glibc/sysdeps/unix/sparc/sysdep.h
David S. Miller 0722d7c2ac Explain why we don't make use of RDPC in the sparc PIC register setup.
* sysdeps/unix/sparc/sysdep.h: Document why we don't use
	"rd %pc" in the PIC register setup sequences.
2012-02-20 17:52:01 -08:00

96 lines
3.0 KiB
C

/* Copyright (C) 1993, 1994, 1995, 1997, 2003, 2011, 2012
Free Software Foundation, Inc.
This file is part of the GNU C Library.
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, see
<http://www.gnu.org/licenses/>. */
#include <sysdeps/unix/sysdep.h>
#include <sysdeps/sparc/sysdep.h>
#ifdef __ASSEMBLER__
/* Since C identifiers are not normally prefixed with an underscore
on this system, the asm identifier `syscall_error' intrudes on the
C name space. Make sure we use an innocuous name. */
#define syscall_error C_SYMBOL_NAME(__syscall_error)
#define SPARC_PIC_THUNK(reg) \
.ifndef __sparc_get_pc_thunk.reg; \
.section .text.__sparc_get_pc_thunk.reg,"axG",@progbits,__sparc_get_pc_thunk.reg,comdat; \
.align 32; \
.weak __sparc_get_pc_thunk.reg; \
.hidden __sparc_get_pc_thunk.reg; \
.type __sparc_get_pc_thunk.reg, #function; \
__sparc_get_pc_thunk.reg: \
jmp %o7 + 8; \
add %o7, %reg, %##reg; \
.previous; \
.endif;
/* Even when v9 we use a call sequence instead of using "rd %pc" because
RDPC is extremely expensive and incurs a full pipeline flush. */
#define SETUP_PIC_REG(reg) \
SPARC_PIC_THUNK(reg) \
sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %##reg; \
call __sparc_get_pc_thunk.reg; \
or %##reg, %lo(_GLOBAL_OFFSET_TABLE_+4), %##reg;
#define SETUP_PIC_REG_LEAF(reg, tmp) \
SPARC_PIC_THUNK(reg) \
sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %##reg; \
mov %o7, %##tmp; \
call __sparc_get_pc_thunk.reg; \
or %##reg, %lo(_GLOBAL_OFFSET_TABLE_+4), %##reg; \
mov %##tmp, %o7;
#define ENTRY(name) \
.global C_SYMBOL_NAME(name); \
.type name,@function; \
.align 4; \
C_LABEL(name)
#define PSEUDO(name, syscall_name, args) \
.global syscall_error; \
ENTRY (name) \
mov SYS_ify(syscall_name), %g1; \
ta 0; \
bcc 1f; \
sethi %hi(syscall_error), %g1; \
jmp %g1 + %lo(syscall_error); nop; \
1:
#define PSEUDO_NOERRNO(name, syscall_name, args) \
.global syscall_error; \
ENTRY (name) \
mov SYS_ify(syscall_name), %g1; \
ta 0
#define PSEUDO_ERRVAL(name, syscall_name, args) \
.global syscall_error; \
ENTRY (name) \
mov SYS_ify(syscall_name), %g1; \
ta 0
#define ret retl; nop
#define ret_NOERRNO retl; nop
#define ret_ERRVAL retl; nop
#define r0 %o0
#define r1 %o1
#define MOVE(x,y) mov x, y
#endif /* __ASSEMBLER__ */