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authorBruce Ashfield <bruce.ashfield@gmail.com>2019-09-26 10:32:26 +0100
committerBorislav Petkov <bp@suse.de>2019-10-01 11:19:40 +0200
commit9e2276fa6eb39817dcc4cda415f0199fb7016b37 (patch)
tree3d9a3ad679a0133b39c85ec96ed86ced58fc9317 /arch/x86/boot
parent54ecb8f7028c5eb3d740bb82b0f1d90f2df63c5c (diff)
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 <bruce.ashfield@gmail.com> Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: George Rimar <grimar@accesssoftek.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190926093226.8568-1-ross.burton@intel.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=204333
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/Makefile1
-rw-r--r--arch/x86/boot/compressed/Makefile1
2 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index e2839b5c246c..3e9f5544820a 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -67,6 +67,7 @@ clean-files += cpustr.h
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 6b84afdd7538..b246f18c5857 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -38,6 +38,7 @@ KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
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