Since the EFI page size is 4KB, it is possible for a !4KB page kernel to
align an EFI runtime map boundaries in a way that they can overlap
within the same page. This requires the current create_pgd_mapping()
code to be able to split existing larger mappings when an overlapping
region needs to be mapped.
With this patch, efi_create_mapping() scans the EFI memory map for
overlapping regions and trims the length of the current map to avoid a
large block mapping and subsequent split.
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
arch/arm64/kernel/efi.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 78f52488f9ff..0d5753c31c7f 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -62,10 +62,26 @@ struct screen_info screen_info __section(.data);
int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
{
pteval_t prot_val = create_mapping_protection(md);
+ phys_addr_t length = md->num_pages << EFI_PAGE_SHIFT;
+ efi_memory_desc_t *next = md;
- create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
- md->num_pages << EFI_PAGE_SHIFT,
- __pgprot(prot_val | PTE_NG));
+ /*
+ * Search for the next EFI runtime map and check for any overlap with
+ * the current map when aligned to PAGE_SIZE. In such case, defer
+ * mapping the end of the current range until the next
+ * efi_create_mapping() call.
+ */
+ for_each_efi_memory_desc_continue(next) {
+ if (!(next->attribute & EFI_MEMORY_RUNTIME))
+ continue;
+ if (next->phys_addr < PAGE_ALIGN(md->phys_addr + length))
+ length -= (md->phys_addr + length) & ~PAGE_MASK;
+ break;
+ }
+
+ if (length)
+ create_pgd_mapping(mm, md->phys_addr, md->virt_addr, length,
+ __pgprot(prot_val | PTE_NG));
return 0;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
