[PATCH v6] RISC-V: enable XIP
Alex Ghiti
alex at ghiti.fr
Tue Mar 30 21:04:18 BST 2021
Le 3/30/21 à 3:33 PM, Palmer Dabbelt a écrit :
> On Tue, 30 Mar 2021 11:39:10 PDT (-0700), alex at ghiti.fr wrote:
>>
>>
>> Le 3/30/21 à 2:26 AM, Vitaly Wool a écrit :
>>> On Tue, Mar 30, 2021 at 8:23 AM Palmer Dabbelt
>>> <palmerdabbelt at google.com> wrote:
>>>>
>>>> On Sun, 21 Mar 2021 17:12:15 PDT (-0700), vitaly.wool at konsulko.com
>>>> wrote:
>>>>> 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: 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
>>>>
>>>> So v5 landed on for-next, which generally means it's best to avoid
>>>> re-spinning the patch and instead send along fixups. That said, the v5
>>>> is causing some testing failures for me.
>>>>
>>>> I'm going to drop the v5 for now as I don't have time to test this
>>>> tonight. I'll try and take a look soon, as it will conflict with
>>>> Alex's
>>>> patches.
>>>
>>> I can come up with the incremental patch instead pretty much straight
>>> away if that works better.
>>>
>>> ~Vitaly
>>>
>>>>> arch/riscv/Kconfig | 49 ++++++++++-
>>>>> arch/riscv/Makefile | 8 +-
>>>>> arch/riscv/boot/Makefile | 13 +++
>>>>> arch/riscv/include/asm/pgtable.h | 65 ++++++++++++--
>>>>> arch/riscv/kernel/cpu_ops_sbi.c | 11 ++-
>>>>> arch/riscv/kernel/head.S | 49 ++++++++++-
>>>>> arch/riscv/kernel/head.h | 3 +
>>>>> arch/riscv/kernel/setup.c | 8 +-
>>>>> arch/riscv/kernel/vmlinux-xip.lds.S | 132
>>>>> ++++++++++++++++++++++++++++
>>>>> arch/riscv/kernel/vmlinux.lds.S | 6 ++
>>>>> arch/riscv/mm/init.c | 100 +++++++++++++++++++--
>>>>> 11 files changed, 426 insertions(+), 18 deletions(-)
>>>>> create mode 100644 arch/riscv/kernel/vmlinux-xip.lds.S
>>>>>
>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>>> index 8ea60a0a19ae..bd6f82240c34 100644
>>>>> --- a/arch/riscv/Kconfig
>>>>> +++ b/arch/riscv/Kconfig
>>>>> @@ -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/pgtable.h
>>>>> b/arch/riscv/include/asm/pgtable.h
>>>>> index ebf817c1bdf4..21a9b2f8d1c7 100644
>>>>> --- a/arch/riscv/include/asm/pgtable.h
>>>>> +++ b/arch/riscv/include/asm/pgtable.h
>>>>> @@ -11,6 +11,33 @@
>>>>>
>>>>> #include <asm/pgtable-bits.h>
>>>>>
>>>>> +#ifdef CONFIG_MMU
>>>>> +
>>>>> +#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
>>>>> +
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> +#define VMALLOC_SIZE ((KERN_VIRT_SIZE >> 1) - SZ_16M)
>>>>> +#define VMALLOC_END (PAGE_OFFSET - SZ_16M - 1)
>>>>> +
>>>>> +#define XIP_OFFSET SZ_8M
>>>>> +#define XIP_MASK (SZ_8M - 1)
>>>>> +#define XIP_VIRT_ADDR(physaddr) \
>>>>> + (PAGE_OFFSET - XIP_OFFSET + ((physaddr) & XIP_MASK))
>>>>> +
>>>>> +#else
>>>>> +
>>>>> +#define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1)
>>>>> +#define VMALLOC_END (PAGE_OFFSET - 1)
>>>>> +
>>>>> +#endif /* CONFIG_XIP_KERNEL */
>>>>> +
>>>>> +#else
>>>>> +
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> +#define XIP_VIRT_ADDR(physaddr) (physaddr)
>>>>> +#endif /* CONFIG_XIP_KERNEL */
>>>>> +#endif /* CONFIG_MMU */
>>>>> +
>>>>> #ifndef __ASSEMBLY__
>>>>>
>>>>> /* Page Upper Directory not used in RISC-V */
>>>>> @@ -21,9 +48,25 @@
>>>>>
>>>>> #ifdef CONFIG_MMU
>>>>>
>>>>> -#define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1)
>>>>> -#define VMALLOC_END (PAGE_OFFSET - 1)
>>>>> -#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> +/*
>>>>> + * Since we use sections to map it, this macro replaces the
>>>>> physical address
>>>>> + * with its virtual address while keeping offset from the base
>>>>> section.
>>>>> + */
>>>>> +#define XIP_PHYS_ADDR(va) \
>>>>> + ((uintptr_t)(va) - PAGE_OFFSET + XIP_OFFSET +
>>>>> CONFIG_XIP_PHYS_ADDR)
>>>>> +
>>>>> +#define XIP_VIRT_ADDR_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
>>>>> +
>>>>> +#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 */
>>>>>
>>>>> #define BPF_JIT_REGION_SIZE (SZ_128M)
>>>>> #define BPF_JIT_REGION_START (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
>>>>> @@ -484,8 +527,20 @@ static inline int
>>>>> ptep_clear_flush_young(struct vm_area_struct *vma,
>>>>>
>>>>> #define kern_addr_valid(addr) (1) /* FIXME */
>>>>>
>>>>> -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/cpu_ops_sbi.c
>>>>> b/arch/riscv/kernel/cpu_ops_sbi.c
>>>>> index 685fae72b7f5..2413c2997350 100644
>>>>> --- a/arch/riscv/kernel/cpu_ops_sbi.c
>>>>> +++ b/arch/riscv/kernel/cpu_ops_sbi.c
>>>>> @@ -53,10 +53,19 @@ static int sbi_hsm_hart_get_status(unsigned
>>>>> long hartid)
>>>>> }
>>>>> #endif
>>>>>
>>>>> +static inline unsigned long get_secondary_start_phys(void)
>>>>> +{
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + return XIP_PHYS_ADDR(secondary_start_sbi);
>>>>> +#else
>>>>> + return __pa_symbol(secondary_start_sbi);
>>>>> +#endif
>>>>> +}
>>>>> +
>>>>> static int sbi_cpu_start(unsigned int cpuid, struct task_struct
>>>>> *tidle)
>>>>> {
>>>>> int rc;
>>>>> - unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
>>>>> + unsigned long boot_addr = get_secondary_start_phys();
>>>>> int hartid = cpuid_to_hartid_map(cpuid);
>>>>>
>>>>> cpu_update_secondary_bootdata(cpuid, tidle);
>>>>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>>>>> index f5a9bad86e58..bbe74e37914f 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)
>>>>> /*
>>>>> @@ -69,7 +81,11 @@ pe_head_start:
>>>>> #ifdef CONFIG_MMU
>>>>> relocate:
>>>>> /* Relocate return address */
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + li a1, XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
>>>>> +#else
>>>>> li a1, PAGE_OFFSET
>>>>> +#endif
>>>>> la a2, _start
>>>>> sub a1, a1, a2
>>>>> add ra, ra, a1
>>>>> @@ -91,6 +107,7 @@ 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
>>>>> @@ -144,7 +161,9 @@ 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)
>>>>> @@ -156,6 +175,7 @@ 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
>>>>> @@ -236,12 +256,33 @@ 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
>>>>> @@ -251,15 +292,18 @@ 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
>>>>> @@ -268,6 +312,7 @@ clear_bss_done:
>>>>> call setup_vm
>>>>> #ifdef CONFIG_MMU
>>>>> la a0, early_pg_dir
>>>>> + XIP_FIXUP_OFFSET a0
>>>>> call relocate
>>>>> #endif /* CONFIG_MMU */
>>>>>
>>>>> @@ -292,7 +337,9 @@ 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 e85bacff1b50..a0384c72c272 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");
>>>>> diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S
>>>>> b/arch/riscv/kernel/vmlinux-xip.lds.S
>>>>> new file mode 100644
>>>>> index 000000000000..9f0f08c34cd3
>>>>> --- /dev/null
>>>>> +++ b/arch/riscv/kernel/vmlinux-xip.lds.S
>>>>> @@ -0,0 +1,132 @@
>>>>> +/* 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
>>>>> + */
>>>>> +
>>>>> +#define LOAD_OFFSET XIP_VIRT_ADDR(CONFIG_XIP_PHYS_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 */
>>>>> + . = XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR);
>>>>> + _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 */
>>>>> + . = PAGE_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 de03cb22d0e9..6745ec325930 100644
>>>>> --- a/arch/riscv/kernel/vmlinux.lds.S
>>>>> +++ b/arch/riscv/kernel/vmlinux.lds.S
>>>>> @@ -4,7 +4,12 @@
>>>>> * Copyright (C) 2017 SiFive
>>>>> */
>>>>>
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> +#include "vmlinux-xip.lds.S"
>>>>> +#else
>>>>> +
>>>>> #define LOAD_OFFSET PAGE_OFFSET
>>>>> +
>>>>> #include <asm/vmlinux.lds.h>
>>>>> #include <asm/page.h>
>>>>> #include <asm/cache.h>
>>>>> @@ -132,3 +137,4 @@ SECTIONS
>>>>>
>>>>> DISCARDS
>>>>> }
>>>>> +#endif /* CONFIG_XIP_KERNEL */
>>>>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>>>>> index 7f5036fbee8c..efe649d41f95 100644
>>>>> --- a/arch/riscv/mm/init.c
>>>>> +++ b/arch/riscv/mm/init.c
>>>>> @@ -31,8 +31,8 @@ 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);
>>>>> @@ -88,6 +88,10 @@ static void print_vm_layout(void)
>>>>> (unsigned long)VMALLOC_END);
>>>>> print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
>>>>> (unsigned long)high_memory);
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + print_mlm("xip", (unsigned long)XIP_VIRT_ADDR_START,
>>>>> + (unsigned long)XIP_VIRT_ADDR_START + SZ_16M);
>>>>> +#endif /* CONFIG_XIP_KERNEL */
>>>>> }
>>>>> #else
>>>>> static void print_vm_layout(void) { }
>>>>> @@ -113,6 +117,10 @@ 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);
>>>>>
>>>>> @@ -149,11 +157,27 @@ 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
>>>>>
>>>>> 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
>>>>> unsigned long pfn_base;
>>>>> EXPORT_SYMBOL(pfn_base);
>>>>>
>>>>> @@ -163,6 +187,12 @@ 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);
>>>>> @@ -238,6 +268,15 @@ 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
>>>>> +pmd_t xip_pmd[PTRS_PER_PMD] __page_aligned_bss;
>>>>> +
>>>>> +#define trampoline_pmd ((pmd_t *)XIP_FIXUP(trampoline_pmd))
>>>>> +#define fixmap_pmd ((pmd_t *)XIP_FIXUP(fixmap_pmd))
>>>>> +#define xip_pmd ((pmd_t *)XIP_FIXUP(xip_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 */
>>>>> @@ -354,6 +393,19 @@ 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);
>>>>> +
>>>>> + memcpy(to, from, sz);
>>>>> +}
>>>>> +#endif
>>>>> +
>>>>> /*
>>>>> * setup_vm() is called from head.S with MMU-off.
>>>>> *
>>>>> @@ -374,7 +426,8 @@ static uintptr_t __init
>>>>> best_map_size(phys_addr_t base, phys_addr_t size)
>>>>>
>>>>> asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>> {
>>>>> - uintptr_t va, pa, end_va;
>>>>> + uintptr_t va, end_va;
>>>>> + uintptr_t __maybe_unused pa;
>>>>> uintptr_t load_pa = (uintptr_t)(&_start);
>>>>> uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
>>>>> uintptr_t map_size;
>>>>> @@ -382,6 +435,13 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>> pmd_t fix_bmap_spmd, fix_bmap_epmd;
>>>>> #endif
>>>>>
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + uintptr_t xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
>>>>> + uintptr_t xiprom_sz = (uintptr_t)(&_exiprom) -
>>>>> (uintptr_t)(&_xiprom);
>>>>> +
>>>>> + load_pa = (uintptr_t)CONFIG_PHYS_RAM_BASE;
>>>>> + load_sz = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);
>>>>> +#endif
>>>>> va_pa_offset = PAGE_OFFSET - load_pa;
>>
>> I should have seen this before, I was too focused on having a XIP kernel
>> boot. I already moved the kernel mapping in the vmalloc zone: the
>> virtual to physical translations need to be handled differently now that
>> the kernel mapping does not lie into linear mapping anymore, we can't
>> use va_pa_offset defined above for both mappings.
>>
>> I was rebasing my patchset on the XIP patch but I believe that doing the
>> other way around would greatly simplify the XIP patch as the kernel
>> mapping would already be moved outside the linear mapping, there would
>> be no need to reserve a zone in vmalloc anymore (that simplifies
>> pgtable.h quite a lot). And the XIP kernel mapping could be implemented
>> in a new create_kernel_page_table (that would also simplify mm/init.c).
>>
>> I can help to do that but I don't think we should merge this patch as is
>> now.
>
> I think that's the right way to go for now: it's a lot harder to test
> the XIP stuff, as it requires a bunch of harness changes. So let's take
> the page table refactoring in now and rebase this stuff on top of it.
> There's really no way to do both without making more work for someone,
> it's just a headache on timing.
>
> Alex: if you want to sign up to spend some time there that'd be great,
> otherwise I will.
I can take care of that, no problem.
> Either way, can you point me (either just indicate
> the old version is OK or send a new one) to what you want me to look at
> WRT the page table code? IIRC it looked pretty much fine, but I'll take
> another look ASAP so we can avoid serializing everything.
The v3 is fine for me:
https://patchwork.kernel.org/project/linux-riscv/list/?series=447699
>
>>
>> Alex
>>
>>>>> pfn_base = PFN_DOWN(load_pa);
>>>>>
>>>>> @@ -420,6 +480,21 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>> load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
>>>>> #endif
>>>>>
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + create_pgd_mapping(trampoline_pg_dir, XIP_VIRT_ADDR_START,
>>>>> + (uintptr_t)xip_pmd, PGDIR_SIZE, PAGE_TABLE);
>>>>> + for (va = XIP_VIRT_ADDR_START;
>>>>> + va < XIP_VIRT_ADDR_START + xiprom_sz;
>>>>> + va += PMD_SIZE) {
>>>>> + create_pmd_mapping(xip_pmd, va,
>>>>> + xiprom + (va - XIP_VIRT_ADDR_START),
>>>>> + PMD_SIZE, PAGE_KERNEL_EXEC);
>>>>> + }
>>>>> +
>>>>> + create_pgd_mapping(early_pg_dir, XIP_VIRT_ADDR_START,
>>>>> + (uintptr_t)xip_pmd, PGDIR_SIZE, PAGE_TABLE);
>>>>> +#endif
>>>>> +
>>>>> /*
>>>>> * Setup early PGD covering entire kernel which will allows
>>>>> * us to reach paging_init(). We map all memory banks later
>>>>> @@ -444,7 +519,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>> pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
>>>>> dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa &
>>>>> (PMD_SIZE - 1));
>>>>> #else /* CONFIG_BUILTIN_DTB */
>>>>> - dtb_early_va = __va(dtb_pa);
>>>>> + dtb_early_va = __va(XIP_FIXUP(dtb_pa));
>>>>> #endif /* CONFIG_BUILTIN_DTB */
>>>>> #else
>>>>> #ifndef CONFIG_BUILTIN_DTB
>>>>> @@ -456,7 +531,7 @@ 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 = __va(dtb_pa);
>>>>> + dtb_early_va = __va(XIP_FIXUP(dtb_pa));
>>>>> #endif /* CONFIG_BUILTIN_DTB */
>>>>> #endif
>>>>> dtb_early_pa = dtb_pa;
>>>>> @@ -497,6 +572,9 @@ static void __init setup_vm_final(void)
>>>>> uintptr_t va, map_size;
>>>>> phys_addr_t pa, start, end;
>>>>> u64 i;
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + uintptr_t xiprom_sz = (uintptr_t)(&_exiprom) -
>>>>> (uintptr_t)(&_xiprom);
>>>>> +#endif
>>>>>
>>>>> /**
>>>>> * MMU is enabled at this point. But page table setup is not
>>>>> complete yet.
>>>>> @@ -528,6 +606,16 @@ static void __init setup_vm_final(void)
>>>>> map_size, PAGE_KERNEL_EXEC);
>>>>> }
>>>>> }
>>>>> +#ifdef CONFIG_XIP_KERNEL
>>>>> + map_size = best_map_size(CONFIG_XIP_PHYS_ADDR, xiprom_sz);
>>>>> + for (va = XIP_VIRT_ADDR_START;
>>>>> + va < XIP_VIRT_ADDR_START + xiprom_sz;
>>>>> + va += map_size)
>>>>> + create_pgd_mapping(swapper_pg_dir, va,
>>>>> + CONFIG_XIP_PHYS_ADDR + (va -
>>>>> XIP_VIRT_ADDR_START),
>>>>> + map_size, PAGE_KERNEL_EXEC);
>>>>> +
>>>>> +#endif
>>>>>
>>>>> /* Clear fixmap PTE and PMD mappings */
>>>>> clear_fixmap(FIX_PTE);
>>>
>>> _______________________________________________
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>>> linux-riscv at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>>>
>
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