ld.so boot cleanup support:

 - put functions and data which are only used before calling the executable's
   start function into their own page-aligned segments for unmapping
   (only done on amd64, arm64, armv7, powerpc, and sparc64 so far)
 - pass .init_array and .preinit_array functions an addition argument which
   is a callback to get a structure which includes a function that frees
   the boot text and data
 - sometimes delay doing RELRO processing: for a shared-object marked
   DF_1_INITFIRST do it after the object's .init_array, for the executable
   do it after the .preinit_array
 - improve test-ld.so to link against libpthread and trigger its initialization
   late
libc changes to use this will come later

ok kettenis@

3 files changed, 76 insertions, 7 deletions

diff --git a/libexec/ld.so/amd64/Makefile.inc b/libexec/ld.so/amd64/Makefile.inc
index 94a3002bc03..cfd3018d9f8 100644
--- a/libexec/ld.so/amd64/Makefile.inc
+++ b/libexec/ld.so/amd64/Makefile.inc
@@ -1,4 +1,5 @@
-#	$OpenBSD: Makefile.inc,v 1.4 2018/04/27 06:49:06 guenther Exp $
+#	$OpenBSD: Makefile.inc,v 1.5 2019/05/10 13:29:21 guenther Exp $
 
 CFLAGS += -fPIC -mno-sse2 -mno-sse -mno-3dnow -mno-mmx
 AFLAGS += -fpic
+LD_SCRIPT = ${.CURDIR}/${MACHINE_CPU}/ld.script
diff --git a/libexec/ld.so/amd64/ld.script b/libexec/ld.so/amd64/ld.script
new file mode 100644
index 00000000000..5629239dd52
--- /dev/null
+++ b/libexec/ld.so/amd64/ld.script
@@ -0,0 +1,69 @@
+PHDRS
+{
+	rodata	PT_LOAD FILEHDR PHDRS FLAGS (4);
+	text	PT_LOAD;
+	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(0x100000) + (. & (0x100000 - 1)) +   0;
+    .boot.text	:
+    {
+	boot_text_start = .;
+	*(.boot.text)
+	boot_text_end = .;
+    } :text =0xcccccccc
+    . = ALIGN(0x1000);
+    .text	: { *(.text .text.*) } :text =0xcccccccc
+
+    /* RELRO DATA */
+    . = DATA_SEGMENT_ALIGN (0x100000, 0x1000);
+    .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
+    .got	: { *(.got.plt) *(.got) } :data :relro
+    . = DATA_SEGMENT_RELRO_END (0, .);
+
+    /* BOOTDATA */
+    . = ALIGN(0x1000);
+    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(0x1000);
+    .data	: { *(.data .data.*) } :data
+    .bss	: { *(.dynbss) *(.bss .bss.*) *(COMMON) } :data
+    . = DATA_SEGMENT_END (.);
+
+    /DISCARD/	: { *(.note.GNU-stack) }
+}
diff --git a/libexec/ld.so/amd64/ldasm.S b/libexec/ld.so/amd64/ldasm.S
index 9f18b87617a..6ae3f8de1d4 100644
--- a/libexec/ld.so/amd64/ldasm.S
+++ b/libexec/ld.so/amd64/ldasm.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ldasm.S,v 1.29 2017/08/28 14:12:09 deraadt Exp $	*/
+/*	$OpenBSD: ldasm.S,v 1.30 2019/05/10 13:29:21 guenther Exp $	*/
 
 /*
  * Copyright (c) 2002,2004 Dale Rahn
@@ -32,7 +32,7 @@
 #define DL_LOFF_OFFSET	(7*8)	/* index 7 */
 #include <machine/asm.h>
 
-	.text
+	.section .boot.text,"ax",@progbits
 	.align	16,0xcc
 	.globl	_dl_start
 	.type	_dl_start,@function
@@ -65,11 +65,9 @@ _dl_start:
 	leaq	_dl_dtors(%rip), %rdx	# %rdx = cleanup
 	movq	%r12, %rsp
 	jmp	*%rax
+END(_dl_start)
 
-	.align 16,0xcc
-	.global _dl_bind_start
-	.type _dl_bind_start,@function
-_dl_bind_start:
+_ENTRY(_dl_bind_start)
 	.cfi_startproc
 	.cfi_adjust_cfa_offset	16
 	pushfq				# save registers
@@ -143,3 +141,4 @@ _dl_bind_start:
 	.cfi_adjust_cfa_offset	-8
 	ret
 	.cfi_endproc
+END(_dl_bind_start)