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ircd::ctx: Add optimized jump_fcontext on x86_64 platforms.

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This commit is contained in:
Jason Volk 2019-10-06 20:22:16 -07:00
parent d2dd638a8a
commit 4af83b83c4
2 changed files with 63 additions and 0 deletions
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2
ircd/Makefile.am
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@ -129,6 +129,7 @@ libircd_la_SOURCES += prof_linux.cc
endif
libircd_la_SOURCES += fs.cc
libircd_la_SOURCES += ios.cc
libircd_la_SOURCES += ctx_x86_64.S
libircd_la_SOURCES += ctx.cc
libircd_la_SOURCES += ctx_eh.cc
libircd_la_SOURCES += ctx_ole.cc
@ -164,6 +165,7 @@ libircd_la_SOURCES += ircd.cc
base.lo: AM_CPPFLAGS := @BOOST_CPPFLAGS@ ${AM_CPPFLAGS}
client.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}
ctx_x86_64.lo: AM_CPPFLAGS := -I$(top_srcdir)/include
ctx.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}
ctx_ole.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}
ctx_eh.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}

61
ircd/ctx_x86_64.S Normal file
View file

@ -0,0 +1,61 @@
// 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 unit contains customization and experimentation for the core context
// switching routines. First note that everything here is platform-specific
// and not implemented on all platforms. Furthermore, boost::context functions
// overriden here are also overriden for the entire address space; if other
// libraries use boost::context our code will hook their context switches
// which we might not want. All of this must be considered to build or change
// any functionality from here.
#include <ircd/config.h>
#if defined(__x86_64__) && defined(__ELF__)
.file "ctx_x86_64.S"
.globl jump_fcontext
.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 $0x08, %rsp // alloc fc_mxcsr | fc_x87_cw
// 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
subq $-0x08, %rsp // free fc_mxcsr | fc_x87_cw
pop %r12 // load r12
pop %r13 // load r13
pop %r14 // load r14
pop %r15 // load r15
pop %rbx // load rbx
pop %rbp // load rbp
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