github.com/4ad/go@v0.0.0-20161219182952-69a12818b605/src/runtime/sys_sparc64.go (about)

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import "unsafe"
     8  
     9  // adjust Gobuf as if it executed a call to fn with context ctxt
    10  // and then did an immediate Gosave.
    11  func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
    12  	if buf.lr != 0 {
    13  		throw("invalid use of gostartcall")
    14  	}
    15  	buf.lr = buf.pc
    16  	buf.pc = uintptr(fn)
    17  	buf.ctxt = ctxt
    18  }
    19  
    20  // Called to rewind context saved during morestack back to beginning of function.
    21  // To help us, the linker emits a call back to the beginning 8 bytes after the
    22  // call to morestack. We just have to decode and apply that jump.
    23  func rewindmorestack(buf *gobuf) {
    24  	var inst uint32
    25  	if buf.pc&3 == 0 && buf.pc != 0 {
    26  		// For sparc, the pc register holds the address of the
    27  		// *current* instruction, rather than the next instruction
    28  		// to execute, and CTIs are padded with a nop to avoid DCTI
    29  		// coupling, so we need to skip ahead to get the jump.
    30  		buf.pc += 8
    31  		inst = *(*uint32)(unsafe.Pointer(buf.pc))
    32  		// Extract opcode
    33  		op1 := inst >> 30
    34  		// call and link
    35  		mop1 := 1 << 30
    36  
    37  		call := uint32(mop1 >> 30)
    38  		if op1 == call {
    39  			// Extract pc-relative address (4*sign_ext(disp30))
    40  			idisp30 := 4 * (int32(inst<<2) >> 2)
    41  
    42  			//ipc := uintptr(unsafe.Pointer(buf.pc))
    43  			buf.pc += uintptr(idisp30)
    44  
    45  			//print("runtime: rewind pc=", hex(ipc), " to pc=", hex(buf.pc), "\n");
    46  			return
    47  		}
    48  	}
    49  	print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n")
    50  	throw("runtime: misuse of rewindmorestack")
    51  }
    52  
    53  func usleep2(us uint32)
    54  
    55  //go:linkname usleep1_go runtime.usleep1
    56  //go:nosplit
    57  func usleep1_go(µs uint32) {
    58  	_g_ := getg()
    59  
    60  	// Check the validity of m because we might be called in cgo callback
    61  	// path early enough where there isn't a m available yet.
    62  	if _g_ != nil && _g_.m != nil {
    63  		sysvicall1(&libc_usleep, uintptr(µs))
    64  		return
    65  	}
    66  	usleep2(µs)
    67  }