Re: [PATCH v8] RISC-V: enable XIP
From: Vitaly Wool
Date: Fri Apr 23 2021 - 17:27:57 EST
Hi Palmer,
On Fri, Apr 23, 2021 at 6:22 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
>
> On Mon, 12 Apr 2021 23:35:14 PDT (-0700), alex@xxxxxxxx wrote:
> > From: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
> >
> > 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@xxxxxxxx> [ Rebase on top of "Move
> > kernel mapping outside the linear mapping" ]
> > Signed-off-by: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
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);