On Wed, Feb 19, 2014 at 01:52:09AM +0000, Sebastian Capella wrote: [...]
> diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c > new file mode 100644 > index 0000000..16f406f > --- /dev/null > +++ b/arch/arm/kernel/hibernate.c > @@ -0,0 +1,106 @@ > +/* > + * Hibernation support specific for ARM > + * > + * Derived from work on ARM hibernation support by: > + * > + * Ubuntu project, hibernation support for mach-dove > + * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu) > + * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.) > + * https://lkml.org/lkml/2010/6/18/4 > + * > https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html > + * https://patchwork.kernel.org/patch/96442/ > + * > + * Copyright (C) 2006 Rafael J. Wysocki <r...@sisk.pl> > + * > + * License terms: GNU General Public License (GPL) version 2 > + */ > + > +#include <linux/mm.h> > +#include <linux/suspend.h> > +#include <asm/tlbflush.h> > +#include <asm/cacheflush.h> > +#include <asm/system_misc.h> > +#include <asm/idmap.h> > +#include <asm/suspend.h> > + > +extern const void __nosave_begin, __nosave_end; > + > +int pfn_is_nosave(unsigned long pfn) > +{ > + unsigned long nosave_begin_pfn = > + __pa_symbol(&__nosave_begin) >> PAGE_SHIFT; > + unsigned long nosave_end_pfn = > + PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT; > + > + return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn); > +} > + > +void notrace save_processor_state(void) > +{ > + WARN_ON(num_online_cpus() != 1); > + flush_thread(); Can you explain to me please why we need to call flush_thread() here ? At this point in time syscore_suspend() was already called and CPU peripheral state saved through CPU PM notifiers. > + local_fiq_disable(); To me it looks like we are using this hook to disable fiqs, since it is not done in generic code. > +} > + > +void notrace restore_processor_state(void) > +{ > + local_fiq_enable(); > +} > + > +/* > + * Snapshot kernel memory and reset the system. > + * After resume, the hibernation snapshot is written out. > + */ > +static int notrace __swsusp_arch_save_image(unsigned long unused) > +{ > + int ret; > + > + ret = swsusp_save(); > + if (ret == 0) > + soft_restart(virt_to_phys(cpu_resume)); By the time the suspend finisher (ie this function) is run, the processor state has been saved and I think that's all you have to do, function can just return after calling swsusp_save(), unless I am missing something. I do not understand why a soft_restart is required here. On a side note, finisher is called with irqs disabled so, since you added a function for soft restart noirq, it should be used, if needed, but I have to understand why in the first place. > + return ret; > +} > + > +/* > + * Save the current CPU state before suspend / poweroff. > + */ > +int notrace swsusp_arch_suspend(void) > +{ > + return cpu_suspend(0, __swsusp_arch_save_image); If the goal of soft_restart is to return 0 on success from this call, you can still do that without requiring a soft_restart in the first place. IIUC all you want to achieve is to save processor context registers so that when you resume from image you will actually return from here. > +} > + > +/* > + * The framework loads the hibernation image into a linked list anchored > + * at restore_pblist, for swsusp_arch_resume() to copy back to the proper > + * destinations. > + * > + * To make this work if resume is triggered from initramfs, the > + * pagetables need to be switched to allow writes to kernel mem. Can you elaborate a bit more on this please ? > + */ > +static void notrace __swsusp_arch_restore_image(void *unused) > +{ > + struct pbe *pbe; > + > + cpu_switch_mm(idmap_pgd, &init_mm); Same here, thanks. > + for (pbe = restore_pblist; pbe; pbe = pbe->next) > + copy_page(pbe->orig_address, pbe->address); > + > + soft_restart_noirq(virt_to_phys(cpu_resume)); This soft_restart is justified so that you resume from the context saved when creating the image. > +} > + > +static u8 __swsusp_resume_stk[PAGE_SIZE/2] __nosavedata; > + > +/* > + * Resume from the hibernation image. > + * Due to the kernel heap / data restore, stack contents change underneath > + * and that would make function calls impossible; switch to a temporary > + * stack within the nosave region to avoid that problem. > + */ > +int __naked swsusp_arch_resume(void) > +{ > + extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); Ok, a function with attribute __naked that still calls C functions, is attr __naked really needed here ? > + cpu_init(); /* get a clean PSR */ cpu_init is called in the cpu_resume path, why is this call needed here ? Thanks, Lorenzo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
