diff options
Diffstat (limited to 'libgo/runtime/go-context.S')
| -rw-r--r-- | libgo/runtime/go-context.S | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/libgo/runtime/go-context.S b/libgo/runtime/go-context.S new file mode 100644 index 0000000..0cd2242 --- /dev/null +++ b/libgo/runtime/go-context.S @@ -0,0 +1,69 @@ +// Copyright 2019 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. + +// This provides a simplified version of getcontext and +// setcontext. They are like the corresponding functions +// in libc, but we only save/restore the callee-save +// registers and PC, SP. Unlike the libc functions, we +// don't save/restore the signal masks and floating point +// environment. + +#if defined(__x86_64__) && defined(__linux__) && !defined(__CET__) + +#define RBP_OFF (0*8) +#define RBX_OFF (1*8) +#define R12_OFF (2*8) +#define R13_OFF (3*8) +#define R14_OFF (4*8) +#define R15_OFF (5*8) +#define SP_OFF (6*8) +#define PC_OFF (7*8) + +.globl __go_getcontext +.text +__go_getcontext: + movq %rbx, RBX_OFF(%rdi) + movq %rbp, RBP_OFF(%rdi) + movq %r12, R12_OFF(%rdi) + movq %r13, R13_OFF(%rdi) + movq %r14, R14_OFF(%rdi) + movq %r15, R15_OFF(%rdi) + + movq (%rsp), %rax // return PC + movq %rax, PC_OFF(%rdi) + leaq 8(%rsp), %rax // the SP before pushing return PC + movq %rax, SP_OFF(%rdi) + + ret + +.globl __go_setcontext +.text +__go_setcontext: + movq RBX_OFF(%rdi), %rbx + movq RBP_OFF(%rdi), %rbp + movq R12_OFF(%rdi), %r12 + movq R13_OFF(%rdi), %r13 + movq R14_OFF(%rdi), %r14 + movq R15_OFF(%rdi), %r15 + movq SP_OFF(%rdi), %rsp + movq PC_OFF(%rdi), %rdx + + jmp *%rdx + +.globl __go_makecontext +.text +__go_makecontext: + addq %rcx, %rdx + + // Align the SP, and push a dummy return address. + andq $~0xfULL, %rdx + subq $8, %rdx + movq $0, (%rdx) + + movq %rdx, SP_OFF(%rdi) + movq %rsi, PC_OFF(%rdi) + + ret + +#endif |