[PATCHv2] arm64: Allow vmalloc regions to be set with set_memory_*

From: Laura Abbott
Date: Tue Jan 12 2016 - 18:22:56 EST



The range of set_memory_* is currently restricted to the module address
range because of difficulties in breaking down larger block sizes.
vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the
function ranges and add a comment explaining why the range is restricted
the way it is.

Signed-off-by: Laura Abbott <labbott@xxxxxxxxxxxxxxxxx>
---
v2: Old version was sent out with vmalloc warnings. Sorry for the noise.
---
arch/arm64/mm/pageattr.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 3571c73..88c8e54 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -36,6 +36,26 @@ static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
return 0;
}

+static bool validate_addr(unsigned long start, unsigned long end)
+{
+ /*
+ * This check explicitly excludes most kernel memory. Most kernel
+ * memory is mapped with a larger page size and breaking down the
+ * larger page size without causing TLB conflicts is very difficult.
+ *
+ * If you need to call set_memory_* on a range, the recommendation is
+ * to use vmalloc since that range is mapped with pages.
+ */
+ if (start >= MODULES_VADDR && start < MODULES_END &&
+ end >= MODULES_VADDR && end < MODULES_END)
+ return true;
+
+ if (is_vmalloc_addr((void *)start) && is_vmalloc_addr((void *)end))
+ return true;
+
+ return false;
+}
+
static int change_memory_common(unsigned long addr, int numpages,
pgprot_t set_mask, pgprot_t clear_mask)
{
@@ -51,10 +71,7 @@ static int change_memory_common(unsigned long addr, int numpages,
WARN_ON_ONCE(1);
}

- if (start < MODULES_VADDR || start >= MODULES_END)
- return -EINVAL;
-
- if (end < MODULES_VADDR || end >= MODULES_END)
+ if (!validate_addr(start, end))
return -EINVAL;

data.set_mask = set_mask;
--
2.5.0