Re: [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols

From: Arvind Sankar
Date: Wed Mar 11 2020 - 20:10:13 EST


On Wed, Mar 11, 2020 at 10:46:01PM +0100, Hans de Goede wrote:
> Since we link purgatory.ro with -r aka we enable "incremental linking"
> no checks for unresolved symbols is done while linking purgatory.ro.
>

Do we actually need to link purgatory with -r? We could use
--emit-relocs to get the relocation sections generated the way the main
x86 kernel does, no?

Eg like the below? This would avoid the double-link creating
purgatory.chk.

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index fb4ee5444379..5332f95ca1d3 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -14,8 +14,8 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE

CFLAGS_sha256.o := -D__DISABLE_EXPORTS

-LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
-targets += purgatory.ro
+LDFLAGS_purgatory := -e purgatory_start --emit-relocs -nostdlib -z nodefaultlib
+targets += purgatory

KASAN_SANITIZE := n
KCOV_INSTRUMENT := n
@@ -55,7 +55,7 @@ CFLAGS_sha256.o += $(PURGATORY_CFLAGS)
CFLAGS_REMOVE_string.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_string.o += $(PURGATORY_CFLAGS)

-$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
+$(obj)/purgatory: $(PURGATORY_OBJS) FORCE
$(call if_changed,ld)

targets += kexec-purgatory.c
@@ -63,7 +63,7 @@ targets += kexec-purgatory.c
quiet_cmd_bin2c = BIN2C $@
cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@

-$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
+$(obj)/kexec-purgatory.c: $(obj)/purgatory FORCE
$(call if_changed,bin2c)

obj-$(CONFIG_KEXEC_FILE) += kexec-purgatory.o