u-boot/arch/arm/lib/bss.c
Albert ARIBAUD 3ebd1cbc49 arm: make __bss_start and __bss_end__ compiler-generated
Turn __bss_start and __bss_end__ from linker-generated
to compiler-generated symbols, causing relocations for
these symbols to change type, from R_ARM_ABS32 to
R_ARM_RELATIVE.

This should have no functional impact, as it affects
references to __bss_start and __bss_end__ only before
relocation, and no such references are done.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
2013-03-12 23:28:32 +01:00

39 lines
1.7 KiB
C

/*
* Copyright 2013 Albert ARIBAUD <albert.u.boot@aribaud.net>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/**
* These two symbols are declared in a C file so that the linker
* uses R_ARM_RELATIVE relocation, rather than the R_ARM_ABS32 one
* it would use if the symbols were defined in the linker file.
* Using only R_ARM_RELATIVE relocation ensures that references to
* the symbols are correct after as well as before relocation.
*
* We need a 0-byte-size type for these symbols, and the compiler
* does not allow defining objects of C type 'void'. Using an empty
* struct is allowed by the compiler, but causes gcc versions 4.4 and
* below to complain about aliasing. Therefore we use the next best
* thing: zero-sized arrays, which are both 0-byte-size and exempt from
* aliasing warnings.
*/
char __bss_start[0] __attribute__((used, section(".__bss_start")));
char __bss_end__[0] __attribute__((used, section(".__bss_end__")));