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References: <20210413063514.23105-1-alex@ghiti.fr> <mhng-308e5471-7834-470f-8111-9d140ad33ac9@palmerdabbelt-glaptop>
In-Reply-To: <mhng-308e5471-7834-470f-8111-9d140ad33ac9@palmerdabbelt-glaptop>
From:   Vitaly Wool <vitaly.wool@konsulko.com>
Date:   Fri, 23 Apr 2021 23:27:26 +0200
Message-ID: <CAM4kBBJChiqkarKwn3roe+BLotsGDptfmYKKDxE45AnFZNUoPw@mail.gmail.com>
Subject: Re: [PATCH v8] RISC-V: enable XIP
To:     Palmer Dabbelt <palmer@dabbelt.com>
Cc:     Alex Ghiti <alex@ghiti.fr>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-arch@vger.kernel.org,
        Linux-MM <linux-mm@kvack.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Palmer,

On Fri, Apr 23, 2021 at 6:22 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
>
> On Mon, 12 Apr 2021 23:35:14 PDT (-0700), alex@ghiti.fr wrote:
> > From: Vitaly Wool <vitaly.wool@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@ghiti.fr> [ Rebase on top of "Move
> > kernel mapping outside the linear mapping" ]
> > Signed-off-by: Vitaly Wool <vitaly.wool@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.

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);