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linux-next/arch/arm64
Marc Zyngier eb7c11ee3c arm64: alternative: Work around .inst assembler bugs
AArch64 toolchains suffer from the following bug:

$ cat blah.S
1:
	.inst	0x01020304
	.if ((. - 1b) != 4)
		.error	"blah"
	.endif
$ aarch64-linux-gnu-gcc -c blah.S
blah.S: Assembler messages:
blah.S:3: Error: non-constant expression in ".if" statement

which precludes the use of msr_s and co as part of alternatives.

We workaround this issue by not directly testing the labels
themselves, but by moving the current output pointer by a value
that should always be zero. If this value is not null, then
we will trigger a backward move, which is expclicitely forbidden.
This triggers the error we're after:

  AS      arch/arm64/kvm/hyp.o
arch/arm64/kvm/hyp.S: Assembler messages:
arch/arm64/kvm/hyp.S:1377: Error: attempt to move .org backwards
scripts/Makefile.build:294: recipe for target 'arch/arm64/kvm/hyp.o' failed
make[1]: *** [arch/arm64/kvm/hyp.o] Error 1
Makefile:946: recipe for target 'arch/arm64/kvm' failed

Not pretty, but at least works on the current toolchains.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-06-05 10:38:54 +01:00
..
boot ARM64: juno: add sp810 support and fix sp804 clock frequency 2015-05-12 16:39:28 +02:00
configs ARM: SoC 64-bit changes for v4.1 2015-04-22 09:23:58 -07:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2015-05-11 11:05:13 -07:00
include arm64: alternative: Work around .inst assembler bugs 2015-06-05 10:38:54 +01:00
kernel arm64: alternative: Merge alternative-asm.h into alternative.h 2015-06-05 10:38:53 +01:00
kvm arm64 updates for 4.1: 2015-04-16 13:58:29 -05:00
lib arm64: __clear_user: handle exceptions on strb 2014-11-13 15:21:26 +00:00
mm arm64: alternative: Merge alternative-asm.h into alternative.h 2015-06-05 10:38:53 +01:00
net arm64: bpf: fix signedness bug in loading 64-bit immediate 2015-05-08 16:15:07 +01:00
xen arm: xen: implement multicall hypercall support. 2014-04-24 13:09:46 +01:00
Kconfig arm64: Allow forced irq threading 2015-05-19 15:27:42 +01:00
Kconfig.debug coresight: moving to new "hwtracing" directory 2015-04-03 16:17:04 +02:00
Makefile arm64: Adjust EFI libstub object include logic 2015-03-17 16:59:47 +00:00