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Diffstat (limited to 'newlib/libc/sys/linux/linuxthreads/machine/i386/sysdep.h')
| -rw-r--r-- | newlib/libc/sys/linux/linuxthreads/machine/i386/sysdep.h | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/newlib/libc/sys/linux/linuxthreads/machine/i386/sysdep.h b/newlib/libc/sys/linux/linuxthreads/machine/i386/sysdep.h new file mode 100644 index 000000000..48aeab195 --- /dev/null +++ b/newlib/libc/sys/linux/linuxthreads/machine/i386/sysdep.h @@ -0,0 +1,291 @@ +/* Copyright (C) 1992, 93, 95, 96, 97, 98, 99, 00 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper, <drepper@gnu.org>, August 1995. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; 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 + +#include "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; \ + PUSH_ERRNO_LOCATION_RETURN; \ + call BP_SYM (__errno_location)@PLT; \ + POP_ERRNO_LOCATION_RETURN; \ + 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 (".L__X'%ebx = 1\n\t" + ".L__X'%ecx = 2\n\t" + ".L__X'%edx = 2\n\t" + ".L__X'%eax = 3\n\t" + ".L__X'%esi = 3\n\t" + ".L__X'%edi = 3\n\t" + ".L__X'%ebp = 3\n\t" + ".L__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 ( \ + LOADARGS_##nr \ + "movl %1, %%eax\n\t" \ + "int $0x80\n\t" \ + RESTOREARGS_##nr \ + : "=a" (resultvar) \ + : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc"); \ + if (resultvar >= 0xfffff001) \ + { \ + __set_errno (-resultvar); \ + resultvar = 0xffffffff; \ + } \ + (int) resultvar; }) + +#define LOADARGS_0 +#define LOADARGS_1 \ + "bpushl .L__X'%k2, %k2\n\t" \ + "bmovl .L__X'%k2, %k2\n\t" +#define LOADARGS_2 LOADARGS_1 +#define LOADARGS_3 LOADARGS_1 +#define LOADARGS_4 LOADARGS_1 +#define LOADARGS_5 LOADARGS_1 + +#define RESTOREARGS_0 +#define RESTOREARGS_1 \ + "bpopl .L__X'%k2, %k2\n\t" +#define RESTOREARGS_2 RESTOREARGS_1 +#define RESTOREARGS_3 RESTOREARGS_1 +#define RESTOREARGS_4 RESTOREARGS_1 +#define RESTOREARGS_5 RESTOREARGS_1 + +#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 */ |