/*
* Low-level CPU initialisation
* Based on arch/arm/kernel/head.S
*
* Copyright (C) 1994-2002 Russell King
* Copyright (C) 2003-2012 ARM Ltd.
* Authors: Catalin Marinas <[email protected]>
* Will Deacon <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/irqchip/arm-gic-v3.h>
#include <asm/assembler.h>
#include <asm/boot.h>
#include <asm/ptrace.h>
#include <asm/asm-offsets.h>
#include <asm/cache.h>
#include <asm/cputype.h>
#include <asm/elf.h>
#include <asm/kernel-pgtable.h>
#include <asm/kvm_arm.h>
#include <asm/memory.h>
#include <asm/pgtable-hwdef.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/smp.h>
#include <asm/sysreg.h>
#include <asm/thread_info.h>
#include <asm/virt.h>
#define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET)
#if (TEXT_OFFSET & 0xfff) != 0
#error TEXT_OFFSET must be at least 4KB aligned
#elif (PAGE_OFFSET & 0x1fffff) != 0
#error PAGE_OFFSET must be at least 2MB aligned
#elif TEXT_OFFSET > 0x1fffff
#error TEXT_OFFSET must be less than 2MB
#endif
/*
* Kernel startup entry point.
* ---------------------------
*
* The requirements are:
* MMU = off, D-cache = off, I-cache = on or off,
* x0 = physical address to the FDT blob.
*
* This code is mostly position independent so you call this at
* __pa(PAGE_OFFSET + TEXT_OFFSET).
*
* Note that the callee-saved registers are used for storing variables
* that are useful before the MMU is enabled. The allocations are described
* in the entry routines.
*/
__HEAD
_head:
/*
* DO NOT MODIFY. Image header expected by Linux boot-loaders.
*/
#ifdef CONFIG_EFI
/*
* This add instruction has no meaningful effect except that
* its opcode forms the magic "MZ" signature required by UEFI.
*/
add x13, x18, #0x16
b stext
#else
b stext // branch to kernel start, magic
.long 0 // reserved
#endif
le64sym _kernel_offset_le // Image load offset from start of RAM, little-endian
le64sym _kernel_size_le // Effective size of kernel image, little-endian
le64sym _kernel_flags_le // Informative flags, little-endian
.quad 0 // reserved
.quad 0 // reserved
.quad 0 // reserved
.byte 0x41 // Magic number, "ARM\x64"
.byte 0x52
.byte 0x4d
.byte 0x64
#ifdef CONFIG_EFI
.long pe_header - _head // Offset to the PE header.
#else
.word 0 // reserved
#endif
#ifdef CONFIG_EFI
.align 3
pe_header:
.ascii "PE"
.short 0
coff_header:
.short 0xaa64 // AArch64
.short 2 // nr_sections
.long 0 // TimeDateStamp
.long 0 // PointerToSymbolTable
.long 1 // NumberOfSymbols
.short section_table - optional_header // SizeOfOptionalHeader
.short 0x206 // Characteristics.
// IMAGE_FILE_DEBUG_STRIPPED |
// IMAGE_FILE_EXECUTABLE_IMAGE |
// IMAGE_FILE_LINE_NUMS_STRIPPED
optional_header:
.short 0x20b // PE32+ format
.byte 0x02 // MajorLinkerVersion
.byte 0x14 // MinorLinkerVersion
.long _end - efi_header_end // SizeOfCode
.long 0 // SizeOfInitializedData
.long 0 // SizeOfUninitializedData
.long __efistub_entry - _head // AddressOfEntryPoint
.long efi_header_end - _head // BaseOfCode
extra_header_fields:
.quad 0 // ImageBase
.long 0x1000 // SectionAlignment
.long PECOFF_FILE_ALIGNMENT // FileAlignment
.short 0 // MajorOperatingSystemVersion
.short 0 // MinorOperatingSystemVersion
.short 0 // MajorImageVersion
.short 0 // MinorImageVersion
.short 0 // MajorSubsystemVersion
.short 0 // MinorSubsystemVersion
.long 0 // Win32VersionValue
.long _end - _head // SizeOfImage
// Everything before the kernel image is considered part of the header
.long efi_header_end - _head // SizeOfHeaders
.long 0 // CheckSum
.short 0xa // Subsystem (EFI application)
.short 0 // DllCharacteristics
.quad 0 // SizeOfStackReserve
.quad 0 // SizeOfStackCommit
.quad 0 // SizeOfHeapReserve
.quad 0 // SizeOfHeapCommit
.long 0 // LoaderFlags
.long 0x6 // NumberOfRvaAndSizes
.quad 0 // ExportTable
.quad 0 // ImportTable
.quad 0 // ResourceTable
.quad 0 // ExceptionTable
.quad 0 // CertificationTable
.quad 0 // BaseRelocationTable
// Section table
section_table:
/*
* The EFI application loader requires a relocation section
* because EFI applications must be relocatable. This is a
* dummy section as far as we are concerned.
*/
.ascii ".reloc"
.byte 0
.byte 0 // end of 0 padding of section name
.long 0
.long 0
.long 0 // SizeOfRawData
.long 0 // PointerToRawData
.long 0 // PointerToRelocations
.long 0 // PointerToLineNumbers
.short 0 // NumberOfRelocations
.short 0 // NumberOfLineNumbers
.long 0x42100040 // Characteristics (section flags)
.ascii ".text"
.byte 0
.byte 0
.byte 0 // end of 0 padding of section name
.long _end - efi_header_end // VirtualSize
.long efi_header_end - _head // VirtualAddress
.long _edata - efi_header_end // SizeOfRawData
.long efi_header_end - _head // PointerToRawData
.long 0 // PointerToRelocations (0 for executables)
.long 0 // PointerToLineNumbers (0 for executables)
.short 0 // NumberOfRelocations (0 for executables)
.short 0 // NumberOfLineNumbers (0 for executables)
.long 0xe0500020 // Characteristics (section flags)
/*
* EFI will load .text onwards at the 4k section alignment
* described in the PE/COFF header. To ensure that instruction
* sequences using an adrp and a :lo12: immediate will function
* correctly at this alignment, we must ensure that .text is
* placed at a 4k boundary in the Image to begin with.
*/
.align 12
efi_header_end:
#endif
__INIT
/*
* The following callee saved general purpose registers are used on the
* primary lowlevel boot path:
*
* Register Scope Purpose
* x21 stext() .. start_kernel() FDT pointer passed at boot in x0
* x23 stext() .. start_kernel() physical misalignment/KASLR offset
* x28 __create_page_tables() callee preserved temp register
* x19/x20 __primary_switch() callee preserved temp registers
*/
ENTRY(stext)
bl preserve_boot_args
bl el2_setup // Drop to EL1, w0=cpu_boot_mode
adrp x23, __PHYS_OFFSET
and x23, x23, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0
bl set_cpu_boot_mode_flag
bl __create_page_tables
/*
* The following calls CPU setup code, see arch/arm64/mm/proc.S for
* details.
* On return, the CPU will be ready for the MMU to be turned on and
* the TCR will have been set.
*/
bl __uart_tx
bl __cpu_setup // initialise processor
b __primary_switch
ENDPROC(stext)
/*
* Preserve the arguments passed by the bootloader in x0 .. x3
*/
preserve_boot_args:
mov x21, x0 // x21=FDT
adr_l x0, boot_args // record the contents of
stp x21, x1, [x0] // x0 .. x3 at kernel entry
stp x2, x3, [x0, #16]
dmb sy // needed before dc ivac with
// MMU off
add x1, x0, #0x20 // 4 x 8 bytes
b __inval_cache_range // tail call
ENDPROC(preserve_boot_args)
ENTRY(__uart_tx)
mov x28, lr
mov x15, #0xa080
lsl x15, x15, #16
mov x16, #0x4000
orr x15, x15, x16 /* x21=uart base */
//add x16, x15, #0x18 /* x16=Flag register (Read only). */
mov x17, #0x31
add x17, x17, #0x01
bl __putc
add x17, x17, #0x01
bl __putc
mov x17, #10
bl __putc
mov x17, #13
bl __putc
ret x28
ENDPROC(__uart_tx)
ENTRY(__putc)
#if 1
3:
ldr x16, [x15, #0x18]
lsr x16, x16, #32
and x16, x16, #0x20
cmp x16, #0x0
b.ne 3b
#endif
/* put char (x17)*/
mov x16, x17
lsl x16, x16, #32
str x16, [x15]
#if 1
4:
ldr x16, [x15, #0x18]
lsr x16, x16, #32
and x16, x16, #0x08
cmp x16, #0x0
b.ne 4b
#endif
ret
ENDPROC(__putc)
/*
* Macro to create a table entry to the next page.
*
* tbl: page table address
* virt: virtual address
* shift: #imm page table shift
* ptrs: #imm pointers per table page
*
* Preserves: virt
* Corrupts: tmp1, tmp2
* Returns: tbl -> next level table page address
*/
.macro create_table_entry, tbl, virt, shift, ptrs, tmp1, tmp2
/*
以4k页表为例，进行注释
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
| | | | | |
| | | | | v
| | | | | [11:0] in-page offset
| | | | +-> [20:12] L3 index
| | | +-----------> [29:21] L2 index
| | +---------------------> [38:30] L1 index
| +-------------------------------> [47:39] L0 index
+-------------------------------------------------> [63] TTBR0/1
*
* (1) 右移操作，右移bit数为表项的shift
* 例如: 如若获取PGD，则shift=39，此处右移后得到PGD[63:39]
*/
lsr \tmp1, \virt, #\shift
/*
* (2) 与操作，和PGD表项掩码相与， 得到PGD[47:39]，也就是页表项的索引index
* 寄存器tmp1存放PGD页表项的索引index
*/
and \tmp1, \tmp1, #\ptrs - 1 // table index
/*
* (3) 累加操作，由于PGD/PUD/PMU/PTE页表是连续的，在vmlinux.lds中已经固定
* 则:下一级页表基地址 = 当前页表基地址+PAGE_SIZE
* tmp2存在到下一级页表基地址
*/
add \tmp2, \tbl, #PAGE_SIZE
/*
* (4) 或操作，将页表类型(立即数PMD_TYPE_TABLE)写入到页表项内容的对应低位。
* tmp2 = tmp2 | PMD_TYPE_TABLE
* 此时，tmp2已经存放了下一级页表基地址及属性
*/
orr \tmp2, \tmp2, #PMD_TYPE_TABLE // address of next table and entry type
/*
* (5) 存储器数据写入，将下级页表基地址填入当前level页表的页表项中
* 因为tmp1是页表项的id，aarch64每个页表项占用8个字节
* 所以，页表项的偏移地址 = 页表项id * 8;
* 页表项地址 = 页表基地址 + 页表项的偏移地址
* 这里，[\tbl, \tmp1, lsl #3] 代表tmp1左移3位加上tbl
*/
str \tmp2, [\tbl, \tmp1, lsl #3]
/*
* (6) 此时将tbl页表基地址等于下一级页表基地址，用于后面再次进行页表填充
*/
add \tbl, \tbl, #PAGE_SIZE // next level table page
.endm
/*
* Macro to populate the PGD (and possibily PUD) for the corresponding
* block entry in the next level (tbl) for the given virtual address.
*
* Preserves: tbl, next, virt
* Corrupts: tmp1, tmp2
*/
/*
* 根据页表级数，连续填充多级页表，最后的block descriptor不填充
* 最后的block descriptor由create_block_map宏填充
*/
.macro create_pgd_entry, tbl, virt, tmp1, tmp2
create_table_entry \tbl, \virt, PGDIR_SHIFT, PTRS_PER_PGD, \tmp1, \tmp2
#if SWAPPER_PGTABLE_LEVELS > 3
create_table_entry \tbl, \virt, PUD_SHIFT, PTRS_PER_PUD, \tmp1, \tmp2
#endif
#if SWAPPER_PGTABLE_LEVELS > 2
create_table_entry \tbl, \virt, SWAPPER_TABLE_SHIFT, PTRS_PER_PTE, \tmp1, \tmp2
#endif
.endm
/*
* Macro to populate block entries in the page table for the start..end
* virtual range (inclusive).
*
* Preserves: tbl, flags
* Corrupts: phys, start, end, pstate
*/
.macro create_block_map, tbl, flags, phys, start, end
lsr \phys, \phys, #SWAPPER_BLOCK_SHIFT
lsr \start, \start, #SWAPPER_BLOCK_SHIFT
and \start, \start, #PTRS_PER_PTE - 1 // table index
orr \phys, \flags, \phys, lsl #SWAPPER_BLOCK_SHIFT // table entry
lsr \end, \end, #SWAPPER_BLOCK_SHIFT
and \end, \end, #PTRS_PER_PTE - 1 // table end index
9999: str \phys, [\tbl, \start, lsl #3] // store the entry
add \start, \start, #1 // next entry
add \phys, \phys, #SWAPPER_BLOCK_SIZE // next block
cmp \start, \end
b.ls 9999b
.endm
/*
* Setup the initial page tables. We only setup the barest amount which is
* required to get the kernel running. The following sections are required:
* - identity mapping to enable the MMU (low address, TTBR0)
* - first few MB of the kernel linear mapping to jump to once the MMU has
* been enabled
*/
__create_page_tables:
mov x28, lr
/*
* Invalidate the idmap and swapper page tables to avoid potential
* dirty cache lines being evicted.
*/
adrp x0, idmap_pg_dir
adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE
bl __inval_cache_range
/*
* Clear the idmap and swapper page tables.
*/
adrp x0, idmap_pg_dir
adrp x6, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE
1: stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
cmp x0, x6
b.lo 1b
mov x7, SWAPPER_MM_MMUFLAGS
/*
* Create the identity mapping.
*/
adrp x0, idmap_pg_dir
adrp x3, __idmap_text_start // __pa(__idmap_text_start)
#ifndef CONFIG_ARM64_VA_BITS_48
#define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3)
#define EXTRA_PTRS (1 << (48 - EXTRA_SHIFT))
/*
* If VA_BITS < 48, it may be too small to allow for an ID mapping to be
* created that covers system RAM if that is located sufficiently high
* in the physical address space. So for the ID map, use an extended
* virtual range in that case, by configuring an additional translation
* level.
* First, we have to verify our assumption that the current value of
* VA_BITS was chosen such that all translation levels are fully
* utilised, and that lowering T0SZ will always result in an additional
* translation level to be configured.
*/
#if VA_BITS != EXTRA_SHIFT
#error "Mismatch between VA_BITS and page size/number of translation levels"
#endif
/*
* Calculate the maximum allowed value for TCR_EL1.T0SZ so that the
* entire ID map region can be mapped. As T0SZ == (64 - #bits used),
* this number conveniently equals the number of leading zeroes in
* the physical address of __idmap_text_end.
*/
adrp x5, __idmap_text_end
clz x5, x5
cmp x5, TCR_T0SZ(VA_BITS) // default T0SZ small enough?
b.ge 1f // .. then skip additional level
adr_l x6, idmap_t0sz
str x5, [x6]
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
create_table_entry x0, x3, EXTRA_SHIFT, EXTRA_PTRS, x5, x6
1:
#endif
create_pgd_entry x0, x3, x5, x6
mov x5, x3 // __pa(__idmap_text_start)
adr_l x6, __idmap_text_end // __pa(__idmap_text_end)
create_block_map x0, x7, x3, x5, x6
/*
* add by yuchen
* Map the uart register memory space
*/
//ldr x5, =0xa0804000
mov x15, #0xa080
lsl x15, x15, #16
mov x16, #0x4000
orr x15, x15, x16 //uart base
adrp x0, idmap_pg_dir
mov x5, x15
create_pgd_entry x0, x5, x3, x6
mov x3, x15
add x6, x5, #0x4000
create_block_map x0, x7, x3, x5, x6
/*
* Map the kernel image (starting with PHYS_OFFSET).
*/
adrp x0, swapper_pg_dir
mov_q x5, KIMAGE_VADDR + TEXT_OFFSET // compile time __va(_text)
add x5, x5, x23 // add KASLR displacement
create_pgd_entry x0, x5, x3, x6
adrp x6, _end // runtime __pa(_end)
adrp x3, _text // runtime __pa(_text)
sub x6, x6, x3 // _end - _text
add x6, x6, x5 // runtime __va(_end)
create_block_map x0, x7, x3, x5, x6
/*
* add by yuchen
* Map the uart register memory space
*/
//ldr x5, =0xa0804000
mov x15, #0xa080
lsl x15, x15, #16
mov x16, #0x4000
orr x15, x15, x16 //uart base
adrp x0, swapper_pg_dir
mov x5, x15
create_pgd_entry x0, x5, x3, x6
mov x3, x15
add x6, x5, #0x4000
create_block_map x0, x7, x3, x5, x6
/*
* Since the page tables have been populated with non-cacheable
* accesses (MMU disabled), invalidate the idmap and swapper page
* tables again to remove any speculatively loaded cache lines.
*/
adrp x0, idmap_pg_dir
adrp x1, swapper_pg_dir + SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE
dmb sy
bl __inval_cache_range
ret x28
ENDPROC(__create_page_tables)
.ltorg
/*
* The following fragment of code is executed with the MMU enabled.
*
* x0 = __PHYS_OFFSET
*/
__primary_switched:
adrp x4, init_thread_union
add sp, x4, #THREAD_SIZE
adr_l x5, init_task
msr sp_el0, x5 // Save thread_info
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
isb
stp xzr, x30, [sp, #-16]!
mov x29, sp
str_l x21, __fdt_pointer, x5 // Save FDT pointer
ldr_l x4, kimage_vaddr // Save the offset between
sub x4, x4, x0 // the kernel virtual and
str_l x4, kimage_voffset, x5 // physical mappings
// Clear BSS
adr_l x0, __bss_start
mov x1, xzr
adr_l x2, __bss_stop
sub x2, x2, x0
bl __pi_memset
dsb ishst // Make zero page visible to PTW
#ifdef CONFIG_KASAN
bl kasan_early_init
#endif
#ifdef CONFIG_RANDOMIZE_BASE
tst x23, ~(MIN_KIMG_ALIGN - 1) // already running randomized?
b.ne 0f
mov x0, x21 // pass FDT address in x0
mov x1, x23 // pass modulo offset in x1
bl kaslr_early_init // parse FDT for KASLR options
cbz x0, 0f // KASLR disabled? just proceed
orr x23, x23, x0 // record KASLR offset
ldp x29, x30, [sp], #16 // we must enable KASLR, return
ret // to __primary_switch()
0:
#endif
b start_kernel
ENDPROC(__primary_switched)
/*
* end early head section, begin head code that is also used for
* hotplug and needs to have the same protections as the text region
*/
.section ".idmap.text","ax"
ENTRY(kimage_vaddr)
.quad _text - TEXT_OFFSET
/*
* If we're fortunate enough to boot at EL2, ensure that the world is
* sane before dropping to EL1.
*
* Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in x20 if
* booted in EL1 or EL2 respectively.
*/
ENTRY(el2_setup)
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL2
b.ne 1f
mrs x0, sctlr_el2
CPU_BE( orr x0, x0, #(1 << 25) ) // Set the EE bit for EL2
CPU_LE( bic x0, x0, #(1 << 25) ) // Clear the EE bit for EL2
msr sctlr_el2, x0
b 2f
1: mrs x0, sctlr_el1
CPU_BE( orr x0, x0, #(3 << 24) ) // Set the EE and E0E bits for EL1
CPU_LE( bic x0, x0, #(3 << 24) ) // Clear the EE and E0E bits for EL1
msr sctlr_el1, x0
mov w0, #BOOT_CPU_MODE_EL1 // This cpu booted in EL1
isb
ret
2:
#ifdef CONFIG_ARM64_VHE
/*
* Check for VHE being present. For the rest of the EL2 setup,
* x2 being non-zero indicates that we do have VHE, and that the
* kernel is intended to run at EL2.
*/
mrs x2, id_aa64mmfr1_el1
ubfx x2, x2, #8, #4
#else
mov x2, xzr
#endif
/* Hyp configuration. */
mov x0, #HCR_RW // 64-bit EL1
cbz x2, set_hcr
orr x0, x0, #HCR_TGE // Enable Host Extensions
orr x0, x0, #HCR_E2H
set_hcr:
msr hcr_el2, x0
isb
/* Generic timers. */
mrs x0, cnthctl_el2
orr x0, x0, #3 // Enable EL1 physical timers
msr cnthctl_el2, x0
msr cntvoff_el2, xzr // Clear virtual offset
#ifdef CONFIG_ARM_GIC_V3
/* GICv3 system register access */
mrs x0, id_aa64pfr0_el1
ubfx x0, x0, #24, #4
cmp x0, #1
b.ne 3f
mrs_s x0, ICC_SRE_EL2
orr x0, x0, #ICC_SRE_EL2_SRE // Set ICC_SRE_EL2.SRE==1
orr x0, x0, #ICC_SRE_EL2_ENABLE // Set ICC_SRE_EL2.Enable==1
msr_s ICC_SRE_EL2, x0
isb // Make sure SRE is now set
mrs_s x0, ICC_SRE_EL2 // Read SRE back,
tbz x0, #0, 3f // and check that it sticks
msr_s ICH_HCR_EL2, xzr // Reset ICC_HCR_EL2 to defaults
3:
#endif
/* Populate ID registers. */
mrs x0, midr_el1
mrs x1, mpidr_el1
msr vpidr_el2, x0
msr vmpidr_el2, x1
/*
* When VHE is not in use, early init of EL2 and EL1 needs to be
* done here.
* When VHE _is_ in use, EL1 will not be used in the host and
* requires no configuration, and all non-hyp-specific EL2 setup
* will be done via the _EL1 system register aliases in __cpu_setup.
*/
cbnz x2, 1f
/* sctlr_el1 */
mov x0, #0x0800 // Set/clear RES{1,0} bits
CPU_BE( movk x0, #0x33d0, lsl #16 ) // Set EE and E0E on BE systems
CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems
msr sctlr_el1, x0
/* Coprocessor traps. */
mov x0, #0x33ff
msr cptr_el2, x0 // Disable copro. traps to EL2
1:
#ifdef CONFIG_COMPAT
msr hstr_el2, xzr // Disable CP15 traps to EL2
#endif
/* EL2 debug */
mrs x0, id_aa64dfr0_el1 // Check ID_AA64DFR0_EL1 PMUVer
sbfx x0, x0, #8, #4
cmp x0, #1
b.lt 4f // Skip if no PMU present
mrs x0, pmcr_el0 // Disable debug access traps
ubfx x0, x0, #11, #5 // to EL2 and allow access to
4:
csel x0, xzr, x0, lt // all PMU counters from EL1
msr mdcr_el2, x0 // (if they exist)
/* Stage-2 translation */
msr vttbr_el2, xzr
cbz x2, install_el2_stub
mov w0, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
isb
ret
install_el2_stub:
/* Hypervisor stub */
adrp x0, __hyp_stub_vectors
add x0, x0, #:lo12:__hyp_stub_vectors
msr vbar_el2, x0
/* spsr */
mov x0, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
PSR_MODE_EL1h)
msr spsr_el2, x0
msr elr_el2, lr
mov w0, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
eret
ENDPROC(el2_setup)
/*
* Sets the __boot_cpu_mode flag depending on the CPU boot mode passed
* in x20. See arch/arm64/include/asm/virt.h for more info.
*/
set_cpu_boot_mode_flag:
adr_l x1, __boot_cpu_mode
cmp w0, #BOOT_CPU_MODE_EL2
b.ne 1f
add x1, x1, #4
1: str w0, [x1] // This CPU has booted in EL1
dmb sy
dc ivac, x1 // Invalidate potentially stale cache line
ret
ENDPROC(set_cpu_boot_mode_flag)
/*
* These values are written with the MMU off, but read with the MMU on.
* Writers will invalidate the corresponding address, discarding up to a
* 'Cache Writeback Granule' (CWG) worth of data. The linker script ensures
* sufficient alignment that the CWG doesn't overlap another section.
*/
.pushsection ".mmuoff.data.write", "aw"
/*
* We need to find out the CPU boot mode long after boot, so we need to
* store it in a writable variable.
*
* This is not in .bss, because we set it sufficiently early that the boot-time
* zeroing of .bss would clobber it.
*/
ENTRY(__boot_cpu_mode)
.long BOOT_CPU_MODE_EL2
.long BOOT_CPU_MODE_EL1
/*
* The booting CPU updates the failed status @__early_cpu_boot_status,
* with MMU turned off.
*/
ENTRY(__early_cpu_boot_status)
.long 0
.popsection
/*
* This provides a "holding pen" for platforms to hold all secondary
* cores are held until we're ready for them to initialise.
*/
ENTRY(secondary_holding_pen)
bl el2_setup // Drop to EL1, w0=cpu_boot_mode
bl set_cpu_boot_mode_flag
mrs x0, mpidr_el1
mov_q x1, MPIDR_HWID_BITMASK
and x0, x0, x1
adr_l x3, secondary_holding_pen_release
pen: ldr x4, [x3]
cmp x4, x0
b.eq secondary_startup
wfe
b pen
ENDPROC(secondary_holding_pen)
/*
* Secondary entry point that jumps straight into the kernel. Only to
* be used where CPUs are brought online dynamically by the kernel.
*/
ENTRY(secondary_entry)
bl el2_setup // Drop to EL1
bl set_cpu_boot_mode_flag
b secondary_startup
ENDPROC(secondary_entry)
secondary_startup:
/*
* Common entry point for secondary CPUs.
*/
bl __cpu_setup // initialise processor
bl __enable_mmu
ldr x8, =__secondary_switched
br x8
ENDPROC(secondary_startup)
__secondary_switched:
adr_l x5, vectors
msr vbar_el1, x5
isb
adr_l x0, secondary_data
ldr x1, [x0, #CPU_BOOT_STACK] // get secondary_data.stack
mov sp, x1
ldr x2, [x0, #CPU_BOOT_TASK]
msr sp_el0, x2
mov x29, #0
b secondary_start_kernel
ENDPROC(__secondary_switched)
/*
* The booting CPU updates the failed status @__early_cpu_boot_status,
* with MMU turned off.
*
* update_early_cpu_boot_status tmp, status
* - Corrupts tmp1, tmp2
* - Writes 'status' to __early_cpu_boot_status and makes sure
* it is committed to memory.
*/
.macro update_early_cpu_boot_status status, tmp1, tmp2
mov \tmp2, #\status
adr_l \tmp1, __early_cpu_boot_status
str \tmp2, [\tmp1]
dmb sy
dc ivac, \tmp1 // Invalidate potentially stale cache line
.endm
/*
* Enable the MMU.
*
* x0 = SCTLR_EL1 value for turning on the MMU.
*
* Returns to the caller via x30/lr. This requires the caller to be covered
* by the .idmap.text section.
*
* Checks if the selected granule size is supported by the CPU.
* If it isn't, park the CPU
*/
ENTRY(__enable_mmu)
mrs x1, ID_AA64MMFR0_EL1
ubfx x2, x1, #ID_AA64MMFR0_TGRAN_SHIFT, 4
cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED
b.ne __no_granule_support
update_early_cpu_boot_status 0, x1, x2
adrp x1, idmap_pg_dir
adrp x2, swapper_pg_dir
msr ttbr0_el1, x1 // load TTBR0
msr ttbr1_el1, x2 // load TTBR1
isb
msr sctlr_el1, x0
isb
/*
* Invalidate the local I-cache so that any instructions fetched
* speculatively from the PoC are discarded, since they may have
* been dynamically patched at the PoU.
*/
ic iallu
dsb nsh
isb
ret
ENDPROC(__enable_mmu)
__no_granule_support:
/* Indicate that this CPU can't boot and is stuck in the kernel */
update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x1, x2
1:
wfe
wfi
b 1b
ENDPROC(__no_granule_support)
#ifdef CONFIG_RELOCATABLE
__relocate_kernel:
/*
* Iterate over each entry in the relocation table, and apply the
* relocations in place.
*/
ldr w9, =__rela_offset // offset to reloc table
ldr w10, =__rela_size // size of reloc table
mov_q x11, KIMAGE_VADDR // default virtual offset
add x11, x11, x23 // actual virtual offset
add x9, x9, x11 // __va(.rela)
add x10, x9, x10 // __va(.rela) + sizeof(.rela)
0: cmp x9, x10
b.hs 1f
ldp x11, x12, [x9], #24
ldr x13, [x9, #-8]
cmp w12, #R_AARCH64_RELATIVE
b.ne 0b
add x13, x13, x23 // relocate
str x13, [x11, x23]
b 0b
1: ret
ENDPROC(__relocate_kernel)
#endif
__primary_switch:
#ifdef CONFIG_RANDOMIZE_BASE
mov x19, x0 // preserve new SCTLR_EL1 value
mrs x20, sctlr_el1 // preserve old SCTLR_EL1 value
#endif
bl __uart_tx
bl __enable_mmu
ldr x8, =__uart_tx
blr x8
#ifdef CONFIG_RELOCATABLE
bl __relocate_kernel
#ifdef CONFIG_RANDOMIZE_BASE
ldr x8, =__primary_switched
adrp x0, __PHYS_OFFSET
blr x8
/*
* If we return here, we have a KASLR displacement in x23 which we need
* to take into account by discarding the current kernel mapping and
* creating a new one.
*/
msr sctlr_el1, x20 // disable the MMU
isb
bl __create_page_tables // recreate kernel mapping
tlbi vmalle1 // Remove any stale TLB entries
dsb nsh
msr sctlr_el1, x19 // re-enable the MMU
isb
ic iallu // flush instructions fetched
dsb nsh // via old mapping
isb
bl __relocate_kernel
#endif
#endif
ldr x8, =__primary_switched
adrp x0, __PHYS_OFFSET
br x8
ENDPROC(__primary_switch)
arm64/aarch64启动汇编代码-详细解析
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转载自blog.csdn.net/y33988979/article/details/81635519
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