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Support malloc() on bare metal

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Your Actually Portable Executables now contains a simple virtual memory
that works similarly to the Linux Kernel in the sense that it maps your
physical memory to negative addresses. This is needed to support mmap()
and malloc(). This functionality has zero code size impact. For example
the MODE=tiny LIFE.COM executable is still only 12KB in size.

The APE bootloader code has also been simplified to improve readibility
and further elevate the elegance by which we're able to support so many
platforms thereby enhancing verifiability so that we may engender trust
in this bootloading process.
This commit is contained in:
Justine Tunney 2021-02-23 20:23:19 -08:00
parent ac3b1dfb21
commit edd9297eba
89 changed files with 900 additions and 1417 deletions
Download patch file Download diff file Expand all files Collapse all files

45
libc/sysv/systemfive.S
View file

@ -104,7 +104,7 @@ __systemfive:
.privileged
.Lanchorpoint:
#if SupportsLinux() || SupportsMetal() || SupportsUefi()
#if SupportsLinux() || SupportsMetal()
systemfive_linux:
and $0xfff,%eax
cmp $0xfff,%eax
@ -198,10 +198,6 @@ systemfive_xnu:
testb $XNU,(%rdi) # @see libc/crt/crt.S
jnz _init_systemfive_xnu
#endif
#if SupportsUefi()
testb $UEFI,(%rdi) # @see ape/ape.S
jnz _init_systemfive_uefi
#endif
#if SupportsMetal()
testb $METAL,(%rdi) # @see ape/ape.S
jnz _init_systemfive_metal
@ -240,13 +236,6 @@ _init_systemfive_metal:
ezlea syscon_linux,si
jmp _init_systemfive_os
#endif
#if SupportsUefi()
_init_systemfive_uefi:
pushb systemfive_linux-.Lanchorpoint
push $UEFI
ezlea syscon_linux,si
jmp _init_systemfive_os
#endif
#if SupportsWindows()
_init_systemfive_windows:
pushb systemfive_enosys-.Lanchorpoint
@ -323,20 +312,22 @@ _init_systemfive_magnums:
// 𝑠𝑙𝑖𝑑𝑒
#if SupportsSystemv() && !defined(TINY)
_init_systemfive_stack: # determinism ftw!
#if SupportsWindows() || SupportsMetal() || SupportsUefi()
testb $WINDOWS|METAL|UEFI,__hostos(%rip)
#if SupportsWindows() || SupportsMetal()
testb $WINDOWS|METAL,__hostos(%rip)
jnz _init_systemfive_done
#endif
push %rdi
push %rsi
mov __NR_mmap,%eax
mov $0x700000000000-STACKSIZE,%rdi
mov $STACKSIZE,%esi
movabs $ape_stack_vaddr,%rdi
mov $ape_stack_memsz,%esi
mov $PROT_READ|PROT_WRITE,%edx
mov $MAP_PRIVATE|MAP_FIXED,%r10d
or MAP_ANONYMOUS,%r10d
or $-1,%r8d
xor %r9d,%r9d
push %rdi # vaddr of stack
push %rsi # size of stack
push %r9 # openbsd:pad
push %r9 # openbsd:align
#if SupportsOpenbsd()
@ -351,6 +342,8 @@ _init_systemfive_stack: # determinism ftw!
syscall
pop %r9
pop %r9
pop %r9 # size of stack
pop %r11 # vaddr of stack
jnc 2f
1: mov %eax,%edi
mov __NR_exit_group,%eax
@ -360,17 +353,23 @@ _init_systemfive_stack: # determinism ftw!
.weak _mmi
ezlea _mmi,cx
test %rcx,%rcx
push %r9 # save the stack size
jz 3f
lea -1(%r11,%r9),%r9 # need incl. interval
shr $16,%r11 # for the stack range
shr $16,%r9
movb $1,(%rcx) # _mmi.i
movl $(0x700000000000-STACKSIZE)>>16,8(%rcx) # _mmi.p[0].x
movl $(0x700000000000-1)>>16,12(%rcx) # _mmi.p[0].y
mov %r11d,8(%rcx) # _mmi.p[0].x
mov %r9d,12(%rcx) # _mmi.p[0].y
mov %edx,20(%rcx) # _mmi.p[0].prot
mov %r10d,24(%rcx) # _mmi.p[0].flags
3: pop %rsi
3: pop %r9 # restore stack size
pop %rsi
pop %rdi
leave
pop %rcx
lea STACKSIZE-16(%rax),%rsp # openbsd:stackbound
lea (%rax,%r9),%rsp
sub $ape_stack_align,%rsp # openbsd:stackbound
mov %rbp,(%rsp)
push %rcx
push %rbp
@ -414,7 +413,7 @@ syscon_end:
.type syscon_end,@object
.globl syscon_start
.globl syscon_end
#if SupportsLinux() || SupportsMetal() || SupportsUefi()
#if SupportsLinux() || SupportsMetal()
.section .sort.rodata.syscon.linux.1,"a",@progbits
.align 1
syscon_linux:/*
@ -468,3 +467,7 @@ syscon_windows:/*
.type syscon_windows,@object
.globl syscon_windows
#endif
.weak ape_stack_vaddr
.weak ape_stack_memsz
.weak ape_stack_align