1  /* Copyright (C) 2011-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #define _SYSDEPS_SYSDEP_H 1
      19  #include <bits/hwcap.h>
      20  
      21  #ifdef	__ASSEMBLER__
      22  
      23  #define SPARC_PIC_THUNK(reg)						\
      24  	.ifndef __sparc_get_pc_thunk.reg;				\
      25  	.section .text.__sparc_get_pc_thunk.reg,"axG",@progbits,__sparc_get_pc_thunk.reg,comdat; \
      26  	.align	 32;							\
      27  	.weak	 __sparc_get_pc_thunk.reg;				\
      28  	.hidden	 __sparc_get_pc_thunk.reg;				\
      29  	.type	 __sparc_get_pc_thunk.reg, #function;			\
      30  __sparc_get_pc_thunk.reg:		   				\
      31  	jmp	%o7 + 8;						\
      32  	 add	%o7, %reg, %##reg;					\
      33  	.previous;							\
      34  	.endif;
      35  
      36  /* The "-4" and "+4" offsets against _GLOBAL_OFFSET_TABLE_ are
      37     critical since they represent the offset from the thunk call to the
      38     instruction containing the _GLOBAL_OFFSET_TABLE_ reference.
      39     Therefore these instructions cannot be moved around without
      40     appropriate adjustments to those offsets.
      41  
      42     Furthermore, these expressions are special in another regard.  When
      43     the assembler sees a reference to _GLOBAL_OFFSET_TABLE_ inside of
      44     a %hi() or %lo(), it emits a PC-relative relocation.  This causes
      45     R_SPARC_HI22 to turn into R_SPARC_PC22, and R_SPARC_LO10 to turn into
      46     R_SPARC_PC10, respectively.
      47  
      48     Even when v9 we use a call sequence instead of using "rd %pc" because
      49     RDPC is extremely expensive and incurs a full pipeline flush.  */
      50  
      51  #define SPARC_PIC_THUNK_CALL(reg)					\
      52  	sethi	%hi(_GLOBAL_OFFSET_TABLE_-4), %##reg;			\
      53  	call	__sparc_get_pc_thunk.reg;				\
      54  	 or	%##reg, %lo(_GLOBAL_OFFSET_TABLE_+4), %##reg;
      55  
      56  #define SETUP_PIC_REG(reg)						\
      57  	SPARC_PIC_THUNK(reg)						\
      58  	SPARC_PIC_THUNK_CALL(reg)
      59  
      60  #define SETUP_PIC_REG_LEAF(reg, tmp)					\
      61  	SPARC_PIC_THUNK(reg)						\
      62  	mov	%o7, %##tmp;		      				\
      63  	SPARC_PIC_THUNK_CALL(reg);					\
      64  	mov	%##tmp, %o7;
      65  
      66  #undef ENTRY
      67  #define ENTRY(name)			\
      68  	.align	4;			\
      69  	.global	C_SYMBOL_NAME(name);	\
      70  	.type	name, @function;	\
      71  C_LABEL(name)				\
      72  	cfi_startproc;
      73  
      74  #undef END
      75  #define END(name)			\
      76  	cfi_endproc;			\
      77  	.size name, . - name
      78  
      79  #undef LOC
      80  #define LOC(name)  .L##name
      81  
      82  #endif	/* __ASSEMBLER__ */