For radix we split the mapping into smaller page sizes (at the cost of
additional TLB overhead), but for hash its best to print a warning. In
the case of hash and no-relocation, the kernel should be well aligned
to provide the least overhead with the current linear mapping size (16M)
Signed-off-by: Balbir Singh <bsinghar...@gmail.com>
---
arch/powerpc/mm/pgtable-hash64.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c
index 443a2c6..656f7f3 100644
--- a/arch/powerpc/mm/pgtable-hash64.c
+++ b/arch/powerpc/mm/pgtable-hash64.c
@@ -434,8 +434,26 @@ static bool hash__change_memory_range(unsigned long start,
unsigned long end,
shift = mmu_psize_defs[mmu_linear_psize].shift;
step = 1 << shift;
- start = ALIGN_DOWN(start, step);
- end = ALIGN(end, step); // aligns up
+ if (!IS_ALIGNED(PHYSICAL_START, step)) {
+ /*
+ * For the relocatable case we might have
+ * a case where _stext shares the page
+ * with rw memory or __init_begin might
+ * share the page with executable text.
+ * This breaks strict RWX, but allows the
+ * kernel to boot. If PHYSICAL_START is mmu_linear_psize
+ * aligned, then we can continue to make the same
+ * assumptions as the non-relocatable case.
+ *
+ * TODO: If we really care about the relocatable
+ * case, we can align __init_begin/end better.
+ */
+ start = ALIGN(start, step);
+ end = ALIGN_DOWN(end, step);
+ } else {
+ start = ALIGN_DOWN(start, step);
+ end = ALIGN(end, step); /* Aligns up */
+ }
if (start >= end)
return false;
@@ -455,6 +473,12 @@ void hash__mark_rodata_ro(void)
{
unsigned long start, end;
+ if (PHYSICAL_START > MEMORY_START)
+ pr_warn("Detected relocation and CONFIG_STRICT_KERNEL_RWX "
+ "permissions are best effort, some non-text area "
+ "might still be left as executable");
+
+
start = (unsigned long)_stext;
end = (unsigned long)__init_begin;
--
2.9.4
