[PATCH v2 1/3] powerpc/mm: Ensure change_page_attr() doesn't invalidate pinned TLBs

Christophe Leroy
2017-04-21T13:02:37Z

__change_page_attr() uses flush_tlb_page().
flush_tlb_page() uses tlbie instruction, which also invalidates
pinned TLBs, which is not what we expect.

This patch modifies the implementation to use flush_tlb_kernel_range()
instead. This will make use of tlbia which will preserve pinned TLBs.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: No change

arch/powerpc/mm/pgtable_32.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index a65c0b4c0669..8e8940fad12f 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -325,7 +325,7 @@ get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)

#ifdef CONFIG_DEBUG_PAGEALLOC

-static int __change_page_attr(struct page *page, pgprot_t prot)
+static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
{
pte_t *kpte;
pmd_t *kpmd;
@@ -339,8 +339,6 @@ static int __change_page_attr(struct page *page, pgprot_t prot)
if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
return -EINVAL;
__set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
- wmb();
- flush_tlb_page(NULL, address);
pte_unmap(kpte);

return 0;
@@ -355,13 +353,17 @@ static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
int i, err = 0;
unsigned long flags;
+ struct page *start = page;

local_irq_save(flags);
for (i = 0; i < numpages; i++, page++) {
- err = __change_page_attr(page, prot);
+ err = __change_page_attr_noflush(page, prot);
if (err)
break;
}
+ wmb();
+ flush_tlb_kernel_range((unsigned long)page_address(start),
+ (unsigned long)page_address(page));
local_irq_restore(flags);
return err;
}
--
2.12.0