Get binaries closer to running without an o/s

blinkenlights now does a pretty good job emulating what happens when binaries boot from BIOS into long mode. So it's been much easier to debug the bare metal process and wrinkle out many issues.
2 years ago · 2d80bbc802
parent feed0d2b0e
commit 2d80bbc802
50 changed files with 973 additions and 1061 deletions
--- a/ape/ape.S
+++ b/ape/ape.S
@ -45,8 +45,11 @@
 #include "libc/nexgen32e/vidya.h"
 #include "libc/nt/pedef.h"
 #include "libc/nexgen32e/vidya.h"
+#include "libc/dce.h"
 #include "libc/sysv/consts/prot.h"

+#define USE_SYMBOL_HACK 0
+
 	.source	"NOTICE"
 	.source	"ape/ape.S"
 	.source	"ape/ape.lds"
@ -179,6 +182,10 @@ stub:	mov	$0x40,%dl		# *literally* dos
 /	@noreturn
 	.code16
 pc:	cld
+#if USE_SYMBOL_HACK
+	.byte	0x0f,0x1f,0207			# nop rdi binbase
+	.short	(0x7c00-IMAGE_BASE_VIRTUAL)/512
+#endif
 	mov	$REAL_STACK_FRAME>>4,%di	# we need a stack
 	xor	%cx,%cx
 	rlstack	%di,%cx
@ -197,6 +204,10 @@ pc:	cld
 	xor	%di,%di
 	rep
 	movsb	%ds:(%si),%es:(%di)
+#if USE_SYMBOL_HACK
+	.byte	0x0f,0x1f,0207			# nop rdi binbase
+	.short	(IMAGE_BASE_REAL-0x7c00)/512
+#endif
 	ljmp	$0,$REAL(1f)			# longjmp()
 1:	mov	$-512,%cx			# memcpy() [relocate this frame]
 	rep
@ -932,9 +943,6 @@ ape.str:
 .Lstr.long:
 	.asciz	"nolong"
 	.endobj	.Lstr.long
-.Lstr.hello:
-	.asciz	"hello\n"
-	.endobj	.Lstr.hello
 	.endobj	ape.str

 /	Serial Line Configuration (8250 UART 16550)
@ -964,7 +972,7 @@ sconf:	.short	1843200/*hz*/ / 16/*wut*/ / 9600/*baud*/
 	.align	8
 gdt:	.short	2f-1f		# table byte length
 	.long	REAL(1f),0	# table address
-	.align	8
+	.zero	2
 1:
 /	          ┌G:granularity (1 → limit *= 0x1000)
 /	          │┌D/B:default operation size (0 = 16|64bit, 1 = 32-bit)
@ -1047,13 +1055,8 @@ ape.grub.entry:
 	nop
 	nop
 realmodeloader:
-	push	%bp
-	mov	%sp,%bp
 	call	rlinit
 	call	sinit4
-	call	vinit
-	mov	%es,XLM(VIDEO_POSITION_FAR_POINTER)
-	mov	%ax,XLM(VIDEO_POSITION_FAR_POINTER)+2
 	mov	$REAL(.Lstr.ape),%di
 	call	rvputs
 	.optfn	_start16
@ -1062,38 +1065,29 @@ realmodeloader:
 	.endfn	realmodeloader,globl,hidden

 	.section .sort.text.real.init.1,"ax",@progbits
-	.type	rrinit,@function
-rlinit:	push	%bp
-	mov	%sp,%bp
-	.previous/*
+	.type	rlinit,@function
+rlinit:	.previous/*
 	...
 	decentralized function
 	...
 	*/.section .sort.text.real.init.3,"ax",@progbits
-	pop	%bp
 	ret
 	.previous

 /	Initializes present PC serial lines.
-sinit4:	push	%bp
-	mov	%sp,%bp
-	movw	$4,%cx
-	movw	$kBiosDataAreaXlm+COM1,%si
-0:	lodsb
-	mov	%al,%dl
-	lodsb
-	mov	%al,%dh
-	test	%dx,%dx
+sinit4:	mov	$4,%cx
+	mov	$kBiosDataAreaXlm+COM1,%si
+0:	lodsw
+	test	%ax,%ax
 	jz	1f
 	push	%cx
 	push	%si
-	mov	%dx,%di
-	movw	$REAL(sconf),%si
+	xchg	%ax,%di
+	mov	$REAL(sconf),%si
 	call	sinit
 	pop	%si
 	pop	%cx
 1:	loop	0b
-	pop	%bp
 	ret
 	.endfn	sinit4,global,hidden

@ -1103,9 +1097,7 @@ sinit4:	push	%bp
 /	@param	char (*{es:,e,r}si)[4] register initial values
 /	@mode	long,legacy,real
 /	@see	www.lammertbies.nl/comm/info/serial-uart.html
-sinit:	push	%bp
-	mov	%sp,%bp
-	mov	%di,%dx
+sinit:	mov	%di,%dx
 	test	%dx,%dx
 	jz	2f
 	push	%dx
@ -1123,8 +1115,7 @@ sinit:	push	%bp
 	add	$1,%dx
 	sub	$1,%cx
 	jns	1b
-2:	pop	%bp
-	ret
+2:	ret
 	.endfn	sinit,global,hidden

 /	Abnormally exits program.
@ -1132,9 +1123,7 @@ sinit:	push	%bp
 /	@param	di message
 /	@mode	real
 /	@noreturn
-rldie:	push	%bp
-	mov	%sp,%bp
-	call	rlpute
+rldie:	call	rlpute
 	call	rloff
 	.endfn	rldie,globl,hidden

@ -1142,9 +1131,7 @@ rldie:	push	%bp
 /
 /	@mode	real
 /	@noreturn
-rloff:	push	%bp
-	mov	%sp,%bp
-	mov	$kBiosDataAreaXlm+COM1,%di
+rloff:	mov	$kBiosDataAreaXlm+COM1,%di
 	mov	$4,%si
 	call	sflush
 	call	apmoff
@ -1154,9 +1141,7 @@ rloff:	push	%bp
 /
 /	@param	di message
 /	@mode	real
-rlpute:	push	%bp
-	mov	%sp,%bp
-	mov	kBiosDataAreaXlm+METAL_STDERR(%bx),%si
+rlpute:	mov	kBiosDataAreaXlm+METAL_STDERR(%bx),%si
 	test	%si,%si
 	jnz	1f
 	mov	kBiosDataAreaXlm+METAL_STDOUT,%si
@ -1176,8 +1161,7 @@ rlpute:	push	%bp
 	pop	%si
 	call	rlput2
 	jmp	1b
-2:	pop	%bp
-	ret
+2:	ret
 	.endfn	rlpute,globl,hidden

 /	Prints string to both video and serial.
@ -1185,9 +1169,7 @@ rlpute:	push	%bp
 /	@param	di NUL-terminated string
 /	@param	si serial port
 /	@mode	real
-rlput2:	push	%bp
-	mov	%sp,%bp
-	push	%di
+rlput2:	push	%di
 	push	%si
 	call	rvputs
 	pop	%si
@ -1195,33 +1177,42 @@ rlput2:	push	%bp
 	test	%si,%si
 	jz	1f
 	call	sputs
-1:	pop	%bp
-	ret
+1:	ret
 	.endfn	rlput2,globl,hidden

 /	Video put string.
 /
 /	@param	di is the string
 /	@mode	real
-rvputs:	push	%bp
-	mov	%sp,%bp
-	mov	%di,%si
-	les	XLM(VIDEO_POSITION_FAR_POINTER),%di
-	call	vputs
-	mov	%es,XLM(VIDEO_POSITION_FAR_POINTER)
-	mov	%ax,XLM(VIDEO_POSITION_FAR_POINTER)+2
-	pop	%bp
-	ret
+rvputs:	mov	%di,%si
+0:	lodsb
+	test	%al,%al
+	je	1f
+	call	rvputc
+	jmp	0b
+1:	ret
 	.endfn	rvputs,globl,hidden

+/	Video put char.
+/
+/	@param	al is the char
+/	@mode	real
+rvputc:	push	%bx				# don't clobber bp,bx,di,si,cx
+	push	%bp				# original ibm pc scroll up bug
+	mov	$7,%bx				# normal mda/cga style page zero
+	mov	$0x0e,%ah			# teletype output al cp437
+	int	$0x10				# vidya service
+	pop	%bp				# preserves al
+	pop	%bx
+	ret
+	.endfn	rvputc
+
 /	Writes string to serial line.
 /
 /	@param	di NUL-terminated string
 /	@param	si serial port
 /	@mode	long,legacy,real
-sputs:	push	%bp
-	mov	%sp,%bp
-	push	%bx
+sputs:	push	%bx
 	mov	%di,%bx
 1:	xchg	%bx,%si
 	lodsb
@ -1234,7 +1225,6 @@ sputs:	push	%bp
 	pop	%si
 	jmp	1b
 2:	pop	%bx
-	pop	%bp
 	ret
 	.endfn	sputs,globl

@ -1290,137 +1280,11 @@ sputc:	push	%ax
 	ret
 	.endfn	sputc,globl

-/	Asks BIOS to initialize Monochrome Display Adapter.
-/
-/	@return	es:ax	start of video page
-/	@mode	real
-vinit:	push	$7
-	pop	%ax
-	int	$VIDYA_SERVICE
-	bbmov	VIDYA_ADDR_MDA>>4,%ax,%ah,%al
-	mov	%ax,%es
-	xor	%ax,%ax
-	ret
-	.endfn	vinit,globl
-
-/	Prints byte to display w/ teletype emulation.
-/
-/	@param	es:di	screen position
-/	@param	sil	byte
-/	@return	es:ax	new screen position
-/	@mode	long,legacy,real
-vputc:	push	%bp
-	mov	%sp,%bp
-	sub	$16,%sp			# goal is to turn sil into a buffer
-	xchg	%si,%ax			# modrm sooo different in real mode
-	mov	%di,%cx
-	mov	%sp,%si
-	mov	%sp,%di
-	stosb
-	mov	%cx,%di
-	pushpop	1,%dx
-	jmp	23f
-
-/	Prints string to display w/ teletype emulation.
-/
-/	@param	es:di	screen position
-/	@param	si	NUL-terminated string
-/	@return	es:ax	new screen position
-/	@mode	long,legacy,real
-vputs:	push	%si			# inlined strlen
-1:	lodsb
-	test	%al,%al
-	jnz	1b
-	mov	%si,%dx
-	pop	%si
-	sub	%si,%dx
-/	fallthrough
-
-/	Prints data to display w/ teletype emulation.
-/
-/	@param	es:di	screen position
-/	@param	si	data address
-/	@param	dx	data size in bytes
-/	@return	es:ax	new screen position
-/	@mode	long,legacy,real
-vtput:	push	%bp
-	mov	%sp,%bp
-23:	push	%bx
-	mov	%dx,%cx
-	mov	%di,%dx
-	bband	VIDYA_REWIND,%dh,%dl
-	bbadd	VIDYA_SIZE,%dh,%dl
-	bbmov	VIDYA_COLUMNS*2-2,%bx,%bh,%bl
-0:	cmp	%dx,%di
-	je	6f
-	ja	3f
-	lodsb				# todo: utf8 → cp437
-	cmp	$'\n,%al
-	je	4f
-	cmp	$'\r,%al
-	je	5f
-1:	stosb
-	mov	$VIDYA_ATTR_NORMAL,%al	# todo: ansi color
-	stosb
-2:	loop	0b
-3:	mov	%di,%ax
-	pop	%bx
-	pop	%bp
-	ret
-4:	add	%bx,%di			# line feed
-	jmp	2b
-5:	mov	%di,%ax			# carriage return
-	push	%dx
-	xor	%dx,%dx
-	idiv	%bx			# todo: division is deprecated
-	sub	%dx,%di
-	pop	%dx
-	jmp	2b
-6:	push	%ax
-	push	%cx
-	push	%dx
-	push	%si
-	mov	%bx,%si
-	rlcall	vscroll
-	mov	%ax,%di
-	pop	%si
-	pop	%dx
-	pop	%cx
-	pop	%ax
-	jmp	2b
-	.endfn	vtput,globl
-	.endfn	vputs,globl
-	.endfn	vputc,globl
-
-/	Scrolls up content in display page.
-/
-/	@param	es:di	cursor address (bytes after aren't moved)
-/	@param	si	byte difference, e.g. VIDYA_COLUMNS*2
-/	@return	es:ax	new cursor address (which is es:di-si)
-/	@mode	long,legacy,real
-vscroll:not	%dx
-	mov	%di,%cx
-	bband	VIDYA_REWIND,%ch,%cl
-	xchg	%cx,%di		# di is now page addr, i.e. top-left
-	sub	%si,%cx		# cx is now future cursor address
-	push	%cx
-	sub	%di,%cx		# cx is now memcpy size
-	mov	%di,%si
-	add	%cx,%si
-	mov	$0,%ax
-	movpp	%ds,%es
-	rep movsb
-	pop	%ax
-	ret
-	.endfn	vscroll,globl
-
 /	Shuts down personal computer.
 /
 /	@mode	real
 /	@noreturn
-apmoff:	push	%bp
-	mov	%sp,%bp
-	mov	$0x5300,%ax		# apm installation check
+apmoff:	mov	$0x5300,%ax		# apm installation check
 	xor	%bx,%bx			# for the apm bios itself
 	int	$APM_SERVICE
 	jc	1f
@ -1485,8 +1349,6 @@ apmoff:	push	%bp
 	long mode is long */

 longmodeloader:
-	push	%bp
-	mov	%sp,%bp
 	call	lcheck
 	call	a20
 	mov	$XLM(E820),%di
@ -1495,15 +1357,13 @@ longmodeloader:
 	jc	9f
 	call	unreal
 	call	hiload
-	call	golong
+	jmp	golong
 9:	mov	$REAL(.Lstr.e820),%ax
 	call	rldie
 	.endfn	longmodeloader,globl,hidden

 /	Long Mode Hardware Check
-lcheck:	push	%bp
-	mov	%sp,%bp
-	pushf				# check for i8086 / i8088 / i80186
+lcheck:	pushf				# check for i8086 / i8088 / i80186
 	pop	%ax
 	test	$0x80,%ah		# see intel manual volume 1 20.1.2
 	jnz	9f			# we now assume 32bit is supported
@ -1534,8 +1394,7 @@ lcheck:	push	%bp
 	cmp	%edi,%edx
 	jne	10f
 	xor	%ax,%ax
-1:	pop	%bp
-	ret
+1:	ret
 9:	mov	$REAL(.Lstr.oldskool),%ax
 	jmp	20f
 10:	mov	$REAL(.Lstr.long),%ax
@ -1587,9 +1446,7 @@ e820:	push	%bp

 /	Unreal Mode.
 /	Makes 4gb of real memory accessible via %fs segment.
-unreal:	push	%bp
-	mov	%sp,%bp
-	cli
+unreal:	cli
 	lgdt	REAL(gdt)
 	mov	%cr0,%eax
 	or	$CR0_PE,%al
@ -1599,16 +1456,13 @@ unreal:	push	%bp
 	mov	%cx,%fs
 	and	$~CR0_PE,%al
 	mov	%eax,%cr0
-	ljmpl	$0,$REAL(1f)
+	ljmp	$0,$REAL(1f)
 1:	sti
-	pop	%bp
 	ret
 	.endfn	unreal

 /	Loads remainder of executable off disk.
-hiload:	push	%bp
-	mov	%sp,%bp
-	push	%bx
+hiload:	push	%bx
 	mov	$IMAGE_BASE_REAL,%esi		# relocate, again
 	mov	$IMAGE_BASE_PHYSICAL,%ebx
 	mov	$v_ape_realsectors,%ecx
@ -1647,7 +1501,6 @@ hiload:	push	%bp
 	pop	%cx
 	jmp	0b
 9:	pop	%bx
-	pop	%bp
 	ret
 	.endfn	hiload

@ -1724,18 +1577,16 @@ a20:	cli
 /	stack segment base. This function only defines enough tables
 /	to get us started.
 #define	TIP REAL_STACK_FRAME
-pinit:	push	%bp
-	mov	%sp,%bp
-	push	%ds
+pinit:	push	%ds
 	mov	$(TIP-0x4000)>>4,%ax
 	mov	%ax,%ds
-	movl	$TIP-0x2000+PAGE_V+PAGE_RW,%ds:0x3000		# PML4T→PDPT
-	movl	$TIP-0x3000+PAGE_V+PAGE_RW,%ds:0x2000		# PDPT→PDT
-	movl	$TIP-0x4000+PAGE_V+PAGE_RW,%ds:0x1000		# PDT→PD
+	movl	$TIP-0x2000+PAGE_V+PAGE_RW,0x3000		# PML4T→PDPT
+	movl	$TIP-0x3000+PAGE_V+PAGE_RW,0x2000		# PDPT→PDT
+	movl	$TIP-0x4000+PAGE_V+PAGE_RW,0x1000		# PDT→PD
 	mov	$0x100000/0x1000,%cx				# PD→512kb
 	mov	$PAGE_V+PAGE_RW,%eax
 	xor	%si,%si
-0:	mov	%eax,%ds:(%si)
+0:	mov	%eax,(%si)
 	add	$0x1000,%eax
 	add	$8,%si
 	loop	0b
@ -1743,7 +1594,6 @@ pinit:	push	%bp
 	movl	$TIP-0x4000,XLM(PAGE_TABLE_STACK_POINTER)	# STACK→XLM
 	mov	$TIP-0x1000,%eax				# PML4T→CR3
 	mov	%eax,%cr3
-	pop	%bp
 	ret
 	.endfn	pinit,globl,hidden

@ -1765,44 +1615,47 @@ golong:	cli
 	or	$CR0_PE|CR0_PG|CR0_MP,%eax
 	and	$~CR0_EM,%eax
 	mov	%eax,%cr0
-	ljmp	$GDT_LONG_CODE,$REAL(1f)
-	.code64
-1:	mov	$GDT_LONG_DATA,%eax
-	mov	%ax,%ds
-	mov	%ax,%fs
-	mov	%ax,%gs
-	xor	%edx,%edx
-	jmp	long
+	ljmp	$GDT_LONG_CODE,$REAL(long)
 	.endfn	golong

 /	Long mode is long.
-/
 /	@noreturn
-long:	.frame0
-	xor	%edi,%edi
-	call	pageunmap
-
-	mov	$e820map_xlm,%edi
-	call	smapsort
-
-	mov	$e820map_xlm,%edi
-	mov	$g_pml4t,%esi
-	mov	$g_ptsp_xlm,%edx
-	call	flattenhighmemory
-
-	mov	$REAL(.Lstr.hello),%edi
-	mov	kBiosDataAreaXlm+METAL_STDOUT,%esi
-	call	sputs
-	mov	$kBiosDataAreaXlm+METAL_STDOUT,%edi
-	mov	$4,%esi
-	call	sflush
-
-	jmp	triplf
-	lea	triplf(%rip),%rdx
-	call	_start
-	jmp	triplf
+	.code64
+long:	push	$GDT_LONG_DATA
+	pop	%rax
+	mov	%eax,%ds
+	mov	%eax,%ss
+	mov	%eax,%es
+	mov	%eax,%fs
+	mov	%eax,%gs
+	xor	%ebp,%ebp
+	mov	$REAL_STACK_FRAME+FRAMESIZE,%esp
+	call	__map_image
+	mov	$_metal,%eax
+	jmp	*%rax
 	.endfn	long

+/	Long mode in virtual address space.
+/	@noreturn
+_metal:
+#if USE_SYMBOL_HACK
+	.byte	0x0f,0x1f,0207			# nop rdi binbase
+	.long	(IMAGE_BASE_VIRTUAL-IMAGE_BASE_REAL)/512
+#endif
+	xor	%eax,%eax			# clear bss
+	mov	$.Lape.bss.vaddr,%edi
+	mov	$.Lape.bss.memsz,%ecx
+	rep stosb
+	movb	$METAL,hostos(%rip)
+	push	$0				# auxv
+	push	$0
+	push	$0				# envp
+	push	$0				# auxv
+	push	$0				# argc
+	xor	%edi,%edi
+	jmp	_start
+	.endfn	_metal
+
 /	Avoid linker script variables appearing as code in objdump.
 	.macro	.ldsvar	name:req
 	.type	\name,@object
--- a/ape/config.h
+++ b/ape/config.h
@ -32,7 +32,7 @@
 #define METAL_STDOUT COM1
 #endif
 #ifndef METAL_STDERR
-#define METAL_STDERR COM2 /* will fallback to stdout if COM2 not present */
+#define METAL_STDERR COM1
 #endif

 /**
--- a/ape/lib/getpagetableentry.c
+++ b/ape/lib/getpagetableentry.c
@ -24,14 +24,16 @@ textreal static uint64_t pushpagetable(uint64_t *ptsp) {
  return (*ptsp -= PAGESIZE) | PAGE_V | PAGE_RW;
 }

-textreal uint64_t *getpagetableentry(uint64_t vaddr, unsigned depth,
+textreal uint64_t *getpagetableentry(int64_t vaddr, unsigned depth,
                                     struct PageTable *pml4t, uint64_t *ptsp) {
+  uint64_t *entry;
+  unsigned char shift;
  assert(depth <= 3);
-  assert(*ptsp % PAGESIZE == 0);
-  assert((intptr_t)pml4t % PAGESIZE == 0);
-  unsigned char shift = 39;
+  assert(!(*ptsp & 0xfff));
+  assert(!((uintptr_t)pml4t & 0xfff));
+  shift = 39;
  for (;;) {
-    uint64_t *entry = &pml4t->p[(vaddr >> shift) & 511];
+    entry = &pml4t->p[(vaddr >> shift) & 511];
    if (!depth--) return entry;
    shift -= 9;
    if (!*entry) *entry = pushpagetable(ptsp);
--- a/ape/lib/kbiosdataarea.S
+++ b/ape/lib/kbiosdataarea.S
@ -37,7 +37,7 @@
 	.size	kBiosDataAreaXlm,XLM_BIOS_DATA_AREA_SIZE
 	kBiosDataAreaXlm = XLM(BIOS_DATA_AREA)

-	.section .sort.real.init.2.kBiosDataArea,"ax",@progbits
+	.section .sort.text.real.init.2.kBiosDataArea,"ax",@progbits
 	movpp	%ds,%es			# copy bios data to valid page
 	mov	$PC_BIOS_DATA_AREA,%si
 	mov	$XLM(BIOS_DATA_AREA),%di
--- a/ape/lib/mapimage.c
+++ b/ape/lib/mapimage.c
@ -0,0 +1,38 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ This program is free software; you can redistribute it and/or modify         │
+│ it under the terms of the GNU General Public License as published by         │
+│ the Free Software Foundation; version 2 of the License.                      │
+│                                                                              │
+│ This program is distributed in the hope that it will be useful, but          │
+│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
+│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
+│ General Public License for more details.                                     │
+│                                                                              │
+│ You should have received a copy of the GNU General Public License            │
+│ along with this program; if not, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "ape/lib/pc.h"
+#include "ape/relocations.h"
+#include "libc/runtime/runtime.h"
+
+textreal static void __map_segment(uint64_t k, uint64_t a, uint64_t b) {
+  uint64_t *e;
+  for (; a < b; a += 0x1000) {
+    e = getpagetableentry(IMAGE_BASE_VIRTUAL + a, 3, &g_pml4t, &g_ptsp_xlm);
+    *e = (IMAGE_BASE_PHYSICAL + a) | k;
+  }
+}
+
+textreal void __map_image(void) {
+  pageunmap(0);
+  __map_segment(PAGE_V | PAGE_U, 0, (uintptr_t)_etext - IMAGE_BASE_VIRTUAL);
+  __map_segment(PAGE_V | PAGE_U | PAGE_RW | PAGE_XD,
+                (uintptr_t)_etext - IMAGE_BASE_VIRTUAL,
+                (uintptr_t)_end - IMAGE_BASE_VIRTUAL);
+}
--- a/ape/lib/pageunmap.c
+++ b/ape/lib/pageunmap.c
@ -20,8 +20,9 @@
 #include "ape/lib/pc.h"
 #include "libc/bits/bits.h"

-textreal void pageunmap(uint64_t vaddr) {
-  uint64_t *entry = getpagetableentry(vaddr, 3, &g_pml4t, &g_ptsp_xlm);
+textreal void pageunmap(int64_t vaddr) {
+  uint64_t *entry;
+  entry = getpagetableentry(vaddr, 3, &g_pml4t, &g_ptsp_xlm);
  *entry &= ~PAGE_V;
  invlpg(vaddr);
 }
--- a/ape/lib/pc.h
+++ b/ape/lib/pc.h
@ -157,6 +157,7 @@
 #define PAGE_1GB /*                                    */ 0b110000000
 #define PAGE_TA  0b11111111111111111111111111111111111111000000000000
 #define PAGE_PA2 0b11111111111111111111111111111000000000000000000000
+#define PAGE_XD  0x8000000000000000

 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 #include "ape/config.h"
@ -213,9 +214,9 @@ extern uint64_t g_ptsp_xlm;
 void bootdr(char drive) noreturn;

 void smapsort(struct SmapEntry *);
-uint64_t *getpagetableentry(uint64_t, unsigned, struct PageTable *, uint64_t *);
+uint64_t *getpagetableentry(int64_t, unsigned, struct PageTable *, uint64_t *);
 void flattenhighmemory(struct SmapEntry *, struct PageTable *, uint64_t *);
-void pageunmap(uint64_t);
+void pageunmap(int64_t);

 forceinline unsigned long eflags(void) {
  unsigned long res;
--- a/examples/hidecursor.c
+++ b/examples/hidecursor.c
@ -1,26 +0,0 @@
-#if 0
-/*─────────────────────────────────────────────────────────────────╗
-│ To the extent possible under law, Justine Tunney has waived      │
-│ all copyright and related or neighboring rights to this file,    │
-│ as it is written in the following disclaimers:                   │
-│   • http://unlicense.org/                                        │
-│   • http://creativecommons.org/publicdomain/zero/1.0/            │
-╚─────────────────────────────────────────────────────────────────*/
-#endif
-#include "libc/nt/console.h"
-#include "libc/nt/runtime.h"
-#include "libc/nt/struct/consolecursorinfo.h"
-#include "libc/nt/synchronization.h"
-
-int main(int argc, char *argv[]) {
-  struct NtConsoleCursorInfo ntcursor;
-  SleepEx(1000, false);
-  GetConsoleCursorInfo(GetStdHandle(kNtStdOutputHandle), &ntcursor);
-  ntcursor.bVisible = false;
-  SetConsoleCursorInfo(GetStdHandle(kNtStdOutputHandle), &ntcursor);
-  SleepEx(1000, false);
-  ntcursor.bVisible = true;
-  SetConsoleCursorInfo(GetStdHandle(kNtStdOutputHandle), &ntcursor);
-  SleepEx(1000, false);
-  return 0;
-}
--- a/examples/package/build.mk
+++ b/examples/package/build.mk
@ -27,7 +27,7 @@ EXAMPLES_PACKAGE_FILES := $(wildcard examples/package/*)
 # Defines sets of files without needing further iops.
 EXAMPLES_PACKAGE_SRCS = $(filter %.c,$(EXAMPLES_PACKAGE_FILES))
 EXAMPLES_PACKAGE_HDRS = $(filter %.h,$(EXAMPLES_PACKAGE_FILES))
-EXAMPLES_PACKAGE_COMS = $(EXAMPLES_PACKAGE_OBJS:%.o=%.com)
+EXAMPLES_PACKAGE_COMS = $(EXAMPLES_PACKAGE_SRCS:%.c=o/$(MODE)/%.com)
 EXAMPLES_PACKAGE_BINS =					\
 	$(EXAMPLES_PACKAGE_COMS)			\
 	$(EXAMPLES_PACKAGE_COMS:%=%.dbg)
--- a/libc/calls/hefty/spawnve-sysv.c
+++ b/libc/calls/hefty/spawnve-sysv.c
@ -84,7 +84,7 @@ int spawnve$sysv(unsigned flags, int stdiofds[3], const char *program,
  }

  if (pid != -1) {
-    if ((pid = fork$sysv()) == 0) {
+    if ((pid = vfork()) == 0) {
      if (flags & SPAWN_DETACH) {
        if (setsid() == -1) abort();
        if ((rc = fork$sysv()) == -1) abort();
--- a/libc/calls/kntwindowsdirectory.S
+++ b/libc/calls/kntwindowsdirectory.S
@ -17,6 +17,7 @@
 │ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
 │ 02110-1301 USA                                                               │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/dce.h"
 #include "libc/macros.h"
 .source	__FILE__

--- a/libc/crt/crt.S
+++ b/libc/crt/crt.S
@ -40,7 +40,8 @@ _start:	test	%rdi,%rdi
 	lea	24(%rsp,%rbx,8),%rdx		# envp
 	.frame0
 /	bofram	9f
-	.weak	idata.iat,idata.iatend
+	.weak	idata.iat
+	.weak	idata.iatend
 	ezlea	missingno,ax			# make win32 imps noop
 	ezlea	idata.iat,di
 	ezlea	idata.iatend,cx
--- a/libc/log/asan.c
+++ b/libc/log/asan.c
@ -140,6 +140,7 @@ static const char *__asan_describe_access_poison(int c) {
    case kAsanUnscoped:
      return "unscoped";
    default:
+      DebugBreak();
      return "poisoned";
  }
 }
--- a/libc/macros.inc
+++ b/libc/macros.inc
@ -186,11 +186,6 @@
 .endif
 .endm

-/	Custom emulator instruction for bottom stack frame.
-.macro	bofram	endfunc:req
-	.byte	0x0f,0x1f,0x45,\endfunc-.	# nopl disp8(%rbp)
-.endm
-
 /	Overrides LOOP instruction.
 /	With its mop-Fusion Mexican equivalent.
 /	Thus avoiding 3x legacy pipeline slowdown.
@ -330,3 +325,8 @@ _init_\name:
 	call	*\symbol(%rip)
 	add	$32,%rsp
 .endm
+
+/	Custom emulator instruction for bottom stack frame.
+.macro	bofram	endfunc:req
+	.byte	0x0f,0x1f,0105,\endfunc-.	# nopl disp8(%rbp)
+.endm
--- a/libc/nexgen32e/rdtscp.h
+++ b/libc/nexgen32e/rdtscp.h
@ -1,5 +1,6 @@
 #ifndef COSMOPOLITAN_LIBC_NEXGEN32E_RDTSCP_H_
 #define COSMOPOLITAN_LIBC_NEXGEN32E_RDTSCP_H_
+#include "libc/bits/bits.h"
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_

@ -32,17 +33,26 @@ COSMOPOLITAN_C_START_
 */
 #define rdpid()                                                           \
  ({                                                                      \
+    bool Ok;                                                              \
    long Msr;                                                             \
+    Ok = false;                                                           \
    if (X86_HAVE(RDPID)) {                                                \
      asm volatile("rdpid\t%0" : "=r"(Msr) : /* no inputs */ : "memory"); \
+      Ok = true;                                                          \
    } else if (IsLinux()) {                                               \
-      asm volatile("lsl\t%1,%0" : "=r"(Msr) : "r"(0x7b) : "memory");      \
-    } else if (X86_HAVE(RDTSCP)) {                                        \
+      asm volatile(ZFLAG_ASM("lsl\t%2,%1")                                \
+                   : ZFLAG_CONSTRAINT(Ok), "=r"(Msr)                      \
+                   : "r"(0x7b)                                            \
+                   : "memory");                                           \
+    }                                                                     \
+    if (!Ok && X86_HAVE(RDTSCP)) {                                        \
      asm volatile("rdtscp"                                               \
                   : "=c"(Msr)                                            \
                   : /* no inputs */                                      \
                   : "eax", "edx", "memory");                             \
-    } else {                                                              \
+      Ok = true;                                                          \
+    }                                                                     \
+    if (!Ok) {                                                            \
      Msr = -1;                                                           \
    }                                                                     \
    Msr;                                                                  \
--- a/libc/nexgen32e/uart.h
+++ b/libc/nexgen32e/uart.h
@ -1,38 +1,3 @@
-/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
-│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8                                :vi│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ This program is free software; you can redistribute it and/or modify         │
-│ it under the terms of the GNU General Public License as published by         │
-│ the Free Software Foundation; version 2 of the License.                      │
-│                                                                              │
-│ This program is distributed in the hope that it will be useful, but          │
-│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
-│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
-│ General Public License for more details.                                     │
-│                                                                              │
-│ You should have received a copy of the GNU General Public License            │
-│ along with this program; if not, write to the Free Software                  │
-│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
-│ 02110-1301 USA                                                               │
-╠──────────────────────────────────────────────────────────────────────────────╣
-│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░█▀█░█▀█░▀█▀░█░█░█▀█░█░░░█░░░█░█░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░█▀█░█░▄░░█░░█░█░█▀█░█░░░█░░░▀█▀░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░▀░▀░▀▀▀░░▀░░▀▀▀░▀░▀░▀▀▀░▀▀▀░░▀░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░█▀█░█▀█░█▀█░▀█▀░█▀█░█▀█░█░░░█▀▀░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░█▀▀░█ █░██▀░░█░░█▀█░█▀█░█░░░█▀▀░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░▀░░░▀▀▀░▀░▀░░▀░░▀░▀░▀▀▀░▀▀▀░▀▀▀░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
-│░░░░░░░█▀▀░█░█░█▀▀░█▀█░█░█░▀█▀░█▀█░█▀█░█░░█▀▀░░░░░░░░░░░░░░░░░░░░░░░░▄▄░░░▐█░░│
-│░░░░░░░█▀▀░▄▀▄░█▀▀░█░▄░█░█░░█░░█▀█░█▀█░█░░█▀▀░░░░░░░░░░░░▄▄▄░░░▄██▄░░█▀░░░█░▄░│
-│░░░░░░░▀▀▀░▀░▀░▀▀▀░▀▀▀░▀▀▀░░▀░░▀░▀░▀▀▀░▀▀░▀▀▀░░░░░░░░░░▄██▀█▌░██▄▄░░▐█▀▄░▐█▀░░│
-│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░▐█▀▀▌░░░▄▀▌░▌░█░▌░░▌░▌░░│
-╠──────────────────────────────────────────────────────▌▀▄─▐──▀▄─▐▄─▐▄▐▄─▐▄─▐▄─│
-│ αcτµαlly pδrταblε εxεcµταblε § telecommunications                            │
-╚─────────────────────────────────────────────────────────────────────────────*/
 #ifndef COSMOPOLITAN_LIBC_NEXGEN32E_UART_H_
 #define COSMOPOLITAN_LIBC_NEXGEN32E_UART_H_

@ -53,22 +18,23 @@
 * @see www.lammertbies.nl/comm/info/serial-uart.html
 */

-#define COM1 0x0 /* offset in pc bios data area with port number (0x400) */
-#define COM2 0x2
-#define COM3 0x4
-#define COM4 0x6
-#define IRQ3 0x0b            /* com2 interrupt number (irq3) */
-#define IRQ4 0x0c            /* com1 interrupt number (irq4) */
-#define UART_DLAB (1 << 7)   /* serial line conf mode bit */
-#define UART_DLL 0           /* divisor latch register */
-#define UART_DLM 1           /* divisor latch register */
-#define UART_IIR 2           /* interrupt identification register */
-#define UART_LCR 3           /* line control register */
-#define UART_LSR 5           /* line status register */
-#define UART_TTYDA (1 << 0)  /* data available (rx ready) */
-#define UART_TTYOE (1 << 1)  /* overrun error */
-#define UART_TTYPE (1 << 2)  /* parity error */
-#define UART_TTYFE (1 << 3)  /* framing error */
+#define COM1        0x0 /* offset in pc bios data area with port number (0x400) */
+#define COM2        0x2
+#define COM3        0x4
+#define COM4        0x6
+#define IRQ3        0x0b     /* com2 interrupt number (irq3) */
+#define IRQ4        0x0c     /* com1 interrupt number (irq4) */
+#define UART_DLAB   (1 << 7) /* serial line conf mode bit */
+#define UART_DLL    0        /* divisor latch register */
+#define UART_DLM    1        /* divisor latch register */
+#define UART_IIR    2        /* interrupt identification register */
+#define UART_LCR    3        /* line control register */
+#define UART_MCR    4        /* modem control register */
+#define UART_LSR    5        /* line status register */
+#define UART_TTYDA  (1 << 0) /* data available (rx ready) */
+#define UART_TTYOE  (1 << 1) /* overrun error */
+#define UART_TTYPE  (1 << 2) /* parity error */
+#define UART_TTYFE  (1 << 3) /* framing error */
 #define UART_TTYBSR (1 << 4) /* break signal received */
 #define UART_TTYTXR (1 << 5) /* serial thr empty (tx ready) */
 #define UART_TTYIDL (1 << 6) /* serial thr empty and line idle */
--- a/libc/stdio/serialstdio.c
+++ b/libc/stdio/serialstdio.c
@ -23,12 +23,12 @@
 #include "libc/stdio/stdio.h"

 static void fin(FILE *f) {
-  f->buf[f->end] = inb(f->fd);
+  f->buf[f->end] = inb(0x3F8);
  f->end = (f->end + 1) & (f->size - 1);
 }

 static void fout(FILE *f) {
-  outb(f->fd, f->buf[f->beg]);
+  outb(0x3F8, f->buf[f->beg]);
  f->beg = (f->beg + 1) & (f->size - 1);
 }

@ -36,7 +36,7 @@ static int serialstdio(FILE *f, unsigned char status, void action(FILE *)) {
  int block = 1;
  unsigned tally = 0;
  while (f->end != f->beg) {
-    if (!(inb(f->fd + UART_LSR) & status)) {
+    if (!(inb(0x3F8 + UART_LSR) & status)) {
      if (!block) break;
      asm("pause");
    } else {
@ -50,6 +50,7 @@ static int serialstdio(FILE *f, unsigned char status, void action(FILE *)) {
 int fsreadbuf(FILE *f) {
  return serialstdio(f, UART_TTYDA, fin);
 }
+
 int fswritebuf(FILE *f) {
  return serialstdio(f, UART_TTYTXR, fout);
 }
--- a/libc/stdio/system.c
+++ b/libc/stdio/system.c
@ -19,54 +19,52 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/bits/weaken.h"
 #include "libc/calls/calls.h"
-#include "libc/calls/hefty/ntspawn.h"
 #include "libc/calls/internal.h"
-#include "libc/dce.h"
 #include "libc/mem/mem.h"
 #include "libc/nt/accounting.h"
 #include "libc/nt/enum/startf.h"
 #include "libc/nt/enum/status.h"
-#include "libc/nt/files.h"
 #include "libc/nt/process.h"
 #include "libc/nt/runtime.h"
-#include "libc/nt/startupinfo.h"
 #include "libc/nt/struct/processinformation.h"
 #include "libc/nt/synchronization.h"
-#include "libc/runtime/runtime.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/fileno.h"
 #include "libc/sysv/errfuns.h"
-#include "libc/x/x.h"

 #define SHELL_BIN "/bin/sh"
 #define SHELL_ARG "-c"
 #define CMD_C     "CMD /C "

 static int system$sysv(const char *cmdline) {
+  int rc, n, wstatus;
+  struct mem {
+    char shell[sizeof(SHELL_BIN)];
+    char arg[sizeof(SHELL_ARG)];
+    char *args[4];
+    char cmdline[];
+  } * mem;
  if (cmdline != NULL) {
-    int pid = fork$sysv();
-    if (pid == 0) {
-      struct mem {
-        char shell[sizeof(SHELL_BIN)];
-        char arg[sizeof(SHELL_ARG)];
-        char *args[4];
-        char cmdline[];
-      } *mem = malloc(sizeof(struct mem) + (strlen(cmdline) + 1));
-      if (!mem) return enomem();
-      strcpy(mem->shell, SHELL_BIN);
-      strcpy(mem->arg, SHELL_ARG);
-      mem->args[0] = mem->shell;
-      mem->args[1] = mem->arg;
-      mem->args[2] = mem->cmdline;
-      mem->args[3] = NULL;
-      strcpy(mem->cmdline, cmdline);
-      execve$sysv(mem->shell, mem->args, environ);
-      abort();
+    mem = malloc(sizeof(struct mem) + (strlen(cmdline) + 1));
+    if (!mem) return enomem();
+    strcpy(mem->shell, SHELL_BIN);
+    strcpy(mem->arg, SHELL_ARG);
+    mem->args[0] = mem->shell;
+    mem->args[1] = mem->arg;
+    mem->args[2] = mem->cmdline;
+    mem->args[3] = NULL;
+    strcpy(mem->cmdline, cmdline);
+    if ((rc = vfork()) != -1) {
+      if (rc == 0) {
+        execve$sysv(mem->shell, mem->args, environ);
+        abort();
+      }
+      if ((rc = wait4$sysv(rc, &wstatus, 0, NULL)) != -1) {
+        rc = wstatus;
+      }
    }
-    int rc;
-    int wstatus;
-    if ((rc = wait4$sysv(pid, &wstatus, 0, NULL)) != -1) rc = wstatus;
+    free(mem);
    return rc;
  } else {
    return fileexists(SHELL_BIN);
@ -74,27 +72,32 @@ static int system$sysv(const char *cmdline) {
 }

 static textwindows noinline int system$nt(const char *cmdline) {
+  char *mem;
+  int rc, status;
+  uint32_t dwExitCode;
+  struct NtStartupInfo startinfo;
+  struct NtProcessInformation *info;
+  uint16_t *cmdline16, *quotedcmdline16;
+  unsigned len, dosquotemultiplier, cmdline16bytes, quotedcmdline16bytes;
  if (cmdline != NULL) {
-    int rc = -1;
-    unsigned dosquotemultiplier = 2;
-    unsigned len = strlen(cmdline);
-    unsigned cmdline16bytes = (len + 1) * sizeof(uint16_t);
-    unsigned quotedcmdline16bytes =
+    rc = -1;
+    dosquotemultiplier = 2;
+    len = strlen(cmdline);
+    cmdline16bytes = (len + 1) * sizeof(uint16_t);
+    quotedcmdline16bytes =
        strlen(CMD_C) * sizeof(uint16_t) + cmdline16bytes * dosquotemultiplier;
-    void *mem = malloc(sizeof(struct NtProcessInformation) + cmdline16bytes +
-                       quotedcmdline16bytes);
-    if (mem == NULL) return enomem();
-    struct NtProcessInformation *info = mem;
-    uint16_t *cmdline16 =
-        (uint16_t *)((char *)mem + sizeof(struct NtProcessInformation));
-    uint16_t *quotedcmdline16 =
-        (uint16_t *)((char *)mem + sizeof(struct NtProcessInformation) +
-                     cmdline16bytes);
+    if (!(mem = malloc(sizeof(struct NtProcessInformation) + cmdline16bytes +
+                       quotedcmdline16bytes))) {
+      return enomem();
+    }
+    info = (struct NtProcessInformation *)mem;
+    cmdline16 = (uint16_t *)(mem + sizeof(struct NtProcessInformation));
+    quotedcmdline16 = (uint16_t *)(mem + sizeof(struct NtProcessInformation) +
+                                   cmdline16bytes);
    strcpyzbw(cmdline16, cmdline);
    strcpyzbw(quotedcmdline16, CMD_C);
    if (escapedos(quotedcmdline16 + strlen(CMD_C), len * dosquotemultiplier,
                  cmdline16, len)) {
-      struct NtStartupInfo startinfo;
      memset(&startinfo, 0, sizeof(startinfo));