From 8903826d0cd99aed9267e792d38284cf3092042b Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Fri, 30 Sep 2011 11:43:29 +0100
Subject: ARM: idmap: populate identity map pgd at init time using .init.text
When disabling and re-enabling the MMU, it is necessary to take out an
identity mapping for the code that manipulates the SCTLR in order to
avoid it disappearing from under our feet. This is useful when soft
rebooting and returning from CPU suspend.
This patch allocates a set of page tables during boot and populates them
with an identity mapping for the .idmap.text section. This means that
users of the identity map do not need to manage their own pgd and can
instead annotate their functions with __idmap or, in the case of assembly
code, place them in the correct section.
Acked-by: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/kernel/smp.c | 1 +
1 file changed, 1 insertion(+)
(limited to 'arch/arm/kernel/smp.c')
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index ef5640b9e218..8afadda37459 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -31,6 +31,7 @@
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/exception.h>
+#include <asm/idmap.h>
#include <asm/topology.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
--
cgit v1.2.3
From 4e8ee7de227e3ab9a72040b448ad728c5428a042 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Wed, 23 Nov 2011 12:26:25 +0000
Subject: ARM: SMP: use idmap_pgd for mapping MMU enable during secondary
booting
The ARM SMP booting code allocates a temporary set of page tables
containing an identity mapping of the kernel image and provides this
to secondary CPUs for initial booting.
In reality, we only need to include the __turn_mmu_on function in the
identity mapping since the rest of the kernel is executing from virtual
addresses after this point.
This patch adds __turn_mmu_on to the .idmap.text section, allowing the
SMP booting code to use the idmap_pgd directly and not have to populate
its own set of page table.
As a result of this patch, we can make the identity_mapping_add function
static (since it is only used within mm/idmap.c) and also remove the
identity_mapping_del function. The identity map population is moved to
an early initcall so that it is setup in time for secondary CPU bringup.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/idmap.h | 3 ---
arch/arm/kernel/head.S | 4 +++-
arch/arm/kernel/smp.c | 31 +------------------------------
arch/arm/mm/idmap.c | 34 ++--------------------------------
4 files changed, 6 insertions(+), 66 deletions(-)
(limited to 'arch/arm/kernel/smp.c')
diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
index 62e3d19c9ad7..bf863edb517d 100644
--- a/arch/arm/include/asm/idmap.h
+++ b/arch/arm/include/asm/idmap.h
@@ -9,9 +9,6 @@
extern pgd_t *idmap_pgd;
-void identity_mapping_add(pgd_t *, unsigned long, unsigned long);
-void identity_mapping_del(pgd_t *, unsigned long, unsigned long);
-
void setup_mm_for_reboot(void);
#endif /* __ASM_IDMAP_H */
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 43e3aa3b0573..64e9943ea4f0 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -398,7 +398,8 @@ ENDPROC(__enable_mmu)
* other registers depend on the function called upon completion
*/
.align 5
-__turn_mmu_on:
+ .pushsection .idmap.text, "ax"
+ENTRY(__turn_mmu_on)
mov r0, r0
mcr p15, 0, r0, c1, c0, 0 @ write control reg
mrc p15, 0, r3, c0, c0, 0 @ read id reg
@@ -407,6 +408,7 @@ __turn_mmu_on:
mov pc, r3
__turn_mmu_on_end:
ENDPROC(__turn_mmu_on)
+ .popsection
#ifdef CONFIG_SMP_ON_UP
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8afadda37459..76ff28d87bf3 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -62,7 +62,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
{
struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
struct task_struct *idle = ci->idle;
- pgd_t *pgd;
int ret;
/*
@@ -84,30 +83,12 @@ int __cpuinit __cpu_up(unsigned int cpu)
init_idle(idle, cpu);
}
- /*
- * Allocate initial page tables to allow the new CPU to
- * enable the MMU safely. This essentially means a set
- * of our "standard" page tables, with the addition of
- * a 1:1 mapping for the physical address of the kernel.
- */
- pgd = pgd_alloc(&init_mm);
- if (!pgd)
- return -ENOMEM;
-
- if (PHYS_OFFSET != PAGE_OFFSET) {
-#ifndef CONFIG_HOTPLUG_CPU
- identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end));
-#endif
- identity_mapping_add(pgd, __pa(_stext), __pa(_etext));
- identity_mapping_add(pgd, __pa(_sdata), __pa(_edata));
- }
-
/*
* We need to tell the secondary core where to find
* its stack and the page tables.
*/
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
- secondary_data.pgdir = virt_to_phys(pgd);
+ secondary_data.pgdir = virt_to_phys(idmap_pgd);
secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
__cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));
@@ -143,16 +124,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
secondary_data.stack = NULL;
secondary_data.pgdir = 0;
- if (PHYS_OFFSET != PAGE_OFFSET) {
-#ifndef CONFIG_HOTPLUG_CPU
- identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end));
-#endif
- identity_mapping_del(pgd, __pa(_stext), __pa(_etext));
- identity_mapping_del(pgd, __pa(_sdata), __pa(_edata));
- }
-
- pgd_free(&init_mm, pgd);
-
return ret;
}
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index b01760e6da18..660f1bc68f99 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -32,7 +32,7 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
} while (pud++, addr = next, addr != end);
}
-void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
{
unsigned long prot, next;
@@ -47,36 +47,6 @@ void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
} while (pgd++, addr = next, addr != end);
}
-#ifdef CONFIG_SMP
-static void idmap_del_pmd(pud_t *pud, unsigned long addr, unsigned long end)
-{
- pmd_t *pmd = pmd_offset(pud, addr);
- pmd_clear(pmd);
-}
-
-static void idmap_del_pud(pgd_t *pgd, unsigned long addr, unsigned long end)
-{
- pud_t *pud = pud_offset(pgd, addr);
- unsigned long next;
-
- do {
- next = pud_addr_end(addr, end);
- idmap_del_pmd(pud, addr, next);
- } while (pud++, addr = next, addr != end);
-}
-
-void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
-{
- unsigned long next;
-
- pgd += pgd_index(addr);
- do {
- next = pgd_addr_end(addr, end);
- idmap_del_pud(pgd, addr, next);
- } while (pgd++, addr = next, addr != end);
-}
-#endif
-
extern char __idmap_text_start[], __idmap_text_end[];
static int __init init_static_idmap(void)
@@ -97,7 +67,7 @@ static int __init init_static_idmap(void)
return 0;
}
-arch_initcall(init_static_idmap);
+early_initcall(init_static_idmap);
/*
* In order to soft-boot, we need to switch to a 1:1 mapping for the
--
cgit v1.2.3