arm/arm64: KVM: Enforce HYP read-only mapping of the kernel's rodata section

In order to be able to use C code in HYP, we're now mapping the kernel's
rodata in HYP. It works absolutely fine, except that we're mapping it RWX,
which is not what it should be.

Add a new HYP_PAGE_RO protection, and pass it as the protection flags
when mapping the rodata section.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 348caab..f332087 100644 (file)
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -98,6 +98,7 @@ extern pgprot_t               pgprot_s2_device;
 #define PAGE_KERNEL            _MOD_PROT(pgprot_kernel, L_PTE_XN)
 #define PAGE_KERNEL_EXEC       pgprot_kernel
 #define PAGE_HYP               _MOD_PROT(pgprot_kernel, L_PTE_HYP)
+#define PAGE_HYP_RO            _MOD_PROT(pgprot_kernel, L_PTE_HYP | L_PTE_RDONLY | L_PTE_XN)
 #define PAGE_HYP_DEVICE                _MOD_PROT(pgprot_hyp_device, L_PTE_HYP)
 #define PAGE_S2                        _MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY)
 #define PAGE_S2_DEVICE         _MOD_PROT(pgprot_s2_device, L_PTE_S2_RDONLY)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 45dd6df..b308976 100644 (file)
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1300,7 +1300,7 @@ static int init_hyp_mode(void)
        }
 
        err = create_hyp_mappings(kvm_ksym_ref(__start_rodata),
-                                 kvm_ksym_ref(__end_rodata), PAGE_HYP);
+                                 kvm_ksym_ref(__end_rodata), PAGE_HYP_RO);
        if (err) {
                kvm_err("Cannot map rodata section\n");
                goto out_err;

diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 29fcb33..88db58c 100644 (file)
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -56,6 +56,7 @@
 #define PAGE_KERNEL_EXEC_CONT  __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_CONT)
 
 #define PAGE_HYP               __pgprot(_PAGE_DEFAULT | PTE_HYP)
+#define PAGE_HYP_RO            __pgprot(_PAGE_DEFAULT | PTE_HYP | PTE_RDONLY | PTE_HYP_XN)
 #define PAGE_HYP_DEVICE                __pgprot(PROT_DEVICE_nGnRE | PTE_HYP)
 
 #define PAGE_S2                        __pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_S2_RDONLY)