From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> To: Sebastian Capella <sebastian.capella@linaro.org> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>, "linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Russ Dill <Russ.Dill@ti.com>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Russell King <linux@arm.linux.org.uk>, Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>, Nicolas Pitre <nico@linaro.org>, Santosh Shilimkar <santosh.shilimkar@ti.com>, Will Deacon <Will.Deacon@arm.com>, Cyril Chemparathy <cyril@ti.com>, Jonathan Austin <Jonathan.Austin@arm.com>, Catalin Marinas <Catalin.Marinas@arm.com>, Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>, Stephen Boyd <sboyd@codeaurora.org> Subject: Re: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Date: Wed, 19 Feb 2014 16:12:54 +0000 [thread overview] Message-ID: <20140219161254.GB19343@e102568-lin.cambridge.arm.com> (raw) In-Reply-To: <1392774729-3235-4-git-send-email-sebastian.capella@linaro.org> 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 <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
WARNING: multiple messages have this Message-ID (diff)
From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Date: Wed, 19 Feb 2014 16:12:54 +0000 [thread overview] Message-ID: <20140219161254.GB19343@e102568-lin.cambridge.arm.com> (raw) In-Reply-To: <1392774729-3235-4-git-send-email-sebastian.capella@linaro.org> 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 <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
next prev parent reply other threads:[~2014-02-19 16:13 UTC|newest] Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-02-19 1:52 [PATCH RFC v1 0/3] hibernation support on ARM Sebastian Capella 2014-02-19 1:52 ` Sebastian Capella 2014-02-19 1:52 ` [PATCH RFC v1 1/3] ARM: Add irq disabled version of soft_restart Sebastian Capella 2014-02-19 1:52 ` Sebastian Capella 2014-02-22 10:26 ` Russell King - ARM Linux 2014-02-22 10:26 ` Russell King - ARM Linux 2014-02-24 23:13 ` Sebastian Capella 2014-02-24 23:13 ` Sebastian Capella 2014-02-25 0:22 ` Sebastian Capella 2014-02-25 0:22 ` Sebastian Capella 2014-02-25 7:56 ` Russ Dill 2014-02-25 7:56 ` Russ Dill 2014-02-25 7:56 ` Russ Dill 2014-02-25 10:27 ` Thomas Gleixner 2014-02-25 10:27 ` Thomas Gleixner 2014-02-25 17:15 ` Russ Dill 2014-02-25 17:15 ` Russ Dill 2014-02-25 17:15 ` Russ Dill 2014-02-25 23:24 ` Sebastian Capella 2014-02-25 23:24 ` Sebastian Capella 2014-02-19 1:52 ` [PATCH RFC v1 2/3] Fix hibernation restore hang in freeze_processes Sebastian Capella 2014-02-19 1:52 ` Sebastian Capella 2014-02-24 7:09 ` Ming Lei 2014-02-24 7:09 ` Ming Lei 2014-02-19 1:52 ` [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Sebastian Capella 2014-02-19 1:52 ` Sebastian Capella 2014-02-19 16:12 ` Lorenzo Pieralisi [this message] 2014-02-19 16:12 ` Lorenzo Pieralisi 2014-02-19 16:12 ` Lorenzo Pieralisi 2014-02-19 19:10 ` Russ Dill 2014-02-19 19:10 ` Russ Dill 2014-02-19 19:10 ` Russ Dill 2014-02-20 10:37 ` Lorenzo Pieralisi 2014-02-20 10:37 ` Lorenzo Pieralisi 2014-02-20 10:37 ` Lorenzo Pieralisi 2014-02-19 19:33 ` Sebastian Capella 2014-02-19 19:33 ` Sebastian Capella 2014-02-20 16:27 ` Lorenzo Pieralisi 2014-02-20 16:27 ` Lorenzo Pieralisi 2014-02-20 16:27 ` Lorenzo Pieralisi 2014-02-21 18:39 ` Sebastian Capella 2014-02-21 18:39 ` Sebastian Capella 2014-02-21 23:59 ` Sebastian Capella 2014-02-21 23:59 ` Sebastian Capella 2014-02-22 4:37 ` Sebastian Capella 2014-02-22 4:37 ` Sebastian Capella 2014-02-22 6:46 ` Russ Dill 2014-02-22 6:46 ` Russ Dill 2014-02-22 6:46 ` Russ Dill 2014-02-22 10:22 ` Russell King - ARM Linux 2014-02-22 10:22 ` Russell King - ARM Linux 2014-02-22 10:22 ` Russell King - ARM Linux 2014-02-22 10:16 ` Russell King - ARM Linux 2014-02-22 10:16 ` Russell King - ARM Linux 2014-02-22 10:16 ` Russell King - ARM Linux 2014-02-22 12:13 ` Lorenzo Pieralisi 2014-02-22 12:13 ` Lorenzo Pieralisi 2014-02-22 12:13 ` Lorenzo Pieralisi 2014-02-22 22:30 ` Pavel Machek 2014-02-22 22:30 ` Pavel Machek 2014-02-22 22:30 ` Pavel Machek 2014-02-21 1:01 ` Sebastian Capella 2014-02-21 1:01 ` Sebastian Capella 2014-02-22 10:38 ` Russell King - ARM Linux 2014-02-22 10:38 ` Russell King - ARM Linux 2014-02-22 10:38 ` Russell King - ARM Linux 2014-02-22 12:09 ` Lorenzo Pieralisi 2014-02-22 12:09 ` Lorenzo Pieralisi 2014-02-22 12:09 ` Lorenzo Pieralisi 2014-02-22 22:28 ` Pavel Machek 2014-02-22 22:28 ` Pavel Machek 2014-02-22 22:28 ` Pavel Machek 2014-02-23 19:52 ` Sebastian Capella 2014-02-23 19:52 ` Sebastian Capella 2014-02-23 19:52 ` Sebastian Capella 2014-02-23 20:02 ` Sebastian Capella 2014-02-23 20:02 ` Sebastian Capella 2014-02-23 20:02 ` Sebastian Capella 2014-02-25 11:32 ` Lorenzo Pieralisi 2014-02-25 11:32 ` Lorenzo Pieralisi 2014-02-25 11:32 ` Lorenzo Pieralisi 2014-02-25 17:55 ` Sebastian Capella 2014-02-25 17:55 ` Sebastian Capella 2014-02-26 10:24 ` Lorenzo Pieralisi 2014-02-26 10:24 ` Lorenzo Pieralisi 2014-02-26 10:24 ` Lorenzo Pieralisi 2014-02-26 17:50 ` Sebastian Capella 2014-02-26 17:50 ` Sebastian Capella 2014-02-26 19:03 ` Lorenzo Pieralisi 2014-02-26 19:03 ` Lorenzo Pieralisi 2014-02-26 19:03 ` Lorenzo Pieralisi
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