From: Christophe Leroy <christophe.leroy@c-s.fr>
From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v3 2/3] powerpc/mm: Fix kernel RAM protection after freeing unused memory on PPC32
Date: Mon, 24 Apr 2017 16:25:48 +0200 (CEST) [thread overview]
Message-ID: <c958c51cdc884f9db8ac86a3f3909a696c8e2572.1493041713.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1493041713.git.christophe.leroy@c-s.fr>
As seen below, allthough the init sections have been freed, the
associated memory area is still marked as executable in the
page tables.
~ dmesg
[ 5.860093] Freeing unused kernel memory: 592K (c0570000 - c0604000)
~ cat /sys/kernel/debug/kernel_page_tables
---[ Start of kernel VM ]---
0xc0000000-0xc0497fff 4704K rw X present dirty accessed shared
0xc0498000-0xc056ffff 864K rw present dirty accessed shared
0xc0570000-0xc059ffff 192K rw X present dirty accessed shared
0xc05a0000-0xc7ffffff 125312K rw present dirty accessed shared
---[ vmalloc() Area ]---
This patch fixes that.
The implementation is done by reusing the change_page_attr()
function implemented for CONFIG_DEBUG_PAGEALLOC
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: No change
v3: No change
arch/powerpc/mm/mem.c | 1 +
arch/powerpc/mm/mmu_decl.h | 3 +++
arch/powerpc/mm/pgtable_32.c | 13 ++++++++++---
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9ee536ec0739..f261dac36a68 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -401,6 +401,7 @@ void free_initmem(void)
{
ppc_md.progress = ppc_printk_progress;
free_initmem_default(POISON_FREE_INITMEM);
+ remap_init_ram();
}
#ifdef CONFIG_BLK_DEV_INITRD
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index f988db655e5b..718fa45310be 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -95,6 +95,7 @@ extern void _tlbia(void);
extern void mapin_ram(void);
extern int map_page(unsigned long va, phys_addr_t pa, int flags);
+void remap_init_ram(void);
extern void setbat(int index, unsigned long virt, phys_addr_t phys,
unsigned int size, pgprot_t prot);
@@ -106,6 +107,8 @@ struct hash_pte;
extern struct hash_pte *Hash, *Hash_end;
extern unsigned long Hash_size, Hash_mask;
+#else
+static inline void remap_init_ram(void) {}
#endif /* CONFIG_PPC32 */
extern unsigned long ioremap_bot;
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 8e8940fad12f..31728f3cdd20 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -323,8 +323,6 @@ get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
return(retval);
}
-#ifdef CONFIG_DEBUG_PAGEALLOC
-
static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
{
pte_t *kpte;
@@ -347,7 +345,7 @@ static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
/*
* Change the page attributes of an page in the linear mapping.
*
- * THIS CONFLICTS WITH BAT MAPPINGS, DEBUG USE ONLY
+ * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
*/
static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
@@ -368,7 +366,16 @@ static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
return err;
}
+void remap_init_ram(void)
+{
+ struct page *page = virt_to_page(_sinittext);
+ unsigned long numpages = PFN_UP((unsigned long)_einittext) -
+ PFN_DOWN((unsigned long)_sinittext);
+
+ change_page_attr(page, numpages, PAGE_KERNEL);
+}
+#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
if (PageHighMem(page))
--
2.12.0
next prev parent reply other threads:[~2017-04-24 14:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-24 13:48 [PATCH v3 0/3] powerpc/mm: Fix kernel protection and implement CONFIG_DEBUG_RODATA on PPC32 Christophe Leroy
2017-04-24 14:25 ` [PATCH v3 1/3] powerpc/mm: Ensure change_page_attr() doesn't invalidate pinned TLBs Christophe Leroy
2017-04-24 14:25 ` Christophe Leroy, Christophe Leroy [this message]
2017-04-24 14:25 ` [PATCH v3 3/3] powerpc/mm: Implement CONFIG_DEBUG_RODATA on PPC32 Christophe Leroy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c958c51cdc884f9db8ac86a3f3909a696c8e2572.1493041713.git.christophe.leroy@c-s.fr \
--to=christophe.leroy@c-s.fr \
--cc=benh@kernel.crashing.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=oss@buserror.net \
--cc=paulus@samba.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).