cosmopolitan/libc/sysv/systemfive.S
Justine Tunney 14e192e5ba Introduce --strace flag for system call tracing
This is similar to the --ftrace (c function call trace) flag, except
it's less noisy since it only logs system calls to stderr. Having this
flag is valuable because (1) system call tracing tells us a lot about
the behavior of complex programs and (2) it's usually very hard to get
system call tracing on various operating systems, e.g. strace, ktrace,
dtruss, truss, nttrace, etc. Especially on Apple platforms where even
with the special boot trick, debuggers still aren't guaranteed to work.

    make -j8 o//examples
    o//examples/hello.com --strace

This is enabled by default in MODE=, MODE=opt, and MODE=dbg. In MODE=dbg
extra information will be printed.

    make -j8 MODE=dbg o/dbg/examples
    o/dbg/examples/hello.com --strace |& less

This change also changes:

- Rename IsText() → _istext()
- Rename IsUtf8() → _isutf8()
- Fix madvise() on Windows NT
- Fix empty string case of inet_ntop()
- vfork() wrapper now saves and restores errno
- Update xsigaction() to yoink syscall support
2022-03-18 18:07:28 -07:00

551 lines
18 KiB
ArmAsm
Raw Blame History

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/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
vi: set et ft=asm ts=8 sw=8 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/calls/strace.internal.h"
#include "libc/dce.h"
#include "libc/macros.internal.h"
#include "libc/nexgen32e/macros.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/nr.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/prot.h"
/*
besiyata
dishmaya
cosmopolitan § bell system five » system call support
*/
.initbss 300,_init_systemfive
__hostos:
.quad 0
.endobj __hostos,globl,hidden
// Performs System Five System Call.
//
// Cosmopolitan is designed to delegate all function calls into the
// Linux, FreeBSD, OpenBSD, and XNU kernels via this function, with
// few exceptions. This function should generally only be called by
// generated thunks in the libc/sysv/syscalls/ directory.
//
// It's safe to call this function on Windows, where it will always
// return -1 with errno == ENOSYS. Further note that -1 is the only
// return value that means error, a common anti-pattern is to check
// for values less than 0 (which is more problematic on 32-bit).
//
// It is important to consider that system calls are one order of a
// magnitude more expensive than normal function calls. For example
// getpid() on Linux usually takes 500ns, and cached i/o calls will
// take 1µs or more. So we don't need to inline them like Chromium.
//
// Another thing to consider is that BSDs only loosely follow the
// System Five ABI for the SYSCALL instruction. For example Linux
// always follows the six argument limit but the FreeBSD sendfile
// system call accepts a seventh argument that is passed on stack
// and OpenBSD modifies functions like mmap so that the sixth arg
// is passed on the stack. There's also the carry flag convention
// that XNU, FreeBSD, and OpenBSD inherited from 386BSD aka Jolix
//
// @param %rax function ordinal supplied by jump slot
// @param %rdi,%rsi,%rdx,%rcx,%r8,%r9 and rest on stack
// @return %rax:%rdx is result, or -1 w/ errno on error
// @clob %rcx,%r10,%r11
// @see syscalls.sh
__systemfive:
.quad 0
.endobj __systemfive,globl,hidden
__pid: .quad 0
.endobj __pid,globl,hidden
.previous
.privileged
.Lanchorpoint:
#if SupportsLinux() || SupportsMetal()
systemfive_linux:
and $0xfff,%eax
cmp $0xfff,%eax
je systemfive_enosys # never taken branches cost nothing
mov %rcx,%r10 # syscall instruction clobbers %rcx
push %rbp # linux never reads args from stack
mov %rsp,%rbp # having frame will help backtraces
syscall # this is known as a context switch
pop %rbp # next we check to see if it failed
cmp $-4095,%rax # system five nexgen32e abi § a.2.1
jae systemfive_error # encodes errno as neg return value
ret
.endfn systemfive_linux,globl,hidden
systemfive_error:
neg %eax
// 𝑠𝑙𝑖𝑑𝑒
.endfn systemfive_error,globl,hidden
#endif
systemfive_errno:
mov %eax,errno(%rip) # normalize to c library convention
push $-1 # negative one is only error result
pop %rax # the push pop is to save code size
ret
.endfn systemfive_errno,globl,hidden
systemfive_enosys:
mov ENOSYS(%rip),%eax
jmp systemfive_errno
.endfn systemfive_enosys,globl,hidden
#if SupportsNetbsd()
systemfive_netbsd:
shr $4*13,%rax
jmp systemfive_bsdscrub
.endfn systemfive_netbsd,globl,hidden
#endif
#if SupportsOpenbsd()
systemfive_openbsd:
shr $4*10,%rax
jmp systemfive_bsdscrub
.endfn systemfive_openbsd,globl,hidden
#endif
#if SupportsFreebsd()
systemfive_freebsd:
shr $4*7,%rax
movzwl %ax,%eax
// 𝑠𝑙𝑖𝑑𝑒
.endfn systemfive_freebsd,globl,hidden
#endif
#if SupportsBsd()
systemfive_bsdscrub:
and $0xfff,%eax
// 𝑠𝑙𝑖𝑑𝑒
.endfn systemfive_bsdscrub,globl,hidden
systemfive_bsd:
cmp $0xfff,%ax
je systemfive_enosys
mov %rcx,%r10 # note: we do not create a stack frame
syscall # bsd will need arg on stack sometimes
jc systemfive_errno # bsd sets carry flag if %rax is errno
ret
.endfn systemfive_bsd
#endif
#if SupportsXnu()
systemfive_xnu:
// 0x?????????2153??? # how syscalls.sh encodes xnu ordinals
//
//
// 0x0000000002000153 # how xnu wants ordinals to be encoded
mov %eax,%r11d
and $0x0f000000,%r11d
shl $8,%eax
shr $20,%eax
or %r11d,%eax
jmp systemfive_bsd
.endfn systemfive_xnu,globl,hidden
#endif
.previous
// Initializes System Five system call support.
//
// (1) Extracts parameters passed by kernel
// (2) Detects OS without issuing system calls
// (3) Unpacks magnums from libc/sysv/consts.sh
// (4) Replaces stack with one we control
//
// @param %r15 is auxv
// @note OpenBSD devs: let us know if you start using auxv
.init.start 300,_init_systemfive
push %rbx
push %rsi
mov (%rdi),%eax
#if SupportsOpenbsd()
cmpq $0,(%r15) # OpenBSD has no auxv
jnz 0f
mov $OPENBSD,%al
0:
#endif
#if SupportsNetbsd()
xor %ecx,%ecx
0: cmpq $2014,(%r15,%rcx,8) # NetBSD AT_EXECFN
jne 1f
mov $NETBSD,%al
1: cmpq $0,(%r15,%rcx,8)
lea 2(%ecx),%ecx
jnz 0b
2:
#endif
test %eax,%eax
jnz 1f
mov $LINUX,%al
1: stosq # __hostos
bsr %eax,%eax
mov $_init_systemfive_jmptab,%ebx
movzbl (%rbx,%rax),%eax
lea (%rbx,%rax),%eax
jmp *%rax
_init_systemfive_jmptab:
.byte _init_systemfive_linux-_init_systemfive_jmptab
.byte _init_systemfive_metal-_init_systemfive_jmptab
.byte _init_systemfive_windows-_init_systemfive_jmptab
.byte _init_systemfive_xnu-_init_systemfive_jmptab
.byte _init_systemfive_openbsd-_init_systemfive_jmptab
.byte _init_systemfive_freebsd-_init_systemfive_jmptab
.byte _init_systemfive_netbsd-_init_systemfive_jmptab
.endobj _init_systemfive_jmptab
_init_systemfive_linux:
#if SupportsLinux()
pushb systemfive_linux-.Lanchorpoint
mov $syscon_linux,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_linux
_init_systemfive_metal:
#if SupportsMetal()
pushb systemfive_enosys-.Lanchorpoint
mov $syscon_linux,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_metal
_init_systemfive_windows:
#if SupportsWindows()
pushb systemfive_enosys-.Lanchorpoint
mov $syscon_windows,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_windows
_init_systemfive_xnu:
#if SupportsXnu()
pushb systemfive_xnu-.Lanchorpoint
mov $syscon_xnu,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_xnu
_init_systemfive_openbsd:
#if SupportsOpenbsd()
pushb systemfive_openbsd-.Lanchorpoint
mov $syscon_openbsd,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_openbsd
_init_systemfive_freebsd:
#if SupportsFreebsd()
pushb systemfive_freebsd-.Lanchorpoint
mov $syscon_freebsd,%esi
jmp _init_systemfive_os
#endif
.endfn _init_systemfive_freebsd
_init_systemfive_netbsd:
#if SupportsNetbsd()
pushb systemfive_netbsd-.Lanchorpoint
mov $syscon_netbsd,%esi
// 𝑠𝑙𝑖𝑑𝑒
#endif
.endfn _init_systemfive_netbsd
_init_systemfive_os:
pop %rax
add $.Lanchorpoint,%eax
stosq # __systemfive
// 𝑠𝑙𝑖𝑑𝑒
.endfn _init_systemfive_os
_init_systemfive_magnums:
push %rdi
mov $syscon_start,%edi
2: cmp $syscon_end,%edi
jnb 5f
xor %ebx,%ebx
xor %ecx,%ecx
xor %edx,%edx
3: lodsb # decodes uleb128
movzbl %al,%edx
and $127,%dl
shl %cl,%rdx
or %rdx,%rbx
add $7,%cl
test $128,%al
jnz 3b
xchg %rbx,%rax
stosq
#ifdef SYSDEBUG
inc %r8d
#endif
jmp 2b
5: nop
#ifdef SYSDEBUG
push %rdi
push %rsi
push %r8
call __describe_os
mov %rax,%rdx
pop %r8
.weak __stracef
ezlea __stracef,ax
test %rax,%rax
jz 5f
ezlea .Llog,di
mov %r8d,%esi
call *%rax
5: pop %rsi
pop %rdi
#endif /* DEBUGSYS */
pop %rdi
pop %rsi
pop %rbx
// 𝑠𝑙𝑖𝑑𝑒
.endfn _init_systemfive_magnums
#if SupportsSystemv()
_init_systemfive_pid:
ezlea __hostos,cx
mov (%rcx),%al
mov (%rdi),%eax
testb $WINDOWS|METAL,(%rcx)
jnz 1f
mov __NR_getpid,%eax
syscall
1: stosq
.endfn _init_systemfive_pid
#endif
#if SupportsSystemv() && !defined(TINY)
// Create a stack with deterministic readable addresses.
// If ape_execve() already created us a stack that meets
// the requirements of STATIC_STACK_SIZE() then we skip.
_init_systemfive_stack:
#if SupportsWindows() || SupportsMetal() || SupportsOpenbsd()
testb $WINDOWS|METAL,__hostos(%rip)
jnz _init_systemfive_done
#endif
push %rdi
push %rsi
mov __NR_mmap,%eax
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()
testb IsOpenbsd()
jz 0f
syscall # openbsd:dubstack
jc 1f
mov __NR_mmap,%eax
#endif
0: or MAP_GROWSDOWN,%r10d # openbsd:mapstack
clc
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
syscall
2: test %rax,%rax
js 1b
// prevent operating system from auto-mapping stack
// we guarantee stack overflows are always detected
// so long as you never use -DSTACK_FRAME_UNLIMITED
// TODO: Why does this fail sometimes with FreeBSD?
testb IsFreebsd()
jnz 9f
push %rax
push %rdx
push %r11
mov __NR_mprotect,%eax
mov $PAGESIZE,%esi
xor %edx,%edx # PROT_NONE
syscall
pop %r11
pop %rdx
pop %rax
9:
// update the memory intervals
// m.i 0 4
// m.n 8 4
// m.p 16 8
// m.p[0].x 24 4
// m.p[0].y 28 4
// m.p[0].h 32 8
// m.p[0].prot 40 4
// m.p[0].flags 44 4
.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
mov %r11d,24(%rcx) # _mmi.s[0].x
mov %r9d,28(%rcx) # _mmi.s[0].y
orq $-1,32(%rcx) # _mmi.s[0].h
mov %edx,40(%rcx) # _mmi.s[0].prot
mov %r10d,44(%rcx) # _mmi.s[0].flags
3: pop %r9 # restore stack size
pop %rsi
pop %rdi
leave
// switch stacks
pop %rcx
lea (%rax,%r9),%rsp
sub $ape_stack_align,%rsp # openbsd:stackbound
mov %rbp,(%rsp)
push %rcx
push %rbp
mov %rsp,%rbp
// 𝑠𝑙𝑖𝑑𝑒
_init_systemfive_syscall:
mov __NR_msyscall,%eax # syscall origin protect
cmp $0xfff,%ax # openbsd is pretty cool
jae _init_systemfive_done
push %rdi
push %rsi
.weak __privileged_addr
.weak __privileged_size
mov $__privileged_addr,%edi
mov $__privileged_size,%esi
syscall
pop %rsi
pop %rdi
// 𝑠𝑙𝑖𝑑𝑒
#endif /* TINY */
_init_systemfive_done:
nop
.init.end 300,_init_systemfive,globl,hidden
// Sections for varint encoded magic numbers.
//
// These sections are all ordered by (group_name, constant_name).
// They're populated by modules simply referencing the symbols.
//
// @see libc/sysv/consts.sh
// @see libc/sysv/consts/syscon_h
.section .piro.bss.sort.syscon.1,"aw",@nobits
.align 8
syscon_start:/*
...decentralized quadwords...
*/.previous
.section .piro.bss.sort.syscon.3,"aw",@nobits
syscon_end:
.previous
.type syscon_start,@object
.type syscon_end,@object
.globl syscon_start
.globl syscon_end
#if SupportsLinux() || SupportsMetal()
.section .sort.rodata.syscon.linux.1,"a",@progbits
.align 1
syscon_linux:/*
...decentralized leb128...
*/.previous
.type syscon_linux,@object
.globl syscon_linux
#endif
#if SupportsXnu()
.section .sort.rodata.syscon.xnu.1,"a",@progbits
.align 1
syscon_xnu:/*
...decentralized leb128...
*/.previous
.type syscon_xnu,@object
.globl syscon_xnu
#endif
#if SupportsFreebsd()
.section .sort.rodata.syscon.freebsd.1,"a",@progbits
.align 1
syscon_freebsd:/*
...decentralized leb128...
*/.previous
.type syscon_freebsd,@object
.globl syscon_freebsd
#endif
#if SupportsOpenbsd()
.section .sort.rodata.syscon.openbsd.1,"a",@progbits
.align 1
syscon_openbsd:/*
...decentralized leb128...
*/.previous
.type syscon_openbsd,@object
.globl syscon_openbsd
#endif
#if SupportsNetbsd()
.section .sort.rodata.syscon.netbsd.1,"a",@progbits
.align 1
syscon_netbsd:/*
...decentralized leb128...
*/.previous
.type syscon_netbsd,@object
.globl syscon_netbsd
#endif
#if SupportsWindows()
.section .sort.rodata.syscon.windows.1,"a",@progbits
.align 1
syscon_windows:/*
...decentralized leb128...
*/.previous
.type syscon_windows,@object
.globl syscon_windows
#endif
#ifdef SYSDEBUG
.rodata.str1.1
.Llog: .ascii STRACE_PROLOGUE
.ascii "bell system five system call support"
.asciz " %'u magnums loaded on %s%n"
.previous
#endif /* DEBUGSYS */
.weak ape_stack_vaddr
.weak ape_stack_memsz
.weak ape_stack_align