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arm64: mm: move pgd_cache initialisation to pgtable_cache_init

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Initialising the suppport for EFI runtime services requires us to
allocate a pgd off the back of an early_initcall. On systems where the
PGD_SIZE is smaller than PAGE_SIZE (e.g. 64k pages and 48-bit VA), the
pgd_cache isn't initialised at this stage, and we panic with a NULL
dereference during boot:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000

  __create_mapping.isra.5+0x84/0x350
  create_pgd_mapping+0x20/0x28
  efi_create_mapping+0x5c/0x6c
  arm_enable_runtime_services+0x154/0x1e4
  do_one_initcall+0x8c/0x190
  kernel_init_freeable+0x84/0x1ec
  kernel_init+0x10/0xe0
  ret_from_fork+0x10/0x50

This patch fixes the problem by initialising the pgd_cache earlier, in
the pgtable_cache_init callback, which sounds suspiciously like what it
was intended for.

Reported-by: Dennis Chen <dennis.chen@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2016-01-05 15:36:59 +00:00
parent f930896967
commit 39b5be9b42
2 changed files with 8 additions and 7 deletions
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3
arch/arm64/include/asm/pgtable.h
View file

@ -676,7 +676,8 @@ extern int kern_addr_valid(unsigned long addr);
#include <asm-generic/pgtable.h>
#define pgtable_cache_init() do { } while (0)
void pgd_cache_init(void);
#define pgtable_cache_init pgd_cache_init
/*
* On AArch64, the cache coherency is handled via the set_pte_at() function.

12
arch/arm64/mm/pgd.c
View file

@ -46,14 +46,14 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd)
kmem_cache_free(pgd_cache, pgd);
}
static int __init pgd_cache_init(void)
void __init pgd_cache_init(void)
{
if (PGD_SIZE == PAGE_SIZE)
return;
/*
* Naturally aligned pgds required by the architecture.
*/
if (PGD_SIZE != PAGE_SIZE)
pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
SLAB_PANIC, NULL);
return 0;
pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
SLAB_PANIC, NULL);
}
core_initcall(pgd_cache_init);