From 47fbd58e4ab871f8e00a364af32dd93cd729fed3 Mon Sep 17 00:00:00 2001
From: visa <visa@openbsd.org>
Date: Sat, 6 Feb 2021 09:31:47 +0000
Subject: [PATCH] Revise kernel's ld.script on octeon

This allows more control over the structure of the linked kernel image.
Now the ELF .openbsd.randomdata segment can be omitted from BOOT kernel.
The segment has caused trouble with broken firmware when the firmware
tries to load it on top of the actual kernel segment.

Discussed with and OK deraadt@
---
 sys/arch/octeon/conf/BOOT            |  3 +-
 sys/arch/octeon/conf/Makefile.octeon | 13 ++++++-
 sys/arch/octeon/conf/ld.script       | 53 ++++++++++++++++++++++------
 3 files changed, 56 insertions(+), 13 deletions(-)

diff --git a/sys/arch/octeon/conf/BOOT b/sys/arch/octeon/conf/BOOT
index fb1a6af6d71..f27d1264e31 100644
--- a/sys/arch/octeon/conf/BOOT
+++ b/sys/arch/octeon/conf/BOOT
@@ -1,4 +1,4 @@
-#	$OpenBSD: BOOT,v 1.9 2020/10/10 10:11:54 visa Exp $
+#	$OpenBSD: BOOT,v 1.10 2021/02/06 09:31:47 visa Exp $
 
 machine		octeon mips64
 maxusers	4
@@ -7,6 +7,7 @@ option		BOOT_QUIET
 
 option		SMALL_KERNEL
 option		NO_PROPOLICE
+option		NO_RANDOMIZE
 
 option		RAMDISK_HOOKS
 option		MINIROOTSIZE=2048
diff --git a/sys/arch/octeon/conf/Makefile.octeon b/sys/arch/octeon/conf/Makefile.octeon
index 45458858677..42ccce9d995 100644
--- a/sys/arch/octeon/conf/Makefile.octeon
+++ b/sys/arch/octeon/conf/Makefile.octeon
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile.octeon,v 1.57 2021/01/28 17:39:03 deraadt Exp $
+#	$OpenBSD: Makefile.octeon,v 1.58 2021/02/06 09:31:47 visa Exp $
 
 # For instructions on building kernels consult the config(8) and options(4)
 # manual pages.
@@ -124,7 +124,18 @@ ioconf.o: ioconf.c
 	${NORMAL_C}
 
 ld.script: ${_machdir}/conf/ld.script
+.if ${IDENT:M-DNO_RANDOMIZE}
+	# Some broken firmware try to load ELF .openbsd.randomdata segment.
+	# This fails because the segment overlaps with the actual kernel
+	# ELF LOAD segment, and the firmware cannot allocate the memory region
+	# as it is already in use. Avoid this by omitting PT_OPENBSD_RANDOMIZE.
+	sed -e '/PT_OPENBSD_RANDOMIZE/d' \
+	    -e 's/ :openbsd_randomize//' \
+	    ${_machdir}/conf/ld.script > $@.tmp
+	mv $@.tmp $@
+.else
 	cp ${_machdir}/conf/ld.script $@
+.endif
 
 gapdummy.o:
 	echo '__asm(".section .rodata,\"a\"");' > gapdummy.c
diff --git a/sys/arch/octeon/conf/ld.script b/sys/arch/octeon/conf/ld.script
index 95b79541e72..9fe8c665b08 100644
--- a/sys/arch/octeon/conf/ld.script
+++ b/sys/arch/octeon/conf/ld.script
@@ -1,32 +1,63 @@
-/*	$OpenBSD: ld.script,v 1.5 2019/11/09 20:07:00 guenther Exp $	*/
+/*	$OpenBSD: ld.script,v 1.6 2021/02/06 09:31:47 visa Exp $	*/
 
 OUTPUT_FORMAT("elf64-tradbigmips")
 OUTPUT_ARCH(mips)
 ENTRY(__start)
 
+/*
+ * When the kernel is built with option NO_RANDOMIZE, PT_OPENBSD_RANDOMIZE
+ * and :openbsd_randomize are removed by the Makefile.
+ */
+
+PHDRS
+{
+	text PT_LOAD;
+	openbsd_randomize PT_OPENBSD_RANDOMIZE;
+}
+
 SECTIONS
 {
-	.text :		{ *(.text .text.* .gnu.linkonce.t.*) }
+	.text :
+	{
+		*(.text .text.* .gnu.linkonce.t.*)
+	} :text
 	PROVIDE (etext = .);
-	.rodata :	{ *(.rodata .rodata.* .gnu.linkonce.r.*) }
-	_gp = ALIGN(16) + 0x7ff0;
-	.data :		{ *(.data .data.* .gnu.linkonce.d.*) }
-	__kernel_randomdata = .;
+	.rodata :
+	{
+		*(.rodata .rodata.* .gnu.linkonce.r.*)
+	} :text
+
+	. = ALIGN(8);
+	PROVIDE (__kernel_randomdata = .);
 	.openbsd.randomdata :
 	{
-		/* XXX shouldn't this be placed next to rodata? */
 		__retguard_start = ABSOLUTE(.);
 		*(.openbsd.randomdata.retguard .openbsd.randomdata.retguard.*)
 		/* XXX . = ALIGN(0x1000); */
 		__retguard_end = ABSOLUTE(.);
 		*(.openbsd.randomdata .openbsd.randomdata.*)
-	}
-	__kernel_randomdata_end = .;
+	} :text :openbsd_randomize
+	. = ALIGN(8);
+	PROVIDE (__kernel_randomdata_end = .);
+
+	_gp = ALIGN(16) + 0x7ff0;
+	.data :
+	{
+		*(.data .data.* .gnu.linkonce.d.*)
+	} :text
 	PROVIDE (edata = .);
-	.sbss :		{ *(.sbss .sbss.* .gnu.linkonce.sb.* .scommon) }
-	.bss :		{ *(.bss .bss.* .gnu.linkonce.b.* COMMON) }
+	.sbss :
+	{
+		*(.sbss .sbss.* .gnu.linkonce.sb.* .scommon)
+	}
+	.bss :
+	{
+		*(.bss .bss.* .gnu.linkonce.b.* COMMON)
+	}
+	. = ALIGN(8);
 	PROVIDE (_end = .);
 	PROVIDE (end = .);
+
 	/DISCARD/ :
 	{
 		*(.pdr)
-- 
2.20.1