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.)
- Copyright (C) 2006 Rafael J. Wysocki rjw@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