alpha: link failure fix

With built-in scsi disk driver, the final link fails with a following
error:
`.exit.text' referenced in section `.rodata' of drivers/built-in.o:
defined in discarded section `.exit.text' of drivers/built-in.o

This happens with -Os (CONFIG_CC_OPTIMIZE_FOR_SIZE=y) with all gcc-4
versions, and also with -O2 and gcc-4.3.

The problem is in sd.c:sd_major() being inlined into __exit function
exit_sd(), and the compiler generating a jump table in .rodata section
for the 'switch' statement in sd_major(). So we have references to
discarded section.

Fixed with a big hammer in the form of -fno-jump-tables.

Note that jump tables vs. discarded sections is a generic problem,
other architectures are just lucky not to suffer from it. But with
a slightly more complex switch/case statement it can be reproduced
on x86 as well. So maybe at some point we should consider
-fno-jump-tables as a generic compile option...

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile
index 4e1a8e2..4759fe7 100644 (file)
--- a/arch/alpha/Makefile
+++ b/arch/alpha/Makefile
@@ -13,6 +13,7 @@ NM := $(NM) -B
 LDFLAGS_vmlinux        := -static -N #-relax
 CHECKFLAGS     += -D__alpha__ -m64
 cflags-y       := -pipe -mno-fp-regs -ffixed-8 -msmall-data
+cflags-y       += $(call cc-option, -fno-jump-tables)
 
 cpuflags-$(CONFIG_ALPHA_EV4)           := -mcpu=ev4
 cpuflags-$(CONFIG_ALPHA_EV5)           := -mcpu=ev5