arm64 fixes for -rc3

- Really fix shadow call stack patching with LTO=full
 
 - Remove unused (empty) header file generated from the compat vDSO
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "Two small fixes.

  The first one is an alternative fix for the SCS patching problem we
  thought we'd fixed in -rc1; it turned out not to be robust with all
  toolchains/configs, so this is a revert+retry which has seen some more
  testing.

  The other one simply removes an unused header file, but I couldn't
  resist the negative diffstat.

   - Really fix shadow call stack patching with LTO=full

   - Remove unused (empty) header file generated from the compat vDSO"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: vdso32: Remove unused vdso32-offsets.h
  arm64: scs: Disable LTO for SCS patching code
  arm64: Revert "scs: Work around full LTO issue with dynamic SCS"

arch/arm64/Makefile

@@ -195,7 +195,7 @@ vdso_prepare: prepare0
 	include/generated/vdso-offsets.h arch/arm64/kernel/vdso/vdso.so
 ifdef CONFIG_COMPAT_VDSO
 	$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \
-	include/generated/vdso32-offsets.h arch/arm64/kernel/vdso32/vdso.so
+	arch/arm64/kernel/vdso32/vdso.so
 endif
 endif
 

arch/arm64/include/asm/vdso.h

@@ -17,9 +17,6 @@
 #ifndef __ASSEMBLY__
 
 #include <generated/vdso-offsets.h>
-#ifdef CONFIG_COMPAT_VDSO
-#include <generated/vdso32-offsets.h>
-#endif
 
 #define VDSO_SYMBOL(base, name)						   \
 ({									   \

arch/arm64/kernel/Makefile

@@ -77,9 +77,9 @@ obj-$(CONFIG_UNWIND_PATCH_PAC_INTO_SCS)	+= patch-scs.o
 # We need to prevent the SCS patching code from patching itself. Using
 # -mbranch-protection=none here to avoid the patchable PAC opcodes from being
 # generated triggers an issue with full LTO on Clang, which stops emitting PAC
-# instructions altogether. So instead, omit the unwind tables used by the
-# patching code, so it will not be able to locate its own PAC instructions.
-CFLAGS_patch-scs.o			+= -fno-asynchronous-unwind-tables -fno-unwind-tables
+# instructions altogether. So disable LTO as well for the compilation unit.
+CFLAGS_patch-scs.o			+= -mbranch-protection=none
+CFLAGS_REMOVE_patch-scs.o		+= $(CC_FLAGS_LTO)
 
 # Force dependency (vdso*-wrap.S includes vdso.so through incbin)
 $(obj)/vdso-wrap.o: $(obj)/vdso/vdso.so

arch/arm64/kernel/vdso32/Makefile

@@ -127,9 +127,6 @@ obj-vdso := $(c-obj-vdso) $(c-obj-vdso-gettimeofday) $(asm-obj-vdso)
 targets += vdso.lds
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
-include/generated/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE
-	$(call if_changed,vdsosym)
-
 # Strip rule for vdso.so
 $(obj)/vdso.so: OBJCOPYFLAGS := -S
 $(obj)/vdso.so: $(obj)/vdso32.so.dbg FORCE
@@ -166,9 +163,3 @@ quiet_cmd_vdsoas = AS32    $@
 
 quiet_cmd_vdsomunge = MUNGE   $@
       cmd_vdsomunge = $(obj)/$(munge) $< $@
-
-# Generate vDSO offsets using helper script (borrowed from the 64-bit vDSO)
-gen-vdsosym := $(srctree)/$(src)/../vdso/gen_vdso_offsets.sh
-quiet_cmd_vdsosym = VDSOSYM $@
-# The AArch64 nm should be able to read an AArch32 binary
-      cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@