONFIG_MMU
>> >  extern unsigned long va_pa_offset;
>> >  extern unsigned long va_kernel_pa_offset;
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +extern unsigned long va_kernel_xip_pa_offset;
>> > +#endif
>> >  extern unsigned long pfn_base;
>> >  #define ARCH_PFN_OFFSET              (pfn_base)
>> >  #else
>> > @@ -102,11 +105,29 @@ extern unsigned long pfn_base;
>> >  extern unsigned long kernel_virt_addr;
>> >
>> >  #define linear_mapping_pa_to_va(x)   ((void *)((unsigned long)(x) + va_pa_offset))
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define kernel_mapping_pa_to_va(y)   ({                                              \
>> > +     unsigned long _y = y;                                                           \
>> > +     (_y >= CONFIG_PHYS_RAM_BASE) ?                                                  \
>> > +             (void *)((unsigned long)(_y) + va_kernel_pa_offset + XIP_OFFSET) :      \
>> > +             (void *)((unsigned long)(_y) + va_kernel_xip_pa_offset);                \
>> > +     })
>> > +#else
>> >  #define kernel_mapping_pa_to_va(x)   ((void *)((unsigned long)(x) + va_kernel_pa_offset))
>> > +#endif
>> >  #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)
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define kernel_mapping_va_to_pa(y) ({                                                \
>> > +     unsigned long _y = y;                                                   \
>> > +     (_y < kernel_virt_addr + XIP_OFFSET) ?                                  \
>> > +             ((unsigned long)(_y) - va_kernel_xip_pa_offset) :               \
>> > +             ((unsigned long)(_y) - va_kernel_pa_offset - XIP_OFFSET);       \
>> > +     })
>> > +#else
>> >  #define kernel_mapping_va_to_pa(x)   ((unsigned long)(x) - va_kernel_pa_offset)
>> > +#endif
>> >  #define __va_to_pa_nodebug(x)        ({                                              \
>> >       unsigned long _x = x;                                                   \
>> >       (_x < kernel_virt_addr) ?                                               \
>> > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> > index 80e63a93e903..c2dc4f83eed8 100644
>> > --- a/arch/riscv/include/asm/pgtable.h
>> > +++ b/arch/riscv/include/asm/pgtable.h
>> > @@ -64,6 +64,19 @@
>> >  #define FIXADDR_SIZE     PGDIR_SIZE
>> >  #endif
>> >  #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
>> > +
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define XIP_OFFSET           SZ_8M
>> > +#define XIP_FIXUP(addr) ({                                                   \
>> > +     uintptr_t __a = (uintptr_t)(addr);                                      \
>> > +     (__a >= CONFIG_XIP_PHYS_ADDR && __a < CONFIG_XIP_PHYS_ADDR + SZ_16M) ?  \
>> > +             __a - CONFIG_XIP_PHYS_ADDR + CONFIG_PHYS_RAM_BASE - XIP_OFFSET :\
>> > +             __a;                                                            \
>> > +     })
>> > +#else
>> > +#define XIP_FIXUP(addr)              (addr)
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  #endif
>> >
>> >  #ifndef __ASSEMBLY__
>> > @@ -499,8 +512,16 @@ 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;
>> > +extern void *_dtb_early_va;
>> > +extern uintptr_t _dtb_early_pa;
>> > +#if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_MMU)
>> > +#define dtb_early_va (*(void **)XIP_FIXUP(&_dtb_early_va))
>> > +#define dtb_early_pa (*(uintptr_t *)XIP_FIXUP(&_dtb_early_pa))
>> > +#else
>> > +#define dtb_early_va _dtb_early_va
>> > +#define dtb_early_pa _dtb_early_pa
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  void setup_bootmem(void);
>> >  void paging_init(void);
>> >  void misc_mem_init(void);
>> > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>> > index 6cb05f22e52a..89cc58ab52b4 100644
>> > --- a/arch/riscv/kernel/head.S
>> > +++ b/arch/riscv/kernel/head.S
>> > @@ -9,11 +9,23 @@
>> >  #include <linux/linkage.h>
>> >  #include <asm/thread_info.h>
>> >  #include <asm/page.h>
>> > +#include <asm/pgtable.h>
>> >  #include <asm/csr.h>
>> >  #include <asm/hwcap.h>
>> >  #include <asm/image.h>
>> >  #include "efi-header.S"
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +.macro XIP_FIXUP_OFFSET reg
>> > +     REG_L t0, _xip_fixup
>> > +     add \reg, \reg, t0
>> > +.endm
>> > +_xip_fixup: .dword CONFIG_PHYS_RAM_BASE - CONFIG_XIP_PHYS_ADDR - XIP_OFFSET
>> > +#else
>> > +.macro XIP_FIXUP_OFFSET reg
>> > +.endm
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  __HEAD
>> >  ENTRY(_start)
>> >       /*
>> > @@ -70,6 +82,7 @@ pe_head_start:
>> >  relocate:
>> >       /* Relocate return address */
>> >       la a1, kernel_virt_addr
>> > +     XIP_FIXUP_OFFSET a1
>> >       REG_L a1, 0(a1)
>> >       la a2, _start
>> >       sub a1, a1, a2
>> > @@ -92,6 +105,7 @@ relocate:
>> >        * to ensure the new translations are in use.
>> >        */
>> >       la a0, trampoline_pg_dir
>> > +     XIP_FIXUP_OFFSET a0
>> >       srl a0, a0, PAGE_SHIFT
>> >       or a0, a0, a1
>> >       sfence.vma
>> > @@ -145,7 +159,9 @@ secondary_start_sbi:
>> >
>> >       slli a3, a0, LGREG
>> >       la a4, __cpu_up_stack_pointer
>> > +     XIP_FIXUP_OFFSET a4
>> >       la a5, __cpu_up_task_pointer
>> > +     XIP_FIXUP_OFFSET a5
>> >       add a4, a3, a4
>> >       add a5, a3, a5
>> >       REG_L sp, (a4)
>> > @@ -157,6 +173,7 @@ secondary_start_common:
>> >  #ifdef CONFIG_MMU
>> >       /* Enable virtual memory and relocate to virtual address */
>> >       la a0, swapper_pg_dir
>> > +     XIP_FIXUP_OFFSET a0
>> >       call relocate
>> >  #endif
>> >       call setup_trap_vector
>> > @@ -237,12 +254,33 @@ pmp_done:
>> >  .Lgood_cores:
>> >  #endif
>> >
>> > +#ifndef CONFIG_XIP_KERNEL
>> >       /* Pick one hart to run the main boot sequence */
>> >       la a3, hart_lottery
>> >       li a2, 1
>> >       amoadd.w a3, a2, (a3)
>> >       bnez a3, .Lsecondary_start
>> >
>> > +#else
>> > +     /* hart_lottery in flash contains a magic number */
>> > +     la a3, hart_lottery
>> > +     mv a2, a3
>> > +     XIP_FIXUP_OFFSET a2
>> > +     lw t1, (a3)
>> > +     amoswap.w t0, t1, (a2)
>> > +     /* first time here if hart_lottery in RAM is not set */
>> > +     beq t0, t1, .Lsecondary_start
>> > +
>> > +     la sp, _end + THREAD_SIZE
>> > +     XIP_FIXUP_OFFSET sp
>> > +     mv s0, a0
>> > +     call __copy_data
>> > +
>> > +     /* Restore a0 copy */
>> > +     mv a0, s0
>> > +#endif
>> > +
>> > +#ifndef CONFIG_XIP_KERNEL
>> >       /* Clear BSS for flat non-ELF images */
>> >       la a3, __bss_start
>> >       la a4, __bss_stop
>> > @@ -252,15 +290,18 @@ clear_bss:
>> >       add a3, a3, RISCV_SZPTR
>> >       blt a3, a4, clear_bss
>> >  clear_bss_done:
>> > -
>> > +#endif
>> >       /* Save hart ID and DTB physical address */
>> >       mv s0, a0
>> >       mv s1, a1
>> > +
>> >       la a2, boot_cpu_hartid
>> > +     XIP_FIXUP_OFFSET a2
>> >       REG_S a0, (a2)
>> >
>> >       /* Initialize page tables and relocate to virtual addresses */
>> >       la sp, init_thread_union + THREAD_SIZE
>> > +     XIP_FIXUP_OFFSET sp
>> >  #ifdef CONFIG_BUILTIN_DTB
>> >       la a0, __dtb_start
>> >  #else
>> > @@ -269,6 +310,7 @@ clear_bss_done:
>> >       call setup_vm
>> >  #ifdef CONFIG_MMU
>> >       la a0, early_pg_dir
>> > +     XIP_FIXUP_OFFSET a0
>> >       call relocate
>> >  #endif /* CONFIG_MMU */
>> >
>> > @@ -293,7 +335,9 @@ clear_bss_done:
>> >
>> >       slli a3, a0, LGREG
>> >       la a1, __cpu_up_stack_pointer
>> > +     XIP_FIXUP_OFFSET a1
>> >       la a2, __cpu_up_task_pointer
>> > +     XIP_FIXUP_OFFSET a2
>> >       add a1, a3, a1
>> >       add a2, a3, a2
>> >
>> > diff --git a/arch/riscv/kernel/head.h b/arch/riscv/kernel/head.h
>> > index b48dda3d04f6..aabbc3ac3e48 100644
>> > --- a/arch/riscv/kernel/head.h
>> > +++ b/arch/riscv/kernel/head.h
>> > @@ -12,6 +12,9 @@ extern atomic_t hart_lottery;
>> >
>> >  asmlinkage void do_page_fault(struct pt_regs *regs);
>> >  asmlinkage void __init setup_vm(uintptr_t dtb_pa);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +asmlinkage void __init __copy_data(void);
>> > +#endif
>> >
>> >  extern void *__cpu_up_stack_pointer[];
>> >  extern void *__cpu_up_task_pointer[];
>> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> > index 30e4af0fd50c..2ddf654c72bb 100644
>> > --- a/arch/riscv/kernel/setup.c
>> > +++ b/arch/riscv/kernel/setup.c
>> > @@ -50,7 +50,11 @@ struct screen_info screen_info __section(".data") = {
>> >   * This is used before the kernel initializes the BSS so it can't be in the
>> >   * BSS.
>> >   */
>> > -atomic_t hart_lottery __section(".sdata");
>> > +atomic_t hart_lottery __section(".sdata")
>> > +#ifdef CONFIG_XIP_KERNEL
>> > += ATOMIC_INIT(0xC001BEEF)
>> > +#endif
>> > +;
>> >  unsigned long boot_cpu_hartid;
>> >  static DEFINE_PER_CPU(struct cpu, cpu_devices);
>> >
>> > @@ -254,7 +258,7 @@ void __init setup_arch(char **cmdline_p)
>> >  #if IS_ENABLED(CONFIG_BUILTIN_DTB)
>> >       unflatten_and_copy_device_tree();
>> >  #else
>> > -     if (early_init_dt_verify(__va(dtb_early_pa)))
>> > +     if (early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa))))
>> >               unflatten_device_tree();
>> >       else
>> >               pr_err("No DTB found in kernel mappings\n");
>> > @@ -266,7 +270,7 @@ 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)
>> > +#if defined(CONFIG_64BIT) && defined(CONFIG_MMU) && !defined(CONFIG_XIP_KERNEL)
>> >       protect_kernel_linear_mapping_text_rodata();
>> >  #endif
>>
>> My tree doesn't look quite like this.  Not sure if I just got the wrong
>> version of something, but I didn't have the CONFIG_MMU check.  It turns
>> out that, as I was merging this in, I saw that failing allnoconfig
>> (which is !MMU).  I went ahead and squashed in
>>
>> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> index ab394d173cd4..3e7930869ee7 100644
>> --- a/arch/riscv/kernel/setup.c
>> +++ b/arch/riscv/kernel/setup.c
>> @@ -266,7 +266,7 @@ void __init setup_arch(char **cmdline_p)
>>
>>         if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
>>                 protect_kernel_text_data();
>> -#ifdef CONFIG_64BIT
>> +#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
>>                 protect_kernel_linear_mapping_text_rodata();
>>  #endif
>>         }
>>
>> to your memory map rearrangement patch, but I'm a bit worried that I managed to
>> miss something in the process.
>>
>> >
>> > diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S
>> > new file mode 100644
>> > index 000000000000..4b29b9917f99
>> > --- /dev/null
>> > +++ b/arch/riscv/kernel/vmlinux-xip.lds.S
>> > @@ -0,0 +1,133 @@
>> > +/* SPDX-License-Identifier: GPL-2.0-only */
>> > +/*
>> > + * Copyright (C) 2012 Regents of the University of California
>> > + * Copyright (C) 2017 SiFive
>> > + * Copyright (C) 2020 Vitaly Wool, Konsulko AB
>> > + */
>> > +
>> > +#include <asm/pgtable.h>
>> > +#define LOAD_OFFSET KERNEL_LINK_ADDR
>> > +/* No __ro_after_init data in the .rodata section - which will always be ro */
>> > +#define RO_AFTER_INIT_DATA
>> > +
>> > +#include <asm/vmlinux.lds.h>
>> > +#include <asm/page.h>
>> > +#include <asm/pgtable.h>
>> > +#include <asm/cache.h>
>> > +#include <asm/thread_info.h>
>> > +
>> > +OUTPUT_ARCH(riscv)
>> > +ENTRY(_start)
>> > +
>> > +jiffies = jiffies_64;
>> > +
>> > +SECTIONS
>> > +{
>> > +     /* Beginning of code and text segment */
>> > +     . = LOAD_OFFSET;
>> > +     _xiprom = .;
>> > +     _start = .;
>> > +     HEAD_TEXT_SECTION
>> > +     INIT_TEXT_SECTION(PAGE_SIZE)
>> > +     /* we have to discard exit text and such at runtime, not link time */
>> > +     .exit.text :
>> > +     {
>> > +             EXIT_TEXT
>> > +     }
>> > +
>> > +     .text : {
>> > +             _text = .;
>> > +             _stext = .;
>> > +             TEXT_TEXT
>> > +             SCHED_TEXT
>> > +             CPUIDLE_TEXT
>> > +             LOCK_TEXT
>> > +             KPROBES_TEXT
>> > +             ENTRY_TEXT
>> > +             IRQENTRY_TEXT
>> > +             SOFTIRQENTRY_TEXT
>> > +             *(.fixup)
>> > +             _etext = .;
>> > +     }
>> > +     RO_DATA(L1_CACHE_BYTES)
>> > +     .srodata : {
>> > +             *(.srodata*)
>> > +     }
>> > +     .init.rodata : {
>> > +             INIT_SETUP(16)
>> > +             INIT_CALLS
>> > +             CON_INITCALL
>> > +             INIT_RAM_FS
>> > +     }
>> > +     _exiprom = .;                   /* End of XIP ROM area */
>> > +
>> > +
>> > +/*
>> > + * From this point, stuff is considered writable and will be copied to RAM
>> > + */
>> > +     __data_loc = ALIGN(16);         /* location in file */
>> > +     . = LOAD_OFFSET + XIP_OFFSET;   /* location in memory */
>> > +
>> > +     _sdata = .;                     /* Start of data section */
>> > +     _data = .;
>> > +     RW_DATA(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
>> > +     _edata = .;
>> > +     __start_ro_after_init = .;
>> > +     .data.ro_after_init : AT(ADDR(.data.ro_after_init) - LOAD_OFFSET) {
>> > +             *(.data..ro_after_init)
>> > +     }
>> > +     __end_ro_after_init = .;
>> > +
>> > +     . = ALIGN(PAGE_SIZE);
>> > +     __init_begin = .;
>> > +     .init.data : {
>> > +             INIT_DATA
>> > +     }
>> > +     .exit.data : {
>> > +             EXIT_DATA
>> > +     }
>> > +     . = ALIGN(8);
>> > +     __soc_early_init_table : {
>> > +             __soc_early_init_table_start = .;
>> > +             KEEP(*(__soc_early_init_table))
>> > +             __soc_early_init_table_end = .;
>> > +     }
>> > +     __soc_builtin_dtb_table : {
>> > +             __soc_builtin_dtb_table_start = .;
>> > +             KEEP(*(__soc_builtin_dtb_table))
>> > +             __soc_builtin_dtb_table_end = .;
>> > +     }
>> > +     PERCPU_SECTION(L1_CACHE_BYTES)
>> > +
>> > +     . = ALIGN(PAGE_SIZE);
>> > +     __init_end = .;
>> > +
>> > +     .sdata : {
>> > +             __global_pointer$ = . + 0x800;
>> > +             *(.sdata*)
>> > +             *(.sbss*)
>> > +     }
>> > +
>> > +     BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0)
>> > +     EXCEPTION_TABLE(0x10)
>> > +
>> > +     .rel.dyn : AT(ADDR(.rel.dyn) - LOAD_OFFSET) {
>> > +             *(.rel.dyn*)
>> > +     }
>> > +
>> > +     /*
>> > +      * End of copied data. We need a dummy section to get its LMA.
>> > +      * Also located before final ALIGN() as trailing padding is not stored
>> > +      * in the resulting binary file and useless to copy.
>> > +      */
>> > +     .data.endmark : AT(ADDR(.data.endmark) - LOAD_OFFSET) { }
>> > +     _edata_loc = LOADADDR(.data.endmark);
>> > +
>> > +     . = ALIGN(PAGE_SIZE);
>> > +     _end = .;
>> > +
>> > +     STABS_DEBUG
>> > +     DWARF_DEBUG
>> > +
>> > +     DISCARDS
>> > +}
>> > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
>> > index 0726c05e0336..0a59b65cf789 100644
>> > --- a/arch/riscv/kernel/vmlinux.lds.S
>> > +++ b/arch/riscv/kernel/vmlinux.lds.S
>> > @@ -4,8 +4,13 @@
>> >   * Copyright (C) 2017 SiFive
>> >   */
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#include "vmlinux-xip.lds.S"
>> > +#else
>> > +
>> >  #include <asm/pgtable.h>
>> >  #define LOAD_OFFSET KERNEL_LINK_ADDR
>> > +
>> >  #include <asm/vmlinux.lds.h>
>> >  #include <asm/page.h>
>> >  #include <asm/cache.h>
>> > @@ -133,3 +138,4 @@ SECTIONS
>> >
>> >       DISCARDS
>> >  }
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> > index 093f3a96ecfc..d03e5e43d2d0 100644
>> > --- a/arch/riscv/mm/init.c
>> > +++ b/arch/riscv/mm/init.c
>> > @@ -27,6 +27,9 @@
>> >
>> >  unsigned long kernel_virt_addr = KERNEL_LINK_ADDR;
>> >  EXPORT_SYMBOL(kernel_virt_addr);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define kernel_virt_addr       (*((unsigned long *)XIP_FIXUP(&kernel_virt_addr)))
>> > +#endif
>> >
>> >  unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>> >                                                       __page_aligned_bss;
>> > @@ -34,8 +37,8 @@ EXPORT_SYMBOL(empty_zero_page);
>> >
>> >  extern char _start[];
>> >  #define DTB_EARLY_BASE_VA      PGDIR_SIZE
>> > -void *dtb_early_va __initdata;
>> > -uintptr_t dtb_early_pa __initdata;
>> > +void *_dtb_early_va __initdata;
>> > +uintptr_t _dtb_early_pa __initdata;
>> >
>> >  struct pt_alloc_ops {
>> >       pte_t *(*get_pte_virt)(phys_addr_t pa);
>> > @@ -118,6 +121,10 @@ void __init setup_bootmem(void)
>> >       phys_addr_t dram_end = memblock_end_of_DRAM();
>> >       phys_addr_t max_mapped_addr = __pa(~(ulong)0);
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +     vmlinux_start = __pa_symbol(&_sdata);
>> > +#endif
>> > +
>> >       /* The maximal physical memory size is -PAGE_OFFSET. */
>> >       memblock_enforce_memory_limit(-PAGE_OFFSET);
>> >
>> > @@ -159,15 +166,39 @@ void __init setup_bootmem(void)
>> >       memblock_allow_resize();
>> >  }
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +
>> > +extern char _xiprom[], _exiprom[];
>> > +extern char _sdata[], _edata[];
>> > +
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  #ifdef CONFIG_MMU
>> > -static struct pt_alloc_ops pt_ops;
>> > +static struct pt_alloc_ops _pt_ops;
>> > +
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define pt_ops (*(struct pt_alloc_ops *)XIP_FIXUP(&_pt_ops))
>> > +#else
>> > +#define pt_ops _pt_ops
>> > +#endif
>> >
>> >  /* Offset between linear mapping virtual address and kernel load address */
>> >  unsigned long va_pa_offset;
>> >  EXPORT_SYMBOL(va_pa_offset);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define va_pa_offset   (*((unsigned long *)XIP_FIXUP(&va_pa_offset)))
>> > +#endif
>> >  /* Offset between kernel mapping virtual address and kernel load address */
>> >  unsigned long va_kernel_pa_offset;
>> >  EXPORT_SYMBOL(va_kernel_pa_offset);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define va_kernel_pa_offset    (*((unsigned long *)XIP_FIXUP(&va_kernel_pa_offset)))
>> > +#endif
>> > +unsigned long va_kernel_xip_pa_offset;
>> > +EXPORT_SYMBOL(va_kernel_xip_pa_offset);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define va_kernel_xip_pa_offset        (*((unsigned long *)XIP_FIXUP(&va_kernel_xip_pa_offset)))
>> > +#endif
>> >  unsigned long pfn_base;
>> >  EXPORT_SYMBOL(pfn_base);
>> >
>> > @@ -177,6 +208,12 @@ pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
>> >
>> >  pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define trampoline_pg_dir      ((pgd_t *)XIP_FIXUP(trampoline_pg_dir))
>> > +#define fixmap_pte             ((pte_t *)XIP_FIXUP(fixmap_pte))
>> > +#define early_pg_dir           ((pgd_t *)XIP_FIXUP(early_pg_dir))
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
>> >  {
>> >       unsigned long addr = __fix_to_virt(idx);
>> > @@ -252,6 +289,12 @@ pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> >  pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>> >  pmd_t early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define trampoline_pmd ((pmd_t *)XIP_FIXUP(trampoline_pmd))
>> > +#define fixmap_pmd     ((pmd_t *)XIP_FIXUP(fixmap_pmd))
>> > +#define early_pmd      ((pmd_t *)XIP_FIXUP(early_pmd))
>> > +#endif /* CONFIG_XIP_KERNEL */
>> > +
>> >  static pmd_t *__init get_pmd_virt_early(phys_addr_t pa)
>> >  {
>> >       /* Before MMU is enabled */
>> > @@ -368,6 +411,19 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
>> >       return PMD_SIZE;
>> >  }
>> >
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +/* called from head.S with MMU off */
>> > +asmlinkage void __init __copy_data(void)
>> > +{
>> > +     void *from = (void *)(&_sdata);
>> > +     void *end = (void *)(&_end);
>> > +     void *to = (void *)CONFIG_PHYS_RAM_BASE;
>> > +     size_t sz = (size_t)(end - from + 1);
>> > +
>> > +     memcpy(to, from, sz);
>> > +}
>> > +#endif
>> > +
>> >  /*
>> >   * setup_vm() is called from head.S with MMU-off.
>> >   *
>> > @@ -387,7 +443,35 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
>> >  #endif
>> >
>> >  uintptr_t load_pa, load_sz;
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +#define load_pa        (*((uintptr_t *)XIP_FIXUP(&load_pa)))
>> > +#define load_sz        (*((uintptr_t *)XIP_FIXUP(&load_sz)))
>> > +#endif
>> > +
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +uintptr_t xiprom, xiprom_sz;
>> > +#define xiprom_sz      (*((uintptr_t *)XIP_FIXUP(&xiprom_sz)))
>> > +#define xiprom         (*((uintptr_t *)XIP_FIXUP(&xiprom)))
>> >
>> > +static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>> > +{
>> > +     uintptr_t va, end_va;
>> > +
>> > +     /* Map the flash resident part */
>> > +     end_va = kernel_virt_addr + xiprom_sz;
>> > +     for (va = kernel_virt_addr; va < end_va; va += map_size)
>> > +             create_pgd_mapping(pgdir, va,
>> > +                                xiprom + (va - kernel_virt_addr),
>> > +                                map_size, PAGE_KERNEL_EXEC);
>> > +
>> > +     /* Map the data in RAM */
>> > +     end_va = kernel_virt_addr + XIP_OFFSET + load_sz;
>> > +     for (va = kernel_virt_addr + XIP_OFFSET; va < end_va; va += map_size)
>> > +             create_pgd_mapping(pgdir, va,
>> > +                                load_pa + (va - (kernel_virt_addr + XIP_OFFSET)),
>> > +                                map_size, PAGE_KERNEL);
>> > +}
>> > +#else
>> >  static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>> >  {
>> >       uintptr_t va, end_va;
>> > @@ -398,16 +482,28 @@ static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>> >                                  load_pa + (va - kernel_virt_addr),
>> >                                  map_size, PAGE_KERNEL_EXEC);
>> >  }
>> > +#endif
>> >
>> >  asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>> >  {
>> > -     uintptr_t pa;
>> > +     uintptr_t __maybe_unused pa;
>> >       uintptr_t map_size;
>> >  #ifndef __PAGETABLE_PMD_FOLDED
>> >       pmd_t fix_bmap_spmd, fix_bmap_epmd;
>> >  #endif
>> > +
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +     xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
>> > +     xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);
>> > +
>> > +     load_pa = (uintptr_t)CONFIG_PHYS_RAM_BASE;
>> > +     load_sz = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);
>> > +
>> > +     va_kernel_xip_pa_offset = kernel_virt_addr - xiprom;
>> > +#else
>> >       load_pa = (uintptr_t)(&_start);
>> >       load_sz = (uintptr_t)(&_end) - load_pa;
>> > +#endif
>> >
>> >       va_pa_offset = PAGE_OFFSET - load_pa;
>> >       va_kernel_pa_offset = kernel_virt_addr - load_pa;
>> > @@ -441,8 +537,13 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>> >       /* Setup trampoline PGD and PMD */
>> >       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>> >                          (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
>> > +#ifdef CONFIG_XIP_KERNEL
>> > +     create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>> > +                        xiprom, PMD_SIZE, PAGE_KERNEL_EXEC);
>> > +#else
>> >       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>> >                          load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>> > +#endif
>> >  #else
>> >       /* Setup trampoline PGD */
>> >       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>> > @@ -474,7 +575,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>> >        * 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);
>> > +     dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
>> >  #endif /* CONFIG_BUILTIN_DTB */
>> >  #else
>> >  #ifndef CONFIG_BUILTIN_DTB
>> > @@ -486,7 +587,7 @@ 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 = kernel_mapping_pa_to_va(dtb_pa);
>> > +     dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
>> >  #endif /* CONFIG_BUILTIN_DTB */
>> >  #endif
>> >       dtb_early_pa = dtb_pa;
>> > @@ -522,7 +623,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>> >  #endif
>> >  }
>> >
>> > -#ifdef CONFIG_64BIT
>> > +#if defined(CONFIG_64BIT) && !defined(CONFIG_XIP_KERNEL)
>> >  void protect_kernel_linear_mapping_text_rodata(void)
>> >  {
>> >       unsigned long text_start = (unsigned long)lm_alias(_start);



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