github.com/c9s/go@v0.0.0-20180120015821-984e81f64e0c/src/runtime/cgo/gcc_s390x.S (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  /*
     6   * void crosscall_s390x(void (*fn)(void), void *g)
     7   *
     8   * Calling into the go tool chain, where all registers are caller save.
     9   * Called from standard s390x C ABI, where r6-r13, r15, and f8-f15 are
    10   * callee-save, so they must be saved explicitly.
    11   */
    12  .globl crosscall_s390x
    13  crosscall_s390x:
    14  	/* save r6-r15 in the register save area of the calling function */
    15  	stmg    %r6, %r15, 48(%r15)
    16  
    17  	/* allocate 64 bytes of stack space to save f8-f15 */
    18  	lay     %r15, -64(%r15)
    19  
    20  	/* save callee-saved floating point registers */
    21  	std     %f8, 0(%r15)
    22  	std     %f9, 8(%r15)
    23  	std     %f10, 16(%r15)
    24  	std     %f11, 24(%r15)
    25  	std     %f12, 32(%r15)
    26  	std     %f13, 40(%r15)
    27  	std     %f14, 48(%r15)
    28  	std     %f15, 56(%r15)
    29  
    30  	/* restore g pointer */
    31  	lgr     %r13, %r3
    32  
    33  	/* call fn */
    34  	basr    %r14, %r2
    35  
    36  	/* restore floating point registers */
    37  	ld      %f8, 0(%r15)
    38  	ld      %f9, 8(%r15)
    39  	ld      %f10, 16(%r15)
    40  	ld      %f11, 24(%r15)
    41  	ld      %f12, 32(%r15)
    42  	ld      %f13, 40(%r15)
    43  	ld      %f14, 48(%r15)
    44  	ld      %f15, 56(%r15)
    45  
    46  	/* de-allocate stack frame */
    47  	la      %r15, 64(%r15)
    48  
    49  	/* restore general purpose registers */
    50  	lmg     %r6, %r15, 48(%r15)
    51  
    52  	br      %r14 /* restored by lmg */
    53  
    54  #ifdef __ELF__
    55  .section .note.GNU-stack,"",%progbits
    56  #endif