MIPS: Fix VZ probe gas errors with binutils <2.24
The VZ guest register & TLB access macros introduced in commit "MIPS:
Add guest CP0 accessors" use VZ ASE specific instructions that aren't
understood by versions of binutils prior to 2.24.
Add a check for whether the toolchain supports the -mvirt option,
similar to the MSA toolchain check, and implement the accessors using
.word if not.
Due to difficulty in converting compiler specified registers (e.g. "$3")
to usable numbers (e.g. "3") in inline asm, we need to copy to/from a
temporary register, namely the assembler temporary (at/$1), and specify
guest CP0 registers numerically in the gc0 macros.
Fixes: 7eb91118227d ("MIPS: Add guest CP0 accessors")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-next@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13255/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index c0b002a..efd7a9d 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -200,6 +200,8 @@
toolchain-msa := $(call cc-option-yn,$(mips-cflags) -mhard-float -mfp64 -Wa$(comma)-mmsa)
cflags-$(toolchain-msa) += -DTOOLCHAIN_SUPPORTS_MSA
endif
+toolchain-virt := $(call cc-option-yn,$(mips-cflags) -mvirt)
+cflags-$(toolchain-virt) += -DTOOLCHAIN_SUPPORTS_VIRT
cflags-$(CONFIG_MIPS_COMPACT_BRANCHES_NEVER) += -mcompact-branches=never
cflags-$(CONFIG_MIPS_COMPACT_BRANCHES_OPTIMAL) += -mcompact-branches=optimal