arch/arm64/kernel/head.S

   1 /*
   2  * Low-level CPU initialisation
   3  * Based on arch/arm/kernel/head.S
   4  *
   5  * Copyright (C) 1994-2002 Russell King
   6  * Copyright (C) 2003-2012 ARM Ltd.
   7  * Authors:     Catalin Marinas <catalin.marinas@arm.com>
   8  *              Will Deacon <will.deacon@arm.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23 #include <linux/linkage.h>
  24 #include <linux/init.h>
  25 #include <linux/irqchip/arm-gic-v3.h>
  26
  27 #include <asm/assembler.h>
  28 #include <asm/boot.h>
  29 #include <asm/ptrace.h>
  30 #include <asm/asm-offsets.h>
  31 #include <asm/cache.h>
  32 #include <asm/cputype.h>
  33 #include <asm/elf.h>
  34 #include <asm/kernel-pgtable.h>
  35 #include <asm/kvm_arm.h>
  36 #include <asm/memory.h>
  37 #include <asm/pgtable-hwdef.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/page.h>
  40 #include <asm/smp.h>
  41 #include <asm/sysreg.h>
  42 #include <asm/thread_info.h>
  43 #include <asm/virt.h>
  44
  45 #define __PHYS_OFFSET   (KERNEL_START - TEXT_OFFSET)
  46
  47 #if (TEXT_OFFSET & 0xfff) != 0
  48 #error TEXT_OFFSET must be at least 4KB aligned
  49 #elif (PAGE_OFFSET & 0x1fffff) != 0
  50 #error PAGE_OFFSET must be at least 2MB aligned
  51 #elif TEXT_OFFSET > 0x1fffff
  52 #error TEXT_OFFSET must be less than 2MB
  53 #endif
  54
  55 /*
  56  * Kernel startup entry point.
  57  * ---------------------------
  58  *
  59  * The requirements are:
  60  *   MMU = off, D-cache = off, I-cache = on or off,
  61  *   x0 = physical address to the FDT blob.
  62  *
  63  * This code is mostly position independent so you call this at
  64  * __pa(PAGE_OFFSET + TEXT_OFFSET).
  65  *
  66  * Note that the callee-saved registers are used for storing variables
  67  * that are useful before the MMU is enabled. The allocations are described
  68  * in the entry routines.
  69  */
  70         __HEAD
  71 _head:
  72         /*
  73          * DO NOT MODIFY. Image header expected by Linux boot-loaders.
  74          */
  75 #ifdef CONFIG_EFI
  76         /*
  77          * This add instruction has no meaningful effect except that
  78          * its opcode forms the magic "MZ" signature required by UEFI.
  79          */
  80         add     x13, x18, #0x16
  81         b       stext
  82 #else
  83         b       stext                           // branch to kernel start, magic
  84         .long   0                               // reserved
  85 #endif
  86         le64sym _kernel_offset_le               // Image load offset from start of RAM, little-endian
  87         le64sym _kernel_size_le                 // Effective size of kernel image, little-endian
  88         le64sym _kernel_flags_le                // Informative flags, little-endian
  89         .quad   0                               // reserved
  90         .quad   0                               // reserved
  91         .quad   0                               // reserved
  92         .byte   0x41                            // Magic number, "ARM\x64"
  93         .byte   0x52
  94         .byte   0x4d
  95         .byte   0x64
  96 #ifdef CONFIG_EFI
  97         .long   pe_header - _head               // Offset to the PE header.
  98 #else
  99         .word   0                               // reserved
 100 #endif
 101
 102 #ifdef CONFIG_EFI
 103         .align 3
 104 pe_header:
 105         .ascii  "PE"
 106         .short  0
 107 coff_header:
 108         .short  0xaa64                          // AArch64
 109         .short  2                               // nr_sections
 110         .long   0                               // TimeDateStamp
 111         .long   0                               // PointerToSymbolTable
 112         .long   1                               // NumberOfSymbols
 113         .short  section_table - optional_header // SizeOfOptionalHeader
 114         .short  0x206                           // Characteristics.
 115                                                 // IMAGE_FILE_DEBUG_STRIPPED |
 116                                                 // IMAGE_FILE_EXECUTABLE_IMAGE |
 117                                                 // IMAGE_FILE_LINE_NUMS_STRIPPED
 118 optional_header:
 119         .short  0x20b                           // PE32+ format
 120         .byte   0x02                            // MajorLinkerVersion
 121         .byte   0x14                            // MinorLinkerVersion
 122         .long   _end - efi_header_end           // SizeOfCode
 123         .long   0                               // SizeOfInitializedData
 124         .long   0                               // SizeOfUninitializedData
 125         .long   __efistub_entry - _head         // AddressOfEntryPoint
 126         .long   efi_header_end - _head          // BaseOfCode
 127
 128 extra_header_fields:
 129         .quad   0                               // ImageBase
 130         .long   0x1000                          // SectionAlignment
 131         .long   PECOFF_FILE_ALIGNMENT           // FileAlignment
 132         .short  0                               // MajorOperatingSystemVersion
 133         .short  0                               // MinorOperatingSystemVersion
 134         .short  0                               // MajorImageVersion
 135         .short  0                               // MinorImageVersion
 136         .short  0                               // MajorSubsystemVersion
 137         .short  0                               // MinorSubsystemVersion
 138         .long   0                               // Win32VersionValue
 139
 140         .long   _end - _head                    // SizeOfImage
 141
 142         // Everything before the kernel image is considered part of the header
 143         .long   efi_header_end - _head          // SizeOfHeaders
 144         .long   0                               // CheckSum
 145         .short  0xa                             // Subsystem (EFI application)
 146         .short  0                               // DllCharacteristics
 147         .quad   0                               // SizeOfStackReserve
 148         .quad   0                               // SizeOfStackCommit
 149         .quad   0                               // SizeOfHeapReserve
 150         .quad   0                               // SizeOfHeapCommit
 151         .long   0                               // LoaderFlags
 152         .long   0x6                             // NumberOfRvaAndSizes
 153
 154         .quad   0                               // ExportTable
 155         .quad   0                               // ImportTable
 156         .quad   0                               // ResourceTable
 157         .quad   0                               // ExceptionTable
 158         .quad   0                               // CertificationTable
 159         .quad   0                               // BaseRelocationTable
 160
 161         // Section table
 162 section_table:
 163
 164         /*
 165          * The EFI application loader requires a relocation section
 166          * because EFI applications must be relocatable.  This is a
 167          * dummy section as far as we are concerned.
 168          */
 169         .ascii  ".reloc"
 170         .byte   0
 171         .byte   0                       // end of 0 padding of section name
 172         .long   0
 173         .long   0
 174         .long   0                       // SizeOfRawData
 175         .long   0                       // PointerToRawData
 176         .long   0                       // PointerToRelocations
 177         .long   0                       // PointerToLineNumbers
 178         .short  0                       // NumberOfRelocations
 179         .short  0                       // NumberOfLineNumbers
 180         .long   0x42100040              // Characteristics (section flags)
 181
 182
 183         .ascii  ".text"
 184         .byte   0
 185         .byte   0
 186         .byte   0                       // end of 0 padding of section name
 187         .long   _end - efi_header_end   // VirtualSize
 188         .long   efi_header_end - _head  // VirtualAddress
 189         .long   _edata - efi_header_end // SizeOfRawData
 190         .long   efi_header_end - _head  // PointerToRawData
 191
 192         .long   0               // PointerToRelocations (0 for executables)
 193         .long   0               // PointerToLineNumbers (0 for executables)
 194         .short  0               // NumberOfRelocations  (0 for executables)
 195         .short  0               // NumberOfLineNumbers  (0 for executables)
 196         .long   0xe0500020      // Characteristics (section flags)
 197
 198         /*
 199          * EFI will load .text onwards at the 4k section alignment
 200          * described in the PE/COFF header. To ensure that instruction
 201          * sequences using an adrp and a :lo12: immediate will function
 202          * correctly at this alignment, we must ensure that .text is
 203          * placed at a 4k boundary in the Image to begin with.
 204          */
 205         .align 12
 206 efi_header_end:
 207 #endif
 208
 209         __INIT
 210
 211         /*
 212          * The following callee saved general purpose registers are used on the
 213          * primary lowlevel boot path:
 214          *
 215          *  Register   Scope                      Purpose
 216          *  x21        stext() .. start_kernel()  FDT pointer passed at boot in x0
 217          *  x23        stext() .. start_kernel()  physical misalignment/KASLR offset
 218          *  x28        __create_page_tables()     callee preserved temp register
 219          *  x19/x20    __primary_switch()         callee preserved temp registers
 220          */
 221 ENTRY(stext)
 222         bl      preserve_boot_args
 223         bl      el2_setup                       // Drop to EL1, w0=cpu_boot_mode
 224         adrp    x23, __PHYS_OFFSET
 225         and     x23, x23, MIN_KIMG_ALIGN - 1    // KASLR offset, defaults to 0
 226         bl      set_cpu_boot_mode_flag
 227         bl      __create_page_tables
 228         /*
 229          * The following calls CPU setup code, see arch/arm64/mm/proc.S for
 230          * details.
 231          * On return, the CPU will be ready for the MMU to be turned on and
 232          * the TCR will have been set.
 233          */
 234         bl      __cpu_setup                     // initialise processor
 235         b       __primary_switch
 236 ENDPROC(stext)
 237
 238 /*
 239  * Preserve the arguments passed by the bootloader in x0 .. x3
 240  */
 241 preserve_boot_args:
 242         mov     x21, x0                         // x21=FDT
 243
 244         adr_l   x0, boot_args                   // record the contents of
 245         stp     x21, x1, [x0]                   // x0 .. x3 at kernel entry
 246         stp     x2, x3, [x0, #16]
 247
 248         dmb     sy                              // needed before dc ivac with
 249                                                 // MMU off
 250
 251         add     x1, x0, #0x20                   // 4 x 8 bytes
 252         b       __inval_cache_range             // tail call
 253 ENDPROC(preserve_boot_args)
 254
 255 /*
 256  * Macro to create a table entry to the next page.
 257  *
 258  *      tbl:    page table address
 259  *      virt:   virtual address
 260  *      shift:  #imm page table shift
 261  *      ptrs:   #imm pointers per table page
 262  *
 263  * Preserves:   virt
 264  * Corrupts:    tmp1, tmp2
 265  * Returns:     tbl -> next level table page address
 266  */
 267         .macro  create_table_entry, tbl, virt, shift, ptrs, tmp1, tmp2
 268         lsr     \tmp1, \virt, #\shift
 269         and     \tmp1, \tmp1, #\ptrs - 1        // table index
 270         add     \tmp2, \tbl, #PAGE_SIZE
 271         orr     \tmp2, \tmp2, #PMD_TYPE_TABLE   // address of next table and entry type
 272         str     \tmp2, [\tbl, \tmp1, lsl #3]
 273         add     \tbl, \tbl, #PAGE_SIZE          // next level table page
 274         .endm
 275
 276 /*
 277  * Macro to populate the PGD (and possibily PUD) for the corresponding
 278  * block entry in the next level (tbl) for the given virtual address.
 279  *
 280  * Preserves:   tbl, next, virt
 281  * Corrupts:    tmp1, tmp2
 282  */
 283         .macro  create_pgd_entry, tbl, virt, tmp1, tmp2
 284         create_table_entry \tbl, \virt, PGDIR_SHIFT, PTRS_PER_PGD, \tmp1, \tmp2
 285 #if SWAPPER_PGTABLE_LEVELS > 3
 286         create_table_entry \tbl, \virt, PUD_SHIFT, PTRS_PER_PUD, \tmp1, \tmp2
 287 #endif
 288 #if SWAPPER_PGTABLE_LEVELS > 2
 289         create_table_entry \tbl, \virt, SWAPPER_TABLE_SHIFT, PTRS_PER_PTE, \tmp1, \tmp2
 290 #endif
 291         .endm
 292
 293 /*
 294  * Macro to populate block entries in the page table for the start..end
 295  * virtual range (inclusive).
 296  *
 297  * Preserves:   tbl, flags
 298  * Corrupts:    phys, start, end, pstate
 299  */
 300         .macro  create_block_map, tbl, flags, phys, start, end
 301         lsr     \phys, \phys, #SWAPPER_BLOCK_SHIFT
 302         lsr     \start, \start, #SWAPPER_BLOCK_SHIFT
 303         and     \start, \start, #PTRS_PER_PTE - 1       // table index
 304         orr     \phys, \flags, \phys, lsl #SWAPPER_BLOCK_SHIFT  // table entry
 305         lsr     \end, \end, #SWAPPER_BLOCK_SHIFT
 306         and     \end, \end, #PTRS_PER_PTE - 1           // table end index
 307 9999:   str     \phys, [\tbl, \start, lsl #3]           // store the entry
 308         add     \start, \start, #1                      // next entry
 309         add     \phys, \phys, #SWAPPER_BLOCK_SIZE               // next block
 310         cmp     \start, \end
 311         b.ls    9999b
 312         .endm
 313
 314 /*
 315  * Setup the initial page tables. We only setup the barest amount which is
 316  * required to get the kernel running. The following sections are required:
 317  *   - identity mapping to enable the MMU (low address, TTBR0)
 318  *   - first few MB of the kernel linear mapping to jump to once the MMU has
 319  *     been enabled
 320  */
 321 __create_page_tables:
 322         mov     x28, lr
 323
 324         /*
 325          * Invalidate the idmap and swapper page tables to avoid potential
 326          * dirty cache lines being evicted.
 327          */
 328         adrp    x0, idmap_pg_dir
 329         adrp    x1, swapper_pg_dir + SWAPPER_DIR_SIZE
 330         bl      __inval_cache_range
 331
 332         /*
 333          * Clear the idmap and swapper page tables.
 334          */
 335         adrp    x0, idmap_pg_dir
 336         adrp    x6, swapper_pg_dir + SWAPPER_DIR_SIZE
 337 1:      stp     xzr, xzr, [x0], #16
 338         stp     xzr, xzr, [x0], #16
 339         stp     xzr, xzr, [x0], #16
 340         stp     xzr, xzr, [x0], #16
 341         cmp     x0, x6
 342         b.lo    1b
 343
 344         mov     x7, SWAPPER_MM_MMUFLAGS
 345
 346         /*
 347          * Create the identity mapping.
 348          */
 349         adrp    x0, idmap_pg_dir
 350         adrp    x3, __idmap_text_start          // __pa(__idmap_text_start)
 351
 352 #ifndef CONFIG_ARM64_VA_BITS_48
 353 #define EXTRA_SHIFT     (PGDIR_SHIFT + PAGE_SHIFT - 3)
 354 #define EXTRA_PTRS      (1 << (48 - EXTRA_SHIFT))
 355
 356         /*
 357          * If VA_BITS < 48, it may be too small to allow for an ID mapping to be
 358          * created that covers system RAM if that is located sufficiently high
 359          * in the physical address space. So for the ID map, use an extended
 360          * virtual range in that case, by configuring an additional translation
 361          * level.
 362          * First, we have to verify our assumption that the current value of
 363          * VA_BITS was chosen such that all translation levels are fully
 364          * utilised, and that lowering T0SZ will always result in an additional
 365          * translation level to be configured.
 366          */
 367 #if VA_BITS != EXTRA_SHIFT
 368 #error "Mismatch between VA_BITS and page size/number of translation levels"
 369 #endif
 370
 371         /*
 372          * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the
 373          * entire ID map region can be mapped. As T0SZ == (64 - #bits used),
 374          * this number conveniently equals the number of leading zeroes in
 375          * the physical address of __idmap_text_end.
 376          */
 377         adrp    x5, __idmap_text_end
 378         clz     x5, x5
 379         cmp     x5, TCR_T0SZ(VA_BITS)   // default T0SZ small enough?
 380         b.ge    1f                      // .. then skip additional level
 381
 382         adr_l   x6, idmap_t0sz
 383         str     x5, [x6]
 384         dmb     sy
 385         dc      ivac, x6                // Invalidate potentially stale cache line
 386
 387         create_table_entry x0, x3, EXTRA_SHIFT, EXTRA_PTRS, x5, x6
 388 1:
 389 #endif
 390
 391         create_pgd_entry x0, x3, x5, x6
 392         mov     x5, x3                          // __pa(__idmap_text_start)
 393         adr_l   x6, __idmap_text_end            // __pa(__idmap_text_end)
 394         create_block_map x0, x7, x3, x5, x6
 395
 396         /*
 397          * Map the kernel image (starting with PHYS_OFFSET).
 398          */
 399         adrp    x0, swapper_pg_dir
 400         mov_q   x5, KIMAGE_VADDR + TEXT_OFFSET  // compile time __va(_text)
 401         add     x5, x5, x23                     // add KASLR displacement
 402         create_pgd_entry x0, x5, x3, x6
 403         adrp    x6, _end                        // runtime __pa(_end)
 404         adrp    x3, _text                       // runtime __pa(_text)
 405         sub     x6, x6, x3                      // _end - _text
 406         add     x6, x6, x5                      // runtime __va(_end)
 407         create_block_map x0, x7, x3, x5, x6
 408
 409         /*
 410          * Since the page tables have been populated with non-cacheable
 411          * accesses (MMU disabled), invalidate the idmap and swapper page
 412          * tables again to remove any speculatively loaded cache lines.
 413          */
 414         adrp    x0, idmap_pg_dir
 415         adrp    x1, swapper_pg_dir + SWAPPER_DIR_SIZE
 416         dmb     sy
 417         bl      __inval_cache_range
 418
 419         ret     x28
 420 ENDPROC(__create_page_tables)
 421         .ltorg
 422
 423 /*
 424  * The following fragment of code is executed with the MMU enabled.
 425  *
 426  *   x0 = __PHYS_OFFSET
 427  */
 428 __primary_switched:
 429         adrp    x4, init_thread_union
 430         add     sp, x4, #THREAD_SIZE
 431         msr     sp_el0, x4                      // Save thread_info
 432
 433         adr_l   x8, vectors                     // load VBAR_EL1 with virtual
 434         msr     vbar_el1, x8                    // vector table address
 435         isb
 436
 437         stp     xzr, x30, [sp, #-16]!
 438         mov     x29, sp
 439
 440         str_l   x21, __fdt_pointer, x5          // Save FDT pointer
 441
 442         ldr_l   x4, kimage_vaddr                // Save the offset between
 443         sub     x4, x4, x0                      // the kernel virtual and
 444         str_l   x4, kimage_voffset, x5          // physical mappings
 445
 446         // Clear BSS
 447         adr_l   x0, __bss_start
 448         mov     x1, xzr
 449         adr_l   x2, __bss_stop
 450         sub     x2, x2, x0
 451         bl      __pi_memset
 452         dsb     ishst                           // Make zero page visible to PTW
 453
 454 #ifdef CONFIG_KASAN
 455         bl      kasan_early_init
 456 #endif
 457 #ifdef CONFIG_RANDOMIZE_BASE
 458         tst     x23, ~(MIN_KIMG_ALIGN - 1)      // already running randomized?
 459         b.ne    0f
 460         mov     x0, x21                         // pass FDT address in x0
 461         mov     x1, x23                         // pass modulo offset in x1
 462         bl      kaslr_early_init                // parse FDT for KASLR options
 463         cbz     x0, 0f                          // KASLR disabled? just proceed
 464         orr     x23, x23, x0                    // record KASLR offset
 465         ldp     x29, x30, [sp], #16             // we must enable KASLR, return
 466         ret                                     // to __primary_switch()
 467 0:
 468 #endif
 469         b       start_kernel
 470 ENDPROC(__primary_switched)
 471
 472 /*
 473  * end early head section, begin head code that is also used for
 474  * hotplug and needs to have the same protections as the text region
 475  */
 476         .section ".idmap.text","ax"
 477
 478 ENTRY(kimage_vaddr)
 479         .quad           _text - TEXT_OFFSET
 480
 481 /*
 482  * If we're fortunate enough to boot at EL2, ensure that the world is
 483  * sane before dropping to EL1.
 484  *
 485  * Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in x20 if
 486  * booted in EL1 or EL2 respectively.
 487  */
 488 ENTRY(el2_setup)
 489         mrs     x0, CurrentEL
 490         cmp     x0, #CurrentEL_EL2
 491         b.ne    1f
 492         mrs     x0, sctlr_el2
 493 CPU_BE( orr     x0, x0, #(1 << 25)      )       // Set the EE bit for EL2
 494 CPU_LE( bic     x0, x0, #(1 << 25)      )       // Clear the EE bit for EL2
 495         msr     sctlr_el2, x0
 496         b       2f
 497 1:      mrs     x0, sctlr_el1
 498 CPU_BE( orr     x0, x0, #(3 << 24)      )       // Set the EE and E0E bits for EL1
 499 CPU_LE( bic     x0, x0, #(3 << 24)      )       // Clear the EE and E0E bits for EL1
 500         msr     sctlr_el1, x0
 501         mov     w0, #BOOT_CPU_MODE_EL1          // This cpu booted in EL1
 502         isb
 503         ret
 504
 505 2:
 506 #ifdef CONFIG_ARM64_VHE
 507         /*
 508          * Check for VHE being present. For the rest of the EL2 setup,
 509          * x2 being non-zero indicates that we do have VHE, and that the
 510          * kernel is intended to run at EL2.
 511          */
 512         mrs     x2, id_aa64mmfr1_el1
 513         ubfx    x2, x2, #8, #4
 514 #else
 515         mov     x2, xzr
 516 #endif
 517
 518         /* Hyp configuration. */
 519         mov     x0, #HCR_RW                     // 64-bit EL1
 520         cbz     x2, set_hcr
 521         orr     x0, x0, #HCR_TGE                // Enable Host Extensions
 522         orr     x0, x0, #HCR_E2H
 523 set_hcr:
 524         msr     hcr_el2, x0
 525         isb
 526
 527         /* Generic timers. */
 528         mrs     x0, cnthctl_el2
 529         orr     x0, x0, #3                      // Enable EL1 physical timers
 530         msr     cnthctl_el2, x0
 531         msr     cntvoff_el2, xzr                // Clear virtual offset
 532
 533 #ifdef CONFIG_ARM_GIC_V3
 534         /* GICv3 system register access */
 535         mrs     x0, id_aa64pfr0_el1
 536         ubfx    x0, x0, #24, #4
 537         cmp     x0, #1
 538         b.ne    3f
 539
 540         mrs_s   x0, ICC_SRE_EL2
 541         orr     x0, x0, #ICC_SRE_EL2_SRE        // Set ICC_SRE_EL2.SRE==1
 542         orr     x0, x0, #ICC_SRE_EL2_ENABLE     // Set ICC_SRE_EL2.Enable==1
 543         msr_s   ICC_SRE_EL2, x0
 544         isb                                     // Make sure SRE is now set
 545         mrs_s   x0, ICC_SRE_EL2                 // Read SRE back,
 546         tbz     x0, #0, 3f                      // and check that it sticks
 547         msr_s   ICH_HCR_EL2, xzr                // Reset ICC_HCR_EL2 to defaults
 548
 549 3:
 550 #endif
 551
 552         /* Populate ID registers. */
 553         mrs     x0, midr_el1
 554         mrs     x1, mpidr_el1
 555         msr     vpidr_el2, x0
 556         msr     vmpidr_el2, x1
 557
 558         /*
 559          * When VHE is not in use, early init of EL2 and EL1 needs to be
 560          * done here.
 561          * When VHE _is_ in use, EL1 will not be used in the host and
 562          * requires no configuration, and all non-hyp-specific EL2 setup
 563          * will be done via the _EL1 system register aliases in __cpu_setup.
 564          */
 565         cbnz    x2, 1f
 566
 567         /* sctlr_el1 */
 568         mov     x0, #0x0800                     // Set/clear RES{1,0} bits
 569 CPU_BE( movk    x0, #0x33d0, lsl #16    )       // Set EE and E0E on BE systems
 570 CPU_LE( movk    x0, #0x30d0, lsl #16    )       // Clear EE and E0E on LE systems
 571         msr     sctlr_el1, x0
 572
 573         /* Coprocessor traps. */
 574         mov     x0, #0x33ff
 575         msr     cptr_el2, x0                    // Disable copro. traps to EL2
 576 1:
 577
 578 #ifdef CONFIG_COMPAT
 579         msr     hstr_el2, xzr                   // Disable CP15 traps to EL2
 580 #endif
 581
 582         /* EL2 debug */
 583         mrs     x0, id_aa64dfr0_el1             // Check ID_AA64DFR0_EL1 PMUVer
 584         sbfx    x0, x0, #8, #4
 585         cmp     x0, #1
 586         b.lt    4f                              // Skip if no PMU present
 587         mrs     x0, pmcr_el0                    // Disable debug access traps
 588         ubfx    x0, x0, #11, #5                 // to EL2 and allow access to
 589         msr     mdcr_el2, x0                    // all PMU counters from EL1
 590 4:
 591
 592         /* Stage-2 translation */
 593         msr     vttbr_el2, xzr
 594
 595         cbz     x2, install_el2_stub
 596
 597         mov     w0, #BOOT_CPU_MODE_EL2          // This CPU booted in EL2
 598         isb
 599         ret
 600
 601 install_el2_stub:
 602         /* Hypervisor stub */
 603         adrp    x0, __hyp_stub_vectors
 604         add     x0, x0, #:lo12:__hyp_stub_vectors
 605         msr     vbar_el2, x0
 606
 607         /* spsr */
 608         mov     x0, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
 609                       PSR_MODE_EL1h)
 610         msr     spsr_el2, x0
 611         msr     elr_el2, lr
 612         mov     w0, #BOOT_CPU_MODE_EL2          // This CPU booted in EL2
 613         eret
 614 ENDPROC(el2_setup)
 615
 616 /*
 617  * Sets the __boot_cpu_mode flag depending on the CPU boot mode passed
 618  * in x20. See arch/arm64/include/asm/virt.h for more info.
 619  */
 620 set_cpu_boot_mode_flag:
 621         adr_l   x1, __boot_cpu_mode
 622         cmp     w0, #BOOT_CPU_MODE_EL2
 623         b.ne    1f
 624         add     x1, x1, #4
 625 1:      str     w0, [x1]                        // This CPU has booted in EL1
 626         dmb     sy
 627         dc      ivac, x1                        // Invalidate potentially stale cache line
 628         ret
 629 ENDPROC(set_cpu_boot_mode_flag)
 630
 631 /*
 632  * These values are written with the MMU off, but read with the MMU on.
 633  * Writers will invalidate the corresponding address, discarding up to a
 634  * 'Cache Writeback Granule' (CWG) worth of data. The linker script ensures
 635  * sufficient alignment that the CWG doesn't overlap another section.
 636  */
 637         .pushsection ".mmuoff.data.write", "aw"
 638 /*
 639  * We need to find out the CPU boot mode long after boot, so we need to
 640  * store it in a writable variable.
 641  *
 642  * This is not in .bss, because we set it sufficiently early that the boot-time
 643  * zeroing of .bss would clobber it.
 644  */
 645 ENTRY(__boot_cpu_mode)
 646         .long   BOOT_CPU_MODE_EL2
 647         .long   BOOT_CPU_MODE_EL1
 648 /*
 649  * The booting CPU updates the failed status @__early_cpu_boot_status,
 650  * with MMU turned off.
 651  */
 652 ENTRY(__early_cpu_boot_status)
 653         .long   0
 654
 655         .popsection
 656
 657         /*
 658          * This provides a "holding pen" for platforms to hold all secondary
 659          * cores are held until we're ready for them to initialise.
 660          */
 661 ENTRY(secondary_holding_pen)
 662         bl      el2_setup                       // Drop to EL1, w0=cpu_boot_mode
 663         bl      set_cpu_boot_mode_flag
 664         mrs     x0, mpidr_el1
 665         mov_q   x1, MPIDR_HWID_BITMASK
 666         and     x0, x0, x1
 667         adr_l   x3, secondary_holding_pen_release
 668 pen:    ldr     x4, [x3]
 669         cmp     x4, x0
 670         b.eq    secondary_startup
 671         wfe
 672         b       pen
 673 ENDPROC(secondary_holding_pen)
 674
 675         /*
 676          * Secondary entry point that jumps straight into the kernel. Only to
 677          * be used where CPUs are brought online dynamically by the kernel.
 678          */
 679 ENTRY(secondary_entry)
 680         bl      el2_setup                       // Drop to EL1
 681         bl      set_cpu_boot_mode_flag
 682         b       secondary_startup
 683 ENDPROC(secondary_entry)
 684
 685 secondary_startup:
 686         /*
 687          * Common entry point for secondary CPUs.
 688          */
 689         bl      __cpu_setup                     // initialise processor
 690         bl      __enable_mmu
 691         ldr     x8, =__secondary_switched
 692         br      x8
 693 ENDPROC(secondary_startup)
 694
 695 __secondary_switched:
 696         adr_l   x5, vectors
 697         msr     vbar_el1, x5
 698         isb
 699
 700         adr_l   x0, secondary_data
 701         ldr     x0, [x0, #CPU_BOOT_STACK]       // get secondary_data.stack
 702         mov     sp, x0
 703         and     x0, x0, #~(THREAD_SIZE - 1)
 704         msr     sp_el0, x0                      // save thread_info
 705         mov     x29, #0
 706         b       secondary_start_kernel
 707 ENDPROC(__secondary_switched)
 708
 709 /*
 710  * The booting CPU updates the failed status @__early_cpu_boot_status,
 711  * with MMU turned off.
 712  *
 713  * update_early_cpu_boot_status tmp, status
 714  *  - Corrupts tmp1, tmp2
 715  *  - Writes 'status' to __early_cpu_boot_status and makes sure
 716  *    it is committed to memory.
 717  */
 718
 719         .macro  update_early_cpu_boot_status status, tmp1, tmp2
 720         mov     \tmp2, #\status
 721         adr_l   \tmp1, __early_cpu_boot_status
 722         str     \tmp2, [\tmp1]
 723         dmb     sy
 724         dc      ivac, \tmp1                     // Invalidate potentially stale cache line
 725         .endm
 726
 727 /*
 728  * Enable the MMU.
 729  *
 730  *  x0  = SCTLR_EL1 value for turning on the MMU.
 731  *
 732  * Returns to the caller via x30/lr. This requires the caller to be covered
 733  * by the .idmap.text section.
 734  *
 735  * Checks if the selected granule size is supported by the CPU.
 736  * If it isn't, park the CPU
 737  */
 738 ENTRY(__enable_mmu)
 739         mrs     x1, ID_AA64MMFR0_EL1
 740         ubfx    x2, x1, #ID_AA64MMFR0_TGRAN_SHIFT, 4
 741         cmp     x2, #ID_AA64MMFR0_TGRAN_SUPPORTED
 742         b.ne    __no_granule_support
 743         update_early_cpu_boot_status 0, x1, x2
 744         adrp    x1, idmap_pg_dir
 745         adrp    x2, swapper_pg_dir
 746         msr     ttbr0_el1, x1                   // load TTBR0
 747         msr     ttbr1_el1, x2                   // load TTBR1
 748         isb
 749         msr     sctlr_el1, x0
 750         isb
 751         /*
 752          * Invalidate the local I-cache so that any instructions fetched
 753          * speculatively from the PoC are discarded, since they may have
 754          * been dynamically patched at the PoU.
 755          */
 756         ic      iallu
 757         dsb     nsh
 758         isb
 759         ret
 760 ENDPROC(__enable_mmu)
 761
 762 __no_granule_support:
 763         /* Indicate that this CPU can't boot and is stuck in the kernel */
 764         update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x1, x2
 765 1:
 766         wfe
 767         wfi
 768         b       1b
 769 ENDPROC(__no_granule_support)
 770
 771 #ifdef CONFIG_RELOCATABLE
 772 __relocate_kernel:
 773         /*
 774          * Iterate over each entry in the relocation table, and apply the
 775          * relocations in place.
 776          */
 777         ldr     w9, =__rela_offset              // offset to reloc table
 778         ldr     w10, =__rela_size               // size of reloc table
 779
 780         mov_q   x11, KIMAGE_VADDR               // default virtual offset
 781         add     x11, x11, x23                   // actual virtual offset
 782         add     x9, x9, x11                     // __va(.rela)
 783         add     x10, x9, x10                    // __va(.rela) + sizeof(.rela)
 784
 785 0:      cmp     x9, x10
 786         b.hs    1f
 787         ldp     x11, x12, [x9], #24
 788         ldr     x13, [x9, #-8]
 789         cmp     w12, #R_AARCH64_RELATIVE
 790         b.ne    0b
 791         add     x13, x13, x23                   // relocate
 792         str     x13, [x11, x23]
 793         b       0b
 794 1:      ret
 795 ENDPROC(__relocate_kernel)
 796 #endif
 797
 798 __primary_switch:
 799 #ifdef CONFIG_RANDOMIZE_BASE
 800         mov     x19, x0                         // preserve new SCTLR_EL1 value
 801         mrs     x20, sctlr_el1                  // preserve old SCTLR_EL1 value
 802 #endif
 803
 804         bl      __enable_mmu
 805 #ifdef CONFIG_RELOCATABLE
 806         bl      __relocate_kernel
 807 #ifdef CONFIG_RANDOMIZE_BASE
 808         ldr     x8, =__primary_switched
 809         adrp    x0, __PHYS_OFFSET
 810         blr     x8
 811
 812         /*
 813          * If we return here, we have a KASLR displacement in x23 which we need
 814          * to take into account by discarding the current kernel mapping and
 815          * creating a new one.
 816          */
 817         msr     sctlr_el1, x20                  // disable the MMU
 818         isb
 819         bl      __create_page_tables            // recreate kernel mapping
 820
 821         tlbi    vmalle1                         // Remove any stale TLB entries
 822         dsb     nsh
 823
 824         msr     sctlr_el1, x19                  // re-enable the MMU
 825         isb
 826         ic      iallu                           // flush instructions fetched
 827         dsb     nsh                             // via old mapping
 828         isb
 829
 830         bl      __relocate_kernel
 831 #endif
 832 #endif
 833         ldr     x8, =__primary_switched
 834         adrp    x0, __PHYS_OFFSET
 835         br      x8
 836 ENDPROC(__primary_switch)