arch/x86/boot: Use prefix map to avoid embedded paths
It was observed that the kernel embeds the absolute build path in the
x86 boot image when the __FILE__ macro is expanded.
> From https://bugzilla.yoctoproject.org/show_bug.cgi?id=13458:
If you turn on the buildpaths QA test, or try a reproducible build, you
discover that the kernel image contains build paths.
$ strings bzImage-5.0.19-yocto-standard |grep tmp/
out of pgt_buf in
/data/poky-tmp/reproducible/tmp/work-shared/qemux86-64/kernel-source/arch/x86/boot/compressed/kaslr_64.c!?
But what's this in the top-level Makefile:
$ git grep prefix-map
Makefile:KBUILD_CFLAGS += $(call
cc-option,-fmacro-prefix-map=$(srctree)/=)
So the __FILE__ shouldn't be using the full path. However
arch/x86/boot/compressed/Makefile has this:
KBUILD_CFLAGS := -m$(BITS) -O2
So that clears KBUILD_FLAGS, removing the -fmacro-prefix-map option.
Use -fmacro-prefix-map to have relative paths in the boot image too.
[ bp: Massage commit message and put the KBUILD_CFLAGS addition in
..boot/Makefile after the KBUILD_AFLAGS assignment because gas
doesn't support -fmacro-prefix-map. ]
Signed-off-by: Bruce Ashfield <[email protected]>
Signed-off-by: Ross Burton <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: George Rimar <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=204333
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index e2839b5..3e9f554 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -67,6 +67,7 @@
KBUILD_CFLAGS := $(REALMODE_CFLAGS) -D_SETUP
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
+KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
GCOV_PROFILE := n
UBSAN_SANITIZE := n
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 6b84afd..b246f18 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -38,6 +38,7 @@
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
KBUILD_CFLAGS += -Wno-pointer-sign
+KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n
