调用函数 safe_svcmode_maskall 确保 CPU 处于 SVC 模式，并且关闭了所有的中断。safe_svcmode_maskall 定义在文件 arch/arm/include/asm/assembler.h 中。
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ENTRY(stext) ARM_BE8(setend be ) @ ensure we are in BE8 mode
THUMB( badr r9, 1f ) @ Kernel is always entered in ARM. THUMB( bx r9 ) @ If this is a Thumb-2 kernel, THUMB( .thumb ) @ switch to Thumb now. THUMB(1: )
#ifdef CONFIG_ARM_VIRT_EXT bl __hyp_stub_install #endif @ ensure svc mode and all interrupts masked safe_svcmode_maskall r9
/* * These use large bootmem allocations and must precede * kmem_cache_init() */ setup_log_buf(0); pidhash_init(); vfs_caches_init_early(); sort_main_extable(); trap_init(); mm_init();
/* * Set up the scheduler prior starting any interrupts (such as the * timer interrupt). Full topology setup happens at smp_init() * time - but meanwhile we still have a functioning scheduler. */ sched_init(); /* * Disable preemption - early bootup scheduling is extremely * fragile until we cpu_idle() for the first time. */ preempt_disable(); if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n")) local_irq_disable(); idr_init_cache(); rcu_init();
/* trace_printk() and trace points may be used after this */ trace_init();
/* * HACK ALERT! This is early. We're enabling the console before * we've done PCI setups etc, and console_init() must be aware of * this. But we do want output early, in case something goes wrong. */ console_init(); if (panic_later) panic("Too many boot %s vars at `%s'", panic_later, panic_param);
lockdep_info();
/* * Need to run this when irqs are enabled, because it wants * to self-test [hard/soft]-irqs on/off lock inversion bugs * too: */ locking_selftest();
#ifdef CONFIG_BLK_DEV_INITRD if (initrd_start && !initrd_below_start_ok && page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) { pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n", page_to_pfn(virt_to_page((void *)initrd_start)), min_low_pfn); initrd_start = 0; } #endif page_ext_init(); debug_objects_mem_init(); kmemleak_init(); setup_per_cpu_pageset(); numa_policy_init(); if (late_time_init) late_time_init(); sched_clock_init(); calibrate_delay(); pidmap_init(); anon_vma_init(); acpi_early_init(); #ifdef CONFIG_X86 if (efi_enabled(EFI_RUNTIME_SERVICES)) efi_enter_virtual_mode(); #endif #ifdef CONFIG_X86_ESPFIX64 /* Should be run before the first non-init thread is created */ init_espfix_bsp(); #endif thread_stack_cache_init(); cred_init(); fork_init(); proc_caches_init(); buffer_init(); key_init(); security_init(); dbg_late_init(); vfs_caches_init(); signals_init(); /* rootfs populating might need page-writeback */ page_writeback_init(); proc_root_init(); nsfs_init(); cpuset_init(); cgroup_init(); taskstats_init_early(); delayacct_init();
check_bugs();
acpi_subsystem_init(); sfi_init_late();
if (efi_enabled(EFI_RUNTIME_SERVICES)) { efi_late_init(); efi_free_boot_services(); }
ftrace_init();
/* Do the rest non-__init'ed, we're now alive */ rest_init();
static noinline void __ref rest_init(void) { int pid;
rcu_scheduler_starting(); /* * We need to spawn init first so that it obtains pid 1, however * the init task will end up wanting to create kthreads, which, if * we schedule it before we create kthreadd, will OOPS. */ kernel_thread(kernel_init, NULL, CLONE_FS); numa_default_policy(); pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); rcu_read_lock(); kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns); rcu_read_unlock(); complete(&kthreadd_done);
/* * The boot idle thread must execute schedule() * at least once to get things moving: */ init_idle_bootup_task(current); schedule_preempt_disabled(); /* Call into cpu_idle with preempt disabled */ cpu_startup_entry(CPUHP_ONLINE); }
static int __ref kernel_init(void *unused) { int ret;
kernel_init_freeable(); /* need to finish all async __init code before freeing the memory */ async_synchronize_full(); free_initmem(); mark_readonly(); system_state = SYSTEM_RUNNING; numa_default_policy();
rcu_end_inkernel_boot();
if (ramdisk_execute_command) { ret = run_init_process(ramdisk_execute_command); if (!ret) return 0; pr_err("Failed to execute %s (error %d)\n", ramdisk_execute_command, ret); }
/* * We try each of these until one succeeds. * * The Bourne shell can be used instead of init if we are * trying to recover a really broken machine. */ if (execute_command) { ret = run_init_process(execute_command); if (!ret) return 0; panic("Requested init %s failed (error %d).", execute_command, ret); } if (!try_to_run_init_process("/sbin/init") || !try_to_run_init_process("/etc/init") || !try_to_run_init_process("/bin/init") || !try_to_run_init_process("/bin/sh")) return 0;
panic("No working init found. Try passing init= option to kernel. " "See Linux Documentation/init.txt for guidance."); }
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