[PATCH v9 1/2] ARM: avoid tracers in soft_restart

[PATCH v9 1/2] ARM: avoid tracers in soft_restart

[Sebastian Capella]

Use of tracers in local_irq_disable is causes abort loops when called
with irqs disabled using a temporary stack.  Replace local_irq_disable
with raw_local_irq_disable instead to avoid tracers.

Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Steven Capper <steve.capper@linaro.org>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>
---
 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

Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart

[Will Deacon]

Hi Sebastian,

On Tue, Mar 18, 2014 at 09:40:57PM +0000, Sebastian Capella wrote:
> Use of tracers in local_irq_disable is causes abort loops when called
> with irqs disabled using a temporary stack.  Replace local_irq_disable
> with raw_local_irq_disable instead to avoid tracers.

Do you have any more information about these aborts? At the time we call
local_irq_disable, the stack is still intact, so if the issue is simply
related to having any tracers active at the call_with_stack invocation, we'd
be better off disabling tracing here altogether.

Will

> Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Robin Holt <holt@sgi.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
> Cc: Steven Capper <steve.capper@linaro.org>
> Cc: Stephen Warren <swarren@nvidia.com>
> Cc: Tejun Heo <tj@kernel.org>
> ---
>  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
> 
> 

Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart

[Sebastian Capella]

Hi Will,

On 14 April 2014 03:53, Will Deacon <will.deacon@arm.com> wrote:
> On Tue, Mar 18, 2014 at 09:40:57PM +0000, Sebastian Capella wrote:
>> Use of tracers in local_irq_disable is causes abort loops when called
>> with irqs disabled using a temporary stack.  Replace local_irq_disable
>> with raw_local_irq_disable instead to avoid tracers.
>
> Do you have any more information about these aborts? At the time we call
> local_irq_disable, the stack is still intact, so if the issue is simply
> related to having any tracers active at the call_with_stack invocation, we'd
> be better off disabling tracing here altogether.

This is specifically for when soft_restart is called in the
hibernation path with tracers enabled.  At that point, we've already
switched to a temporary stack, and when we call local_irq_disable,
we'll see this:

In the local_irq_disable, it ends up calling trace_hardirqs_off
(CONFIG_TRACE_IRQFLAGS_SUPPORT is enabled), which calls
trace_hardirqs_off_caller which checks lockdep_recursion in the
current task, but we've switched to a temporary stack with the
call_with_stack, and get_current is returning NULL.  This
triggers a data abort, which calls trace_hardirqs_off
again and so on.

We originally had a patch which added a soft restart called
soft_restart_noirq which avoided the irq disable.

You can see the discussion here:
https://patchwork.kernel.org/patch/3677591/

Thanks!

Sebastian

[PATCH v9 2/2] ARM hibernation / suspend-to-disk

[Sebastian Capella]

From: Russ Dill <Russ.Dill@ti.com>

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 <Russ.Dill@ti.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Len Brown <len.brown@intel.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jonathan Austin <jonathan.austin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com
Cc: Victor Kamensky <victor.kamensky@linaro.org>
Cc: Sricharan R <r.sricharan@ti.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
---
 arch/arm/Kconfig              |    5 ++
 arch/arm/include/asm/memory.h |    1 +
 arch/arm/kernel/Makefile      |    1 +
 arch/arm/kernel/hibernate.c   |  107 +++++++++++++++++++++++++++++++++++++++++
 include/linux/suspend.h       |    2 +
 5 files changed, 116 insertions(+)
 create mode 100644 arch/arm/kernel/hibernate.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1594945..d204231 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -2279,6 +2279,11 @@ config ARCH_SUSPEND_POSSIBLE
 config ARM_CPU_SUSPEND
 	def_bool PM_SLEEP
 
+config ARCH_HIBERNATION_POSSIBLE
+	bool
+	depends on MMU
+	default y if ARCH_SUSPEND_POSSIBLE
+
 endmenu
 
 source "net/Kconfig"
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 4afb376..47347dd 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -289,6 +289,7 @@ 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 pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
+#define virt_to_pfn(kaddr)      (__pa(kaddr) >> 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..bb8b796
--- /dev/null
+++ b/arch/arm/kernel/hibernate.c
@@ -0,0 +1,107 @@
+/*
+ * 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/system_misc.h>
+#include <asm/idmap.h>
+#include <asm/suspend.h>
+#include <asm/memory.h>
+
+extern const void __nosave_begin, __nosave_end;
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = virt_to_pfn(&__nosave_begin);
+	unsigned long nosave_end_pfn = virt_to_pfn(&__nosave_end - 1);
+
+	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);
+}
+
+/*
+ * Restore page contents for physical pages that were in use during loading
+ * hibernation image.  Switch to idmap_pgd so the physical page tables
+ * are overwritten with the same contents.
+ */
+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 u64 resume_stack[PAGE_SIZE/2/sizeof(u64)] __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 + ARRAY_SIZE(resume_stack));
+	return 0;
+}
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