[PATCH v5 02/14] ARM: Section based HYP idmap

Christoffer Dall
2013-01-08T18:38:51Z

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 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>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.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 | 1 +
arch/arm/include/asm/pgtable-3level-hwdef.h | 1 +
arch/arm/kernel/vmlinux.lds.S | 6 +++
arch/arm/mm/idmap.c | 54 ++++++++++++++++++++++-----
4 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
index bf863ed..1a66f907 100644
--- a/arch/arm/include/asm/idmap.h
+++ b/arch/arm/include/asm/idmap.h
@@ -8,6 +8,7 @@
#define __idmap __section(.idmap.text) noinline notrace

extern pgd_t *idmap_pgd;
+extern pgd_t *hyp_pgd;

void setup_mm_for_reboot(void);

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 11c1785..b571484 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 99db769..d9213a5 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;

@@ -74,28 +86,48 @@ static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long e
} while (pgd++, addr = next, addr != end);
}

+#ifdef CONFIG_ARM_VIRT_EXT
+pgd_t *hyp_pgd;
+
+extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
+
+static int __init init_static_idmap_hyp(void)
+{
+ hyp_pgd = kzalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL);
+ if (!hyp_pgd)
+ return -ENOMEM;
+
+ identity_mapping_add(hyp_pgd, __hyp_idmap_text_start,
+ __hyp_idmap_text_end, PMD_SECT_AP1);
+
+ return 0;
+}
+#else
+static int __init init_static_idmap_hyp(void)
+{
+ return 0;
+}
+#endif
+
extern char __idmap_text_start[], __idmap_text_end[];

static int __init init_static_idmap(void)
{
- phys_addr_t idmap_start, idmap_end;
+ int ret;

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);
+ identity_mapping_add(idmap_pgd, __idmap_text_start,
+ __idmap_text_end, 0);

- 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);
+ ret = init_static_idmap_hyp();

/* Flush L1 for the hardware to see this page table content */
flush_cache_louis();

- return 0;
+ return ret;
}
early_initcall(init_static_idmap);