From 6fb14755a676282a4e6caa05a08c92db8e45cfff Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 2 May 2007 19:27:10 +0200 Subject: [PATCH] x86: tighten kernel image page access rights On x86-64, kernel memory freed after init can be entirely unmapped instead of just getting 'poisoned' by overwriting with a debug pattern. On i386 and x86-64 (under CONFIG_DEBUG_RODATA), kernel text and bug table can also be write-protected. Compared to the first version, this one prevents re-creating deleted mappings in the kernel image range on x86-64, if those got removed previously. This, together with the original changes, prevents temporarily having inconsistent mappings when cacheability attributes are being changed on such pages (e.g. from AGP code). While on i386 such duplicate mappings don't exist, the same change is done there, too, both for consistency and because checking pte_present() before using various other pte_XXX functions is a requirement anyway. At once, i386 code gets adjusted to use pte_huge() instead of open coding this. AK: split out cpa() changes Signed-off-by: Jan Beulich Signed-off-by: Andi Kleen --- arch/x86_64/kernel/head.S | 1 - arch/x86_64/kernel/vmlinux.lds.S | 5 +++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86_64/kernel') diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S index 36aa98a6d15c..fd9fdfdd143e 100644 --- a/arch/x86_64/kernel/head.S +++ b/arch/x86_64/kernel/head.S @@ -280,7 +280,6 @@ early_idt_ripmsg: .balign PAGE_SIZE ENTRY(stext) -ENTRY(_stext) #define NEXT_PAGE(name) \ .balign PAGE_SIZE; \ diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S index 5176ecf006ee..3bdeb88d28f4 100644 --- a/arch/x86_64/kernel/vmlinux.lds.S +++ b/arch/x86_64/kernel/vmlinux.lds.S @@ -29,6 +29,7 @@ SECTIONS .text : AT(ADDR(.text) - LOAD_OFFSET) { /* First the code that has to be first for bootstrapping */ *(.bootstrap.text) + _stext = .; /* Then all the functions that are "hot" in profiles, to group them onto the same hugetlb entry */ #include "functionlist" @@ -50,10 +51,10 @@ SECTIONS __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { *(__ex_table) } __stop___ex_table = .; - RODATA - BUG_TABLE + RODATA + . = ALIGN(PAGE_SIZE); /* Align data segment to page size boundary */ /* Data */ .data : AT(ADDR(.data) - LOAD_OFFSET) { -- cgit v1.2.2