linux-kernel - [PATCH 2/7] powerpc/mm: Ensure change_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <368a42bcb9481c5b7007c1e66d02e713603e6946.1496070452.git.christophe.leroy@c-s.fr>
Date:   Mon, 29 May 2017 17:31:58 +0200 (CEST)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>,
        Balbir Singh <bsingharora@...il.com>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 2/7] powerpc/mm: Ensure change_page_attr() doesn't invalidate
 pinned TLBs

__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@....fr>
---
 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 9c23c0965566..bdfee8e62a6a 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