[PATCH v3 02/31] arm64: Kernel booting and initialisation
Catalin Marinas
catalin.marinas at arm.com
Fri Sep 7 12:26:37 EDT 2012
The patch adds the kernel booting and the initial setup code.
Documentation/arm64/booting.txt describes the booting protocol on the
AArch64 Linux kernel. This is subject to change following the work on
boot standardisation, ACPI.
Signed-off-by: Will Deacon <will.deacon at arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
Acked-by: Nicolas Pitre <nico at linaro.org>
Acked-by: Tony Lindgren <tony at atomide.com>
---
Documentation/arm64/booting.txt | 152 ++++++++++++
arch/arm64/include/asm/setup.h | 26 ++
arch/arm64/kernel/head.S | 510 +++++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/setup.c | 351 +++++++++++++++++++++++++++
4 files changed, 1039 insertions(+), 0 deletions(-)
create mode 100644 Documentation/arm64/booting.txt
create mode 100644 arch/arm64/include/asm/setup.h
create mode 100644 arch/arm64/kernel/head.S
create mode 100644 arch/arm64/kernel/setup.c
diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
new file mode 100644
index 0000000..9c4d388
--- /dev/null
+++ b/Documentation/arm64/booting.txt
@@ -0,0 +1,152 @@
+ Booting AArch64 Linux
+ =====================
+
+Author: Will Deacon <will.deacon at arm.com>
+Date : 07 September 2012
+
+This document is based on the ARM booting document by Russell King and
+is relevant to all public releases of the AArch64 Linux kernel.
+
+The AArch64 exception model is made up of a number of exception levels
+(EL0 - EL3), with EL0 and EL1 having a secure and a non-secure
+counterpart. EL2 is the hypervisor level and exists only in non-secure
+mode. EL3 is the highest priority level and exists only in secure mode.
+
+For the purposes of this document, we will use the term `boot loader'
+simply to define all software that executes on the CPU(s) before control
+is passed to the Linux kernel. This may include secure monitor and
+hypervisor code, or it may just be a handful of instructions for
+preparing a minimal boot environment.
+
+Essentially, the boot loader should provide (as a minimum) the
+following:
+
+1. Setup and initialise the RAM
+2. Setup the device tree
+3. Decompress the kernel image
+4. Call the kernel image
+
+
+1. Setup and initialise RAM
+---------------------------
+
+Requirement: MANDATORY
+
+The boot loader is expected to find and initialise all RAM that the
+kernel will use for volatile data storage in the system. It performs
+this in a machine dependent manner. (It may use internal algorithms
+to automatically locate and size all RAM, or it may use knowledge of
+the RAM in the machine, or any other method the boot loader designer
+sees fit.)
+
+
+2. Setup the device tree
+-------------------------
+
+Requirement: MANDATORY
+
+The device tree blob (dtb) must be no bigger than 2 megabytes in size
+and placed at a 2-megabyte boundary within the first 512 megabytes from
+the start of the kernel image. This is to allow the kernel to map the
+blob using a single section mapping in the initial page tables.
+
+
+3. Decompress the kernel image
+------------------------------
+
+Requirement: OPTIONAL
+
+The AArch64 kernel does not currently provide a decompressor and
+therefore requires decompression (gzip etc.) to be performed by the boot
+loader if a compressed Image target (e.g. Image.gz) is used. For
+bootloaders that do not implement this requirement, the uncompressed
+Image target is available instead.
+
+
+4. Call the kernel image
+------------------------
+
+Requirement: MANDATORY
+
+The decompressed kernel image contains a 32-byte header as follows:
+
+ u32 magic = 0x14000008; /* branch to stext, little-endian */
+ u32 res0 = 0; /* reserved */
+ u64 text_offset; /* Image load offset */
+ u64 res1 = 0; /* reserved */
+ u64 res2 = 0; /* reserved */
+
+The image must be placed at the specified offset (currently 0x80000)
+from the start of the system RAM and called there. The start of the
+system RAM must be aligned to 2MB.
+
+Before jumping into the kernel, the following conditions must be met:
+
+- Quiesce all DMA capable devices so that memory does not get
+ corrupted by bogus network packets or disk data. This will save
+ you many hours of debug.
+
+- Primary CPU general-purpose register settings
+ x0 = physical address of device tree blob (dtb) in system RAM.
+ x1 = 0 (reserved for future use)
+ x2 = 0 (reserved for future use)
+ x3 = 0 (reserved for future use)
+
+- CPU mode
+ All forms of interrupts must be masked in PSTATE.DAIF (Debug, SError,
+ IRQ and FIQ).
+ The CPU must be in either EL2 (RECOMMENDED in order to have access to
+ the virtualisation extensions) or non-secure EL1.
+
+- Caches, MMUs
+ The MMU must be off.
+ Instruction cache may be on or off.
+ Data cache must be off and invalidated.
+ External caches (if present) must be configured and disabled.
+
+- Architected timers
+ CNTFRQ must be programmed with the timer frequency.
+ If entering the kernel at EL1, CNTHCTL_EL2 must have EL1PCTEN (bit 0)
+ set where available.
+
+- Coherency
+ All CPUs to be booted by the kernel must be part of the same coherency
+ domain on entry to the kernel. This may require IMPLEMENTATION DEFINED
+ initialisation to enable the receiving of maintenance operations on
+ each CPU.
+
+- System registers
+ All writable architected system registers at the exception level where
+ the kernel image will be entered must be initialised by software at a
+ higher exception level to prevent execution in an UNKNOWN state.
+
+The boot loader is expected to enter the kernel on each CPU in the
+following manner:
+
+- The primary CPU must jump directly to the first instruction of the
+ kernel image. The device tree blob passed by this CPU must contain
+ for each CPU node:
+
+ 1. An 'enable-method' property. Currently, the only supported value
+ for this field is the string "spin-table".
+
+ 2. A 'cpu-release-addr' property identifying a 64-bit,
+ zero-initialised memory location.
+
+ It is expected that the bootloader will generate these device tree
+ properties and insert them into the blob prior to kernel entry.
+
+- Any secondary CPUs must spin outside of the kernel in a reserved area
+ of memory (communicated to the kernel by a /memreserve/ region in the
+ device tree) polling their cpu-release-addr location, which must be
+ contained in the reserved region. A wfe instruction may be inserted
+ to reduce the overhead of the busy-loop and a sev will be issued by
+ the primary CPU. When a read of the location pointed to by the
+ cpu-release-addr returns a non-zero value, the CPU must jump directly
+ to this value.
+
+- Secondary CPU general-purpose register settings
+ x0 = 0 (reserved for future use)
+ x1 = 0 (reserved for future use)
+ x2 = 0 (reserved for future use)
+ x3 = 0 (reserved for future use)
diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
new file mode 100644
index 0000000..9cf2e46
--- /dev/null
+++ b/arch/arm64/include/asm/setup.h
@@ -0,0 +1,26 @@
+/*
+ * Based on arch/arm/include/asm/setup.h
+ *
+ * Copyright (C) 1997-1999 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * 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/>.
+ */
+#ifndef __ASM_SETUP_H
+#define __ASM_SETUP_H
+
+#include <linux/types.h>
+
+#define COMMAND_LINE_SIZE 2048
+
+#endif
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
new file mode 100644
index 0000000..b158f17
--- /dev/null
+++ b/arch/arm64/kernel/head.S
@@ -0,0 +1,510 @@
+/*
+ * 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 at arm.com>
+ * Will Deacon <will.deacon at arm.com>
+ *
+ * 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 <asm/assembler.h>
+#include <asm/ptrace.h>
+#include <asm/asm-offsets.h>
+#include <asm/memory.h>
+#include <asm/thread_info.h>
+#include <asm/pgtable-hwdef.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+
+/*
+ * swapper_pg_dir is the virtual address of the initial page table. We place
+ * the page tables 3 * PAGE_SIZE below KERNEL_RAM_VADDR. The idmap_pg_dir has
+ * 2 pages and is placed below swapper_pg_dir.
+ */
+#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
+
+#if (KERNEL_RAM_VADDR & 0xfffff) != 0x80000
+#error KERNEL_RAM_VADDR must start at 0xXXX80000
+#endif
+
+#define SWAPPER_DIR_SIZE (3 * PAGE_SIZE)
+#define IDMAP_DIR_SIZE (2 * PAGE_SIZE)
+
+ .globl swapper_pg_dir
+ .equ swapper_pg_dir, KERNEL_RAM_VADDR - SWAPPER_DIR_SIZE
+
+ .globl idmap_pg_dir
+ .equ idmap_pg_dir, swapper_pg_dir - IDMAP_DIR_SIZE
+
+ .macro pgtbl, ttb0, ttb1, phys
+ add \ttb1, \phys, #TEXT_OFFSET - SWAPPER_DIR_SIZE
+ sub \ttb0, \ttb1, #IDMAP_DIR_SIZE
+ .endm
+
+#ifdef CONFIG_ARM64_64K_PAGES
+#define BLOCK_SHIFT PAGE_SHIFT
+#define BLOCK_SIZE PAGE_SIZE
+#else
+#define BLOCK_SHIFT SECTION_SHIFT
+#define BLOCK_SIZE SECTION_SIZE
+#endif
+
+#define KERNEL_START KERNEL_RAM_VADDR
+#define KERNEL_END _end
+
+/*
+ * Initial memory map attributes.
+ */
+#ifndef CONFIG_SMP
+#define PTE_FLAGS PTE_ATTRINDX(MT_NORMAL) | PTE_AF
+#define PMD_FLAGS PMD_ATTRINDX(MT_NORMAL) | PMD_SECT_AF
+#else
+#define PTE_FLAGS PTE_ATTRINDX(MT_NORMAL) | PTE_AF | PTE_SHARED
+#define PMD_FLAGS PMD_ATTRINDX(MT_NORMAL) | PMD_SECT_AF | PMD_SECT_S
+#endif
+
+#ifdef CONFIG_ARM64_64K_PAGES
+#define MM_MMUFLAGS PTE_TYPE_PAGE | PTE_FLAGS
+#define IO_MMUFLAGS PTE_TYPE_PAGE | PTE_XN | PTE_FLAGS
+#else
+#define MM_MMUFLAGS PMD_TYPE_SECT | PMD_FLAGS
+#define IO_MMUFLAGS PMD_TYPE_SECT | PMD_SECT_XN | PMD_FLAGS
+#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
+
+ /*
+ * DO NOT MODIFY. Image header expected by Linux boot-loaders.
+ */
+ b stext // branch to kernel start, magic
+ .long 0 // reserved
+ .quad TEXT_OFFSET // Image load offset from start of RAM
+ .quad 0 // reserved
+ .quad 0 // reserved
+
+ENTRY(stext)
+ mov x21, x0 // x21=FDT
+ bl el2_setup // Drop to EL1
+ mrs x22, midr_el1 // x22=cpuid
+ mov x0, x22
+ bl lookup_processor_type
+ mov x23, x0 // x23=current cpu_table
+ cbz x23, __error_p // invalid processor (x23=0)?
+ bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
+ bl __vet_fdt
+ bl __create_page_tables // x25=TTBR0, x26=TTBR1
+ /*
+ * The following calls CPU specific code in a position independent
+ * manner. See arch/arm64/mm/proc.S for details. x23 = base of
+ * cpu_info structure selected by lookup_processor_type above.
+ * On return, the CPU will be ready for the MMU to be turned on and
+ * the TCR will have been set.
+ */
+ ldr x27, __switch_data // address to jump to after
+ // MMU has been enabled
+ adr lr, __enable_mmu // return (PIC) address
+ ldr x12, [x23, #CPU_INFO_SETUP]
+ add x12, x12, x28 // __virt_to_phys
+ br x12 // initialise processor
+ENDPROC(stext)
+
+/*
+ * If we're fortunate enough to boot at EL2, ensure that the world is
+ * sane before dropping to EL1.
+ */
+ENTRY(el2_setup)
+ mrs x0, CurrentEL
+ cmp x0, #PSR_MODE_EL2t
+ ccmp x0, #PSR_MODE_EL2h, #0x4, ne
+ b.eq 1f
+ ret
+
+ /* Hyp configuration. */
+1: mov x0, #(1 << 31) // 64-bit EL1
+ msr hcr_el2, x0
+
+ /* Generic timers. */
+ mrs x0, cnthctl_el2
+ orr x0, x0, #3 // Enable EL1 physical timers
+ msr cnthctl_el2, x0
+
+ /* Populate ID registers. */
+ mrs x0, midr_el1
+ mrs x1, mpidr_el1
+ msr vpidr_el2, x0
+ msr vmpidr_el2, x1
+
+ /* sctlr_el1 */
+ mov x0, #0x0800 // Set/clear RES{1,0} bits
+ movk x0, #0x30d0, lsl #16
+ msr sctlr_el1, x0
+
+ /* Coprocessor traps. */
+ mov x0, #0x33ff
+ msr cptr_el2, x0 // Disable copro. traps to EL2
+
+#ifdef CONFIG_COMPAT
+ msr hstr_el2, xzr // Disable CP15 traps to EL2
+#endif
+
+ /* 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
+ eret
+ENDPROC(el2_setup)
+
+ .align 3
+2: .quad .
+ .quad PAGE_OFFSET
+
+#ifdef CONFIG_SMP
+ .pushsection .smp.pen.text, "ax"
+ .align 3
+1: .quad .
+ .quad secondary_holding_pen_release
+
+ /*
+ * 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
+ mrs x0, mpidr_el1
+ and x0, x0, #15 // CPU number
+ adr x1, 1b
+ ldp x2, x3, [x1]
+ sub x1, x1, x2
+ add x3, x3, x1
+pen: ldr x4, [x3]
+ cmp x4, x0
+ b.eq secondary_startup
+ wfe
+ b pen
+ENDPROC(secondary_holding_pen)
+ .popsection
+
+ENTRY(secondary_startup)
+ /*
+ * Common entry point for secondary CPUs.
+ */
+ mrs x22, midr_el1 // x22=cpuid
+ mov x0, x22
+ bl lookup_processor_type
+ mov x23, x0 // x23=current cpu_table
+ cbz x23, __error_p // invalid processor (x23=0)?
+
+ bl __calc_phys_offset // x24=phys offset
+ pgtbl x25, x26, x24 // x25=TTBR0, x26=TTBR1
+ ldr x12, [x23, #CPU_INFO_SETUP]
+ add x12, x12, x28 // __virt_to_phys
+ blr x12 // initialise processor
+
+ ldr x21, =secondary_data
+ ldr x27, =__secondary_switched // address to jump to after enabling the MMU
+ b __enable_mmu
+ENDPROC(secondary_startup)
+
+ENTRY(__secondary_switched)
+ ldr x0, [x21] // get secondary_data.stack
+ mov sp, x0
+ mov x29, #0
+ b secondary_start_kernel
+ENDPROC(__secondary_switched)
+#endif /* CONFIG_SMP */
+
+/*
+ * Setup common bits before finally enabling the MMU. Essentially this is just
+ * loading the page table pointer and vector base registers.
+ *
+ * On entry to this code, x0 must contain the SCTLR_EL1 value for turning on
+ * the MMU.
+ */
+__enable_mmu:
+ ldr x5, =vectors
+ msr vbar_el1, x5
+ msr ttbr0_el1, x25 // load TTBR0
+ msr ttbr1_el1, x26 // load TTBR1
+ isb
+ b __turn_mmu_on
+ENDPROC(__enable_mmu)
+
+/*
+ * Enable the MMU. This completely changes the structure of the visible memory
+ * space. You will not be able to trace execution through this.
+ *
+ * x0 = system control register
+ * x27 = *virtual* address to jump to upon completion
+ *
+ * other registers depend on the function called upon completion
+ */
+ .align 6
+__turn_mmu_on:
+ msr sctlr_el1, x0
+ isb
+ br x27
+ENDPROC(__turn_mmu_on)
+
+/*
+ * Calculate the start of physical memory.
+ */
+__calc_phys_offset:
+ adr x0, 1f
+ ldp x1, x2, [x0]
+ sub x28, x0, x1 // x28 = PHYS_OFFSET - PAGE_OFFSET
+ add x24, x2, x28 // x24 = PHYS_OFFSET
+ ret
+ENDPROC(__calc_phys_offset)
+
+ .align 3
+1: .quad .
+ .quad PAGE_OFFSET
+
+/*
+ * Macro to populate the PGD for the corresponding block entry in the next
+ * level (tbl) for the given virtual address.
+ *
+ * Preserves: pgd, tbl, virt
+ * Corrupts: tmp1, tmp2
+ */
+ .macro create_pgd_entry, pgd, tbl, virt, tmp1, tmp2
+ lsr \tmp1, \virt, #PGDIR_SHIFT
+ and \tmp1, \tmp1, #PTRS_PER_PGD - 1 // PGD index
+ orr \tmp2, \tbl, #3 // PGD entry table type
+ str \tmp2, [\pgd, \tmp1, lsl #3]
+ .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, idmap=0
+ lsr \phys, \phys, #BLOCK_SHIFT
+ .if \idmap
+ and \start, \phys, #PTRS_PER_PTE - 1 // table index
+ .else
+ lsr \start, \start, #BLOCK_SHIFT
+ and \start, \start, #PTRS_PER_PTE - 1 // table index
+ .endif
+ orr \phys, \flags, \phys, lsl #BLOCK_SHIFT // table entry
+ .ifnc \start,\end
+ lsr \end, \end, #BLOCK_SHIFT
+ and \end, \end, #PTRS_PER_PTE - 1 // table end index
+ .endif
+9999: str \phys, [\tbl, \start, lsl #3] // store the entry
+ .ifnc \start,\end
+ add \start, \start, #1 // next entry
+ add \phys, \phys, #BLOCK_SIZE // next block
+ cmp \start, \end
+ b.ls 9999b
+ .endif
+ .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, including the FDT blob (TTBR1)
+ */
+__create_page_tables:
+ pgtbl x25, x26, x24 // idmap_pg_dir and swapper_pg_dir addresses
+
+ /*
+ * Clear the idmap and swapper page tables.
+ */
+ mov x0, x25
+ add x6, x26, #SWAPPER_DIR_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
+
+ ldr x7, =MM_MMUFLAGS
+
+ /*
+ * Create the identity mapping.
+ */
+ add x0, x25, #PAGE_SIZE // section table address
+ adr x3, __turn_mmu_on // virtual/physical address
+ create_pgd_entry x25, x0, x3, x5, x6
+ create_block_map x0, x7, x3, x5, x5, idmap=1
+
+ /*
+ * Map the kernel image (starting with PHYS_OFFSET).
+ */
+ add x0, x26, #PAGE_SIZE // section table address
+ mov x5, #PAGE_OFFSET
+ create_pgd_entry x26, x0, x5, x3, x6
+ ldr x6, =KERNEL_END - 1
+ mov x3, x24 // phys offset
+ create_block_map x0, x7, x3, x5, x6
+
+ /*
+ * Map the FDT blob (maximum 2MB; must be within 512MB of
+ * PHYS_OFFSET).
+ */
+ mov x3, x21 // FDT phys address
+ and x3, x3, #~((1 << 21) - 1) // 2MB aligned
+ mov x6, #PAGE_OFFSET
+ sub x5, x3, x24 // subtract PHYS_OFFSET
+ tst x5, #~((1 << 29) - 1) // within 512MB?
+ csel x21, xzr, x21, ne // zero the FDT pointer
+ b.ne 1f
+ add x5, x5, x6 // __va(FDT blob)
+ add x6, x5, #1 << 21 // 2MB for the FDT blob
+ sub x6, x6, #1 // inclusive range
+ create_block_map x0, x7, x3, x5, x6
+1:
+ ret
+ENDPROC(__create_page_tables)
+ .ltorg
+
+ .align 3
+ .type __switch_data, %object
+__switch_data:
+ .quad __mmap_switched
+ .quad __data_loc // x4
+ .quad _data // x5
+ .quad __bss_start // x6
+ .quad _end // x7
+ .quad processor_id // x4
+ .quad __fdt_pointer // x5
+ .quad memstart_addr // x6
+ .quad init_thread_union + THREAD_START_SP // sp
+
+/*
+ * The following fragment of code is executed with the MMU on in MMU mode, and
+ * uses absolute addresses; this is not position independent.
+ */
+__mmap_switched:
+ adr x3, __switch_data + 8
+
+ ldp x4, x5, [x3], #16
+ ldp x6, x7, [x3], #16
+ cmp x4, x5 // Copy data segment if needed
+1: ccmp x5, x6, #4, ne
+ b.eq 2f
+ ldr x16, [x4], #8
+ str x16, [x5], #8
+ b 1b
+2:
+1: cmp x6, x7
+ b.hs 2f
+ str xzr, [x6], #8 // Clear BSS
+ b 1b
+2:
+ ldp x4, x5, [x3], #16
+ ldr x6, [x3], #8
+ ldr x16, [x3]
+ mov sp, x16
+ str x22, [x4] // Save processor ID
+ str x21, [x5] // Save FDT pointer
+ str x24, [x6] // Save PHYS_OFFSET
+ mov x29, #0
+ b start_kernel
+ENDPROC(__mmap_switched)
+
+/*
+ * Exception handling. Something went wrong and we can't proceed. We ought to
+ * tell the user, but since we don't have any guarantee that we're even
+ * running on the right architecture, we do virtually nothing.
+ */
+__error_p:
+ENDPROC(__error_p)
+
+__error:
+1: nop
+ b 1b
+ENDPROC(__error)
+
+/*
+ * This function gets the processor ID in w0 and searches the cpu_table[] for
+ * a match. It returns a pointer to the struct cpu_info it found. The
+ * cpu_table[] must end with an empty (all zeros) structure.
+ *
+ * This routine can be called via C code and it needs to work with the MMU
+ * both disabled and enabled (the offset is calculated automatically).
+ */
+ENTRY(lookup_processor_type)
+ adr x1, __lookup_processor_type_data
+ ldp x2, x3, [x1]
+ sub x1, x1, x2 // get offset between VA and PA
+ add x3, x3, x1 // convert VA to PA
+1:
+ ldp w5, w6, [x3] // load cpu_id_val and cpu_id_mask
+ cbz w5, 2f // end of list?
+ and w6, w6, w0
+ cmp w5, w6
+ b.eq 3f
+ add x3, x3, #CPU_INFO_SZ
+ b 1b
+2:
+ mov x3, #0 // unknown processor
+3:
+ mov x0, x3
+ ret
+ENDPROC(lookup_processor_type)
+
+ .align 3
+ .type __lookup_processor_type_data, %object
+__lookup_processor_type_data:
+ .quad .
+ .quad cpu_table
+ .size __lookup_processor_type_data, . - __lookup_processor_type_data
+
+/*
+ * Determine validity of the x21 FDT pointer.
+ * The dtb must be 8-byte aligned and live in the first 512M of memory.
+ */
+__vet_fdt:
+ tst x21, #0x7
+ b.ne 1f
+ cmp x21, x24
+ b.lt 1f
+ mov x0, #(1 << 29)
+ add x0, x0, x24
+ cmp x21, x0
+ b.ge 1f
+ ret
+1:
+ mov x21, #0
+ ret
+ENDPROC(__vet_fdt)
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
new file mode 100644
index 0000000..79f2971
--- /dev/null
+++ b/arch/arm64/kernel/setup.c
@@ -0,0 +1,351 @@
+/*
+ * Based on arch/arm/kernel/setup.c
+ *
+ * Copyright (C) 1995-2001 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * 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/export.h>
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/utsname.h>
+#include <linux/initrd.h>
+#include <linux/console.h>
+#include <linux/bootmem.h>
+#include <linux/seq_file.h>
+#include <linux/screen_info.h>
+#include <linux/init.h>
+#include <linux/kexec.h>
+#include <linux/crash_dump.h>
+#include <linux/root_dev.h>
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/smp.h>
+#include <linux/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/memblock.h>
+#include <linux/of_fdt.h>
+
+#include <asm/cputype.h>
+#include <asm/elf.h>
+#include <asm/cputable.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/traps.h>
+#include <asm/memblock.h>
+
+extern void paging_init(void);
+
+unsigned int processor_id;
+EXPORT_SYMBOL(processor_id);
+
+unsigned int elf_hwcap __read_mostly;
+EXPORT_SYMBOL_GPL(elf_hwcap);
+
+static const char *cpu_name;
+static const char *machine_name;
+phys_addr_t __fdt_pointer __initdata;
+
+/*
+ * Standard memory resources
+ */
+static struct resource mem_res[] = {
+ {
+ .name = "Kernel code",
+ .start = 0,
+ .end = 0,
+ .flags = IORESOURCE_MEM
+ },
+ {
+ .name = "Kernel data",
+ .start = 0,
+ .end = 0,
+ .flags = IORESOURCE_MEM
+ }
+};
+
+#define kernel_code mem_res[0]
+#define kernel_data mem_res[1]
+
+void __init early_print(const char *str, ...)
+{
+ char buf[256];
+ va_list ap;
+
+ va_start(ap, str);
+ vsnprintf(buf, sizeof(buf), str, ap);
+ va_end(ap);
+
+ printk("%s", buf);
+}
+
+static void __init setup_processor(void)
+{
+ struct cpu_info *cpu_info;
+
+ /*
+ * locate processor in the list of supported processor
+ * types. The linker builds this table for us from the
+ * entries in arch/arm/mm/proc.S
+ */
+ cpu_info = lookup_processor_type(read_cpuid_id());
+ if (!cpu_info) {
+ printk("CPU configuration botched (ID %08x), unable to continue.\n",
+ read_cpuid_id());
+ while (1);
+ }
+
+ cpu_name = cpu_info->cpu_name;
+
+ printk("CPU: %s [%08x] revision %d\n",
+ cpu_name, read_cpuid_id(), read_cpuid_id() & 15);
+
+ sprintf(init_utsname()->machine, "aarch64");
+ elf_hwcap = 0;
+
+ cpu_proc_init();
+}
+
+static void __init setup_machine_fdt(phys_addr_t dt_phys)
+{
+ struct boot_param_header *devtree;
+ unsigned long dt_root;
+
+ /* Check we have a non-NULL DT pointer */
+ if (!dt_phys) {
+ early_print("\n"
+ "Error: NULL or invalid device tree blob\n"
+ "The dtb must be 8-byte aligned and passed in the first 512MB of memory\n"
+ "\nPlease check your bootloader.\n");
+
+ while (true)
+ cpu_relax();
+
+ }
+
+ devtree = phys_to_virt(dt_phys);
+
+ /* Check device tree validity */
+ if (be32_to_cpu(devtree->magic) != OF_DT_HEADER) {
+ early_print("\n"
+ "Error: invalid device tree blob at physical address 0x%p (virtual address 0x%p)\n"
+ "Expected 0x%x, found 0x%x\n"
+ "\nPlease check your bootloader.\n",
+ dt_phys, devtree, OF_DT_HEADER,
+ be32_to_cpu(devtree->magic));
+
+ while (true)
+ cpu_relax();
+ }
+
+ initial_boot_params = devtree;
+ dt_root = of_get_flat_dt_root();
+
+ machine_name = of_get_flat_dt_prop(dt_root, "model", NULL);
+ if (!machine_name)
+ machine_name = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+ if (!machine_name)
+ machine_name = "<unknown>";
+ pr_info("Machine: %s\n", machine_name);
+
+ /* Retrieve various information from the /chosen node */
+ of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+ /* Initialize {size,address}-cells info */
+ of_scan_flat_dt(early_init_dt_scan_root, NULL);
+ /* Setup memory, calling early_init_dt_add_memory_arch */
+ of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+}
+
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+ size &= PAGE_MASK;
+ memblock_add(base, size);
+}
+
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+ return __va(memblock_alloc(size, align));
+}
+
+/*
+ * Limit the memory size that was specified via FDT.
+ */
+static int __init early_mem(char *p)
+{
+ phys_addr_t limit;
+
+ if (!p)
+ return 1;
+
+ limit = memparse(p, &p) & PAGE_MASK;
+ pr_notice("Memory limited to %lldMB\n", limit >> 20);
+
+ memblock_enforce_memory_limit(limit);
+
+ return 0;
+}
+early_param("mem", early_mem);
+
+static void __init request_standard_resources(void)
+{
+ struct memblock_region *region;
+ struct resource *res;
+
+ kernel_code.start = virt_to_phys(_text);
+ kernel_code.end = virt_to_phys(_etext - 1);
+ kernel_data.start = virt_to_phys(_sdata);
+ kernel_data.end = virt_to_phys(_end - 1);
+
+ for_each_memblock(memory, region) {
+ res = alloc_bootmem_low(sizeof(*res));
+ res->name = "System RAM";
+ res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
+ res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
+ res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+
+ request_resource(&iomem_resource, res);
+
+ if (kernel_code.start >= res->start &&
+ kernel_code.end <= res->end)
+ request_resource(res, &kernel_code);
+ if (kernel_data.start >= res->start &&
+ kernel_data.end <= res->end)
+ request_resource(res, &kernel_data);
+ }
+}
+
+void __init setup_arch(char **cmdline_p)
+{
+ setup_processor();
+
+ setup_machine_fdt(__fdt_pointer);
+
+ init_mm.start_code = (unsigned long) _text;
+ init_mm.end_code = (unsigned long) _etext;
+ init_mm.end_data = (unsigned long) _edata;
+ init_mm.brk = (unsigned long) _end;
+
+ *cmdline_p = boot_command_line;
+
+ parse_early_param();
+
+ arm64_memblock_init();
+
+ paging_init();
+ request_standard_resources();
+
+ unflatten_device_tree();
+
+#ifdef CONFIG_SMP
+ smp_init_cpus();
+#endif
+
+#ifdef CONFIG_VT
+#if defined(CONFIG_VGA_CONSOLE)
+ conswitchp = &vga_con;
+#elif defined(CONFIG_DUMMY_CONSOLE)
+ conswitchp = &dummy_con;
+#endif
+#endif
+}
+
+static DEFINE_PER_CPU(struct cpu, cpu_data);
+
+static int __init topology_init(void)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ struct cpu *cpu = &per_cpu(cpu_data, i);
+ cpu->hotpluggable = 1;
+ register_cpu(cpu, i);
+ }
+
+ return 0;
+}
+subsys_initcall(topology_init);
+
+static const char *hwcap_str[] = {
+ "fp",
+ "asimd",
+ NULL
+};
+
+static int c_show(struct seq_file *m, void *v)
+{
+ int i;
+
+ seq_printf(m, "Processor\t: %s rev %d (%s)\n",
+ cpu_name, read_cpuid_id() & 15, ELF_PLATFORM);
+
+ for_each_online_cpu(i) {
+ /*
+ * glibc reads /proc/cpuinfo to determine the number of
+ * online processors, looking for lines beginning with
+ * "processor". Give glibc what it expects.
+ */
+#ifdef CONFIG_SMP
+ seq_printf(m, "processor\t: %d\n", i);
+#endif
+ seq_printf(m, "BogoMIPS\t: %lu.%02lu\n\n",
+ loops_per_jiffy / (500000UL/HZ),
+ loops_per_jiffy / (5000UL/HZ) % 100);
+ }
+
+ /* dump out the processor features */
+ seq_puts(m, "Features\t: ");
+
+ for (i = 0; hwcap_str[i]; i++)
+ if (elf_hwcap & (1 << i))
+ seq_printf(m, "%s ", hwcap_str[i]);
+
+ seq_printf(m, "\nCPU implementer\t: 0x%02x\n", read_cpuid_id() >> 24);
+ seq_printf(m, "CPU architecture: AArch64\n");
+ seq_printf(m, "CPU variant\t: 0x%x\n", (read_cpuid_id() >> 20) & 15);
+ seq_printf(m, "CPU part\t: 0x%03x\n", (read_cpuid_id() >> 4) & 0xfff);
+ seq_printf(m, "CPU revision\t: %d\n", read_cpuid_id() & 15);
+
+ seq_puts(m, "\n");
+
+ seq_printf(m, "Hardware\t: %s\n", machine_name);
+
+ return 0;
+}
+
+static void *c_start(struct seq_file *m, loff_t *pos)
+{
+ return *pos < 1 ? (void *)1 : NULL;
+}
+
+static void *c_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ ++*pos;
+ return NULL;
+}
+
+static void c_stop(struct seq_file *m, void *v)
+{
+}
+
+const struct seq_operations cpuinfo_op = {
+ .start = c_start,
+ .next = c_next,
+ .stop = c_stop,
+ .show = c_show
+};
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