github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/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  .file "gcc_s390x.S"
     6  
     7  /*
     8   * void crosscall_s390x(void (*fn)(void), void *g)
     9   *
    10   * Calling into the go tool chain, where all registers are caller save.
    11   * Called from standard s390x C ABI, where r6-r13, r15, and f8-f15 are
    12   * callee-save, so they must be saved explicitly.
    13   */
    14  .globl crosscall_s390x
    15  crosscall_s390x:
    16  	/* save r6-r15 in the register save area of the calling function */
    17  	stmg    %r6, %r15, 48(%r15)
    18  
    19  	/* allocate 64 bytes of stack space to save f8-f15 */
    20  	lay     %r15, -64(%r15)
    21  
    22  	/* save callee-saved floating point registers */
    23  	std     %f8, 0(%r15)
    24  	std     %f9, 8(%r15)
    25  	std     %f10, 16(%r15)
    26  	std     %f11, 24(%r15)
    27  	std     %f12, 32(%r15)
    28  	std     %f13, 40(%r15)
    29  	std     %f14, 48(%r15)
    30  	std     %f15, 56(%r15)
    31  
    32  	/* restore g pointer */
    33  	lgr     %r13, %r3
    34  
    35  	/* call fn */
    36  	basr    %r14, %r2
    37  
    38  	/* restore floating point registers */
    39  	ld      %f8, 0(%r15)
    40  	ld      %f9, 8(%r15)
    41  	ld      %f10, 16(%r15)
    42  	ld      %f11, 24(%r15)
    43  	ld      %f12, 32(%r15)
    44  	ld      %f13, 40(%r15)
    45  	ld      %f14, 48(%r15)
    46  	ld      %f15, 56(%r15)
    47  
    48  	/* de-allocate stack frame */
    49  	la      %r15, 64(%r15)
    50  
    51  	/* restore general purpose registers */
    52  	lmg     %r6, %r15, 48(%r15)
    53  
    54  	br      %r14 /* restored by lmg */
    55  
    56  #ifdef __ELF__
    57  .section .note.GNU-stack,"",%progbits
    58  #endif