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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* 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 <catalin.marinas@arm.com>
* Will Deacon <will.deacon@arm.com>
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/pgtable.h>
#include <asm/asm_pointer_auth.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/el2_setup.h>
#include <asm/elf.h>
#include <asm/image.h>
#include <asm/kernel-pgtable.h>
#include <asm/kvm_arm.h>
#include <asm/memory.h>
#include <asm/pgtable-hwdef.h>
#include <asm/page.h>
#include <asm/scs.h>
#include <asm/smp.h>
#include <asm/sysreg.h>
#include <asm/thread_info.h>
#include <asm/virt.h>
#include "efi-header.S"
#define __PHYS_OFFSET KERNEL_START
#if (PAGE_OFFSET & 0x1fffff) != 0
#error PAGE_OFFSET must be at least 2MB aligned
#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).
*
* 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
/*
* DO NOT MODIFY. Image header expected by Linux boot-loaders.
*/
efi_signature_nop // special NOP to identity as PE/COFF executable
b primary_entry // branch to kernel start, magic
.quad 0 // 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
.ascii ARM64_IMAGE_MAGIC // Magic number
.long .Lpe_header_offset // Offset to the PE header.
__EFI_PE_HEADER
__INIT
/*
* The following callee saved general purpose registers are used on the
* primary lowlevel boot path:
*
* Register Scope Purpose
* x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
* x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset
* x28 __create_page_tables() callee preserved temp register
* x19/x20 __primary_switch() callee preserved temp registers
* x24 __primary_switch() .. relocate_kernel() current RELR displacement
*/
SYM_CODE_START(primary_entry)
bl preserve_boot_args
bl init_kernel_el // 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 __cpu_setup // initialise processor
b __primary_switch
SYM_CODE_END(primary_entry)
/*
* Preserve the arguments passed by the bootloader in x0 .. x3
*/
SYM_CODE_START_LOCAL(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
mov x1, #0x20 // 4 x 8 bytes
b __inval_dcache_area // tail call
SYM_CODE_END(preserve_boot_args)
/*
* 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: ptrs, tmp1, tmp2
* Returns: tbl -> next level table page address
*/
.macro create_table_entry, tbl, virt, shift, ptrs, tmp1, tmp2
add \tmp1, \tbl, #PAGE_SIZE
phys_to_pte \tmp2, \tmp1
orr \tmp2, \tmp2, #PMD_TYPE_TABLE // address of next table and entry type
lsr \tmp1, \virt, #\shift
sub \ptrs, \ptrs, #1
and \tmp1, \tmp1, \ptrs // table index
str \tmp2, [\tbl, \tmp1, lsl #3]
add \tbl, \tbl, #PAGE_SIZE // next level table page
.endm
/*
* Macro to populate page table entries, these entries can be pointers to the next level
* or last level entries pointing to physical memory.
*
* tbl: page table address
* rtbl: pointer to page table or physical memory
* index: start index to write
* eindex: end index to write - [index, eindex] written to
* flags: flags for pagetable entry to or in
* inc: increment to rtbl between each entry
* tmp1: temporary variable
*
* Preserves: tbl, eindex, flags, inc
* Corrupts: index, tmp1
* Returns: rtbl
*/
.macro populate_entries, tbl, rtbl, index, eindex, flags, inc, tmp1
.Lpe\@: phys_to_pte \tmp1, \rtbl
orr \tmp1, \tmp1, \flags // tmp1 = table entry
str \tmp1, [\tbl, \index, lsl #3]
add \rtbl, \rtbl, \inc // rtbl = pa next level
add \index, \index, #1
cmp \index, \eindex
b.ls .Lpe\@
.endm
/*
* Compute indices of table entries from virtual address range. If multiple entries
* were needed in the previous page table level then the next page table level is assumed
* to be composed of multiple pages. (This effectively scales the end index).
*
* vstart: virtual address of start of range
* vend: virtual address of end of range
* shift: shift used to transform virtual address into index
* ptrs: number of entries in page table
* istart: index in table corresponding to vstart
* iend: index in table corresponding to vend
* count: On entry: how many extra entries were required in previous level, scales
* our end index.
* On exit: returns how many extra entries required for next page table level
*
* Preserves: vstart, vend, shift, ptrs
* Returns: istart, iend, count
*/
.macro compute_indices, vstart, vend, shift, ptrs, istart, iend, count
lsr \iend, \vend, \shift
mov \istart, \ptrs
sub \istart, \istart, #1
and \iend, \iend, \istart // iend = (vend >> shift) & (ptrs - 1)
mov \istart, \ptrs
mul \istart, \istart, \count
add \iend, \iend, \istart // iend += (count - 1) * ptrs
// our entries span multiple tables
lsr \istart, \vstart, \shift
mov \count, \ptrs
sub \count, \count, #1
and \istart, \istart, \count
sub \count, \iend, \istart
.endm
/*
* Map memory for specified virtual address range. Each level of page table needed supports
* multiple entries. If a level requires n entries the next page table level is assumed to be
* formed from n pages.
*
* tbl: location of page table
* rtbl: address to be used for first level page table entry (typically tbl + PAGE_SIZE)
* vstart: start address to map
* vend: end address to map - we map [vstart, vend]
* flags: flags to use to map last level entries
* phys: physical address corresponding to vstart - physical memory is contiguous
* pgds: the number of pgd entries
*
* Temporaries: istart, iend, tmp, count, sv - these need to be different registers
* Preserves: vstart, vend, flags
* Corrupts: tbl, rtbl, istart, iend, tmp, count, sv
*/
.macro map_memory, tbl, rtbl, vstart, vend, flags, phys, pgds, istart, iend, tmp, count, sv
add \rtbl, \tbl, #PAGE_SIZE
mov \sv, \rtbl
mov \count, #0
compute_indices \vstart, \vend, #PGDIR_SHIFT, \pgds, \istart, \iend, \count
populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
mov \tbl, \sv
mov \sv, \rtbl
#if SWAPPER_PGTABLE_LEVELS > 3
compute_indices \vstart, \vend, #PUD_SHIFT, #PTRS_PER_PUD, \istart, \iend, \count
populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
mov \tbl, \sv
mov \sv, \rtbl
#endif
#if SWAPPER_PGTABLE_LEVELS > 2
compute_indices \vstart, \vend, #SWAPPER_TABLE_SHIFT, #PTRS_PER_PMD, \istart, \iend, \count
populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
mov \tbl, \sv
#endif
compute_indices \vstart, \vend, #SWAPPER_BLOCK_SHIFT, #PTRS_PER_PTE, \istart, \iend, \count
bic \count, \phys, #SWAPPER_BLOCK_SIZE - 1
populate_entries \tbl, \count, \istart, \iend, \flags, #SWAPPER_BLOCK_SIZE, \tmp
.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
*/
SYM_FUNC_START_LOCAL(__create_page_tables)
mov x28, lr
/*
* Invalidate the init page tables to avoid potential dirty cache lines
* being evicted. Other page tables are allocated in rodata as part of
* the kernel image, and thus are clean to the PoC per the boot
* protocol.
*/
adrp x0, init_pg_dir
adrp x1, init_pg_end
sub x1, x1, x0
bl __inval_dcache_area
/*
* Clear the init page tables.
*/
adrp x0, init_pg_dir
adrp x1, init_pg_end
sub x1, x1, x0
1: stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
stp xzr, xzr, [x0], #16
subs x1, x1, #64
b.ne 1b
mov x7, SWAPPER_MM_MMUFLAGS
/*
* Create the identity mapping.
*/
adrp x0, idmap_pg_dir
adrp x3, __idmap_text_start // __pa(__idmap_text_start)
#ifdef CONFIG_ARM64_VA_BITS_52
mrs_s x6, SYS_ID_AA64MMFR2_EL1
and x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
mov x5, #52
cbnz x6, 1f
#endif
mov x5, #VA_BITS_MIN
1:
adr_l x6, vabits_actual
str x5, [x6]
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
/*
* VA_BITS 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, and configure an additional translation level
* if needed.
*
* 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_MIN) // default T0SZ small enough?
b.ge 1f // .. then skip VA range extension
adr_l x6, idmap_t0sz
str x5, [x6]
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
#if (VA_BITS < 48)
#define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3)
#define EXTRA_PTRS (1 << (PHYS_MASK_SHIFT - EXTRA_SHIFT))
/*
* If VA_BITS < 48, we have to configure an additional table 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
mov x4, EXTRA_PTRS
create_table_entry x0, x3, EXTRA_SHIFT, x4, x5, x6
#else
/*
* If VA_BITS == 48, we don't have to configure an additional
* translation level, but the top-level table has more entries.
*/
mov x4, #1 << (PHYS_MASK_SHIFT - PGDIR_SHIFT)
str_l x4, idmap_ptrs_per_pgd, x5
#endif
1:
ldr_l x4, idmap_ptrs_per_pgd
mov x5, x3 // __pa(__idmap_text_start)
adr_l x6, __idmap_text_end // __pa(__idmap_text_end)
map_memory x0, x1, x3, x6, x7, x3, x4, x10, x11, x12, x13, x14
/*
* Map the kernel image (starting with PHYS_OFFSET).
*/
adrp x0, init_pg_dir
mov_q x5, KIMAGE_VADDR // compile time __va(_text)
add x5, x5, x23 // add KASLR displacement
mov x4, PTRS_PER_PGD
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)
map_memory x0, x1, x5, x6, x7, x3, x4, x10, x11, x12, x13, x14
/*
* Since the page tables have been populated with non-cacheable
* accesses (MMU disabled), invalidate those tables again to
* remove any speculatively loaded cache lines.
*/
dmb sy
adrp x0, idmap_pg_dir
adrp x1, idmap_pg_end
sub x1, x1, x0
bl __inval_dcache_area
adrp x0, init_pg_dir
adrp x1, init_pg_end
sub x1, x1, x0
bl __inval_dcache_area
ret x28
SYM_FUNC_END(__create_page_tables)
/*
* The following fragment of code is executed with the MMU enabled.
*
* x0 = __PHYS_OFFSET
*/
SYM_FUNC_START_LOCAL(__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
#ifdef CONFIG_SHADOW_CALL_STACK
adr_l scs_sp, init_shadow_call_stack // Set shadow call stack
#endif
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
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
bl kasan_early_init
#endif
mov x0, x21 // pass FDT address in x0
bl early_fdt_map // Try mapping the FDT early
bl init_feature_override // Parse cpu feature overrides
#ifdef CONFIG_RANDOMIZE_BASE
tst x23, ~(MIN_KIMG_ALIGN - 1) // already running randomized?
b.ne 0f
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
bl switch_to_vhe // Prefer VHE if possible
add sp, sp, #16
mov x29, #0
mov x30, #0
b start_kernel
SYM_FUNC_END(__primary_switched)
.pushsection ".rodata", "a"
SYM_DATA_START(kimage_vaddr)
.quad _text
SYM_DATA_END(kimage_vaddr)
EXPORT_SYMBOL(kimage_vaddr)
.popsection
/*
* 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","awx"
/*
* Starting from EL2 or EL1, configure the CPU to execute at the highest
* reachable EL supported by the kernel in a chosen default state. If dropping
* from EL2 to EL1, configure EL2 before configuring EL1.
*
* Since we cannot always rely on ERET synchronizing writes to sysregs (e.g. if
* SCTLR_ELx.EOS is clear), we place an ISB prior to ERET.
*
* Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in w0 if
* booted in EL1 or EL2 respectively.
*/
SYM_FUNC_START(init_kernel_el)
mov_q x0, INIT_SCTLR_EL1_MMU_OFF
msr sctlr_el1, x0
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL2
b.eq init_el2
SYM_INNER_LABEL(init_el1, SYM_L_LOCAL)
isb
mov_q x0, INIT_PSTATE_EL1
msr spsr_el1, x0
msr elr_el1, lr
mov w0, #BOOT_CPU_MODE_EL1
eret
SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
mov_q x0, HCR_HOST_NVHE_FLAGS
msr hcr_el2, x0
isb
init_el2_state
/* Hypervisor stub */
adr_l x0, __hyp_stub_vectors
msr vbar_el2, x0
isb
msr elr_el2, lr
mov w0, #BOOT_CPU_MODE_EL2
eret
SYM_FUNC_END(init_kernel_el)
/*
* Sets the __boot_cpu_mode flag depending on the CPU boot mode passed
* in w0. See arch/arm64/include/asm/virt.h for more info.
*/
SYM_FUNC_START_LOCAL(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
SYM_FUNC_END(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.
*/
SYM_DATA_START(__boot_cpu_mode)
.long BOOT_CPU_MODE_EL2
.long BOOT_CPU_MODE_EL1
SYM_DATA_END(__boot_cpu_mode)
/*
* The booting CPU updates the failed status @__early_cpu_boot_status,
* with MMU turned off.
*/
SYM_DATA_START(__early_cpu_boot_status)
.quad 0
SYM_DATA_END(__early_cpu_boot_status)
.popsection
/*
* This provides a "holding pen" for platforms to hold all secondary
* cores are held until we're ready for them to initialise.
*/
SYM_FUNC_START(secondary_holding_pen)
bl init_kernel_el // 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
SYM_FUNC_END(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.
*/
SYM_FUNC_START(secondary_entry)
bl init_kernel_el // w0=cpu_boot_mode
bl set_cpu_boot_mode_flag
b secondary_startup
SYM_FUNC_END(secondary_entry)
SYM_FUNC_START_LOCAL(secondary_startup)
/*
* Common entry point for secondary CPUs.
*/
bl switch_to_vhe
bl __cpu_secondary_check52bitva
bl __cpu_setup // initialise processor
adrp x1, swapper_pg_dir
bl __enable_mmu
ldr x8, =__secondary_switched
br x8
SYM_FUNC_END(secondary_startup)
SYM_FUNC_START_LOCAL(__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
cbz x1, __secondary_too_slow
mov sp, x1
ldr x2, [x0, #CPU_BOOT_TASK]
cbz x2, __secondary_too_slow
msr sp_el0, x2
scs_load x2, x3
mov x29, #0
mov x30, #0
#ifdef CONFIG_ARM64_PTR_AUTH
ptrauth_keys_init_cpu x2, x3, x4, x5
#endif
b secondary_start_kernel
SYM_FUNC_END(__secondary_switched)
SYM_FUNC_START_LOCAL(__secondary_too_slow)
wfe
wfi
b __secondary_too_slow
SYM_FUNC_END(__secondary_too_slow)
/*
* 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.
* x1 = TTBR1_EL1 value
*
* 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
*/
SYM_FUNC_START(__enable_mmu)
mrs x2, ID_AA64MMFR0_EL1
ubfx x2, x2, #ID_AA64MMFR0_TGRAN_SHIFT, 4
cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED_MIN
b.lt __no_granule_support
cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED_MAX
b.gt __no_granule_support
update_early_cpu_boot_status 0, x2, x3
adrp x2, idmap_pg_dir
phys_to_ttbr x1, x1
phys_to_ttbr x2, x2
msr ttbr0_el1, x2 // load TTBR0
offset_ttbr1 x1, x3
msr ttbr1_el1, x1 // load TTBR1
isb
set_sctlr_el1 x0
ret
SYM_FUNC_END(__enable_mmu)
SYM_FUNC_START(__cpu_secondary_check52bitva)
#ifdef CONFIG_ARM64_VA_BITS_52
ldr_l x0, vabits_actual
cmp x0, #52
b.ne 2f
mrs_s x0, SYS_ID_AA64MMFR2_EL1
and x0, x0, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
cbnz x0, 2f
update_early_cpu_boot_status \
CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_52_BIT_VA, x0, x1
1: wfe
wfi
b 1b
#endif
2: ret
SYM_FUNC_END(__cpu_secondary_check52bitva)
SYM_FUNC_START_LOCAL(__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 | CPU_STUCK_REASON_NO_GRAN, x1, x2
1:
wfe
wfi
b 1b
SYM_FUNC_END(__no_granule_support)
#ifdef CONFIG_RELOCATABLE
SYM_FUNC_START_LOCAL(__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 x12, x13, [x9], #24
ldr x14, [x9, #-8]
cmp w13, #R_AARCH64_RELATIVE
b.ne 0b
add x14, x14, x23 // relocate
str x14, [x12, x23]
b 0b
1:
#ifdef CONFIG_RELR
/*
* Apply RELR relocations.
*
* RELR is a compressed format for storing relative relocations. The
* encoded sequence of entries looks like:
* [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
*
* i.e. start with an address, followed by any number of bitmaps. The
* address entry encodes 1 relocation. The subsequent bitmap entries
* encode up to 63 relocations each, at subsequent offsets following
* the last address entry.
*
* The bitmap entries must have 1 in the least significant bit. The
* assumption here is that an address cannot have 1 in lsb. Odd
* addresses are not supported. Any odd addresses are stored in the RELA
* section, which is handled above.
*
* Excluding the least significant bit in the bitmap, each non-zero
* bit in the bitmap represents a relocation to be applied to
* a corresponding machine word that follows the base address
* word. The second least significant bit represents the machine
* word immediately following the initial address, and each bit
* that follows represents the next word, in linear order. As such,
* a single bitmap can encode up to 63 relocations in a 64-bit object.
*
* In this implementation we store the address of the next RELR table
* entry in x9, the address being relocated by the current address or
* bitmap entry in x13 and the address being relocated by the current
* bit in x14.
*
* Because addends are stored in place in the binary, RELR relocations
* cannot be applied idempotently. We use x24 to keep track of the
* currently applied displacement so that we can correctly relocate if
* __relocate_kernel is called twice with non-zero displacements (i.e.
* if there is both a physical misalignment and a KASLR displacement).
*/
ldr w9, =__relr_offset // offset to reloc table
ldr w10, =__relr_size // size of reloc table
add x9, x9, x11 // __va(.relr)
add x10, x9, x10 // __va(.relr) + sizeof(.relr)
sub x15, x23, x24 // delta from previous offset
cbz x15, 7f // nothing to do if unchanged
mov x24, x23 // save new offset
2: cmp x9, x10
b.hs 7f
ldr x11, [x9], #8
tbnz x11, #0, 3f // branch to handle bitmaps
add x13, x11, x23
ldr x12, [x13] // relocate address entry
add x12, x12, x15
str x12, [x13], #8 // adjust to start of bitmap
b 2b
3: mov x14, x13
4: lsr x11, x11, #1
cbz x11, 6f
tbz x11, #0, 5f // skip bit if not set
ldr x12, [x14] // relocate bit
add x12, x12, x15
str x12, [x14]
5: add x14, x14, #8 // move to next bit's address
b 4b
6: /*
* Move to the next bitmap's address. 8 is the word size, and 63 is the
* number of significant bits in a bitmap entry.
*/
add x13, x13, #(8 * 63)
b 2b
7:
#endif
ret
SYM_FUNC_END(__relocate_kernel)
#endif
SYM_FUNC_START_LOCAL(__primary_switch)
#ifdef CONFIG_RANDOMIZE_BASE
mov x19, x0 // preserve new SCTLR_EL1 value
mrs x20, sctlr_el1 // preserve old SCTLR_EL1 value
#endif
adrp x1, init_pg_dir
bl __enable_mmu
#ifdef CONFIG_RELOCATABLE
#ifdef CONFIG_RELR
mov x24, #0 // no RELR displacement yet
#endif
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.
*/
pre_disable_mmu_workaround
msr sctlr_el1, x20 // disable the MMU
isb
bl __create_page_tables // recreate kernel mapping
tlbi vmalle1 // Remove any stale TLB entries
dsb nsh
isb
set_sctlr_el1 x19 // re-enable the MMU
bl __relocate_kernel
#endif
#endif
ldr x8, =__primary_switched
adrp x0, __PHYS_OFFSET
br x8
SYM_FUNC_END(__primary_switch)