arm64: mm: Fix CFI failure due to kpti_ng_pgd_alloc function signature

Seen during KPTI initialization:

CFI failure at create_kpti_ng_temp_pgd+0x124/0xce8 (target: kpti_ng_pgd_alloc+0x0/0x14; expected type: 0xd61b88b6)

The call site is alloc_init_pud() at arch/arm64/mm/mmu.c:

   pud_phys = pgtable_alloc(TABLE_PUD);

alloc_init_pud() has the prototype:

static void alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot, phys_addr_t (*pgtable_alloc)(enum pgtable_type), int flags)

where the pgtable_alloc() prototype is declared.

The target (kpti_ng_pgd_alloc) is used in arch/arm64/kernel/cpufeature.c:

   create_kpti_ng_temp_pgd(kpti_ng_temp_pgd, __pa(alloc), KPTI_NG_TEMP_VA,
                           PAGE_SIZE, PAGE_KERNEL, kpti_ng_pgd_alloc, 0);

which is an alias for __create_pgd_mapping_locked() with prototype:

extern __alias(__create_pgd_mapping_locked)
void create_kpti_ng_temp_pgd(pgd_t *pgdir, phys_addr_t phys,
unsigned long virt,
phys_addr_t size, pgprot_t prot, phys_addr_t (*pgtable_alloc)(enum pgtable_type), int flags);

__create_pgd_mapping_locked() passes the function pointer down:

   __create_pgd_mapping_locked() -> alloc_init_p4d() -> alloc_init_pud()

But the target function (kpti_ng_pgd_alloc) has the wrong signature:

   static phys_addr_t __init kpti_ng_pgd_alloc(int shift);

The "int" should be "enum pgtable_type".

To make "enum pgtable_type" available to cpufeature.c, move enum pgtable_type definition from arch/arm64/mm/mmu.c to arch/arm64/include/asm/mmu.h.

Adjust kpti_ng_pgd_alloc to use "enum pgtable_type" instead of "int". The function behavior remains identical (parameter is unused).

Fixes c64f46ee1377 ("arm64: mm: use enum to identify pgtable level instead of *_SHIFT")

Signed-off-by Kees Cook <[email protected]>

---
v2: Fixed the Fixes line. ;)
v1: https://lore.kernel.org/lkml/[email protected]/
Cc: Kevin Brodsky <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Yue Haibing <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: <[email protected]>

---
  arch/arm64/include/asm/mmu.h   | 7 +++++++
  arch/arm64/kernel/cpufeature.c | 5 +++--
  arch/arm64/mm/mmu.c            | 7 -------
  3 files changed, 10 insertions(+), 9 deletions(-)

arch/arm64/include/asm/mmu.h +0 -0

index 6e8aa8e72601..49f1a810df16 100644

Quoted 11 lines

[...]

arch/arm64/include/asm/mmu.h +1 -0

index 6e8aa8e72601..49f1a810df16 100644
@@ -17,6 +17,13 @@
   #include <linux/refcount.h>
   #include <asm/cpufeature.h>
   +enum pgtable_type {
+    TABLE_PTE, m68k_table_types

arch/arm64/include/asm/mmu.h line 25

Quoted 4 lines

arch/arm64/include/asm/mmu.h +4 -0

+    TABLE_PMD,
+    TABLE_PUD,
+    TABLE_P4D,
+};

Just noting that we now have "enum pgtable_level" in include/linux/pgtable.h that could at some point possibly be used here instead (not in this fix).

Seen during KPTI initialization:

CFI failure at create_kpti_ng_temp_pgd+0x124/0xce8 (target: kpti_ng_pgd_alloc+0x0/0x14; expected type: 0xd61b88b6)

The call site is alloc_init_pud() at arch/arm64/mm/mmu.c:

  pud_phys = pgtable_alloc(TABLE_PUD);

[...]