x86/purgatory: Don't generate debug info for purgatory.ro

Purgatory.ro is a standalone binary that is not linked against the rest of
the kernel.  Its image is copied into an array that is linked to the
kernel, and from there kexec relocates it wherever it desires.

Unlike the debug info for vmlinux, which can be used for analyzing crash
such info is useless in purgatory.ro. And discarding them can save about
200K space.

 Original:
   259080  kexec-purgatory.o
 Stripped debug info:
    29152  kexec-purgatory.o

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Acked-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/r/1596433788-3784-1-git-send-email-kernelfans@gmail.com

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 088bd764e0b7f6fe23c6456530ef5cf57c8c0fc8..d24b43a4451a962e5309bbb60562573608197938 100644 (file)
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -32,7 +32,7 @@ KCOV_INSTRUMENT := n
 # make up the standalone purgatory.ro
 
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
-PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
+PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0
 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)
 
@@ -64,6 +64,9 @@ CFLAGS_sha256.o                       += $(PURGATORY_CFLAGS)
 CFLAGS_REMOVE_string.o         += $(PURGATORY_CFLAGS_REMOVE)
 CFLAGS_string.o                        += $(PURGATORY_CFLAGS)
 
+AFLAGS_REMOVE_setup-x86_$(BITS).o      += -Wa,-gdwarf-2
+AFLAGS_REMOVE_entry64.o                        += -Wa,-gdwarf-2
+
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
                $(call if_changed,ld)