[PATCH 2/4] ARM: suspend: use idmap_pgd instead of suspend_pgd

Will Deacon
2011-11-16T16:48:12Z

The ARM CPU suspend code requires cpu_resume_mmu to be identity mapped
in order to re-enable the MMU when coming out of suspend. Currently,
this is accomplished by maintaining a suspend_pgd with the relevant
mapping put in place at init time.

This patch replaces the use of suspend_pgd with the new idmap_pgd.
cpu_resume_mmu is placed in the .idmap.text section so that it is
included in the identity map.

Tested-by: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/kernel/sleep.S | 2 ++
arch/arm/kernel/suspend.c | 17 +++--------------
2 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 020e99c..9e64231 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -54,6 +54,7 @@ ENDPROC(cpu_suspend_abort)
* r0 = control register value
*/
.align 5
+ .pushsection .idmap.text,"ax"
ENTRY(cpu_resume_mmu)
ldr r3, =cpu_resume_after_mmu
mcr p15, 0, r0, c1, c0, 0 @ turn on MMU, I-cache, etc
@@ -62,6 +63,7 @@ ENTRY(cpu_resume_mmu)
mov r0, r0
mov pc, r3 @ jump to virtual address
ENDPROC(cpu_resume_mmu)
+ .popsection
cpu_resume_after_mmu:
bl cpu_init @ restore the und/abt/irq banked regs
mov r0, #0 @ return zero on success
diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
index 93a22d2..8880f94 100644
--- a/arch/arm/kernel/suspend.c
+++ b/arch/arm/kernel/suspend.c
@@ -6,7 +6,7 @@
#include <asm/suspend.h>
#include <asm/tlbflush.h>

-static pgd_t *suspend_pgd;
+extern pgd_t *idmap_pgd;

extern int __cpu_suspend(unsigned long, int (*)(unsigned long));
extern void cpu_resume_mmu(void);
@@ -21,7 +21,7 @@ void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr)
*save_ptr = virt_to_phys(ptr);

/* This must correspond to the LDM in cpu_resume() assembly */
- *ptr++ = virt_to_phys(suspend_pgd);
+ *ptr++ = virt_to_phys(idmap_pgd);
*ptr++ = sp;
*ptr++ = virt_to_phys(cpu_do_resume);

@@ -42,7 +42,7 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
struct mm_struct *mm = current->active_mm;
int ret;

- if (!suspend_pgd)
+ if (!idmap_pgd)
return -EINVAL;

/*
@@ -59,14 +59,3 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))

return ret;
}
-
-static int __init cpu_suspend_init(void)
-{
- suspend_pgd = pgd_alloc(&init_mm);
- if (suspend_pgd) {
- unsigned long addr = virt_to_phys(cpu_resume_mmu);
- identity_mapping_add(suspend_pgd, addr, addr + SECTION_SIZE);
- }
- return suspend_pgd ? 0 : -ENOMEM;
-}
-core_initcall(cpu_suspend_init);
--
1.7.4.1