From 3184cc4b6f6a1dc0c1745aafe2b14b1206ef3187 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 2 Aug 2017 15:51:03 +0200 Subject: [PATCH] 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 Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman --- 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)) -- 2.11.0