Re: [PATCH v7] RISC-V: enable XIP

David Hildenbrand
2021-04-09T08:23:19Z

On 09.04.21 09:14, Alex Ghiti wrote:
> Le 4/9/21 à 2:51 AM, Alexandre Ghiti a écrit :
>> 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.
>>
> 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 ?

Just wondering, why can't we create a memmap for that memory -- or is it
even desireable to not do that explicity? There might be some nasty side
effects when not having a memmap for text and rodata.

I would assume stimply exposing the physical memory range to memblock as
RAM and marking it reserved would create a memmap that's fully
initialized like any bootmem (PG_reserved).

Or is there a reason why we cannot do that?

Also, will that memory properly be exposed in the resource tree as
System RAM (e.g., /proc/iomem) ? Otherwise some things (/proc/kcore)
won't work as expected - the kernel won't be included in a dump.

>
> Thanks,
>
> Alex
>
>> 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>
>> ---
>>
>> 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);
>>
>

--
Thanks,

David / dhildenb