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dnl x86 fat binary entrypoints.
dnl Copyright 2003, 2012 Free Software Foundation, Inc.
dnl
dnl This file is part of the GNU MP Library.
dnl
dnl The GNU MP Library is free software; you can redistribute it and/or
dnl modify it under the terms of the GNU Lesser General Public License as
dnl published by the Free Software Foundation; either version 3 of the
dnl License, or (at your option) any later version.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful,
dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
dnl Lesser General Public License for more details.
dnl
dnl You should have received a copy of the GNU Lesser General Public License
dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
include(`../config.m4')
dnl Forcibly disable profiling.
dnl
dnl The entrypoints and inits are small enough not to worry about, the real
dnl routines arrived at will have any profiling. Also, the way the code
dnl here ends with a jump means we won't work properly with the
dnl "instrument" profiling scheme anyway.
define(`WANT_PROFILING',no)
TEXT
dnl Usage: FAT_ENTRY(name, offset)
dnl
dnl Emit a fat binary entrypoint function of the given name. This is the
dnl normal entry for applications, eg. __gmpn_add_n.
dnl
dnl The code simply jumps through the function pointer in __gmpn_cpuvec at
dnl the given "offset" (in bytes).
dnl
dnl For non-PIC, the jumps are 5 bytes each, aligning them to 8 should be
dnl fine for all x86s.
dnl
dnl For PIC, the jumps are 20 bytes each, and are best aligned to 16 to
dnl ensure at least the first two instructions don't cross a cache line
dnl boundary.
dnl
dnl Note the extra `' ahead of PROLOGUE obscures it from the HAVE_NATIVE
dnl grepping in configure, stopping that code trying to eval something with
dnl $1 in it.
define(FAT_ENTRY,
m4_assert_numargs(2)
` ALIGN(ifdef(`PIC',16,8))
`'PROLOGUE($1)
ifdef(`PIC',
` call L(movl_eip_edx)
L(entry_here$2):
addl $_GLOBAL_OFFSET_TABLE_+[.-L(entry_here$2)], %edx
movl GSYM_PREFIX`'__gmpn_cpuvec@GOT(%edx), %edx
jmp *m4_empty_if_zero($2)(%edx)
',`dnl non-PIC
jmp *GSYM_PREFIX`'__gmpn_cpuvec+$2
')
EPILOGUE()
')
dnl FAT_ENTRY for each CPUVEC_FUNCS_LIST
dnl
define(`CPUVEC_offset',0)
foreach(i,
`FAT_ENTRY(MPN(i),CPUVEC_offset)
define(`CPUVEC_offset',eval(CPUVEC_offset + 4))',
CPUVEC_FUNCS_LIST)
ifdef(`PIC',`
ALIGN(8)
L(movl_eip_edx):
movl (%esp), %edx
ret_internal
')
dnl Usage: FAT_INIT(name, offset)
dnl
dnl Emit a fat binary initializer function of the given name. These
dnl functions are the initial values for the pointers in __gmpn_cpuvec.
dnl
dnl The code simply calls __gmpn_cpuvec_init, and then jumps back through
dnl the __gmpn_cpuvec pointer, at the given "offset" (in bytes).
dnl __gmpn_cpuvec_init will have stored the address of the selected
dnl implementation there.
dnl
dnl Only one of these routines will be executed, and only once, since after
dnl that all the __gmpn_cpuvec pointers go to real routines. So there's no
dnl need for anything special here, just something small and simple. To
dnl keep code size down, "fat_init" is a shared bit of code, arrived at
dnl with the offset in %al. %al is used since the movb instruction is 2
dnl bytes where %eax would be 4.
dnl
dnl Note having `PROLOGUE in FAT_INIT obscures that PROLOGUE from the
dnl HAVE_NATIVE grepping in configure, preventing that code trying to eval
dnl something with $1 in it.
define(FAT_INIT,
m4_assert_numargs(2)
`PROLOGUE($1)
movb $`'$2, %al
jmp L(fat_init)
EPILOGUE()
')
L(fat_init):
C al __gmpn_cpuvec byte offset
movzbl %al, %eax
pushl %eax
ifdef(`PIC',`
pushl %ebx
call L(movl_eip_ebx)
L(init_here):
addl $_GLOBAL_OFFSET_TABLE_+[.-L(init_here)], %ebx
call GSYM_PREFIX`'__gmpn_cpuvec_init@PLT
movl GSYM_PREFIX`'__gmpn_cpuvec@GOT(%ebx), %edx
popl %ebx
popl %eax
jmp *(%edx,%eax)
L(movl_eip_ebx):
movl (%esp), %ebx
ret_internal
',`dnl non-PIC
call GSYM_PREFIX`'__gmpn_cpuvec_init
popl %eax
jmp *GSYM_PREFIX`'__gmpn_cpuvec(%eax)
')
dnl FAT_INIT for each CPUVEC_FUNCS_LIST
dnl
define(`CPUVEC_offset',0)
foreach(i,
`FAT_INIT(MPN(i`'_init),CPUVEC_offset)
define(`CPUVEC_offset',eval(CPUVEC_offset + 4))',
CPUVEC_FUNCS_LIST)
C long __gmpn_cpuid (char dst[12], int id);
C
C This is called only once, so just something simple and compact is fine.
defframe(PARAM_ID, 8)
defframe(PARAM_DST, 4)
deflit(`FRAME',0)
PROLOGUE(__gmpn_cpuid)
pushl %esi FRAME_pushl()
pushl %ebx FRAME_pushl()
movl PARAM_ID, %eax
cpuid
movl PARAM_DST, %esi
movl %ebx, (%esi)
movl %edx, 4(%esi)
movl %ecx, 8(%esi)
popl %ebx
popl %esi
ret
EPILOGUE()
C int __gmpn_cpuid_available (void);
C
C Return non-zero if the cpuid instruction is available, which means late
C model 80486 and higher. 80386 and early 80486 don't have cpuid.
C
C The test follows Intel AP-485 application note, namely that if bit 21 is
C modifiable then cpuid is supported. This test is reentrant and thread
C safe, since of course any interrupt or context switch will preserve the
C flags while we're tinkering with them.
C
C This is called only once, so just something simple and compact is fine.
PROLOGUE(__gmpn_cpuid_available)
pushf
popl %ecx C old flags
movl %ecx, %edx
xorl $0x200000, %edx
pushl %edx
popf
pushf
popl %edx C tweaked flags
movl $1, %eax
cmpl %ecx, %edx
jne L(available)
xorl %eax, %eax C not changed, so cpuid not available
L(available):
ret
EPILOGUE()
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