ARM: 6504/1: Thumb-2: Fix long-distance conditional branches in head.S for Thumb-2.

The 32-bit conditional branches in Thumb-2 have a shorter range
(+/-512K) than their ARM counterparts (+/-32MB).  The linker does
not currently generate trampolines to extend the range of these
Thumb-2 conditional branches, resulting in link errors when vmlinux
is sufficiently large, e.g.:

head.o:(.text+0x464): relocation truncated to fit: R_ARM_THM_JUMP19

This patch forces the longer-range, unconditional branch encoding
by use of an explicit IT instruction.  The resulting branches are
triggered on the same conditions as before.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 591c097..6bd82d2 100644 (file)
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -85,9 +85,11 @@ ENTRY(stext)
        mrc     p15, 0, r9, c0, c0              @ get processor id
        bl      __lookup_processor_type         @ r5=procinfo r9=cpuid
        movs    r10, r5                         @ invalid processor (r5=0)?
+ THUMB( it     eq )            @ force fixup-able long branch encoding
        beq     __error_p                       @ yes, error 'p'
        bl      __lookup_machine_type           @ r5=machinfo
        movs    r8, r5                          @ invalid machine (r5=0)?
+ THUMB( it     eq )            @ force fixup-able long branch encoding
        beq     __error_a                       @ yes, error 'a'
        bl      __vet_atags
 #ifdef CONFIG_SMP_ON_UP
@@ -283,6 +285,7 @@ ENTRY(secondary_startup)
        bl      __lookup_processor_type
        movs    r10, r5                         @ invalid processor?
        moveq   r0, #'p'                        @ yes, error 'p'
+ THUMB( it     eq )            @ force fixup-able long branch encoding
        beq     __error_p
 
        /*