Nick reports that the following error is produced in some cases when using GCC+ld.bfd to build the ARM defconfig with Thumb2 enabled:
arch/arm/vfp/vfphw.o: in function `vfp_support_entry': (.text+0xa): relocation truncated to fit: R_ARM_THM_JUMP19 against symbol `vfp_kmode_exception' defined in .text.unlikely section in arch/arm/vfp/vfpmodule.o
$ arm-linux-gnueabihf-ld --version GNU ld (GNU Binutils for Debian) 2.34
Generally, the linker should be able to fix up out of range branches by emitting veneers, but apparently, it fails to do so in this particular case, i.e., a conditional 'tail call' to vfp_kmode_exception(), which is not defined in the same object file.
So let's force the use of a non-conditional encoding of the B instruction, which has more space for an immediate offset.
Cc: stable@vger.kernel.org Reported-by: Nick Desaulniers ndesaulniers@google.com Tested-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Ard Biesheuvel ardb@kernel.org --- arch/arm/vfp/vfphw.S | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 4fcff9f59947..f1468702fbc9 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -82,6 +82,7 @@ ENTRY(vfp_support_entry) ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions and r3, r3, #MODE_MASK @ are supported in kernel mode teq r3, #USR_MODE +THUMB( it ne ) bne vfp_kmode_exception @ Returns through lr
VFPFMRX r1, FPEXC @ Is the VFP enabled?