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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2017-08-02 15:51:03 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-08-15 22:55:56 +1000 |
| commit | 3184cc4b6f6a1dc0c1745aafe2b14b1206ef3187 (patch) | |
| tree | 17341318eeeb4e3d4611620b8b6db846ab10e52d /arch/powerpc/mm/pgtable_32.c | |
| parent | e611939fc8ec13387018df88083de7102a438730 (diff) | |
| download | lwn-3184cc4b6f6a1dc0c1745aafe2b14b1206ef3187.tar.gz lwn-3184cc4b6f6a1dc0c1745aafe2b14b1206ef3187.zip | |
powerpc/mm: Fix kernel RAM protection after freeing unused memory on PPC32
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>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm/pgtable_32.c')
| -rw-r--r-- | arch/powerpc/mm/pgtable_32.c | 13 |
1 files changed, 10 insertions, 3 deletions
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)) |