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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/bug.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"
+
+#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.
+ *
+ * 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
+ * x20 primary_entry() .. __primary_switch() CPU boot mode
+ * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
+ * x22 create_idmap() .. start_kernel() ID map VA of the DT blob
+ * x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset
+ * x24 __primary_switch() linear map KASLR seed
+ * x25 primary_entry() .. start_kernel() supported VA size
+ * x28 create_idmap() callee preserved temp register
+ */
+SYM_CODE_START(primary_entry)
+ bl preserve_boot_args
+ bl init_kernel_el // w0=cpu_boot_mode
+ mov x20, x0
+ bl create_idmap
+
+ /*
+ * 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.
+ */
+#if VA_BITS > 48
+ mrs_s x0, SYS_ID_AA64MMFR2_EL1
+ tst x0, #0xf << ID_AA64MMFR2_EL1_VARange_SHIFT
+ mov x0, #VA_BITS
+ mov x25, #VA_BITS_MIN
+ csel x25, x25, x0, eq
+ mov x0, x25
+#endif
+ 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
+
+ add x1, x0, #0x20 // 4 x 8 bytes
+ b dcache_inval_poc // tail call
+SYM_CODE_END(preserve_boot_args)
+
+SYM_FUNC_START_LOCAL(clear_page_tables)
+ /*
+ * Clear the init page tables.
+ */
+ adrp x0, init_pg_dir
+ adrp x1, init_pg_end
+ sub x2, x1, x0
+ mov x1, xzr
+ b __pi_memset // tail call
+SYM_FUNC_END(clear_page_tables)
+
+/*
+ * 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 - we map [vstart, vend]
+ * shift: shift used to transform virtual address into index
+ * order: #imm 2log(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
+ * Returns: istart, iend, count
+ */
+ .macro compute_indices, vstart, vend, shift, order, istart, iend, count
+ ubfx \istart, \vstart, \shift, \order
+ ubfx \iend, \vend, \shift, \order
+ add \iend, \iend, \count, lsl \order
+ 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: virtual address of start of range
+ * vend: virtual address of end of range - we map [vstart, vend - 1]
+ * flags: flags to use to map last level entries
+ * phys: physical address corresponding to vstart - physical memory is contiguous
+ * order: #imm 2log(number of entries in PGD table)
+ *
+ * If extra_shift is set, an extra level will be populated if the end address does
+ * not fit in 'extra_shift' bits. This assumes vend is in the TTBR0 range.
+ *
+ * Temporaries: istart, iend, tmp, count, sv - these need to be different registers
+ * Preserves: vstart, flags
+ * Corrupts: tbl, rtbl, vend, istart, iend, tmp, count, sv
+ */
+ .macro map_memory, tbl, rtbl, vstart, vend, flags, phys, order, istart, iend, tmp, count, sv, extra_shift
+ sub \vend, \vend, #1
+ add \rtbl, \tbl, #PAGE_SIZE
+ mov \count, #0
+
+ .ifnb \extra_shift
+ tst \vend, #~((1 << (\extra_shift)) - 1)
+ b.eq .L_\@
+ compute_indices \vstart, \vend, #\extra_shift, #(PAGE_SHIFT - 3), \istart, \iend, \count
+ mov \sv, \rtbl
+ populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
+ mov \tbl, \sv
+ .endif
+.L_\@:
+ compute_indices \vstart, \vend, #PGDIR_SHIFT, #\order, \istart, \iend, \count
+ mov \sv, \rtbl
+ populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
+ mov \tbl, \sv
+
+#if SWAPPER_PGTABLE_LEVELS > 3
+ compute_indices \vstart, \vend, #PUD_SHIFT, #(PAGE_SHIFT - 3), \istart, \iend, \count
+ mov \sv, \rtbl
+ populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
+ mov \tbl, \sv
+#endif
+
+#if SWAPPER_PGTABLE_LEVELS > 2
+ compute_indices \vstart, \vend, #SWAPPER_TABLE_SHIFT, #(PAGE_SHIFT - 3), \istart, \iend, \count
+ mov \sv, \rtbl
+ populate_entries \tbl, \rtbl, \istart, \iend, #PMD_TYPE_TABLE, #PAGE_SIZE, \tmp
+ mov \tbl, \sv
+#endif
+
+ compute_indices \vstart, \vend, #SWAPPER_BLOCK_SHIFT, #(PAGE_SHIFT - 3), \istart, \iend, \count
+ bic \rtbl, \phys, #SWAPPER_BLOCK_SIZE - 1
+ populate_entries \tbl, \rtbl, \istart, \iend, \flags, #SWAPPER_BLOCK_SIZE, \tmp
+ .endm
+
+/*
+ * Remap a subregion created with the map_memory macro with modified attributes
+ * or output address. The entire remapped region must have been covered in the
+ * invocation of map_memory.
+ *
+ * x0: last level table address (returned in first argument to map_memory)
+ * x1: start VA of the existing mapping
+ * x2: start VA of the region to update
+ * x3: end VA of the region to update (exclusive)
+ * x4: start PA associated with the region to update
+ * x5: attributes to set on the updated region
+ * x6: order of the last level mappings
+ */
+SYM_FUNC_START_LOCAL(remap_region)
+ sub x3, x3, #1 // make end inclusive
+
+ // Get the index offset for the start of the last level table
+ lsr x1, x1, x6
+ bfi x1, xzr, #0, #PAGE_SHIFT - 3
+
+ // Derive the start and end indexes into the last level table
+ // associated with the provided region
+ lsr x2, x2, x6
+ lsr x3, x3, x6
+ sub x2, x2, x1
+ sub x3, x3, x1
+
+ mov x1, #1
+ lsl x6, x1, x6 // block size at this level
+
+ populate_entries x0, x4, x2, x3, x5, x6, x7
+ ret
+SYM_FUNC_END(remap_region)
+
+SYM_FUNC_START_LOCAL(create_idmap)
+ mov x28, lr
+ /*
+ * The ID map carries a 1:1 mapping of the physical address range
+ * covered by the loaded image, which could be anywhere in DRAM. This
+ * means that the required size of the VA (== PA) space is decided at
+ * boot time, and could be more than the configured size of the VA
+ * space for ordinary kernel and user space mappings.
+ *
+ * There are three cases to consider here:
+ * - 39 <= VA_BITS < 48, and the ID map needs up to 48 VA bits to cover
+ * the placement of the image. In this case, we configure one extra
+ * level of translation on the fly for the ID map only. (This case
+ * also covers 42-bit VA/52-bit PA on 64k pages).
+ *
+ * - VA_BITS == 48, and the ID map needs more than 48 VA bits. This can
+ * only happen when using 64k pages, in which case we need to extend
+ * the root level table rather than add a level. Note that we can
+ * treat this case as 'always extended' as long as we take care not
+ * to program an unsupported T0SZ value into the TCR register.
+ *
+ * - Combinations that would require two additional levels of
+ * translation are not supported, e.g., VA_BITS==36 on 16k pages, or
+ * VA_BITS==39/4k pages with 5-level paging, where the input address
+ * requires more than 47 or 48 bits, respectively.
+ */
+#if (VA_BITS < 48)
+#define IDMAP_PGD_ORDER (VA_BITS - PGDIR_SHIFT)
+#define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3)
+
+ /*
+ * 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
+#else
+#define IDMAP_PGD_ORDER (PHYS_MASK_SHIFT - PGDIR_SHIFT)
+#define EXTRA_SHIFT
+ /*
+ * If VA_BITS == 48, we don't have to configure an additional
+ * translation level, but the top-level table has more entries.
+ */
+#endif
+ adrp x0, init_idmap_pg_dir
+ adrp x3, _text
+ adrp x6, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
+ mov x7, SWAPPER_RX_MMUFLAGS
+
+ map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
+
+ /* Remap the kernel page tables r/w in the ID map */
+ adrp x1, _text
+ adrp x2, init_pg_dir
+ adrp x3, init_pg_end
+ bic x4, x2, #SWAPPER_BLOCK_SIZE - 1
+ mov x5, SWAPPER_RW_MMUFLAGS
+ mov x6, #SWAPPER_BLOCK_SHIFT
+ bl remap_region
+
+ /* Remap the FDT after the kernel image */
+ adrp x1, _text
+ adrp x22, _end + SWAPPER_BLOCK_SIZE
+ bic x2, x22, #SWAPPER_BLOCK_SIZE - 1
+ bfi x22, x21, #0, #SWAPPER_BLOCK_SHIFT // remapped FDT address
+ add x3, x2, #MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
+ bic x4, x21, #SWAPPER_BLOCK_SIZE - 1
+ mov x5, SWAPPER_RW_MMUFLAGS
+ mov x6, #SWAPPER_BLOCK_SHIFT
+ bl remap_region
+
+ /*
+ * 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, init_idmap_pg_dir
+ adrp x1, init_idmap_pg_end
+ bl dcache_inval_poc
+ ret x28
+SYM_FUNC_END(create_idmap)
+
+SYM_FUNC_START_LOCAL(create_kernel_mapping)
+ adrp x0, init_pg_dir
+ mov_q x5, KIMAGE_VADDR // compile time __va(_text)
+#ifdef CONFIG_RELOCATABLE
+ add x5, x5, x23 // add KASLR displacement
+#endif
+ 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)
+ mov x7, SWAPPER_RW_MMUFLAGS
+
+ map_memory x0, x1, x5, x6, x7, x3, (VA_BITS - PGDIR_SHIFT), x10, x11, x12, x13, x14
+
+ dsb ishst // sync with page table walker
+ ret
+SYM_FUNC_END(create_kernel_mapping)
+
+ /*
+ * Initialize CPU registers with task-specific and cpu-specific context.
+ *
+ * Create a final frame record at task_pt_regs(current)->stackframe, so
+ * that the unwinder can identify the final frame record of any task by
+ * its location in the task stack. We reserve the entire pt_regs space
+ * for consistency with user tasks and kthreads.
+ */
+ .macro init_cpu_task tsk, tmp1, tmp2
+ msr sp_el0, \tsk
+
+ ldr \tmp1, [\tsk, #TSK_STACK]
+ add sp, \tmp1, #THREAD_SIZE
+ sub sp, sp, #PT_REGS_SIZE
+
+ stp xzr, xzr, [sp, #S_STACKFRAME]
+ add x29, sp, #S_STACKFRAME
+
+ scs_load_current
+
+ adr_l \tmp1, __per_cpu_offset
+ ldr w\tmp2, [\tsk, #TSK_TI_CPU]
+ ldr \tmp1, [\tmp1, \tmp2, lsl #3]
+ set_this_cpu_offset \tmp1
+ .endm
+
+/*
+ * The following fragment of code is executed with the MMU enabled.
+ *
+ * x0 = __pa(KERNEL_START)
+ */
+SYM_FUNC_START_LOCAL(__primary_switched)
+ adr_l x4, init_task
+ init_cpu_task x4, x5, x6
+
+ adr_l x8, vectors // load VBAR_EL1 with virtual
+ msr vbar_el1, x8 // vector table address
+ isb
+
+ stp x29, 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
+
+ mov x0, x20
+ bl set_cpu_boot_mode_flag
+
+ // 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 VA_BITS > 48
+ adr_l x8, vabits_actual // Set this early so KASAN early init
+ str x25, [x8] // ... observes the correct value
+ dc civac, x8 // Make visible to booting secondaries
+#endif
+
+#ifdef CONFIG_RANDOMIZE_BASE
+ adrp x5, memstart_offset_seed // Save KASLR linear map seed
+ strh w24, [x5, :lo12:memstart_offset_seed]
+#endif
+#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
+ mov x0, x20 // pass the full boot status
+ bl init_feature_override // Parse cpu feature overrides
+ mov x0, x20
+ bl finalise_el2 // Prefer VHE if possible
+ ldp x29, x30, [sp], #16
+ bl start_kernel
+ ASM_BUG()
+SYM_FUNC_END(__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","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 x0 if
+ * booted in EL1 or EL2 respectively, with the top 32 bits containing
+ * potential context flags. These flags are *not* stored in __boot_cpu_mode.
+ */
+SYM_FUNC_START(init_kernel_el)
+ mrs x0, CurrentEL
+ cmp x0, #CurrentEL_EL2
+ b.eq init_el2
+
+SYM_INNER_LABEL(init_el1, SYM_L_LOCAL)
+ mov_q x0, INIT_SCTLR_EL1_MMU_OFF
+ msr sctlr_el1, x0
+ 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
+
+ mov_q x1, INIT_SCTLR_EL1_MMU_OFF
+
+ /*
+ * Fruity CPUs seem to have HCR_EL2.E2H set to RES1,
+ * making it impossible to start in nVHE mode. Is that
+ * compliant with the architecture? Absolutely not!
+ */
+ mrs x0, hcr_el2
+ and x0, x0, #HCR_E2H
+ cbz x0, 1f
+
+ /* Set a sane SCTLR_EL1, the VHE way */
+ msr_s SYS_SCTLR_EL12, x1
+ mov x2, #BOOT_CPU_FLAG_E2H
+ b 2f
+
+1:
+ msr sctlr_el1, x1
+ mov x2, xzr
+2:
+ msr elr_el2, lr
+ mov w0, #BOOT_CPU_MODE_EL2
+ orr x0, x0, x2
+ 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] // Save CPU boot mode
+ ret
+SYM_FUNC_END(set_cpu_boot_mode_flag)
+
+ /*
+ * 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
+ mrs x2, mpidr_el1
+ mov_q x1, MPIDR_HWID_BITMASK
+ and x2, x2, x1
+ adr_l x3, secondary_holding_pen_release
+pen: ldr x4, [x3]
+ cmp x4, x2
+ 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
+ b secondary_startup
+SYM_FUNC_END(secondary_entry)
+
+SYM_FUNC_START_LOCAL(secondary_startup)
+ /*
+ * Common entry point for secondary CPUs.
+ */
+ mov x20, x0 // preserve boot mode
+ bl finalise_el2
+ bl __cpu_secondary_check52bitva
+#if VA_BITS > 48
+ ldr_l x0, vabits_actual
+#endif
+ bl __cpu_setup // initialise processor
+ adrp x1, swapper_pg_dir
+ adrp x2, idmap_pg_dir
+ bl __enable_mmu
+ ldr x8, =__secondary_switched
+ br x8
+SYM_FUNC_END(secondary_startup)
+
+SYM_FUNC_START_LOCAL(__secondary_switched)
+ mov x0, x20
+ bl set_cpu_boot_mode_flag
+ str_l xzr, __early_cpu_boot_status, x3
+ adr_l x5, vectors
+ msr vbar_el1, x5
+ isb
+
+ adr_l x0, secondary_data
+ ldr x2, [x0, #CPU_BOOT_TASK]
+ cbz x2, __secondary_too_slow
+
+ init_cpu_task x2, x1, x3
+
+#ifdef CONFIG_ARM64_PTR_AUTH
+ ptrauth_keys_init_cpu x2, x3, x4, x5
+#endif
+
+ bl secondary_start_kernel
+ ASM_BUG()
+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
+ * x2 = ID map root table address
+ *
+ * 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 x3, ID_AA64MMFR0_EL1
+ ubfx x3, x3, #ID_AA64MMFR0_EL1_TGRAN_SHIFT, 4
+ cmp x3, #ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MIN
+ b.lt __no_granule_support
+ cmp x3, #ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MAX
+ b.gt __no_granule_support
+ phys_to_ttbr x2, x2
+ msr ttbr0_el1, x2 // load TTBR0
+ load_ttbr1 x1, x1, x3
+
+ set_sctlr_el1 x0
+
+ ret
+SYM_FUNC_END(__enable_mmu)
+
+SYM_FUNC_START(__cpu_secondary_check52bitva)
+#if VA_BITS > 48
+ ldr_l x0, vabits_actual
+ cmp x0, #52
+ b.ne 2f
+
+ mrs_s x0, SYS_ID_AA64MMFR2_EL1
+ and x0, x0, #(0xf << ID_AA64MMFR2_EL1_VARange_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.
+ */
+ adr_l x9, __rela_start
+ adr_l x10, __rela_end
+ mov_q x11, KIMAGE_VADDR // default virtual offset
+ add x11, x11, x23 // actual virtual offset
+
+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.
+ */
+ adr_l x9, __relr_start
+ adr_l x10, __relr_end
+
+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, x23
+ 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, x23
+ 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)
+ adrp x1, reserved_pg_dir
+ adrp x2, init_idmap_pg_dir
+ bl __enable_mmu
+#ifdef CONFIG_RELOCATABLE
+ adrp x23, KERNEL_START
+ and x23, x23, MIN_KIMG_ALIGN - 1
+#ifdef CONFIG_RANDOMIZE_BASE
+ mov x0, x22
+ adrp x1, init_pg_end
+ mov sp, x1
+ mov x29, xzr
+ bl __pi_kaslr_early_init
+ and x24, x0, #SZ_2M - 1 // capture memstart offset seed
+ bic x0, x0, #SZ_2M - 1
+ orr x23, x23, x0 // record kernel offset
+#endif
+#endif
+ bl clear_page_tables
+ bl create_kernel_mapping
+
+ adrp x1, init_pg_dir
+ load_ttbr1 x1, x1, x2
+#ifdef CONFIG_RELOCATABLE
+ bl __relocate_kernel
+#endif
+ ldr x8, =__primary_switched
+ adrp x0, KERNEL_START // __pa(KERNEL_START)
+ br x8
+SYM_FUNC_END(__primary_switch)