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arm64: kernel: Rework finisher callback out of __cpu_suspend_enter()

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Hibernate could make use of the cpu_suspend() code to save/restore cpu
state, however it needs to be able to return '0' from the 'finisher'.

Rework cpu_suspend() so that the finisher is called from C code,
independently from the save/restore of cpu state. Space to save the context
in is allocated in the caller's stack frame, and passed into
__cpu_suspend_enter().

Hibernate's use of this API will look like a copy of the cpu_suspend()
function.

Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
James Morse
2016-04-27 17:47:06 +01:00
committed by Will Deacon
parent 67f6919766
commit adc9b2dfd0
4 changed files with 97 additions and 90 deletions
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72
arch/arm64/kernel/suspend.c
View File

@@ -10,22 +10,22 @@
#include <asm/suspend.h>
#include <asm/tlbflush.h>
extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
/*
* This is called by __cpu_suspend_enter() to save the state, and do whatever
* flushing is required to ensure that when the CPU goes to sleep we have
* the necessary data available when the caches are not searched.
*
* ptr: CPU context virtual address
* ptr: sleep_stack_data containing cpu state virtual address.
* save_ptr: address of the location where the context physical address
* must be saved
*/
void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
void notrace __cpu_suspend_save(struct sleep_stack_data *ptr,
phys_addr_t *save_ptr)
{
*save_ptr = virt_to_phys(ptr);
cpu_do_suspend(ptr);
cpu_do_suspend(&ptr->system_regs);
/*
* Only flush the context that must be retrieved with the MMU
* off. VA primitives ensure the flush is applied to all
@@ -51,6 +51,30 @@ void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
hw_breakpoint_restore = hw_bp_restore;
}
void notrace __cpu_suspend_exit(void)
{
/*
* We are resuming from reset with the idmap active in TTBR0_EL1.
* We must uninstall the idmap and restore the expected MMU
* state before we can possibly return to userspace.
*/
cpu_uninstall_idmap();
/*
* Restore per-cpu offset before any kernel
* subsystem relying on it has a chance to run.
*/
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
* Restore HW breakpoint registers to sane values
* before debug exceptions are possibly reenabled
* through local_dbg_restore.
*/
if (hw_breakpoint_restore)
hw_breakpoint_restore(NULL);
}
/*
* cpu_suspend
*
@@ -60,8 +84,9 @@ void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
*/
int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
{
int ret;
int ret = 0;
unsigned long flags;
struct sleep_stack_data state;
/*
* From this point debug exceptions are disabled to prevent
@@ -77,34 +102,21 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
*/
pause_graph_tracing();
/*
* mm context saved on the stack, it will be restored when
* the cpu comes out of reset through the identity mapped
* page tables, so that the thread address space is properly
* set-up on function return.
*/
ret = __cpu_suspend_enter(arg, fn);
if (ret == 0) {
/*
* We are resuming from reset with the idmap active in TTBR0_EL1.
* We must uninstall the idmap and restore the expected MMU
* state before we can possibly return to userspace.
*/
cpu_uninstall_idmap();
if (__cpu_suspend_enter(&state)) {
/* Call the suspend finisher */
ret = fn(arg);
/*
* Restore per-cpu offset before any kernel
* subsystem relying on it has a chance to run.
* Never gets here, unless the suspend finisher fails.
* Successful cpu_suspend() should return from cpu_resume(),
* returning through this code path is considered an error
* If the return value is set to 0 force ret = -EOPNOTSUPP
* to make sure a proper error condition is propagated
*/
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
* Restore HW breakpoint registers to sane values
* before debug exceptions are possibly reenabled
* through local_dbg_restore.
*/
if (hw_breakpoint_restore)
hw_breakpoint_restore(NULL);
if (!ret)
ret = -EOPNOTSUPP;
} else {
__cpu_suspend_exit();
}
unpause_graph_tracing();