From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762479AbdDSLAH (ORCPT ); Wed, 19 Apr 2017 07:00:07 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:10776 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762457AbdDSLAD (ORCPT ); Wed, 19 Apr 2017 07:00:03 -0400 Message-Id: <954181ecfaf0db395348347fa00c419e9f0d41bc.1492596044.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH 2/3] powerpc/mm: Fix kernel RAM protection after freeing unused memory on PPC32 To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Scott Wood Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Wed, 19 Apr 2017 13:00:01 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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