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construct/ircd/ctx_x86_64.S

70 lines
2.6 KiB
ArmAsm

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
//
// This context switch is smaller than asio's and fits in a single iline
//
#include <ircd/config.h>
#include <boost/version.hpp>
#if defined(__x86_64__) && defined(__ELF__)
.file "ctx_x86_64.S"
.globl jump_fcontext
// Sizes of additional items saved on context switch
.equiv x87_ctrl_sz, 0x04
.equiv mmx_ctrl_sz, 0x04
.equiv stack_prot_sz, 0x08
// Total size of all additional items
.if BOOST_VERSION >= 108100
.equiv alloc_sz, x87_ctrl_sz + mmx_ctrl_sz + stack_prot_sz
.else
.equiv alloc_sz, x87_ctrl_sz + mmx_ctrl_sz
.endif
.text
.type jump_fcontext, @function
.align 16
// returns struct transfer_t { void *fctx, *data; };
// param DI = void *to
// param SI = void *vp
jump_fcontext:
push %rbp // store rbp 0x30
push %rbx // store rbx 0x28
push %r15 // store r15 0x20
push %r14 // store r14 0x18
push %r13 // store r13 0x10
push %r12 // store r12 0x08
subq $alloc_sz, %rsp // additional allocation
fnstcw 0x04(%rsp) // store x87 control-word
stmxcsr 0x00(%rsp) // store MMX control- and status-word
xchgq %rsp, %rdi // swap stack
movq %rsi, %rdx // store transfer_t.data (retval)
movq %rdi, %rax // store transfer_t.fctx (retval)
ldmxcsr 0x00(%rsp) // load MMX control- and status-word
fldcw 0x04(%rsp) // load x87 control-word
addq $alloc_sz, %rsp // free allocation
pop %r12 // load r12 <-- LLd miss
pop %r13 // load r13
pop %r14 // load r14
pop %r15 // load r15
pop %rbx // load rbx
pop %rbp // load rbp <-- LLd miss
retq // enter context
// mark the size of jump_fcontext
.size jump_fcontext, .-jump_fcontext
// Mark that we don't need executable stack.
.section .note.GNU-stack, "", %progbits
#endif