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-rw-r--r--arch/x86/Makefile8
-rw-r--r--arch/x86/include/asm/i387.h2
2 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 8aa1b59b9074..40668a96ca0c 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -96,8 +96,12 @@ cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_en
# is .cfi_signal_frame supported too?
cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1)
cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
-KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections)
-KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections)
+
+# does binutils support specific instructions?
+asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1)
+
+KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr)
+KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr)
LDFLAGS := -m elf_$(UTS_MACHINE)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index a73a8d5a5e69..70f105b352ee 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -175,7 +175,7 @@ static inline void fpu_fxsave(struct fpu *fpu)
uses any extended registers for addressing, a second REX prefix
will be generated (to the assembler, rex64 followed by semicolon
is a separate instruction), and hence the 64-bitness is lost. */
-#if 0
+#ifdef CONFIG_AS_FXSAVEQ
/* Using "fxsaveq %0" would be the ideal choice, but is only supported
starting with gas 2.16. */
__asm__ __volatile__("fxsaveq %0"