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.le...@c-s.fr>
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
v3: Function remap_init_ram() renamed mark_initmem_nx() to match new
PPC64 implementation
arch/powerpc/include/asm/pgtable.h | 2 +-
arch/powerpc/mm/pgtable_32.c | 13 ++++++++++---
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/pgtable.h
b/arch/powerpc/include/asm/pgtable.h
index afae9a336136..ab7f44475b1f 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -81,7 +81,7 @@ unsigned long vmalloc_to_phys(void *vmalloc_addr);
void pgtable_cache_add(unsigned shift, void (*ctor)(void *));
void pgtable_cache_init(void);
-#ifdef CONFIG_STRICT_KERNEL_RWX
+#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_PPC32)
void mark_initmem_nx(void);
#else
static inline void mark_initmem_nx(void) { }
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 991036f818bb..85e8f0e0efe6 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 mark_initmem_nx(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))
--
2.13.3
