[PATCH v7] RISC-V: enable XIP
Alex Ghiti
alex at ghiti.fr
Fri Apr 9 08:14:55 BST 2021
Le 4/9/21 à 2:51 AM, Alexandre Ghiti a écrit :
> 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.
>
I added linux-mm and linux-arch to get feedbacks because I noticed that
DEBUG_VM_PGTABLE fails for SPARSEMEM (it works for FLATMEM but I think
it does not do what is expected): the fact that we don't have any struct
page to back the text and rodata in flash is the problem but to which
extent ?
Thanks,
Alex
> 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>
> ---
>
> Changes in v2:
> - dedicated macro for XIP address fixup when MMU is not enabled yet
> o both for 32-bit and 64-bit RISC-V
> - SP is explicitly set to a safe place in RAM before __copy_data call
> - removed redundant alignment requirements in vmlinux-xip.lds.S
> - changed long -> uintptr_t typecast in __XIP_FIXUP macro.
> Changes in v3:
> - rebased against latest for-next
> - XIP address fixup macro now takes an argument
> - SMP related fixes
> Changes in v4:
> - rebased against the current for-next
> - less #ifdef's in C/ASM code
> - dedicated XIP_FIXUP_OFFSET assembler macro in head.S
> - C-specific definitions moved into #ifndef __ASSEMBLY__
> - Fixed multi-core boot
> Changes in v5:
> - fixed build error for non-XIP kernels
> Changes in v6:
> - XIP_PHYS_RAM_BASE config option renamed to PHYS_RAM_BASE
> - added PHYS_RAM_BASE_FIXED config flag to allow usage of
> PHYS_RAM_BASE in non-XIP configurations if needed
> - XIP_FIXUP macro rewritten with a tempoarary variable to avoid side
> effects
> - fixed crash for non-XIP kernels that don't use built-in DTB
> Changes in v7:
> - Fix pfn_base that required FIXUP
> - Fix copy_data which lacked + 1 in size to copy
> - Fix pfn_valid for FLATMEM
> - Rebased on top of "Move kernel mapping outside the linear mapping":
> this is the biggest change and affected mm/init.c,
> kernel/vmlinux-xip.lds.S and include/asm/pgtable.h: XIP kernel is now
> mapped like 'normal' kernel at the end of the address space.
>
> arch/riscv/Kconfig | 51 ++++++++++-
> arch/riscv/Makefile | 8 +-
> arch/riscv/boot/Makefile | 13 +++
> arch/riscv/include/asm/page.h | 28 ++++++
> 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 | 118 ++++++++++++++++++++++--
> 11 files changed, 424 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..4d0153805927 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
> 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 +465,56 @@ 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
> + 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.
> +
> + 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..6fe0ff8c8fa9 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) ? \
> @@ -139,9 +160,16 @@ extern phys_addr_t __phys_addr_symbol(unsigned long x);
> #define phys_to_page(paddr) (pfn_to_page(phys_to_pfn(paddr)))
>
> #ifdef CONFIG_FLATMEM
> +#ifdef CONFIG_XIP_KERNEL
> +#define pfn_valid(pfn) \
> + ((((pfn) >= ARCH_PFN_OFFSET) && (((pfn) - ARCH_PFN_OFFSET) < max_mapnr)) || \
> + ((pfn) >= PFN_DOWN(CONFIG_XIP_PHYS_ADDR) && \
> + (((pfn) - PFN_DOWN(CONFIG_XIP_PHYS_ADDR)) < XIP_OFFSET)))
> +#else
> #define pfn_valid(pfn) \
> (((pfn) >= ARCH_PFN_OFFSET) && (((pfn) - ARCH_PFN_OFFSET) < max_mapnr))
> #endif
> +#endif
>
> #endif /* __ASSEMBLY__ */
>
> 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
>
> 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..9961573f9a55 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);
>
> @@ -159,17 +166,44 @@ 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);
> +#ifdef CONFIG_XIP_KERNEL
> +#define pfn_base (*((unsigned long *)XIP_FIXUP(&pfn_base)))
> +#endif
>
> pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> @@ -177,6 +211,12 @@ 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 +292,12 @@ 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 +414,19 @@ 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 +446,35 @@ 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 +485,28 @@ 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 +540,13 @@ 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 +578,7 @@ 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 +590,7 @@ 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 +626,7 @@ 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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