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| // Copyright 2009 The Go Authors. All rights reserved.
| // Use of this source code is governed by a BSD-style
| // license that can be found in the LICENSE file.
|
| //
| // System calls and other sys.stuff for 386, Linux
| //
|
| #include "go_asm.h"
| #include "go_tls.h"
| #include "textflag.h"
|
| // Most linux systems use glibc's dynamic linker, which puts the
| // __kernel_vsyscall vdso helper at 0x10(GS) for easy access from position
| // independent code and setldt in runtime does the same in the statically
| // linked case. However, systems that use alternative libc such as Android's
| // bionic and musl, do not save the helper anywhere, and so the only way to
| // invoke a syscall from position independent code is boring old int $0x80
| // (which is also what syscall wrappers in bionic/musl use).
| //
| // The benchmarks also showed that using int $0x80 is as fast as calling
| // *%gs:0x10 except on AMD Opteron. See https://golang.org/cl/19833
| // for the benchmark program and raw data.
| //#define INVOKE_SYSCALL CALL 0x10(GS) // non-portable
| #define INVOKE_SYSCALL INT $0x80
|
| #define SYS_exit 1
| #define SYS_read 3
| #define SYS_write 4
| #define SYS_open 5
| #define SYS_close 6
| #define SYS_getpid 20
| #define SYS_access 33
| #define SYS_kill 37
| #define SYS_brk 45
| #define SYS_fcntl 55
| #define SYS_munmap 91
| #define SYS_socketcall 102
| #define SYS_setittimer 104
| #define SYS_clone 120
| #define SYS_sched_yield 158
| #define SYS_nanosleep 162
| #define SYS_rt_sigreturn 173
| #define SYS_rt_sigaction 174
| #define SYS_rt_sigprocmask 175
| #define SYS_sigaltstack 186
| #define SYS_mmap2 192
| #define SYS_mincore 218
| #define SYS_madvise 219
| #define SYS_gettid 224
| #define SYS_futex 240
| #define SYS_sched_getaffinity 242
| #define SYS_set_thread_area 243
| #define SYS_exit_group 252
| #define SYS_epoll_create 254
| #define SYS_epoll_ctl 255
| #define SYS_epoll_wait 256
| #define SYS_clock_gettime 265
| #define SYS_tgkill 270
| #define SYS_epoll_create1 329
|
| TEXT runtime·exit(SB),NOSPLIT,$0
| MOVL $SYS_exit_group, AX
| MOVL code+0(FP), BX
| INVOKE_SYSCALL
| INT $3 // not reached
| RET
|
| TEXT exit1<>(SB),NOSPLIT,$0
| MOVL $SYS_exit, AX
| MOVL code+0(FP), BX
| INVOKE_SYSCALL
| INT $3 // not reached
| RET
|
| // func exitThread(wait *uint32)
| TEXT runtime·exitThread(SB),NOSPLIT,$0-4
| MOVL wait+0(FP), AX
| // We're done using the stack.
| MOVL $0, (AX)
| MOVL $1, AX // exit (just this thread)
| MOVL $0, BX // exit code
| INT $0x80 // no stack; must not use CALL
| // We may not even have a stack any more.
| INT $3
| JMP 0(PC)
|
| TEXT runtime·open(SB),NOSPLIT,$0
| MOVL $SYS_open, AX
| MOVL name+0(FP), BX
| MOVL mode+4(FP), CX
| MOVL perm+8(FP), DX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| MOVL $-1, AX
| MOVL AX, ret+12(FP)
| RET
|
| TEXT runtime·closefd(SB),NOSPLIT,$0
| MOVL $SYS_close, AX
| MOVL fd+0(FP), BX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| MOVL $-1, AX
| MOVL AX, ret+4(FP)
| RET
|
| TEXT runtime·write(SB),NOSPLIT,$0
| MOVL $SYS_write, AX
| MOVL fd+0(FP), BX
| MOVL p+4(FP), CX
| MOVL n+8(FP), DX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| MOVL $-1, AX
| MOVL AX, ret+12(FP)
| RET
|
| TEXT runtime·read(SB),NOSPLIT,$0
| MOVL $SYS_read, AX
| MOVL fd+0(FP), BX
| MOVL p+4(FP), CX
| MOVL n+8(FP), DX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| MOVL $-1, AX
| MOVL AX, ret+12(FP)
| RET
|
| TEXT runtime·usleep(SB),NOSPLIT,$8
| MOVL $0, DX
| MOVL usec+0(FP), AX
| MOVL $1000000, CX
| DIVL CX
| MOVL AX, 0(SP)
| MOVL $1000, AX // usec to nsec
| MULL DX
| MOVL AX, 4(SP)
|
| // nanosleep(&ts, 0)
| MOVL $SYS_nanosleep, AX
| LEAL 0(SP), BX
| MOVL $0, CX
| INVOKE_SYSCALL
| RET
|
| TEXT runtime·gettid(SB),NOSPLIT,$0-4
| MOVL $SYS_gettid, AX
| INVOKE_SYSCALL
| MOVL AX, ret+0(FP)
| RET
|
| TEXT runtime·raise(SB),NOSPLIT,$12
| MOVL $SYS_getpid, AX
| INVOKE_SYSCALL
| MOVL AX, BX // arg 1 pid
| MOVL $SYS_gettid, AX
| INVOKE_SYSCALL
| MOVL AX, CX // arg 2 tid
| MOVL sig+0(FP), DX // arg 3 signal
| MOVL $SYS_tgkill, AX
| INVOKE_SYSCALL
| RET
|
| TEXT runtime·raiseproc(SB),NOSPLIT,$12
| MOVL $SYS_getpid, AX
| INVOKE_SYSCALL
| MOVL AX, BX // arg 1 pid
| MOVL sig+0(FP), CX // arg 2 signal
| MOVL $SYS_kill, AX
| INVOKE_SYSCALL
| RET
|
| TEXT runtime·setitimer(SB),NOSPLIT,$0-12
| MOVL $SYS_setittimer, AX
| MOVL mode+0(FP), BX
| MOVL new+4(FP), CX
| MOVL old+8(FP), DX
| INVOKE_SYSCALL
| RET
|
| TEXT runtime·mincore(SB),NOSPLIT,$0-16
| MOVL $SYS_mincore, AX
| MOVL addr+0(FP), BX
| MOVL n+4(FP), CX
| MOVL dst+8(FP), DX
| INVOKE_SYSCALL
| MOVL AX, ret+12(FP)
| RET
|
| // func walltime() (sec int64, nsec int32)
| TEXT runtime·walltime(SB), NOSPLIT, $0-12
| // We don't know how much stack space the VDSO code will need,
| // so switch to g0.
|
| MOVL SP, BP // Save old SP; BP unchanged by C code.
|
| get_tls(CX)
| MOVL g(CX), AX
| MOVL g_m(AX), SI // SI unchanged by C code.
|
| // Set vdsoPC and vdsoSP for SIGPROF traceback.
| MOVL 0(SP), DX
| MOVL DX, m_vdsoPC(SI)
| LEAL sec+0(SP), DX
| MOVL DX, m_vdsoSP(SI)
|
| CMPL AX, m_curg(SI) // Only switch if on curg.
| JNE noswitch
|
| MOVL m_g0(SI), DX
| MOVL (g_sched+gobuf_sp)(DX), SP // Set SP to g0 stack
|
| noswitch:
| SUBL $16, SP // Space for results
| ANDL $~15, SP // Align for C code
|
| // Stack layout, depending on call path:
| // x(SP) vDSO INVOKE_SYSCALL
| // 12 ts.tv_nsec ts.tv_nsec
| // 8 ts.tv_sec ts.tv_sec
| // 4 &ts -
| // 0 CLOCK_<id> -
|
| MOVL runtime·vdsoClockgettimeSym(SB), AX
| CMPL AX, $0
| JEQ fallback
|
| LEAL 8(SP), BX // &ts (struct timespec)
| MOVL BX, 4(SP)
| MOVL $0, 0(SP) // CLOCK_REALTIME
| CALL AX
| JMP finish
|
| fallback:
| MOVL $SYS_clock_gettime, AX
| MOVL $0, BX // CLOCK_REALTIME
| LEAL 8(SP), CX
| INVOKE_SYSCALL
|
| finish:
| MOVL 8(SP), AX // sec
| MOVL 12(SP), BX // nsec
|
| MOVL BP, SP // Restore real SP
| MOVL $0, m_vdsoSP(SI)
|
| // sec is in AX, nsec in BX
| MOVL AX, sec_lo+0(FP)
| MOVL $0, sec_hi+4(FP)
| MOVL BX, nsec+8(FP)
| RET
|
| // int64 nanotime(void) so really
| // void nanotime(int64 *nsec)
| TEXT runtime·nanotime(SB), NOSPLIT, $0-8
| // Switch to g0 stack. See comment above in runtime·walltime.
|
| MOVL SP, BP // Save old SP; BP unchanged by C code.
|
| get_tls(CX)
| MOVL g(CX), AX
| MOVL g_m(AX), SI // SI unchanged by C code.
|
| // Set vdsoPC and vdsoSP for SIGPROF traceback.
| MOVL 0(SP), DX
| MOVL DX, m_vdsoPC(SI)
| LEAL ret+0(SP), DX
| MOVL DX, m_vdsoSP(SI)
|
| CMPL AX, m_curg(SI) // Only switch if on curg.
| JNE noswitch
|
| MOVL m_g0(SI), DX
| MOVL (g_sched+gobuf_sp)(DX), SP // Set SP to g0 stack
|
| noswitch:
| SUBL $16, SP // Space for results
| ANDL $~15, SP // Align for C code
|
| MOVL runtime·vdsoClockgettimeSym(SB), AX
| CMPL AX, $0
| JEQ fallback
|
| LEAL 8(SP), BX // &ts (struct timespec)
| MOVL BX, 4(SP)
| MOVL $1, 0(SP) // CLOCK_MONOTONIC
| CALL AX
| JMP finish
|
| fallback:
| MOVL $SYS_clock_gettime, AX
| MOVL $1, BX // CLOCK_MONOTONIC
| LEAL 8(SP), CX
| INVOKE_SYSCALL
|
| finish:
| MOVL 8(SP), AX // sec
| MOVL 12(SP), BX // nsec
|
| MOVL BP, SP // Restore real SP
| MOVL $0, m_vdsoSP(SI)
|
| // sec is in AX, nsec in BX
| // convert to DX:AX nsec
| MOVL $1000000000, CX
| MULL CX
| ADDL BX, AX
| ADCL $0, DX
|
| MOVL AX, ret_lo+0(FP)
| MOVL DX, ret_hi+4(FP)
| RET
|
| TEXT runtime·rtsigprocmask(SB),NOSPLIT,$0
| MOVL $SYS_rt_sigprocmask, AX
| MOVL how+0(FP), BX
| MOVL new+4(FP), CX
| MOVL old+8(FP), DX
| MOVL size+12(FP), SI
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| INT $3
| RET
|
| TEXT runtime·rt_sigaction(SB),NOSPLIT,$0
| MOVL $SYS_rt_sigaction, AX
| MOVL sig+0(FP), BX
| MOVL new+4(FP), CX
| MOVL old+8(FP), DX
| MOVL size+12(FP), SI
| INVOKE_SYSCALL
| MOVL AX, ret+16(FP)
| RET
|
| TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
| MOVL fn+0(FP), AX
| MOVL sig+4(FP), BX
| MOVL info+8(FP), CX
| MOVL ctx+12(FP), DX
| MOVL SP, SI
| SUBL $32, SP
| ANDL $-15, SP // align stack: handler might be a C function
| MOVL BX, 0(SP)
| MOVL CX, 4(SP)
| MOVL DX, 8(SP)
| MOVL SI, 12(SP) // save SI: handler might be a Go function
| CALL AX
| MOVL 12(SP), AX
| MOVL AX, SP
| RET
|
| TEXT runtime·sigtramp(SB),NOSPLIT,$28
| // Save callee-saved C registers, since the caller may be a C signal handler.
| MOVL BX, bx-4(SP)
| MOVL BP, bp-8(SP)
| MOVL SI, si-12(SP)
| MOVL DI, di-16(SP)
| // We don't save mxcsr or the x87 control word because sigtrampgo doesn't
| // modify them.
|
| MOVL sig+0(FP), BX
| MOVL BX, 0(SP)
| MOVL info+4(FP), BX
| MOVL BX, 4(SP)
| MOVL ctx+8(FP), BX
| MOVL BX, 8(SP)
| CALL runtime·sigtrampgo(SB)
|
| MOVL di-16(SP), DI
| MOVL si-12(SP), SI
| MOVL bp-8(SP), BP
| MOVL bx-4(SP), BX
| RET
|
| TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
| JMP runtime·sigtramp(SB)
|
| TEXT runtime·sigreturn(SB),NOSPLIT,$0
| MOVL $SYS_rt_sigreturn, AX
| // Sigreturn expects same SP as signal handler,
| // so cannot CALL 0x10(GS) here.
| INT $0x80
| INT $3 // not reached
| RET
|
| TEXT runtime·mmap(SB),NOSPLIT,$0
| MOVL $SYS_mmap2, AX
| MOVL addr+0(FP), BX
| MOVL n+4(FP), CX
| MOVL prot+8(FP), DX
| MOVL flags+12(FP), SI
| MOVL fd+16(FP), DI
| MOVL off+20(FP), BP
| SHRL $12, BP
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS ok
| NOTL AX
| INCL AX
| MOVL $0, p+24(FP)
| MOVL AX, err+28(FP)
| RET
| ok:
| MOVL AX, p+24(FP)
| MOVL $0, err+28(FP)
| RET
|
| TEXT runtime·munmap(SB),NOSPLIT,$0
| MOVL $SYS_munmap, AX
| MOVL addr+0(FP), BX
| MOVL n+4(FP), CX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| INT $3
| RET
|
| TEXT runtime·madvise(SB),NOSPLIT,$0
| MOVL $SYS_madvise, AX
| MOVL addr+0(FP), BX
| MOVL n+4(FP), CX
| MOVL flags+8(FP), DX
| INVOKE_SYSCALL
| MOVL AX, ret+12(FP)
| RET
|
| // int32 futex(int32 *uaddr, int32 op, int32 val,
| // struct timespec *timeout, int32 *uaddr2, int32 val2);
| TEXT runtime·futex(SB),NOSPLIT,$0
| MOVL $SYS_futex, AX
| MOVL addr+0(FP), BX
| MOVL op+4(FP), CX
| MOVL val+8(FP), DX
| MOVL ts+12(FP), SI
| MOVL addr2+16(FP), DI
| MOVL val3+20(FP), BP
| INVOKE_SYSCALL
| MOVL AX, ret+24(FP)
| RET
|
| // int32 clone(int32 flags, void *stack, M *mp, G *gp, void (*fn)(void));
| TEXT runtime·clone(SB),NOSPLIT,$0
| MOVL $SYS_clone, AX
| MOVL flags+0(FP), BX
| MOVL stk+4(FP), CX
| MOVL $0, DX // parent tid ptr
| MOVL $0, DI // child tid ptr
|
| // Copy mp, gp, fn off parent stack for use by child.
| SUBL $16, CX
| MOVL mp+8(FP), SI
| MOVL SI, 0(CX)
| MOVL gp+12(FP), SI
| MOVL SI, 4(CX)
| MOVL fn+16(FP), SI
| MOVL SI, 8(CX)
| MOVL $1234, 12(CX)
|
| // cannot use CALL 0x10(GS) here, because the stack changes during the
| // system call (after CALL 0x10(GS), the child is still using the
| // parent's stack when executing its RET instruction).
| INT $0x80
|
| // In parent, return.
| CMPL AX, $0
| JEQ 3(PC)
| MOVL AX, ret+20(FP)
| RET
|
| // Paranoia: check that SP is as we expect.
| MOVL 12(SP), BP
| CMPL BP, $1234
| JEQ 2(PC)
| INT $3
|
| // Initialize AX to Linux tid
| MOVL $SYS_gettid, AX
| INVOKE_SYSCALL
|
| MOVL 0(SP), BX // m
| MOVL 4(SP), DX // g
| MOVL 8(SP), SI // fn
|
| CMPL BX, $0
| JEQ nog
| CMPL DX, $0
| JEQ nog
|
| MOVL AX, m_procid(BX) // save tid as m->procid
|
| // set up ldt 7+id to point at m->tls.
| LEAL m_tls(BX), BP
| MOVL m_id(BX), DI
| ADDL $7, DI // m0 is LDT#7. count up.
| // setldt(tls#, &tls, sizeof tls)
| PUSHAL // save registers
| PUSHL $32 // sizeof tls
| PUSHL BP // &tls
| PUSHL DI // tls #
| CALL runtime·setldt(SB)
| POPL AX
| POPL AX
| POPL AX
| POPAL
|
| // Now segment is established. Initialize m, g.
| get_tls(AX)
| MOVL DX, g(AX)
| MOVL BX, g_m(DX)
|
| CALL runtime·stackcheck(SB) // smashes AX, CX
| MOVL 0(DX), DX // paranoia; check they are not nil
| MOVL 0(BX), BX
|
| // more paranoia; check that stack splitting code works
| PUSHAL
| CALL runtime·emptyfunc(SB)
| POPAL
|
| nog:
| CALL SI // fn()
| CALL exit1<>(SB)
| MOVL $0x1234, 0x1005
|
| TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
| MOVL $SYS_sigaltstack, AX
| MOVL new+0(FP), BX
| MOVL old+4(FP), CX
| INVOKE_SYSCALL
| CMPL AX, $0xfffff001
| JLS 2(PC)
| INT $3
| RET
|
| // <asm-i386/ldt.h>
| // struct user_desc {
| // unsigned int entry_number;
| // unsigned long base_addr;
| // unsigned int limit;
| // unsigned int seg_32bit:1;
| // unsigned int contents:2;
| // unsigned int read_exec_only:1;
| // unsigned int limit_in_pages:1;
| // unsigned int seg_not_present:1;
| // unsigned int useable:1;
| // };
| #define SEG_32BIT 0x01
| // contents are the 2 bits 0x02 and 0x04.
| #define CONTENTS_DATA 0x00
| #define CONTENTS_STACK 0x02
| #define CONTENTS_CODE 0x04
| #define READ_EXEC_ONLY 0x08
| #define LIMIT_IN_PAGES 0x10
| #define SEG_NOT_PRESENT 0x20
| #define USEABLE 0x40
|
| // `-1` means the kernel will pick a TLS entry on the first setldt call,
| // which happens during runtime init, and that we'll store back the saved
| // entry and reuse that on subsequent calls when creating new threads.
| DATA runtime·tls_entry_number+0(SB)/4, $-1
| GLOBL runtime·tls_entry_number(SB), NOPTR, $4
|
| // setldt(int entry, int address, int limit)
| // We use set_thread_area, which mucks with the GDT, instead of modify_ldt,
| // which would modify the LDT, but is disabled on some kernels.
| // The name, setldt, is a misnomer, although we leave this name as it is for
| // the compatibility with other platforms.
| TEXT runtime·setldt(SB),NOSPLIT,$32
| MOVL address+4(FP), DX // base address
|
| #ifdef GOOS_android
| /*
| * Same as in sys_darwin_386.s:/ugliness, different constant.
| * address currently holds m->tls, which must be %gs:0xf8.
| * See cgo/gcc_android_386.c for the derivation of the constant.
| */
| SUBL $0xf8, DX
| MOVL DX, 0(DX)
| #else
| /*
| * When linking against the system libraries,
| * we use its pthread_create and let it set up %gs
| * for us. When we do that, the private storage
| * we get is not at 0(GS), but -4(GS).
| * To insulate the rest of the tool chain from this
| * ugliness, 8l rewrites 0(TLS) into -4(GS) for us.
| * To accommodate that rewrite, we translate
| * the address here and bump the limit to 0xffffffff (no limit)
| * so that -4(GS) maps to 0(address).
| * Also, the final 0(GS) (current 4(DX)) has to point
| * to itself, to mimic ELF.
| */
| ADDL $0x4, DX // address
| MOVL DX, 0(DX)
| #endif
|
| // get entry number
| MOVL runtime·tls_entry_number(SB), CX
|
| // set up user_desc
| LEAL 16(SP), AX // struct user_desc
| MOVL CX, 0(AX) // unsigned int entry_number
| MOVL DX, 4(AX) // unsigned long base_addr
| MOVL $0xfffff, 8(AX) // unsigned int limit
| MOVL $(SEG_32BIT|LIMIT_IN_PAGES|USEABLE|CONTENTS_DATA), 12(AX) // flag bits
|
| // call set_thread_area
| MOVL AX, BX // user_desc
| MOVL $SYS_set_thread_area, AX
| // We can't call this via 0x10(GS) because this is called from setldt0 to set that up.
| INT $0x80
|
| // breakpoint on error
| 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 $SYS_sched_yield, AX
| INVOKE_SYSCALL
| RET
|
| TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
| MOVL $SYS_sched_getaffinity, AX
| 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 $SYS_epoll_create, 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 $SYS_epoll_create1, 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 $SYS_epoll_ctl, 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 $SYS_epoll_wait, 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 $SYS_fcntl, AX
| 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 $SYS_access, AX
| 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 $SYS_socketcall, AX
| 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 $SYS_socketcall, AX
| 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 $SYS_brk, AX
| MOVL $0, BX // NULL
| INVOKE_SYSCALL
| MOVL AX, ret+0(FP)
| RET
|
|
