diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-12 14:56:36 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-12 22:32:43 +1000 |
| commit | 03dfee6d5f824d14e3ecb742518740de69e603cc (patch) | |
| tree | 43b020cc6eb3c23bbbaef2ae0ffdf3f403c13314 /arch/powerpc/include/asm/book3s/64/pgtable.h | |
| parent | 3c19d5ada1bec8b97119215298df7669d3ffb3db (diff) | |
powerpc/mm: Fix swapper_pg_dir size on 64-bit hash w/64K pages
Recently in commit f6eedbba7a26 ("powerpc/mm/hash: Increase VA range to 128TB"),
we increased H_PGD_INDEX_SIZE to 15 when we're building with 64K pages. This
makes it larger than RADIX_PGD_INDEX_SIZE (13), which means the logic to
calculate MAX_PGD_INDEX_SIZE in book3s/64/pgtable.h is wrong.
The end result is that the PGD (Page Global Directory, ie top level page table)
of the kernel (aka. swapper_pg_dir), is too small.
This generally doesn't lead to a crash, as we don't use the full range in normal
operation. However if we try to dump the kernel pagetables we can trigger a
crash because we walk off the end of the pgd into other memory and eventually
try to dereference something bogus:
$ cat /sys/kernel/debug/kernel_pagetables
Unable to handle kernel paging request for data at address 0xe8fece0000000000
Faulting instruction address: 0xc000000000072314
cpu 0xc: Vector: 380 (Data SLB Access) at [c0000000daa13890]
pc: c000000000072314: ptdump_show+0x164/0x430
lr: c000000000072550: ptdump_show+0x3a0/0x430
dar: e802cf0000000000
seq_read+0xf8/0x560
full_proxy_read+0x84/0xc0
__vfs_read+0x6c/0x1d0
vfs_read+0xbc/0x1b0
SyS_read+0x6c/0x110
system_call+0x38/0xfc
The root cause is that MAX_PGD_INDEX_SIZE isn't actually computed to be
the max of H_PGD_INDEX_SIZE or RADIX_PGD_INDEX_SIZE. To fix that move
the calculation into asm-offsets.c where we can do it easily using
max().
Fixes: f6eedbba7a26 ("powerpc/mm/hash: Increase VA range to 128TB")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/pgtable.h')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/pgtable.h | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index fb72ff6b98e6..fb8380a2d8d5 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -232,10 +232,6 @@ extern unsigned long __pte_frag_nr; extern unsigned long __pte_frag_size_shift; #define PTE_FRAG_SIZE_SHIFT __pte_frag_size_shift #define PTE_FRAG_SIZE (1UL << PTE_FRAG_SIZE_SHIFT) -/* - * Pgtable size used by swapper, init in asm code - */ -#define MAX_PGD_TABLE_SIZE (sizeof(pgd_t) << RADIX_PGD_INDEX_SIZE) #define PTRS_PER_PTE (1 << PTE_INDEX_SIZE) #define PTRS_PER_PMD (1 << PMD_INDEX_SIZE) |