arm64: Change cpu_resume() to enable mmu early then access sleep_sp by va

By enabling the MMU early in cpu_resume(), the sleep_save_sp and stack can
be accessed by VA, which avoids the need to convert-addresses and clean to
PoC on the suspend path.

MMU setup is shared with the boot path, meaning the swapper_pg_dir is
restored directly: ttbr1_el1 is no longer saved/restored.

struct sleep_save_sp is removed, replacing it with a single array of
pointers.

cpu_do_{suspend,resume} could be further reduced to not restore: cpacr_el1,
mdscr_el1, tcr_el1, vbar_el1 and sctlr_el1, all of which are set by
__cpu_setup(). However these values all contain res0 bits that may be used
to enable future features.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index 365d8cd..29d3c71 100644
--- a/arch/arm64/include/asm/suspend.h
+++ b/arch/arm64/include/asm/suspend.h
@@ -1,7 +1,7 @@
 #ifndef __ASM_SUSPEND_H
 #define __ASM_SUSPEND_H
 
-#define NR_CTX_REGS 11
+#define NR_CTX_REGS 10
 #define NR_CALLEE_SAVED_REGS 12
 
 /*
@@ -17,11 +17,6 @@ struct cpu_suspend_ctx {
 	u64 sp;
 } __aligned(16);
 
-struct sleep_save_sp {
-	phys_addr_t *save_ptr_stash;
-	phys_addr_t save_ptr_stash_phys;
-};
-
 /*
  * Memory to save the cpu state is allocated on the stack by
  * __cpu_suspend_enter()'s caller, and populated by __cpu_suspend_enter().
@@ -39,6 +34,8 @@ struct sleep_stack_data {
 	unsigned long		callee_saved_regs[NR_CALLEE_SAVED_REGS];
 };
 
+extern unsigned long *sleep_save_stash;
+
 extern int cpu_suspend(unsigned long arg, int (*fn)(unsigned long));
 extern void cpu_resume(void);
 int __cpu_suspend_enter(struct sleep_stack_data *state);