From 19edda9e59693f92b50dbac0ff131d07b57b7808 Mon Sep 17 00:00:00 2001 From: bluhm Date: Tue, 23 Jun 2015 14:19:21 +0000 Subject: [PATCH] If the kernel symbols fit completely into the 2 MB alignment hole after kernel bss but before end of the image, the page tables used the read-only mapping of the hole. When booting a small non-generic kernel, this resulted in a crash, while writing to the page tables later. Make sure that the page tables are created after esym and after end. OK mlarkin@ deraadt@ --- sys/arch/amd64/amd64/locore.S | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/sys/arch/amd64/amd64/locore.S b/sys/arch/amd64/amd64/locore.S index c264f9a2de1..c2e4d4f9508 100644 --- a/sys/arch/amd64/amd64/locore.S +++ b/sys/arch/amd64/amd64/locore.S @@ -1,4 +1,4 @@ -/* $OpenBSD: locore.S,v 1.65 2015/05/18 19:59:27 guenther Exp $ */ +/* $OpenBSD: locore.S,v 1.66 2015/06/23 14:19:21 bluhm Exp $ */ /* $NetBSD: locore.S,v 1.13 2004/03/25 18:33:17 drochner Exp $ */ /* @@ -264,6 +264,10 @@ start: movw $0x1234,0x472 # warm boot movl 8(%esp),%eax movl %eax, RELOC(bootdev) + /* + * Syms are placed after last load and bss of the kernel. + * XXX Boot ignores 2MB roundup of _end, so esyms can be < _end. + */ movl 16(%esp), %eax testl %eax,%eax jz 1f @@ -423,6 +427,9 @@ cont: testl %eax,%eax jz 1f subl $KERNBASE_LO,%eax /* XXX */ + /* Page tables must be after symbols and after kernel image. */ + cmpl %eax,%edi + jg 1f movl %eax,%edi 1: #endif -- 2.20.1