/* * cpu_suspend * * arg: argument to pass to the finisher function * fn: finisher function pointer * */ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) { int ret; unsigned long flags; /* * From this point debug exceptions are disabled to prevent * updates to mdscr register (saved and restored along with * general purpose registers) from kernel debuggers. */ local_dbg_save(flags); /* * Function graph tracer state gets incosistent when the kernel * calls functions that never return (aka suspend finishers) hence * disable graph tracing during their execution. */ pause_graph_tracing(); /* * mm context saved on the stack, it will be restored when * the cpu comes out of reset through the identity mapped * page tables, so that the thread address space is properly * set-up on function return. */ ret = __cpu_suspend_enter(arg, fn); if (ret == 0) { /* * We are resuming from reset with the idmap active in TTBR0_EL1. * We must uninstall the idmap and restore the expected MMU * state before we can possibly return to userspace. */ cpu_uninstall_idmap(); /* * Restore per-cpu offset before any kernel * subsystem relying on it has a chance to run. */ set_my_cpu_offset(per_cpu_offset(smp_processor_id())); /* * Restore HW breakpoint registers to sane values * before debug exceptions are possibly reenabled * through local_dbg_restore. */ if (hw_breakpoint_restore) hw_breakpoint_restore(NULL); } unpause_graph_tracing(); /* * Restore pstate flags. OS lock and mdscr have been already * restored, so from this point onwards, debugging is fully * renabled if it was enabled when core started shutdown. */ local_dbg_restore(flags); return ret; }
/* * __cpu_suspend * * arg: argument to pass to the finisher function * fn: finisher function pointer * */ int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) { struct mm_struct *mm = current->active_mm; int ret; unsigned long flags; /* * From this point debug exceptions are disabled to prevent * updates to mdscr register (saved and restored along with * general purpose registers) from kernel debuggers. */ local_dbg_save(flags); /* * Function graph tracer state gets incosistent when the kernel * calls functions that never return (aka suspend finishers) hence * disable graph tracing during their execution. */ pause_graph_tracing(); /* * mm context saved on the stack, it will be restored when * the cpu comes out of reset through the identity mapped * page tables, so that the thread address space is properly * set-up on function return. */ ret = __cpu_suspend_enter(arg, fn); if (ret == 0) { /* * We are resuming from reset with TTBR0_EL1 set to the * idmap to enable the MMU; restore the active_mm mappings in * TTBR0_EL1 unless the active_mm == &init_mm, in which case * the thread entered __cpu_suspend with TTBR0_EL1 set to * reserved TTBR0 page tables and should be restored as such. */ if (mm == &init_mm) cpu_set_reserved_ttbr0(); else cpu_switch_mm(mm->pgd, mm); flush_tlb_all(); /* * Restore per-cpu offset before any kernel * subsystem relying on it has a chance to run. */ set_my_cpu_offset(per_cpu_offset(smp_processor_id())); /* * Restore HW breakpoint registers to sane values * before debug exceptions are possibly reenabled * through local_dbg_restore. */ if (hw_breakpoint_restore) hw_breakpoint_restore(NULL); } unpause_graph_tracing(); /* * Restore pstate flags. OS lock and mdscr have been already * restored, so from this point onwards, debugging is fully * renabled if it was enabled when core started shutdown. */ local_dbg_restore(flags); return ret; }