在 2025/10/28 21:42, Ard Biesheuvel 写道:

On Mon, 27 Oct 2025 at 04:46, Qiang Ma [off-list ref] wrote:

quoted

在 2025/10/23 16:30, Ard Biesheuvel 写道:

quoted

On Thu, 23 Oct 2025 at 10:22, Qiang Ma [off-list ref] wrote:

quoted

In the efi_virtmap_init(), permission settings have been applied:

static bool __init efi_virtmap_init(void)
{
          ...
          for_each_efi_memory_desc(md)
                  ...
                  efi_create_mapping(&efi_mm, md);
          ...
          efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions);
          ...
}

Therefore, there is no need to apply it again in the efi_create_mapping().

Fixes: 9fc68b717c24 ("ARM/efi: Apply strict permissions for UEFI Runtime Services regions")

Signed-off-by: Qiang Ma <redacted>

No, efi_memattr_apply_permissions() uses the /optional/ memory
attributes table, whereas efi_create_mapping() uses the permission
attributes in the EFI memory map. The memory attributes table is
optional, in which case any RO/XP attributes from the memory map
should be used.

I see.

Then, can it be modified like this?

No

quoted

--- a/arch/arm/kernel/efi.c
+++ b/arch/arm/kernel/efi.c

@@ -65,16 +65,13 @@ int __init efi_create_mapping(struct mm_struct *mm,

efi_memory_desc_t *md)
                  desc.type = MT_MEMORY_RWX_NONCACHED;
          else if (md->attribute & EFI_MEMORY_WC)
                  desc.type = MT_DEVICE_WC;
+       else if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))

This will be true for RO, XP or RO+XP.

quoted

+               desc.type = MT_MEMORY_RO;

This will apply RO permissions even to XP regions, which need to be writable.

Thanks for your review.
I see.

I can introduce a new type MT_MEMORY_RO_XP, to describe RO+XP,
and then we can use the RO+XP attribute to implement memory mapping.

--- a/arch/arm/kernel/efi.c
+++ b/arch/arm/kernel/efi.c

@@ -68,13 +68,16 @@ int __init efi_create_mapping(struct mm_struct *mm, 

efi_memory_desc_t *md)
         else
                 desc.type = MT_DEVICE;

+       if ((md->attribute & EFI_MEMORY_RO) &&
+           (md->attribute & EFI_MEMORY_XP))
+               desc.type = MT_MEMORY_RO_XP;
+       else if ((md->attribute & EFI_MEMORY_RO)
+               desc.type = MT_MEMORY_RO;
+       else if (md->attribute & EFI_MEMORY_XP)
+               desc.type = MT_MEMORY_RW;
+
         create_mapping_late(mm, &desc, true);