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

commit 34bdfccb8fc87eb7b33a6d980d3cc79148ad465a upstream.

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
[Alyssa: fixed for LLVM_IAS=1 by adding -g to AFLAGS_REMOVE_*]
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 9733d1cc791dd5796b7d9e3b300057f651ee0eab..969d2b2eb7d716374b8bd3022e1089d2cf847a2b 100644 (file)
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -27,7 +27,7 @@ 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
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
@@ -58,6 +58,9 @@ CFLAGS_sha256.o                       += $(PURGATORY_CFLAGS)
 CFLAGS_REMOVE_string.o         += $(PURGATORY_CFLAGS_REMOVE)
 CFLAGS_string.o                        += $(PURGATORY_CFLAGS)
 
+AFLAGS_REMOVE_setup-x86_$(BITS).o      += -g -Wa,-gdwarf-2
+AFLAGS_REMOVE_entry64.o                        += -g -Wa,-gdwarf-2
+
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
                $(call if_changed,ld)