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>

diff --git a/arch/arm/cpu/ixp/u-boot.lds b/arch/arm/cpu/ixp/u-boot.lds
index 81d954f2de7fce029d5e74b81bdfcc00ff9b82cb..bba91d5d2465a8a68cea365c4f106b0f1f54a843 100644 (file)
--- a/arch/arm/cpu/ixp/u-boot.lds
+++ b/arch/arm/cpu/ixp/u-boot.lds
@@ -67,11 +67,17 @@ SECTIONS
 
        _end = .;
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               __bss_end__ = .;
+                ___bssend___ = .;
+       }
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
        }
 
        /DISCARD/ : { *(.dynstr*) }

diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
index e6b202bd14765a1a24e8bd87f88e2166df79383e..e1bc8e7a417c5786fa2c793f9f66f94bbbbb1c82 100644 (file)
--- a/arch/arm/cpu/u-boot.lds
+++ b/arch/arm/cpu/u-boot.lds
@@ -81,11 +81,17 @@ SECTIONS
                *(.mmutable)
        }
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               __bss_end__ = .;
+                ___bssend___ = .;
+       }
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
        }
 
        /DISCARD/ : { *(.dynstr*) }

diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 57111afd90c1427fd8a0b27b137c25857102ef1d..11c267451afaedfb4fdeb6b34763621416605455 100644 (file)
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -39,6 +39,7 @@ GLCOBJS       += div0.o
 SOBJS-y += crt0.o
 
 ifndef CONFIG_SPL_BUILD
+COBJS-y += bss.o
 COBJS-y        += board.o
 COBJS-y        += bootm.o
 COBJS-$(CONFIG_SYS_L2_PL310) += cache-pl310.o

diff --git a/arch/arm/lib/bss.c b/arch/arm/lib/bss.c
new file mode 100644 (file)
index 0000000..7c0b154
--- /dev/null
+++ b/arch/arm/lib/bss.c
@@ -0,0 +1,39 @@
+/*
+ * 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__")));

diff --git a/board/actux1/u-boot.lds b/board/actux1/u-boot.lds
index c41eed0e6f08c71812792e1398e118bba6100196..572bcea5d01eaa1feb60f779c0bae2b27c0ff9f9 100644 (file)
--- a/board/actux1/u-boot.lds
+++ b/board/actux1/u-boot.lds
@@ -41,15 +41,15 @@ SECTIONS
                *(.text*)
        }
 
-       . = ALIGN (4);
+       . = ALIGN(4);
        .rodata : {
                *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*)))
        }
-       . = ALIGN (4);
+       . = ALIGN(4);
        .data : {
                *(.data*)
        }
-       . = ALIGN (4);
+       . = ALIGN(4);
        .got : {
                *(.got)
        }
@@ -72,13 +72,21 @@ SECTIONS
                *(.dynsym)
        }
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       _end = .;
+
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               _end = .;
+                ___bssend___ = .;
        }
-       __bss_end__ =.;
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
+       }
+
        /DISCARD/ : { *(.dynstr*) }
        /DISCARD/ : { *(.dynamic*) }
        /DISCARD/ : { *(.plt*) }

diff --git a/board/actux2/u-boot.lds b/board/actux2/u-boot.lds
index 84099840b55b35b78539623ee97ec6bdb0a37c07..6272a10d1cb40557d06a1a896e219e994863a49b 100644 (file)
--- a/board/actux2/u-boot.lds
+++ b/board/actux2/u-boot.lds
@@ -41,15 +41,15 @@ SECTIONS
                *(.text*)
        }
 
-       . = ALIGN (4);
+       . = ALIGN(4);
        .rodata : {
                *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*)))
        }
-       . = ALIGN (4);
+       . = ALIGN(4);
        .data : {
                *(.data*)
        }
-       . = ALIGN (4);
+       . = ALIGN(4);
        .got : {
                *(.got)
        }
@@ -72,13 +72,21 @@ SECTIONS
                *(.dynsym)
        }
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       _end = .;
+
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               _end = .;
+                ___bssend___ = .;
        }
-       __bss_end__ =.;
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
+       }
+
        /DISCARD/ : { *(.dynstr*) }
        /DISCARD/ : { *(.dynamic*) }
        /DISCARD/ : { *(.plt*) }

diff --git a/board/actux3/u-boot.lds b/board/actux3/u-boot.lds
index a3bd02b0d2b2a016561ed2692fd70410df456bc7..488e1e7e5b5def83f7cdfc75c4842995ac8ddb49 100644 (file)
--- a/board/actux3/u-boot.lds
+++ b/board/actux3/u-boot.lds
@@ -72,13 +72,21 @@ SECTIONS
                *(.dynsym)
        }
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       _end = .;
+
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               _end = .;
+                ___bssend___ = .;
        }
-       __bss_end__ =.;
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
+       }
+
        /DISCARD/ : { *(.dynstr*) }
        /DISCARD/ : { *(.dynamic*) }
        /DISCARD/ : { *(.plt*) }

diff --git a/board/dvlhost/u-boot.lds b/board/dvlhost/u-boot.lds
index 1bd1700aa202272fb39ed9bf0cfcd2a4b3383623..6dc26c872750dbd9d390065b4b942a71ff65e7e0 100644 (file)
--- a/board/dvlhost/u-boot.lds
+++ b/board/dvlhost/u-boot.lds
@@ -72,13 +72,21 @@ SECTIONS
                *(.dynsym)
        }
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
+       _end = .;
+
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
                *(.bss*)
                 . = ALIGN(4);
-               _end = .;
+                ___bssend___ = .;
        }
-       __bss_end__ =.;
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
+       }
+
        /DISCARD/ : { *(.dynstr*) }
        /DISCARD/ : { *(.dynamic*) }
        /DISCARD/ : { *(.plt*) }

diff --git a/board/freescale/mx31ads/u-boot.lds b/board/freescale/mx31ads/u-boot.lds
index 52677299e889a384a32ecc0d1de1c77be6222473..12d7c1256f4f2bef532ac99c95344c01e655d18a 100644 (file)
--- a/board/freescale/mx31ads/u-boot.lds
+++ b/board/freescale/mx31ads/u-boot.lds
@@ -80,11 +80,17 @@ SECTIONS
 
        _end = .;
 
-       .bss __rel_dyn_start (OVERLAY) : {
-               __bss_start = .;
-               *(.bss)
+       .bss_start __rel_dyn_start (OVERLAY) : {
+               KEEP(*(.__bss_start));
+       }
+
+       .bss __bss_start (OVERLAY) : {
+               *(.bss*)
                 . = ALIGN(4);
-               __bss_end__ = .;
+                ___bssend___ = .;
+       }
+       .bss_end ___bssend___ (OVERLAY) : {
+               KEEP(*(.__bss_end__));
        }
 
        /DISCARD/ : { *(.bss*) }