Patches adding support for hibernation on ARM
- ARM hibernation / suspend-to-disk
- Change soft_restart to use non-tracing raw_local_irq_disable
Patches based on v3.13 tag, verified hibernation on beaglebone black on a
branch based on 3.13 merged with initial omap support from Russ Dill which
can be found here (includes v1 patchset):
http://git.linaro.org/git-ro/people/sebastian.capella/linux.git hibernation_3.13_russMerge
[PATCH v6 1/2] ARM: avoid tracers in soft_restart
arch/arm/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Use raw_local_irq_disable in place of local_irq_disable to avoid
infinite abort recursion while tracing. (unchanged since v3)
[PATCH v6 2/2] ARM hibernation / suspend-to-disk
arch/arm/include/asm/memory.h | 1 +
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/hibernate.c | 113 +++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/Kconfig | 5 ++
include/linux/suspend.h | 2 +
5 files changed, 122 insertions(+)
Adds support for ARM based hibernation
Additional notes:
-----------------
There are two checkpatch warnings added by this patch. These follow
behavior in existing hibernation implementations on other platforms.
WARNING: externs should be avoided in .c files
#116: FILE: arch/arm/kernel/hibernate.c:26:
+extern const void __nosave_begin, __nosave_end;
This extern is picking up the linker nosave region definitions, only
used in hibernate. Follows same extern line used mips, powerpc, s390,
sh, sparc, x86 & unicore32
WARNING: externs should be avoided in .c files
#199: FILE: arch/arm/kernel/hibernate.c:109:
+extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
This extern is used in the arch/arm/ in hibernate, process and bL_switcher
Changes in v6:
--------------
* Simplify static variable names
Changes in v5:
--------------
* Fixed checkpatch warning on trailing whitespace
Changes in v4:
--------------
* updated comment for soft_restart with review feedback
* dropped freeze_processes patch which was queued separately
to 3.14 by Rafael Wysocki:
https://lkml.org/lkml/2014/2/25/683
Changes in v3:
--------------
* added comment to use of soft_restart
* drop irq disable soft_restart patch
* add patch to avoid tracers in soft_restart by using raw_local_irq_*
Changes in v2:
--------------
* Removed unneeded flush_thread, use of __naked and cpu_init.
* dropped Cyril Chemparathy <[email protected]> from Cc: list as
emails are bouncing.
Thanks,
Sebastian Capella
Use of tracers in local_irq_disable is causes recursive aborts when
called with irqs disabled and using a temporary stack (hibernation).
Replace local_irq_disable with raw_local_irq_disable instead to
avoid tracers.
Signed-off-by: Sebastian Capella <[email protected]>
Cc: Russell King <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: Lorenzo Pieralisi <[email protected]>
---
arch/arm/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 92f7b15..f58b723 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -100,7 +100,7 @@ void soft_restart(unsigned long addr)
u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
/* Disable interrupts first */
- local_irq_disable();
+ raw_local_irq_disable();
local_fiq_disable();
/* Disable the L2 if we're the last man standing. */
--
1.7.9.5
From: Russ Dill <[email protected]>
Enable hibernation for ARM architectures and provide ARM
architecture specific calls used during hibernation.
The swsusp hibernation framework depends on the
platform first having functional suspend/resume.
Then, in order to enable hibernation on a given platform, a
platform_hibernation_ops structure may need to be registered with
the system in order to save/restore any SoC-specific / cpu specific
state needing (re)init over a suspend-to-disk/resume-from-disk cycle.
For example:
- "secure" SoCs that have different sets of control registers
and/or different CR reg access patterns.
- SoCs with L2 caches as the activation sequence there is
SoC-dependent; a full off-on cycle for L2 is not done
by the hibernation support code.
- SoCs requiring steps on wakeup _before_ the "generic" parts
done by cpu_suspend / cpu_resume can work correctly.
- SoCs having persistent state which is maintained during suspend
and resume, but will be lost during the power off cycle after
suspend-to-disk.
This is a rebase/rework of Frank Hofmann's v5 hibernation patchset.
Acked-by: Russ Dill <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Sebastian Capella <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Cc: Russell King <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Jonathan Austin <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: "Uwe Kleine-König" <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Lorenzo Pieralisi <[email protected]>
---
arch/arm/include/asm/memory.h | 1 +
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/hibernate.c | 113 +++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/Kconfig | 5 ++
include/linux/suspend.h | 2 +
5 files changed, 122 insertions(+)
create mode 100644 arch/arm/kernel/hibernate.c
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 8756e4b..1079ea8 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -291,6 +291,7 @@ static inline void *phys_to_virt(phys_addr_t x)
*/
#define __pa(x) __virt_to_phys((unsigned long)(x))
#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
+#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
extern phys_addr_t (*arch_virt_to_idmap)(unsigned long x);
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index a30fc9b..8afa848 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_ARTHUR) += arthur.o
obj-$(CONFIG_ISA_DMA) += dma-isa.o
obj-$(CONFIG_PCI) += bios32.o isa.o
obj-$(CONFIG_ARM_CPU_SUSPEND) += sleep.o suspend.o
+obj-$(CONFIG_HIBERNATION) += hibernate.o
obj-$(CONFIG_SMP) += smp.o
ifdef CONFIG_MMU
obj-$(CONFIG_SMP) += smp_tlb.o
diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c
new file mode 100644
index 0000000..a41e0e3
--- /dev/null
+++ b/arch/arm/kernel/hibernate.c
@@ -0,0 +1,113 @@
+/*
+ * 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 <[email protected]>
+ *
+ * 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);
+ local_fiq_disable();
+}
+
+void notrace restore_processor_state(void)
+{
+ local_fiq_enable();
+}
+
+/*
+ * Snapshot kernel memory and reset the system.
+ *
+ * swsusp_save() is executed in the suspend finisher so that the CPU
+ * context pointer and memory are part of the saved image, which is
+ * required by the resume kernel image to restart execution from
+ * swsusp_arch_suspend().
+ *
+ * soft_restart is not technically needed, but is used to get success
+ * returned from cpu_suspend.
+ *
+ * When soft reboot completes, the hibernation snapshot is written out.
+ */
+static int notrace arch_save_image(unsigned long unused)
+{
+ int ret;
+
+ ret = swsusp_save();
+ if (ret == 0)
+ soft_restart(virt_to_phys(cpu_resume));
+ return ret;
+}
+
+/*
+ * Save the current CPU state before suspend / poweroff.
+ */
+int notrace swsusp_arch_suspend(void)
+{
+ return cpu_suspend(0, arch_save_image);
+}
+
+/*
+ * 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.
+ */
+static void notrace arch_restore_image(void *unused)
+{
+ struct pbe *pbe;
+
+ cpu_switch_mm(idmap_pgd, &init_mm);
+ for (pbe = restore_pblist; pbe; pbe = pbe->next)
+ copy_page(pbe->orig_address, pbe->address);
+
+ soft_restart(virt_to_phys(cpu_resume));
+}
+
+static u8 resume_stack[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 swsusp_arch_resume(void)
+{
+ extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
+ call_with_stack(arch_restore_image, 0,
+ resume_stack + sizeof(resume_stack));
+ return 0;
+}
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 1f8fed9..83707702 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -611,6 +611,11 @@ config CPU_USE_DOMAINS
config IO_36
bool
+config ARCH_HIBERNATION_POSSIBLE
+ bool
+ depends on MMU
+ default y if CPU_ARM920T || CPU_ARM926T || CPU_SA1100 || CPU_XSCALE || CPU_XSC3 || CPU_V6 || CPU_V6K || CPU_V7
+
comment "Processor Features"
config ARM_LPAE
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index f73cabf..38bbf95 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -320,6 +320,8 @@ extern unsigned long get_safe_page(gfp_t gfp_mask);
extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
extern int hibernate(void);
extern bool system_entering_hibernation(void);
+asmlinkage int swsusp_save(void);
+extern struct pbe *restore_pblist;
#else /* CONFIG_HIBERNATION */
static inline void register_nosave_region(unsigned long b, unsigned long e) {}
static inline void register_nosave_region_late(unsigned long b, unsigned long e) {}
--
1.7.9.5
On 02/27/14 15:57, Sebastian Capella wrote:
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 8756e4b..1079ea8 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -291,6 +291,7 @@ static inline void *phys_to_virt(phys_addr_t x)
> */
> #define __pa(x) __virt_to_phys((unsigned long)(x))
> #define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
> +#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
Just curious, is there a reason for the RELOC_HIDE() here? Or
__pa_symbol() for that matter? It looks like only x86 uses this on the
__nosave_{begin,end} symbol. Maybe it's copy-pasta?
I also wonder if anyone has thought about making a __weak
pfn_is_nosave() function so that architectures don't need to implement
the same thing every time. Consolidating those shouldn't be part of this
patch though.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
On 02/27/2014 04:09 PM, Stephen Boyd wrote:
> On 02/27/14 15:57, Sebastian Capella wrote:
>> diff --git a/arch/arm/include/asm/memory.h
>> b/arch/arm/include/asm/memory.h index 8756e4b..1079ea8 100644 ---
>> a/arch/arm/include/asm/memory.h +++
>> b/arch/arm/include/asm/memory.h @@ -291,6 +291,7 @@ static inline
>> void *phys_to_virt(phys_addr_t x) */ #define __pa(x)
>> __virt_to_phys((unsigned long)(x)) #define __va(x) ((void
>> *)__phys_to_virt((phys_addr_t)(x))) +#define __pa_symbol(x)
>> __pa(RELOC_HIDE((unsigned long)(x), 0))
>
> Just curious, is there a reason for the RELOC_HIDE() here? Or
> __pa_symbol() for that matter? It looks like only x86 uses this on
> the __nosave_{begin,end} symbol. Maybe it's copy-pasta?
>From my understanding this needs to stick around so long as gcc 3.x is
supported (did it get dropped yet?) on ARM Linux since it doesn't
support -fno-strict-overflow.
> I also wonder if anyone has thought about making a __weak
> pfn_is_nosave() function so that architectures don't need to
> implement the same thing every time. Consolidating those shouldn't
> be part of this patch though.
>
Yes, I think just a couple of the architectures do anything besides
checking if the address falls within the nosave section.
On 02/27/14 17:47, Russ Dill wrote:
> On 02/27/2014 04:09 PM, Stephen Boyd wrote:
>> On 02/27/14 15:57, Sebastian Capella wrote:
>>> diff --git a/arch/arm/include/asm/memory.h
>>> b/arch/arm/include/asm/memory.h index 8756e4b..1079ea8 100644 ---
>>> a/arch/arm/include/asm/memory.h +++
>>> b/arch/arm/include/asm/memory.h @@ -291,6 +291,7 @@ static inline
>>> void *phys_to_virt(phys_addr_t x) */ #define __pa(x)
>>> __virt_to_phys((unsigned long)(x)) #define __va(x) ((void
>>> *)__phys_to_virt((phys_addr_t)(x))) +#define __pa_symbol(x)
>>> __pa(RELOC_HIDE((unsigned long)(x), 0))
>> Just curious, is there a reason for the RELOC_HIDE() here? Or
>> __pa_symbol() for that matter? It looks like only x86 uses this on
>> the __nosave_{begin,end} symbol. Maybe it's copy-pasta?
> From my understanding this needs to stick around so long as gcc 3.x is
> supported (did it get dropped yet?) on ARM Linux since it doesn't
> support -fno-strict-overflow.
I don't think it's been dropped yet but I wonder if anyone has tried
recent kernels with such a compiler?
Would the usage of &__pv_table_begin in arch/arm/mm/mmu.c also need the
same treatment? Or the tagtable loop in atags_parse.c? Do the other
architectures also need to be fixed? That link Sebastian points to says
that ppc originally needed it but pfn_is_nosave() on ppc doesn't use
RELOC_HIDE anywhere in their __pa() macro from what I can tell.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
On Thu, Feb 27, 2014 at 11:57:58PM +0000, Sebastian Capella wrote:
[...]
> diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c
> new file mode 100644
> index 0000000..a41e0e3
> --- /dev/null
> +++ b/arch/arm/kernel/hibernate.c
> @@ -0,0 +1,113 @@
> +/*
> + * 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 <[email protected]>
> + *
> + * 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>
You can drop tlbflush.h and cacheflush.h, they do not seem to be needed.
> +#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);
> + local_fiq_disable();
> +}
> +
> +void notrace restore_processor_state(void)
> +{
> + local_fiq_enable();
> +}
> +
> +/*
> + * Snapshot kernel memory and reset the system.
> + *
> + * swsusp_save() is executed in the suspend finisher so that the CPU
> + * context pointer and memory are part of the saved image, which is
> + * required by the resume kernel image to restart execution from
> + * swsusp_arch_suspend().
> + *
> + * soft_restart is not technically needed, but is used to get success
> + * returned from cpu_suspend.
> + *
> + * When soft reboot completes, the hibernation snapshot is written out.
> + */
> +static int notrace arch_save_image(unsigned long unused)
> +{
> + int ret;
> +
> + ret = swsusp_save();
> + if (ret == 0)
> + soft_restart(virt_to_phys(cpu_resume));
> + return ret;
> +}
> +
> +/*
> + * Save the current CPU state before suspend / poweroff.
> + */
> +int notrace swsusp_arch_suspend(void)
> +{
> + return cpu_suspend(0, arch_save_image);
> +}
> +
> +/*
> + * 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.
> + */
Comment above needs updating. We are switching page tables to a set of
page tables that are certain to live at the same location in the older
kernel, that's the only reason, as we discussed. soft_restart will make
sure (again) to switch to 1:1 page tables so that we can call cpu_resume
with the MMU off.
> +static void notrace arch_restore_image(void *unused)
> +{
> + struct pbe *pbe;
> +
> + cpu_switch_mm(idmap_pgd, &init_mm);
> + for (pbe = restore_pblist; pbe; pbe = pbe->next)
> + copy_page(pbe->orig_address, pbe->address);
> +
> + soft_restart(virt_to_phys(cpu_resume));
> +}
> +
> +static u8 resume_stack[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 swsusp_arch_resume(void)
> +{
> + extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
> + call_with_stack(arch_restore_image, 0,
> + resume_stack + sizeof(resume_stack));
This does not guarantee your stack is 8-byte aligned, that's not AAPCS
compliant and might buy you trouble.
Either you align the stack or you align the pointer you are passing.
Please have a look at kernel/process.c
Thanks,
Lorenzo
On Thu, Feb 27, 2014 at 06:19:49PM -0800, Stephen Boyd wrote:
> On 02/27/14 17:47, Russ Dill wrote:
> > On 02/27/2014 04:09 PM, Stephen Boyd wrote:
> >> On 02/27/14 15:57, Sebastian Capella wrote:
> >>> diff --git a/arch/arm/include/asm/memory.h
> >>> b/arch/arm/include/asm/memory.h index 8756e4b..1079ea8 100644 ---
> >>> a/arch/arm/include/asm/memory.h +++
> >>> b/arch/arm/include/asm/memory.h @@ -291,6 +291,7 @@ static inline
> >>> void *phys_to_virt(phys_addr_t x) */ #define __pa(x)
> >>> __virt_to_phys((unsigned long)(x)) #define __va(x) ((void
> >>> *)__phys_to_virt((phys_addr_t)(x))) +#define __pa_symbol(x)
> >>> __pa(RELOC_HIDE((unsigned long)(x), 0))
> >> Just curious, is there a reason for the RELOC_HIDE() here? Or
> >> __pa_symbol() for that matter? It looks like only x86 uses this on
> >> the __nosave_{begin,end} symbol. Maybe it's copy-pasta?
> > From my understanding this needs to stick around so long as gcc 3.x is
> > supported (did it get dropped yet?) on ARM Linux since it doesn't
> > support -fno-strict-overflow.
>
> I don't think it's been dropped yet but I wonder if anyone has tried
> recent kernels with such a compiler?
>
> Would the usage of &__pv_table_begin in arch/arm/mm/mmu.c also need the
> same treatment?
We've never had to play these kinds of games on ARM irrespective of
compiler version.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
On Fri, Feb 28, 2014 at 08:15:57PM +0000, Sebastian Capella wrote:
[...]
> > > +
> > > +/*
> > > + * 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.
> > > + */
> >
> > Comment above needs updating. We are switching page tables to a set of
> > page tables that are certain to live at the same location in the older
> > kernel, that's the only reason, as we discussed. soft_restart will make
> > sure (again) to switch to 1:1 page tables so that we can call cpu_resume
> > with the MMU off.
>
> How does this look?
>
> The framework loads as much of the hibernation image to final physical
> pages as possible. Any pages that were in use, will need to be restored
> prior to the soft_restart. The pages to restore are maintained in
> the list anchored at restore_pblist. At this point, we can swap the
> pages to their final location. We must switch the mapping to 1:1 to
> ensure that when we overwrite the page table physical pages we're using
> a known physical location (idmap_pgd) with known contents.
It is ok, a tad too verbose. All I care about is a comment describing
what's really needed, the existing one was confusing and wrong.
> > > +/*
> > > + * 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 swsusp_arch_resume(void)
> > > +{
> > > + extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
> > > + call_with_stack(arch_restore_image, 0,
> > > + resume_stack + sizeof(resume_stack));
> >
> > This does not guarantee your stack is 8-byte aligned, that's not AAPCS
> > compliant and might buy you trouble.
> >
> > Either you align the stack or you align the pointer you are passing.
> >
> > Please have a look at kernel/process.c
>
> I've added this for now, do you see any issues?
>
> -static u8 resume_stack[PAGE_SIZE/2] __nosavedata;
> +static u64 resume_stack[PAGE_SIZE/2/sizeof(u64)] __nosavedata;
> - resume_stack + sizeof(resume_stack));
> + resume_stack + ARRAY_SIZE(resume_stack));
I do not see why the stack depends on the PAGE_SIZE. I would be surprised
if you need more than a few bytes (given that soft_restart switches stack
again...), go through it with a debugger, it is easy to check the stack
usage and allow for some extra buffer (but half a page is not needed).
My main concern was alignment, and now that's fixed.
Thanks !
Lorenzo
Want to log my new email with this thread in case any questions arise
later and people have trouble finding me.
[email protected]
Thanks!
Sebastian Capella