mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-23 03:10:05 +00:00
78e5779b1e
1998-10-22 12:49 Ulrich Drepper <drepper@cygnus.com> * sysdeps/unix/sysv/linux/i386/sysdep.h: Drastically simplify and improve INLINE_SYSCALL using macro assembler magic.
275 lines
8.9 KiB
C
275 lines
8.9 KiB
C
/* Copyright (C) 1992, 93, 95, 96, 97, 98 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>, August 1995.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public License as
|
|
published by the Free Software Foundation; either version 2 of the
|
|
License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#ifndef _LINUX_I386_SYSDEP_H
|
|
#define _LINUX_I386_SYSDEP_H 1
|
|
|
|
/* There is some commonality. */
|
|
#include <sysdeps/unix/i386/sysdep.h>
|
|
|
|
/* For Linux we can use the system call table in the header file
|
|
/usr/include/asm/unistd.h
|
|
of the kernel. But these symbols do not follow the SYS_* syntax
|
|
so we have to redefine the `SYS_ify' macro here. */
|
|
#undef SYS_ify
|
|
#define SYS_ify(syscall_name) __NR_##syscall_name
|
|
|
|
/* ELF-like local names start with `.L'. */
|
|
#undef L
|
|
#define L(name) .L##name
|
|
|
|
#ifdef __ASSEMBLER__
|
|
|
|
/* Linux uses a negative return value to indicate syscall errors,
|
|
unlike most Unices, which use the condition codes' carry flag.
|
|
|
|
Since version 2.1 the return value of a system call might be
|
|
negative even if the call succeeded. E.g., the `lseek' system call
|
|
might return a large offset. Therefore we must not anymore test
|
|
for < 0, but test for a real error by making sure the value in %eax
|
|
is a real error number. Linus said he will make sure the no syscall
|
|
returns a value in -1 .. -4095 as a valid result so we can savely
|
|
test with -4095. */
|
|
|
|
/* We don't want the label for the error handle to be global when we define
|
|
it here. */
|
|
#ifdef PIC
|
|
# define SYSCALL_ERROR_LABEL 0f
|
|
#else
|
|
# define SYSCALL_ERROR_LABEL syscall_error
|
|
#endif
|
|
|
|
#undef PSEUDO
|
|
#define PSEUDO(name, syscall_name, args) \
|
|
.text; \
|
|
ENTRY (name) \
|
|
DO_CALL (args, syscall_name); \
|
|
cmpl $-4095, %eax; \
|
|
jae SYSCALL_ERROR_LABEL; \
|
|
L(pseudo_end):
|
|
|
|
#undef PSEUDO_END
|
|
#define PSEUDO_END(name) \
|
|
SYSCALL_ERROR_HANDLER \
|
|
END (name)
|
|
|
|
#ifndef PIC
|
|
#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
|
|
#else
|
|
/* Store (- %eax) into errno through the GOT. */
|
|
#ifdef _LIBC_REENTRANT
|
|
#define SYSCALL_ERROR_HANDLER \
|
|
0:pushl %ebx; \
|
|
call 1f; \
|
|
1:popl %ebx; \
|
|
xorl %edx, %edx; \
|
|
addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx; \
|
|
subl %eax, %edx; \
|
|
pushl %edx; \
|
|
call __errno_location@PLT; \
|
|
popl %ecx; \
|
|
popl %ebx; \
|
|
movl %ecx, (%eax); \
|
|
orl $-1, %eax; \
|
|
jmp L(pseudo_end);
|
|
/* A quick note: it is assumed that the call to `__errno_location' does
|
|
not modify the stack! */
|
|
#else
|
|
#define SYSCALL_ERROR_HANDLER \
|
|
0:call 1f; \
|
|
1:popl %ecx; \
|
|
xorl %edx, %edx; \
|
|
addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ecx; \
|
|
subl %eax, %edx; \
|
|
movl errno@GOT(%ecx), %ecx; \
|
|
movl %edx, (%ecx); \
|
|
orl $-1, %eax; \
|
|
jmp L(pseudo_end);
|
|
#endif /* _LIBC_REENTRANT */
|
|
#endif /* PIC */
|
|
|
|
/* Linux takes system call arguments in registers:
|
|
|
|
syscall number %eax call-clobbered
|
|
arg 1 %ebx call-saved
|
|
arg 2 %ecx call-clobbered
|
|
arg 3 %edx call-clobbered
|
|
arg 4 %esi call-saved
|
|
arg 5 %edi call-saved
|
|
|
|
The stack layout upon entering the function is:
|
|
|
|
20(%esp) Arg# 5
|
|
16(%esp) Arg# 4
|
|
12(%esp) Arg# 3
|
|
8(%esp) Arg# 2
|
|
4(%esp) Arg# 1
|
|
(%esp) Return address
|
|
|
|
(Of course a function with say 3 arguments does not have entries for
|
|
arguments 4 and 5.)
|
|
|
|
The following code tries hard to be optimal. A general assumption
|
|
(which is true according to the data books I have) is that
|
|
|
|
2 * xchg is more expensive than pushl + movl + popl
|
|
|
|
Beside this a neat trick is used. The calling conventions for Linux
|
|
tell that among the registers used for parameters %ecx and %edx need
|
|
not be saved. Beside this we may clobber this registers even when
|
|
they are not used for parameter passing.
|
|
|
|
As a result one can see below that we save the content of the %ebx
|
|
register in the %edx register when we have less than 3 arguments
|
|
(2 * movl is less expensive than pushl + popl).
|
|
|
|
Second unlike for the other registers we don't save the content of
|
|
%ecx and %edx when we have more than 1 and 2 registers resp.
|
|
|
|
The code below might look a bit long but we have to take care for
|
|
the pipelined processors (i586). Here the `pushl' and `popl'
|
|
instructions are marked as NP (not pairable) but the exception is
|
|
two consecutive of these instruction. This gives no penalty on
|
|
other processors though. */
|
|
|
|
#undef DO_CALL
|
|
#define DO_CALL(args, syscall_name) \
|
|
PUSHARGS_##args \
|
|
DOARGS_##args \
|
|
movl $SYS_ify (syscall_name), %eax; \
|
|
int $0x80 \
|
|
POPARGS_##args
|
|
|
|
#define PUSHARGS_0 /* No arguments to push. */
|
|
#define DOARGS_0 /* No arguments to frob. */
|
|
#define POPARGS_0 /* No arguments to pop. */
|
|
#define _PUSHARGS_0 /* No arguments to push. */
|
|
#define _DOARGS_0(n) /* No arguments to frob. */
|
|
#define _POPARGS_0 /* No arguments to pop. */
|
|
|
|
#define PUSHARGS_1 movl %ebx, %edx; PUSHARGS_0
|
|
#define DOARGS_1 _DOARGS_1 (4)
|
|
#define POPARGS_1 POPARGS_0; movl %edx, %ebx
|
|
#define _PUSHARGS_1 pushl %ebx; _PUSHARGS_0
|
|
#define _DOARGS_1(n) movl n(%esp), %ebx; _DOARGS_0(n-4)
|
|
#define _POPARGS_1 _POPARGS_0; popl %ebx
|
|
|
|
#define PUSHARGS_2 PUSHARGS_1
|
|
#define DOARGS_2 _DOARGS_2 (8)
|
|
#define POPARGS_2 POPARGS_1
|
|
#define _PUSHARGS_2 _PUSHARGS_1
|
|
#define _DOARGS_2(n) movl n(%esp), %ecx; _DOARGS_1 (n-4)
|
|
#define _POPARGS_2 _POPARGS_1
|
|
|
|
#define PUSHARGS_3 _PUSHARGS_2
|
|
#define DOARGS_3 _DOARGS_3 (16)
|
|
#define POPARGS_3 _POPARGS_3
|
|
#define _PUSHARGS_3 _PUSHARGS_2
|
|
#define _DOARGS_3(n) movl n(%esp), %edx; _DOARGS_2 (n-4)
|
|
#define _POPARGS_3 _POPARGS_2
|
|
|
|
#define PUSHARGS_4 _PUSHARGS_4
|
|
#define DOARGS_4 _DOARGS_4 (24)
|
|
#define POPARGS_4 _POPARGS_4
|
|
#define _PUSHARGS_4 pushl %esi; _PUSHARGS_3
|
|
#define _DOARGS_4(n) movl n(%esp), %esi; _DOARGS_3 (n-4)
|
|
#define _POPARGS_4 _POPARGS_3; popl %esi
|
|
|
|
#define PUSHARGS_5 _PUSHARGS_5
|
|
#define DOARGS_5 _DOARGS_5 (32)
|
|
#define POPARGS_5 _POPARGS_5
|
|
#define _PUSHARGS_5 pushl %edi; _PUSHARGS_4
|
|
#define _DOARGS_5(n) movl n(%esp), %edi; _DOARGS_4 (n-4)
|
|
#define _POPARGS_5 _POPARGS_4; popl %edi
|
|
|
|
#else /* !__ASSEMBLER__ */
|
|
|
|
/* We need some help from the assembler to generate optimal code. We
|
|
define some macros here which later will be used. */
|
|
asm ("__X'%ebx = 1\n\t"
|
|
"__X'%ecx = 2\n\t"
|
|
"__X'%edx = 2\n\t"
|
|
"__X'%eax = 3\n\t"
|
|
"__X'%esi = 3\n\t"
|
|
"__X'%edi = 3\n\t"
|
|
"__X'%ebp = 3\n\t"
|
|
"__X'%esp = 3\n\t"
|
|
".macro bpushl name reg\n\t"
|
|
".if 1 - \\name\n\t"
|
|
".if 2 - \\name\n\t"
|
|
"pushl %ebx\n\t"
|
|
".else\n\t"
|
|
"xchgl \\reg, %ebx\n\t"
|
|
".endif\n\t"
|
|
".endif\n\t"
|
|
".endm\n\t"
|
|
".macro bpopl name reg\n\t"
|
|
".if 1 - \\name\n\t"
|
|
".if 2 - \\name\n\t"
|
|
"popl %ebx\n\t"
|
|
".else\n\t"
|
|
"xchgl \\reg, %ebx\n\t"
|
|
".endif\n\t"
|
|
".endif\n\t"
|
|
".endm\n\t"
|
|
".macro bmovl name reg\n\t"
|
|
".if 1 - \\name\n\t"
|
|
".if 2 - \\name\n\t"
|
|
"movl \\reg, %ebx\n\t"
|
|
".endif\n\t"
|
|
".endif\n\t"
|
|
".endm\n\t");
|
|
|
|
/* Define a macro which expands inline into the wrapper code for a system
|
|
call. */
|
|
#undef INLINE_SYSCALL
|
|
#define INLINE_SYSCALL(name, nr, args...) \
|
|
({ \
|
|
unsigned int resultvar; \
|
|
asm volatile ( \
|
|
"bpushl __X'%k2, %k2\n\t" \
|
|
"bmovl __X'%k2, %k2\n\t" \
|
|
"movl %1, %%eax\n\t" \
|
|
"int $0x80\n\t" \
|
|
"bpopl __X'%k2, %k2\n\t" \
|
|
: "=a" (resultvar) \
|
|
: "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc"); \
|
|
if (resultvar >= 0xfffff001) \
|
|
{ \
|
|
__set_errno (-resultvar); \
|
|
resultvar = 0xffffffff; \
|
|
} \
|
|
(int) resultvar; })
|
|
|
|
#define ASMFMT_0()
|
|
#define ASMFMT_1(arg1) \
|
|
, "acdSD" (arg1)
|
|
#define ASMFMT_2(arg1, arg2) \
|
|
, "adCD" (arg1), "c" (arg2)
|
|
#define ASMFMT_3(arg1, arg2, arg3) \
|
|
, "aCD" (arg1), "c" (arg2), "d" (arg3)
|
|
#define ASMFMT_4(arg1, arg2, arg3, arg4) \
|
|
, "aD" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
|
|
#define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
|
|
, "a" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
|
|
|
|
#endif /* __ASSEMBLER__ */
|
|
|
|
#endif /* linux/i386/sysdep.h */
|