mirror of
https://github.com/golang/go
synced 2024-11-19 17:44:43 -07:00
bb6309cd63
On 32-bit architectures (or if we fail to map a 64-bit-style arena), we try to map the heap arena just above the end of the process image. While we can accept any address, using lower addresses is preferable because lower addresses cause us to map less of the heap bitmap. However, if a program is linked against C code that has global constructors, those constructors may call brk/sbrk to allocate memory (e.g., many C malloc implementations do this for small allocations). The brk also starts just above the process image, so this may adjust the brk past the beginning of where we want to put the heap arena. In this case, the kernel will pick a different address for the arena and it will usually be very high (at least, as these things go in a 32-bit address space). Fix this by consulting the current value of the brk and using this in addition to the end of the process image to compute the initial arena placement. This is implemented only on Linux currently, since we have no evidence that it's an issue on any other OSes. Fixes #19831. Change-Id: Id64b45d08d8c91e4f50d92d0339146250b04f2f8 Reviewed-on: https://go-review.googlesource.com/39810 Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
608 lines
14 KiB
ArmAsm
608 lines
14 KiB
ArmAsm
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// System calls and other sys.stuff for 386, Linux
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//
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#include "go_asm.h"
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#include "go_tls.h"
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#include "textflag.h"
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// Most linux systems use glibc's dynamic linker, which puts the
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// __kernel_vsyscall vdso helper at 0x10(GS) for easy access from position
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// independent code and setldt in runtime does the same in the statically
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// linked case. However, systems that use alternative libc such as Android's
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// bionic and musl, do not save the helper anywhere, and so the only way to
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// invoke a syscall from position independent code is boring old int $0x80
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// (which is also what syscall wrappers in bionic/musl use).
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//
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// The benchmarks also showed that using int $0x80 is as fast as calling
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// *%gs:0x10 except on AMD Opteron. See https://golang.org/cl/19833
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// for the benchmark program and raw data.
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//#define INVOKE_SYSCALL CALL 0x10(GS) // non-portable
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#define INVOKE_SYSCALL INT $0x80
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TEXT runtime·exit(SB),NOSPLIT,$0
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MOVL $252, AX // syscall number
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MOVL code+0(FP), BX
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INVOKE_SYSCALL
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INT $3 // not reached
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RET
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TEXT runtime·exit1(SB),NOSPLIT,$0
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MOVL $1, AX // exit - exit the current os thread
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MOVL code+0(FP), BX
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INVOKE_SYSCALL
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INT $3 // not reached
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RET
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TEXT runtime·open(SB),NOSPLIT,$0
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MOVL $5, AX // syscall - open
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MOVL name+0(FP), BX
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MOVL mode+4(FP), CX
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MOVL perm+8(FP), DX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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MOVL $-1, AX
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MOVL AX, ret+12(FP)
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RET
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TEXT runtime·closefd(SB),NOSPLIT,$0
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MOVL $6, AX // syscall - close
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MOVL fd+0(FP), BX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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MOVL $-1, AX
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MOVL AX, ret+4(FP)
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RET
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TEXT runtime·write(SB),NOSPLIT,$0
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MOVL $4, AX // syscall - write
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MOVL fd+0(FP), BX
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MOVL p+4(FP), CX
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MOVL n+8(FP), DX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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MOVL $-1, AX
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MOVL AX, ret+12(FP)
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RET
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TEXT runtime·read(SB),NOSPLIT,$0
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MOVL $3, AX // syscall - read
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MOVL fd+0(FP), BX
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MOVL p+4(FP), CX
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MOVL n+8(FP), DX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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MOVL $-1, AX
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MOVL AX, ret+12(FP)
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RET
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TEXT runtime·getrlimit(SB),NOSPLIT,$0
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MOVL $191, AX // syscall - ugetrlimit
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MOVL kind+0(FP), BX
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MOVL limit+4(FP), CX
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INVOKE_SYSCALL
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MOVL AX, ret+8(FP)
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RET
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TEXT runtime·usleep(SB),NOSPLIT,$8
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MOVL $0, DX
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MOVL usec+0(FP), AX
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MOVL $1000000, CX
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DIVL CX
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MOVL AX, 0(SP)
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MOVL DX, 4(SP)
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// select(0, 0, 0, 0, &tv)
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MOVL $142, AX
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MOVL $0, BX
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MOVL $0, CX
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MOVL $0, DX
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MOVL $0, SI
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LEAL 0(SP), DI
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INVOKE_SYSCALL
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RET
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TEXT runtime·gettid(SB),NOSPLIT,$0-4
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MOVL $224, AX // syscall - gettid
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INVOKE_SYSCALL
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MOVL AX, ret+0(FP)
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RET
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TEXT runtime·raise(SB),NOSPLIT,$12
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MOVL $224, AX // syscall - gettid
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INVOKE_SYSCALL
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MOVL AX, BX // arg 1 tid
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MOVL sig+0(FP), CX // arg 2 signal
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MOVL $238, AX // syscall - tkill
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INVOKE_SYSCALL
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RET
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TEXT runtime·raiseproc(SB),NOSPLIT,$12
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MOVL $20, AX // syscall - getpid
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INVOKE_SYSCALL
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MOVL AX, BX // arg 1 pid
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MOVL sig+0(FP), CX // arg 2 signal
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MOVL $37, AX // syscall - kill
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INVOKE_SYSCALL
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RET
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TEXT runtime·setitimer(SB),NOSPLIT,$0-12
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MOVL $104, AX // syscall - setitimer
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MOVL mode+0(FP), BX
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MOVL new+4(FP), CX
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MOVL old+8(FP), DX
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INVOKE_SYSCALL
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RET
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TEXT runtime·mincore(SB),NOSPLIT,$0-16
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MOVL $218, AX // syscall - mincore
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MOVL addr+0(FP), BX
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MOVL n+4(FP), CX
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MOVL dst+8(FP), DX
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INVOKE_SYSCALL
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MOVL AX, ret+12(FP)
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RET
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// func walltime() (sec int64, nsec int32)
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TEXT runtime·walltime(SB), NOSPLIT, $32
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MOVL $265, AX // syscall - clock_gettime
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MOVL $0, BX // CLOCK_REALTIME
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LEAL 8(SP), CX
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MOVL $0, DX
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INVOKE_SYSCALL
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MOVL 8(SP), AX // sec
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MOVL 12(SP), BX // nsec
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// sec is in AX, nsec in BX
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MOVL AX, sec_lo+0(FP)
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MOVL $0, sec_hi+4(FP)
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MOVL BX, nsec+8(FP)
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RET
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// int64 nanotime(void) so really
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// void nanotime(int64 *nsec)
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TEXT runtime·nanotime(SB), NOSPLIT, $32
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MOVL $265, AX // syscall - clock_gettime
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MOVL $1, BX // CLOCK_MONOTONIC
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LEAL 8(SP), CX
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MOVL $0, DX
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INVOKE_SYSCALL
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MOVL 8(SP), AX // sec
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MOVL 12(SP), BX // nsec
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// sec is in AX, nsec in BX
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// convert to DX:AX nsec
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MOVL $1000000000, CX
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MULL CX
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ADDL BX, AX
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ADCL $0, DX
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MOVL AX, ret_lo+0(FP)
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MOVL DX, ret_hi+4(FP)
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RET
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TEXT runtime·rtsigprocmask(SB),NOSPLIT,$0
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MOVL $175, AX // syscall entry
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MOVL how+0(FP), BX
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MOVL new+4(FP), CX
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MOVL old+8(FP), DX
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MOVL size+12(FP), SI
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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INT $3
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RET
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TEXT runtime·rt_sigaction(SB),NOSPLIT,$0
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MOVL $174, AX // syscall - rt_sigaction
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MOVL sig+0(FP), BX
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MOVL new+4(FP), CX
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MOVL old+8(FP), DX
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MOVL size+12(FP), SI
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INVOKE_SYSCALL
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MOVL AX, ret+16(FP)
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RET
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TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
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MOVL fn+0(FP), AX
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MOVL sig+4(FP), BX
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MOVL info+8(FP), CX
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MOVL ctx+12(FP), DX
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MOVL SP, SI
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SUBL $32, SP
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ANDL $-15, SP // align stack: handler might be a C function
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MOVL BX, 0(SP)
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MOVL CX, 4(SP)
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MOVL DX, 8(SP)
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MOVL SI, 12(SP) // save SI: handler might be a Go function
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CALL AX
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MOVL 12(SP), AX
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MOVL AX, SP
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RET
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TEXT runtime·sigtramp(SB),NOSPLIT,$28
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// Save callee-saved C registers, since the caller may be a C signal handler.
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MOVL BX, bx-4(SP)
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MOVL BP, bp-8(SP)
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MOVL SI, si-12(SP)
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MOVL DI, di-16(SP)
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// We don't save mxcsr or the x87 control word because sigtrampgo doesn't
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// modify them.
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MOVL sig+0(FP), BX
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MOVL BX, 0(SP)
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MOVL info+4(FP), BX
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MOVL BX, 4(SP)
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MOVL ctx+8(FP), BX
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MOVL BX, 8(SP)
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CALL runtime·sigtrampgo(SB)
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MOVL di-16(SP), DI
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MOVL si-12(SP), SI
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MOVL bp-8(SP), BP
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MOVL bx-4(SP), BX
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RET
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TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
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JMP runtime·sigtramp(SB)
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TEXT runtime·sigreturn(SB),NOSPLIT,$0
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MOVL $173, AX // rt_sigreturn
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// Sigreturn expects same SP as signal handler,
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// so cannot CALL 0x10(GS) here.
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INT $0x80
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INT $3 // not reached
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RET
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TEXT runtime·mmap(SB),NOSPLIT,$0
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MOVL $192, AX // mmap2
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MOVL addr+0(FP), BX
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MOVL n+4(FP), CX
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MOVL prot+8(FP), DX
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MOVL flags+12(FP), SI
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MOVL fd+16(FP), DI
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MOVL off+20(FP), BP
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SHRL $12, BP
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 3(PC)
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NOTL AX
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INCL AX
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MOVL AX, ret+24(FP)
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RET
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TEXT runtime·munmap(SB),NOSPLIT,$0
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MOVL $91, AX // munmap
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MOVL addr+0(FP), BX
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MOVL n+4(FP), CX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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INT $3
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RET
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TEXT runtime·madvise(SB),NOSPLIT,$0
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MOVL $219, AX // madvise
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MOVL addr+0(FP), BX
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MOVL n+4(FP), CX
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MOVL flags+8(FP), DX
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INVOKE_SYSCALL
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// ignore failure - maybe pages are locked
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RET
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// int32 futex(int32 *uaddr, int32 op, int32 val,
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// struct timespec *timeout, int32 *uaddr2, int32 val2);
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TEXT runtime·futex(SB),NOSPLIT,$0
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MOVL $240, AX // futex
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MOVL addr+0(FP), BX
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MOVL op+4(FP), CX
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MOVL val+8(FP), DX
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MOVL ts+12(FP), SI
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MOVL addr2+16(FP), DI
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MOVL val3+20(FP), BP
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INVOKE_SYSCALL
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MOVL AX, ret+24(FP)
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RET
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// int32 clone(int32 flags, void *stack, M *mp, G *gp, void (*fn)(void));
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TEXT runtime·clone(SB),NOSPLIT,$0
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MOVL $120, AX // clone
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MOVL flags+0(FP), BX
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MOVL stk+4(FP), CX
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MOVL $0, DX // parent tid ptr
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MOVL $0, DI // child tid ptr
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// Copy mp, gp, fn off parent stack for use by child.
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SUBL $16, CX
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MOVL mp+8(FP), SI
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MOVL SI, 0(CX)
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MOVL gp+12(FP), SI
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MOVL SI, 4(CX)
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MOVL fn+16(FP), SI
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MOVL SI, 8(CX)
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MOVL $1234, 12(CX)
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// cannot use CALL 0x10(GS) here, because the stack changes during the
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// system call (after CALL 0x10(GS), the child is still using the
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// parent's stack when executing its RET instruction).
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INT $0x80
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// In parent, return.
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CMPL AX, $0
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JEQ 3(PC)
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MOVL AX, ret+20(FP)
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RET
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// Paranoia: check that SP is as we expect.
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MOVL 12(SP), BP
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CMPL BP, $1234
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JEQ 2(PC)
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INT $3
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// Initialize AX to Linux tid
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MOVL $224, AX
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INVOKE_SYSCALL
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MOVL 0(SP), BX // m
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MOVL 4(SP), DX // g
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MOVL 8(SP), SI // fn
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CMPL BX, $0
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JEQ nog
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CMPL DX, $0
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JEQ nog
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MOVL AX, m_procid(BX) // save tid as m->procid
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// set up ldt 7+id to point at m->tls.
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LEAL m_tls(BX), BP
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MOVL m_id(BX), DI
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ADDL $7, DI // m0 is LDT#7. count up.
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// setldt(tls#, &tls, sizeof tls)
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PUSHAL // save registers
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PUSHL $32 // sizeof tls
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PUSHL BP // &tls
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PUSHL DI // tls #
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CALL runtime·setldt(SB)
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POPL AX
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POPL AX
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POPL AX
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POPAL
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// Now segment is established. Initialize m, g.
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get_tls(AX)
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MOVL DX, g(AX)
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MOVL BX, g_m(DX)
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CALL runtime·stackcheck(SB) // smashes AX, CX
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MOVL 0(DX), DX // paranoia; check they are not nil
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MOVL 0(BX), BX
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// more paranoia; check that stack splitting code works
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PUSHAL
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CALL runtime·emptyfunc(SB)
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POPAL
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nog:
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CALL SI // fn()
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CALL runtime·exit1(SB)
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MOVL $0x1234, 0x1005
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TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
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MOVL $186, AX // sigaltstack
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MOVL new+0(FP), BX
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MOVL old+4(FP), CX
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INVOKE_SYSCALL
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CMPL AX, $0xfffff001
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JLS 2(PC)
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INT $3
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RET
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// <asm-i386/ldt.h>
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// struct user_desc {
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// unsigned int entry_number;
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// unsigned long base_addr;
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// unsigned int limit;
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// unsigned int seg_32bit:1;
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// unsigned int contents:2;
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// unsigned int read_exec_only:1;
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// unsigned int limit_in_pages:1;
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// unsigned int seg_not_present:1;
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// unsigned int useable:1;
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// };
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#define SEG_32BIT 0x01
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// contents are the 2 bits 0x02 and 0x04.
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#define CONTENTS_DATA 0x00
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#define CONTENTS_STACK 0x02
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#define CONTENTS_CODE 0x04
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#define READ_EXEC_ONLY 0x08
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#define LIMIT_IN_PAGES 0x10
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#define SEG_NOT_PRESENT 0x20
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#define USEABLE 0x40
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// `-1` means the kernel will pick a TLS entry on the first setldt call,
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// which happens during runtime init, and that we'll store back the saved
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// entry and reuse that on subsequent calls when creating new threads.
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DATA runtime·tls_entry_number+0(SB)/4, $-1
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GLOBL runtime·tls_entry_number(SB), NOPTR, $4
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// setldt(int entry, int address, int limit)
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// We use set_thread_area, which mucks with the GDT, instead of modify_ldt,
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// which would modify the LDT, but is disabled on some kernels.
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// The name, setldt, is a misnomer, although we leave this name as it is for
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// the compatibility with other platforms.
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TEXT runtime·setldt(SB),NOSPLIT,$32
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MOVL address+4(FP), DX // base address
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#ifdef GOOS_android
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/*
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* Same as in sys_darwin_386.s:/ugliness, different constant.
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* address currently holds m->tls, which must be %gs:0xf8.
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* See cgo/gcc_android_386.c for the derivation of the constant.
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*/
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SUBL $0xf8, DX
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MOVL DX, 0(DX)
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#else
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/*
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* When linking against the system libraries,
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* we use its pthread_create and let it set up %gs
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* for us. When we do that, the private storage
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* we get is not at 0(GS), but -4(GS).
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* To insulate the rest of the tool chain from this
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* ugliness, 8l rewrites 0(TLS) into -4(GS) for us.
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* To accommodate that rewrite, we translate
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* the address here and bump the limit to 0xffffffff (no limit)
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* so that -4(GS) maps to 0(address).
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* Also, the final 0(GS) (current 4(DX)) has to point
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* to itself, to mimic ELF.
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*/
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ADDL $0x4, DX // address
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MOVL DX, 0(DX)
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#endif
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// get entry number
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MOVL runtime·tls_entry_number(SB), CX
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// set up user_desc
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LEAL 16(SP), AX // struct user_desc
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MOVL CX, 0(AX) // unsigned int entry_number
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MOVL DX, 4(AX) // unsigned long base_addr
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MOVL $0xfffff, 8(AX) // unsigned int limit
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MOVL $(SEG_32BIT|LIMIT_IN_PAGES|USEABLE|CONTENTS_DATA), 12(AX) // flag bits
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// call set_thread_area
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MOVL AX, BX // user_desc
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MOVL $243, AX // syscall - set_thread_area
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// We can't call this via 0x10(GS) because this is called from setldt0 to set that up.
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INT $0x80
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// breakpoint on error
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CMPL AX, $0xfffff001
|
|
JLS 2(PC)
|
|
INT $3
|
|
|
|
// read allocated entry number back out of user_desc
|
|
LEAL 16(SP), AX // get our user_desc back
|
|
MOVL 0(AX), AX
|
|
|
|
// store entry number if the kernel allocated it
|
|
CMPL CX, $-1
|
|
JNE 2(PC)
|
|
MOVL AX, runtime·tls_entry_number(SB)
|
|
|
|
// compute segment selector - (entry*8+3)
|
|
SHLL $3, AX
|
|
ADDL $3, AX
|
|
MOVW AX, GS
|
|
|
|
RET
|
|
|
|
TEXT runtime·osyield(SB),NOSPLIT,$0
|
|
MOVL $158, AX
|
|
INVOKE_SYSCALL
|
|
RET
|
|
|
|
TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
|
|
MOVL $242, AX // syscall - sched_getaffinity
|
|
MOVL pid+0(FP), BX
|
|
MOVL len+4(FP), CX
|
|
MOVL buf+8(FP), DX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+12(FP)
|
|
RET
|
|
|
|
// int32 runtime·epollcreate(int32 size);
|
|
TEXT runtime·epollcreate(SB),NOSPLIT,$0
|
|
MOVL $254, AX
|
|
MOVL size+0(FP), BX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+4(FP)
|
|
RET
|
|
|
|
// int32 runtime·epollcreate1(int32 flags);
|
|
TEXT runtime·epollcreate1(SB),NOSPLIT,$0
|
|
MOVL $329, AX
|
|
MOVL flags+0(FP), BX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+4(FP)
|
|
RET
|
|
|
|
// func epollctl(epfd, op, fd int32, ev *epollEvent) int
|
|
TEXT runtime·epollctl(SB),NOSPLIT,$0
|
|
MOVL $255, AX
|
|
MOVL epfd+0(FP), BX
|
|
MOVL op+4(FP), CX
|
|
MOVL fd+8(FP), DX
|
|
MOVL ev+12(FP), SI
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+16(FP)
|
|
RET
|
|
|
|
// int32 runtime·epollwait(int32 epfd, EpollEvent *ev, int32 nev, int32 timeout);
|
|
TEXT runtime·epollwait(SB),NOSPLIT,$0
|
|
MOVL $256, AX
|
|
MOVL epfd+0(FP), BX
|
|
MOVL ev+4(FP), CX
|
|
MOVL nev+8(FP), DX
|
|
MOVL timeout+12(FP), SI
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+16(FP)
|
|
RET
|
|
|
|
// void runtime·closeonexec(int32 fd);
|
|
TEXT runtime·closeonexec(SB),NOSPLIT,$0
|
|
MOVL $55, AX // fcntl
|
|
MOVL fd+0(FP), BX // fd
|
|
MOVL $2, CX // F_SETFD
|
|
MOVL $1, DX // FD_CLOEXEC
|
|
INVOKE_SYSCALL
|
|
RET
|
|
|
|
// int access(const char *name, int mode)
|
|
TEXT runtime·access(SB),NOSPLIT,$0
|
|
MOVL $33, AX // syscall - access
|
|
MOVL name+0(FP), BX
|
|
MOVL mode+4(FP), CX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+8(FP)
|
|
RET
|
|
|
|
// int connect(int fd, const struct sockaddr *addr, socklen_t addrlen)
|
|
TEXT runtime·connect(SB),NOSPLIT,$0-16
|
|
// connect is implemented as socketcall(NR_socket, 3, *(rest of args))
|
|
// stack already should have fd, addr, addrlen.
|
|
MOVL $102, AX // syscall - socketcall
|
|
MOVL $3, BX // connect
|
|
LEAL fd+0(FP), CX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+12(FP)
|
|
RET
|
|
|
|
// int socket(int domain, int type, int protocol)
|
|
TEXT runtime·socket(SB),NOSPLIT,$0-16
|
|
// socket is implemented as socketcall(NR_socket, 1, *(rest of args))
|
|
// stack already should have domain, type, protocol.
|
|
MOVL $102, AX // syscall - socketcall
|
|
MOVL $1, BX // socket
|
|
LEAL domain+0(FP), CX
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+12(FP)
|
|
RET
|
|
|
|
// func sbrk0() uintptr
|
|
TEXT runtime·sbrk0(SB),NOSPLIT,$0-4
|
|
// Implemented as brk(NULL).
|
|
MOVL $45, AX // syscall - brk
|
|
MOVL $0, BX // NULL
|
|
INVOKE_SYSCALL
|
|
MOVL AX, ret+0(FP)
|
|
RET
|