From fe251f38f10b11dedeb43525126aaf28b2b4d0de Mon Sep 17 00:00:00 2001
From: visa <visa@openbsd.org>
Date: Fri, 25 Nov 2022 14:56:56 +0000
Subject: [PATCH] Add ld.so linker script for mips64

Since the introduction of automatic immutable from the kernel, the munmap()
of ld.so boot.text region is now (silently) failing because the region is
contained within the text LOAD, which is immutable.  So create a new btext
LOAD with flags PF_X|PF_R|PF_OPENBSD_MUTABLE, and place all boot.text objects
in there.  This LOAD must also be page-aligned so it doesn't skip unmapping
some of the object region, previously it was hilariously unaligned.

OK deraadt@
---
 libexec/ld.so/mips64/Makefile.inc |  3 +-
 libexec/ld.so/mips64/ld.script    | 75 +++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 libexec/ld.so/mips64/ld.script

diff --git a/libexec/ld.so/mips64/Makefile.inc b/libexec/ld.so/mips64/Makefile.inc
index 61bba392f36..f60c19b7a9f 100644
--- a/libexec/ld.so/mips64/Makefile.inc
+++ b/libexec/ld.so/mips64/Makefile.inc
@@ -1,7 +1,8 @@
-#	$OpenBSD: Makefile.inc,v 1.8 2019/11/10 22:18:14 guenther Exp $
+#	$OpenBSD: Makefile.inc,v 1.9 2022/11/25 14:56:56 visa Exp $
 
 # no jump tables in _dl_boot_bind()
 CFLAGS += -fno-jump-tables
+LD_SCRIPT = ${.CURDIR}/${MACHINE_CPU}/ld.script
 
 CHECK_LDSO=c() {							\
 	! readelf -Wr $$1 |						\
diff --git a/libexec/ld.so/mips64/ld.script b/libexec/ld.so/mips64/ld.script
new file mode 100644
index 00000000000..2c141a6c22b
--- /dev/null
+++ b/libexec/ld.so/mips64/ld.script
@@ -0,0 +1,75 @@
+PHDRS
+{
+	rodata	PT_LOAD FILEHDR PHDRS FLAGS (4);
+	text	PT_LOAD;
+	btext	PT_LOAD FLAGS (0x08000005);
+	data	PT_LOAD;
+	random	PT_OPENBSD_RANDOMIZE;
+	relro	PT_GNU_RELRO;
+	dynamic	PT_DYNAMIC;
+	note	PT_NOTE;
+}
+
+SECTIONS
+{
+    . = 0 + SIZEOF_HEADERS;
+    /* RODATA */
+    .gnu.hash	: { *(.gnu.hash) } :rodata
+    .dynsym	: { *(.dynsym) } :rodata
+    .dynstr	: { *(.dynstr) } :rodata
+    .rodata	: { *(.rodata .rodata.*) } :rodata
+    .eh_frame	: { *(.eh_frame) } :rodata
+
+    /* TEXT */
+    . = ALIGN(0x4000);
+    .boot.text	:
+    {
+	. = ALIGN(0x4000);
+	boot_text_start = .;
+	*(.boot.text)
+	. = ALIGN(0x4000);
+	boot_text_end = .;
+    } :btext =0xefefefef
+    . = ALIGN(0x4000);
+    .text	: { *(.text .text.*) } :text =0xefefefef
+
+    /* RELRO DATA */
+    . = DATA_SEGMENT_ALIGN (0x10000, 0x4000);
+    .openbsd.randomdata :
+    {
+	*(.openbsd.randomdata .openbsd.randomdata.*)
+    } :data :relro :random
+    .data.rel.ro : { *(.data.rel.ro.local*) *(.data.rel.ro*) } :data :relro
+    .dynamic	: { *(.dynamic) } :data :relro :dynamic
+    _gp = ALIGN(16) + 0x7ff0;
+    .got	: { *(.got.plt) *(.got) } :data :relro
+    . = DATA_SEGMENT_RELRO_END (0, .);
+
+    /* BOOTDATA */
+    . = ALIGN(0x4000);
+    boot_data_start = .;
+    .rela.dyn       :
+    {
+	*(.rela.text .rela.text.*)
+	*(.rela.rodata .rela.rodata.*)
+	*(.rela.data .rela.data.*)
+	*(.rela.got)
+	*(.rela.bss .rela.bss.*)
+    } :data
+/* XXX .rela.plt is unused but cannot delete: ld.bfd zeros DT_RELASZ then! */
+    .rela.plt	: { *(.rela.plt) } :data
+    .note	: { *(.note.openbsd.*) } :data :note
+    .hash	: { *(.hash) } :data
+    .boot.data	: { *(.boot.data .boot.data.*) } :data
+    boot_data_end = .;
+
+    /* DATA */
+    . = ALIGN(0x4000);
+    .sdata	: { *(.sdata .sdata.*) } :data
+    .data	: { *(.data .data.*) } :data
+    .sbss	: { *(.sbss .sbss.*) } :data
+    .bss	: { *(.dynbss) *(.bss .bss.*) *(COMMON) } :data
+    . = DATA_SEGMENT_END (.);
+
+    /DISCARD/	: { *(.note.GNU-stack) }
+}
-- 
2.20.1