[PATCH] powerpc: Fix 64 bit builds with binutils 2.24

From: Guenter Roeck
Date: Thu May 15 2014 - 12:34:16 EST


With binutils 2.24, various 64 bit builds fail with relocation errors
such as

arch/powerpc/kernel/built-in.o: In function `exc_debug_crit_book3e':
(.text+0x165ee): relocation truncated to fit: R_PPC64_ADDR16_HI
against symbol `interrupt_base_book3e' defined in .text section
in arch/powerpc/kernel/built-in.o
arch/powerpc/kernel/built-in.o: In function `exc_debug_crit_book3e':
(.text+0x16602): relocation truncated to fit: R_PPC64_ADDR16_HI
against symbol `interrupt_end_book3e' defined in .text section
in arch/powerpc/kernel/built-in.o

The assembler maintainer says:

I changed the ABI, something that had to be done but unfortunately
happens to break the booke kernel code. When building up a 64-bit
value with lis, ori, shl, oris, ori or similar sequences, you now
should use @high and @higha in place of @h and @ha. @h and @ha
(and their associated relocs R_PPC64_ADDR16_HI and R_PPC64_ADDR16_HA)
now report overflow if the value is out of 32-bit signed range.
ie. @h and @ha assume you're building a 32-bit value. This is needed
to report out-of-range -mcmodel=medium toc pointer offsets in @toc@h
and @toc@ha expressions, and for consistency I did the same for all
other @h and @ha relocs.

Replacing @h with @high in one strategic location fixes the relocation
errors. This has to be done conditionally since the assembler either
supports @h or @high but not both.

Cc: Alan Modra <amodra@xxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
All my test targets build with both binutils 2.23 and 2.24
with this patch applied.

The patch generates two checkpatch errors, but I consider those to be
false positives. checkpatch requests spaces after , in the assembler
instructions.

Please consider adding Cc: stable.

arch/powerpc/Makefile | 4 +++-
arch/powerpc/include/asm/ppc_asm.h | 7 ++++++-
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 4c0cedf..ce4c68a 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -150,7 +150,9 @@ endif

CFLAGS-$(CONFIG_TUNE_CELL) += $(call cc-option,-mtune=cell)

-KBUILD_CPPFLAGS += -Iarch/$(ARCH)
+asinstr := $(call as-instr,lis 9$(comma)foo@high,-DHAVE_AS_ATHIGH=1)
+
+KBUILD_CPPFLAGS += -Iarch/$(ARCH) $(asinstr)
KBUILD_AFLAGS += -Iarch/$(ARCH)
KBUILD_CFLAGS += -msoft-float -pipe -Iarch/$(ARCH) $(CFLAGS-y)
CPP = $(CC) -E $(KBUILD_CFLAGS)
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 6586a40..cded7c1 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -318,11 +318,16 @@ n:
addi reg,reg,(name - 0b)@l;

#ifdef __powerpc64__
+#ifdef HAVE_AS_ATHIGH
+#define __AS_ATHIGH high
+#else
+#define __AS_ATHIGH h
+#endif
#define LOAD_REG_IMMEDIATE(reg,expr) \
lis reg,(expr)@highest; \
ori reg,reg,(expr)@higher; \
rldicr reg,reg,32,31; \
- oris reg,reg,(expr)@h; \
+ oris reg,reg,(expr)@__AS_ATHIGH; \
ori reg,reg,(expr)@l;

#define LOAD_REG_ADDR(reg,name) \
--
1.9.1

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