[PATCH v2 02/14] ARM: Section based HYP idmap

Christoffer Dall
2012-10-01T09:10:16Z

Add a method (hyp_idmap_setup) to populate a hyp pgd with an
identity mapping of the code contained in the .hyp.idmap.text
section.

Offer a method to drop the this identity mapping through
hyp_idmap_teardown.

Make all the above depend on CONFIG_ARM_VIRT_EXT and CONFIG_ARM_LPAE.

Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
arch/arm/include/asm/idmap.h | 5 ++
arch/arm/include/asm/pgtable-3level-hwdef.h | 1
arch/arm/kernel/vmlinux.lds.S | 6 ++
arch/arm/mm/idmap.c | 74 +++++++++++++++++++++++----
4 files changed, 73 insertions(+), 13 deletions(-)

diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
index bf863ed..36708ba 100644
--- a/arch/arm/include/asm/idmap.h
+++ b/arch/arm/include/asm/idmap.h
@@ -11,4 +11,9 @@ extern pgd_t *idmap_pgd;

void setup_mm_for_reboot(void);

+#ifdef CONFIG_ARM_VIRT_EXT
+void hyp_idmap_teardown(pgd_t *hyp_pgd);
+void hyp_idmap_setup(pgd_t *hyp_pgd);
+#endif
+
#endif /* __ASM_IDMAP_H */
diff --git a/arch/arm/include/asm/pgtable-3level-hwdef.h b/arch/arm/include/asm/pgtable-3level-hwdef.h
index d795282..a2d404e 100644
--- a/arch/arm/include/asm/pgtable-3level-hwdef.h
+++ b/arch/arm/include/asm/pgtable-3level-hwdef.h
@@ -44,6 +44,7 @@
#define PMD_SECT_XN (_AT(pmdval_t, 1) << 54)
#define PMD_SECT_AP_WRITE (_AT(pmdval_t, 0))
#define PMD_SECT_AP_READ (_AT(pmdval_t, 0))
+#define PMD_SECT_AP1 (_AT(pmdval_t, 1) << 6)
#define PMD_SECT_TEX(x) (_AT(pmdval_t, 0))

/*
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 36ff15b..12fd2eb 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -19,7 +19,11 @@
ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__idmap_text_start) = .; \
*(.idmap.text) \
- VMLINUX_SYMBOL(__idmap_text_end) = .;
+ VMLINUX_SYMBOL(__idmap_text_end) = .; \
+ ALIGN_FUNCTION(); \
+ VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \
+ *(.hyp.idmap.text) \
+ VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;

#ifdef CONFIG_HOTPLUG_CPU
#define ARM_CPU_DISCARD(x)
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index ab88ed4..ea7430e 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -1,4 +1,6 @@
+#include <linux/module.h>
#include <linux/kernel.h>
+#include <linux/slab.h>

#include <asm/cputype.h>
#include <asm/idmap.h>
@@ -6,6 +8,7 @@
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/system_info.h>
+#include <asm/virt.h>

pgd_t *idmap_pgd;

@@ -59,11 +62,20 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
} while (pud++, addr = next, addr != end);
}

-static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+static void identity_mapping_add(pgd_t *pgd, const char *text_start,
+ const char *text_end, unsigned long prot)
{
- unsigned long prot, next;
+ unsigned long addr, end;
+ unsigned long next;
+
+ addr = virt_to_phys(text_start);
+ end = virt_to_phys(text_end);
+
+ pr_info("Setting up static %sidentity map for 0x%llx - 0x%llx\n",
+ prot ? "HYP " : "",
+ (long long)addr, (long long)end);
+ prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;

- prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
prot |= PMD_BIT4;

@@ -78,24 +90,62 @@ 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);
+ identity_mapping_add(idmap_pgd, __idmap_text_start,
+ __idmap_text_end, 0);

return 0;
}
early_initcall(init_static_idmap);

+#if defined(CONFIG_ARM_VIRT_EXT) && defined(CONFIG_ARM_LPAE)
+static void hyp_idmap_del_pmd(pgd_t *pgd, unsigned long addr)
+{
+ pud_t *pud;
+ pmd_t *pmd;
+
+ pud = pud_offset(pgd, addr);
+ pmd = pmd_offset(pud, addr);
+ pud_clear(pud);
+ clean_pmd_entry(pmd);
+ pmd_free(NULL, (pmd_t *)((unsigned long)pmd & PAGE_MASK));
+}
+
+extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
+
+/*
+ * This version actually frees the underlying pmds for all pgds in range and
+ * clear the pgds themselves afterwards.
+ */
+void hyp_idmap_teardown(pgd_t *hyp_pgd)
+{
+ unsigned long addr, end;
+ unsigned long next;
+ pgd_t *pgd = hyp_pgd;
+
+ addr = virt_to_phys(__hyp_idmap_text_start);
+ end = virt_to_phys(__hyp_idmap_text_end);
+
+ pgd += pgd_index(addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (!pgd_none_or_clear_bad(pgd))
+ hyp_idmap_del_pmd(pgd, addr);
+ } while (pgd++, addr = next, addr < end);
+}
+EXPORT_SYMBOL_GPL(hyp_idmap_teardown);
+
+void hyp_idmap_setup(pgd_t *hyp_pgd)
+{
+ identity_mapping_add(hyp_pgd, __hyp_idmap_text_start,
+ __hyp_idmap_text_end, PMD_SECT_AP1);
+}
+EXPORT_SYMBOL_GPL(hyp_idmap_setup);
+#endif
+
/*
* In order to soft-boot, we need to switch to a 1:1 mapping for the
* cpu_reset functions. This will then ensure that we have predictable