1 #include <linux/ftrace.h> 2 #include <linux/percpu.h> 3 #include <linux/slab.h> 4 #include <asm/cacheflush.h> 5 #include <asm/debug-monitors.h> 6 #include <asm/pgtable.h> 7 #include <asm/memory.h> 8 #include <asm/mmu_context.h> 9 #include <asm/smp_plat.h> 10 #include <asm/suspend.h> 11 #include <asm/tlbflush.h> 12 13 extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long)); 14 /* 15 * This is called by __cpu_suspend_enter() to save the state, and do whatever 16 * flushing is required to ensure that when the CPU goes to sleep we have 17 * the necessary data available when the caches are not searched. 18 * 19 * ptr: CPU context virtual address 20 * save_ptr: address of the location where the context physical address 21 * must be saved 22 */ 23 void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr, 24 phys_addr_t *save_ptr) 25 { 26 *save_ptr = virt_to_phys(ptr); 27 28 cpu_do_suspend(ptr); 29 /* 30 * Only flush the context that must be retrieved with the MMU 31 * off. VA primitives ensure the flush is applied to all 32 * cache levels so context is pushed to DRAM. 33 */ 34 __flush_dcache_area(ptr, sizeof(*ptr)); 35 __flush_dcache_area(save_ptr, sizeof(*save_ptr)); 36 } 37 38 /* 39 * This hook is provided so that cpu_suspend code can restore HW 40 * breakpoints as early as possible in the resume path, before reenabling 41 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 42 * time the notifier runs debug exceptions might have been enabled already, 43 * with HW breakpoints registers content still in an unknown state. 44 */ 45 static void (*hw_breakpoint_restore)(void *); 46 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)) 47 { 48 /* Prevent multiple restore hook initializations */ 49 if (WARN_ON(hw_breakpoint_restore)) 50 return; 51 hw_breakpoint_restore = hw_bp_restore; 52 } 53 54 /* 55 * cpu_suspend 56 * 57 * arg: argument to pass to the finisher function 58 * fn: finisher function pointer 59 * 60 */ 61 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 62 { 63 int ret; 64 unsigned long flags; 65 66 /* 67 * From this point debug exceptions are disabled to prevent 68 * updates to mdscr register (saved and restored along with 69 * general purpose registers) from kernel debuggers. 70 */ 71 local_dbg_save(flags); 72 73 /* 74 * Function graph tracer state gets incosistent when the kernel 75 * calls functions that never return (aka suspend finishers) hence 76 * disable graph tracing during their execution. 77 */ 78 pause_graph_tracing(); 79 80 /* 81 * mm context saved on the stack, it will be restored when 82 * the cpu comes out of reset through the identity mapped 83 * page tables, so that the thread address space is properly 84 * set-up on function return. 85 */ 86 ret = __cpu_suspend_enter(arg, fn); 87 if (ret == 0) { 88 /* 89 * We are resuming from reset with the idmap active in TTBR0_EL1. 90 * We must uninstall the idmap and restore the expected MMU 91 * state before we can possibly return to userspace. 92 */ 93 cpu_uninstall_idmap(); 94 95 /* 96 * Restore per-cpu offset before any kernel 97 * subsystem relying on it has a chance to run. 98 */ 99 set_my_cpu_offset(per_cpu_offset(smp_processor_id())); 100 101 /* 102 * Restore HW breakpoint registers to sane values 103 * before debug exceptions are possibly reenabled 104 * through local_dbg_restore. 105 */ 106 if (hw_breakpoint_restore) 107 hw_breakpoint_restore(NULL); 108 } 109 110 unpause_graph_tracing(); 111 112 /* 113 * Restore pstate flags. OS lock and mdscr have been already 114 * restored, so from this point onwards, debugging is fully 115 * renabled if it was enabled when core started shutdown. 116 */ 117 local_dbg_restore(flags); 118 119 return ret; 120 } 121 122 struct sleep_save_sp sleep_save_sp; 123 124 static int __init cpu_suspend_init(void) 125 { 126 void *ctx_ptr; 127 128 /* ctx_ptr is an array of physical addresses */ 129 ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL); 130 131 if (WARN_ON(!ctx_ptr)) 132 return -ENOMEM; 133 134 sleep_save_sp.save_ptr_stash = ctx_ptr; 135 sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr); 136 __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp)); 137 138 return 0; 139 } 140 early_initcall(cpu_suspend_init); 141