Revert "UBUNTU: SAUCE: rfi-flush: Make DEBUG_RFI a CONFIG option"

This reverts commit 8319f6cd.

CVE-2017-5754

BugLink: http://bugs.launchpad.net/bugs/1756121

The functionality of this commit is provided by the following upstream
patch series:
  * powerpc/64s: Allow control of RFI flush via debugfs
  * powerpc/64s: Wire up cpu_show_meltdown()
  * powerpc/powernv: Check device-tree for RFI flush settings
  * powerpc/pseries: Query hypervisor for RFI flush settings
  * powerpc/64s: Support disabling RFI flush with no_rfi_flush and nopti
  * powerpc/64s: Add support for RFI flush of L1-D cache
  * powerpc/64s: Convert slb_miss_common to use RFI_TO_USER/KERNEL
  * powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL
  * powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL
  * powerpc/64s: Simple RFI macro conversions
  * powerpc/64: Add macros for annotating the destination of rfid/hrfid
  * powerpc/pseries: Add H_GET_CPU_CHARACTERISTICS flags & wrapper
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/powerpc/Kconfig.debug

@@ -356,14 +356,4 @@ config FAIL_IOMMU
 
 	  If you are unsure, say N.
 
-config PPC_DEBUG_RFI
-	bool "Debug RFIs (Return From Interrupt)"
-	depends on PPC_BOOK3S_64
-	help
-	  The enables extra debug code in some RFI (Return From Interrupt)
-	  sequences, to detect that we are returning to the correct context
-	  (user, kernel or guest). This adds some performance overhead.
-
-	  If unsure, say N.
-
 endmenu

arch/powerpc/include/asm/exception-64s.h

@@ -64,7 +64,9 @@
 	RFI_FLUSH_FIXUP_SECTION;					\
 	nop
 
-#ifdef CONFIG_PPC_DEBUG_RFI
+#define DEBUG_RFI
+
+#ifdef DEBUG_RFI
 #define CHECK_TARGET_MSR_PR(srr_reg, expected_pr)			\
 	SET_SCRATCH0(r3);						\
 	mfspr	r3,srr_reg;						\