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authorWill Deacon <will.deacon@arm.com>2011-09-30 11:43:29 +0100
committerWill Deacon <will.deacon@arm.com>2011-12-06 14:04:14 +0000
commit8903826d0cd99aed9267e792d38284cf3092042b (patch)
treeec75fed09f62c215e2057d8c5e82c343e627c8fe /arch/arm/mm
parentba8bb18a03f8c7508565c385576a5431a4ad804a (diff)
downloadop-kernel-dev-8903826d0cd99aed9267e792d38284cf3092042b.zip
op-kernel-dev-8903826d0cd99aed9267e792d38284cf3092042b.tar.gz
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>
Diffstat (limited to 'arch/arm/mm')
-rw-r--r--arch/arm/mm/idmap.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index 296ad2e..cda5ea3 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -1,8 +1,12 @@
#include <linux/kernel.h>
#include <asm/cputype.h>
+#include <asm/idmap.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
+#include <asm/sections.h>
+
+pgd_t *idmap_pgd;
static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
unsigned long prot)
@@ -73,6 +77,28 @@ void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
}
#endif
+extern char __idmap_text_start[], __idmap_text_end[];
+
+static int __init init_static_idmap(void)
+{
+ phys_addr_t idmap_start, idmap_end;
+
+ idmap_pgd = pgd_alloc(&init_mm);
+ if (!idmap_pgd)
+ return -ENOMEM;
+
+ /* Add an identity mapping for the physical address of the section. */
+ idmap_start = virt_to_phys((void *)__idmap_text_start);
+ idmap_end = virt_to_phys((void *)__idmap_text_end);
+
+ pr_info("Setting up static identity map for 0x%llx - 0x%llx\n",
+ (long long)idmap_start, (long long)idmap_end);
+ identity_mapping_add(idmap_pgd, idmap_start, idmap_end);
+
+ return 0;
+}
+arch_initcall(init_static_idmap);
+
/*
* In order to soft-boot, we need to insert a 1:1 mapping in place of
* the user-mode pages. This will then ensure that we have predictable
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