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FAILED: patch "[PATCH] x86/purgatory: Use CFLAGS_REMOVE rather than reset" failed to apply to 4.9-stable tree

PATCH [email protected] 3 participants 3 messages Aug 13, 2019

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#0 lore raw

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b059f801a937d164e03b33c1848bb3dca67c0b04 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <[email protected]>
Date: Wed, 7 Aug 2019 15:15:33 -0700
Subject: [PATCH] x86/purgatory: Use CFLAGS_REMOVE rather than reset
KBUILD_CFLAGS

KBUILD_CFLAGS is very carefully built up in the top level Makefile, particularly when cross compiling or using different build tools. Resetting KBUILD_CFLAGS via := assignment is an antipattern.

The comment above the reset mentions that -pg is problematic. Other Makefiles use CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE) when CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of the important KBUILD_CFLAGS then manually having to re-add them. Seems also that __stack_chk_fail references are generated when using CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.

Fixes 8fc5b4d4121c ("purgatory: core purgatory functionality")
Reported-by Vaibhav Rustagi <[email protected]>
Suggested-by Peter Zijlstra <[email protected]>
Suggested-by Thomas Gleixner <[email protected]>
Signed-off-by Nick Desaulniers <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Tested-by Vaibhav Rustagi <[email protected]>
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here
arch/x86/purgatory/Makefile +28 -5
index 91ef244026d2..8901a1f89cf5 100644
@@ -20,11 +20,34 @@ KCOV_INSTRUMENT := n
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not
-# sure how to relocate those. Like kexec-tools, use custom flags.
-
-KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large
-KBUILD_CFLAGS += -m$(BITS)
-KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
+# sure how to relocate those.
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_sha256.o		+= $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_purgatory.o	+= $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_string.o		+= $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_kexec-purgatory.o	+= $(CC_FLAGS_FTRACE)
+endif
+
+ifdef CONFIG_STACKPROTECTOR
+CFLAGS_REMOVE_sha256.o		+= -fstack-protector
+CFLAGS_REMOVE_purgatory.o	+= -fstack-protector
+CFLAGS_REMOVE_string.o		+= -fstack-protector
+CFLAGS_REMOVE_kexec-purgatory.o	+= -fstack-protector
+endif
+
+ifdef CONFIG_STACKPROTECTOR_STRONG
+CFLAGS_REMOVE_sha256.o		+= -fstack-protector-strong
+CFLAGS_REMOVE_purgatory.o	+= -fstack-protector-strong
+CFLAGS_REMOVE_string.o		+= -fstack-protector-strong
+CFLAGS_REMOVE_kexec-purgatory.o	+= -fstack-protector-strong
+endif
+
+ifdef CONFIG_RETPOLINE
+CFLAGS_REMOVE_sha256.o		+= $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_purgatory.o	+= $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_string.o		+= $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_kexec-purgatory.o	+= $(RETPOLINE_CFLAGS)
+endif
 
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 		$(call if_changed,ld)
#1 lore raw

Hi Vaibhav,
What LTS kernel are you basing your distro off of? IIRC, 4.19, or was it further back?

Quoted 85 lines · On Tue, Aug 13, 2019 at 11:40 AM <[email protected]> wrote:

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b059f801a937d164e03b33c1848bb3dca67c0b04 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <[email protected]>
Date: Wed, 7 Aug 2019 15:15:33 -0700
Subject: [PATCH] x86/purgatory: Use CFLAGS_REMOVE rather than reset
KBUILD_CFLAGS

KBUILD_CFLAGS is very carefully built up in the top level Makefile, particularly when cross compiling or using different build tools. Resetting KBUILD_CFLAGS via := assignment is an antipattern.

The comment above the reset mentions that -pg is problematic. Other Makefiles use CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE) when CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of the important KBUILD_CFLAGS then manually having to re-add them. Seems also that __stack_chk_fail references are generated when using CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.

Fixes 8fc5b4d4121c ("purgatory: core purgatory functionality")
Reported-by Vaibhav Rustagi <[email protected]>
Suggested-by Peter Zijlstra <[email protected]>
Suggested-by Thomas Gleixner <[email protected]>
Signed-off-by Nick Desaulniers <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Tested-by Vaibhav Rustagi <[email protected]>
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here
arch/x86/purgatory/Makefile +28 -5
index 91ef244026d2..8901a1f89cf5 100644
@@ -20,11 +20,34 @@ KCOV_INSTRUMENT := n
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not
-# sure how to relocate those. Like kexec-tools, use custom flags.
-
-KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large
-KBUILD_CFLAGS += -m$(BITS)
-KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
+# sure how to relocate those.
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_sha256.o         += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_purgatory.o      += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_string.o         += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_kexec-purgatory.o        += $(CC_FLAGS_FTRACE)
+endif
+
+ifdef CONFIG_STACKPROTECTOR
+CFLAGS_REMOVE_sha256.o         += -fstack-protector
+CFLAGS_REMOVE_purgatory.o      += -fstack-protector
+CFLAGS_REMOVE_string.o         += -fstack-protector
+CFLAGS_REMOVE_kexec-purgatory.o        += -fstack-protector
+endif
+
+ifdef CONFIG_STACKPROTECTOR_STRONG
+CFLAGS_REMOVE_sha256.o         += -fstack-protector-strong
+CFLAGS_REMOVE_purgatory.o      += -fstack-protector-strong
+CFLAGS_REMOVE_string.o         += -fstack-protector-strong
+CFLAGS_REMOVE_kexec-purgatory.o        += -fstack-protector-strong
+endif
+
+ifdef CONFIG_RETPOLINE
+CFLAGS_REMOVE_sha256.o         += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_purgatory.o      += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_string.o         += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_kexec-purgatory.o        += $(RETPOLINE_CFLAGS)
+endif
 
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
                $(call if_changed,ld)
Signature · 2 lines
Thanks,
~Nick Desaulniers
#2 lore raw
Quoted 5 lines · Nick Desaulniers

Hi Vaibhav,
What LTS kernel are you basing your distro off of? IIRC, 4.19, or was it further back?

We are using 4.19.

Quoted 91 lines · On Tue, Aug 13, 2019 at 11:40 AM <[email protected]> wrote:
Quoted 75 lines

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b059f801a937d164e03b33c1848bb3dca67c0b04 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <[email protected]>
Date: Wed, 7 Aug 2019 15:15:33 -0700
Subject: [PATCH] x86/purgatory: Use CFLAGS_REMOVE rather than reset
KBUILD_CFLAGS

KBUILD_CFLAGS is very carefully built up in the top level Makefile, particularly when cross compiling or using different build tools. Resetting KBUILD_CFLAGS via := assignment is an antipattern.

The comment above the reset mentions that -pg is problematic. Other Makefiles use CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE) when CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of the important KBUILD_CFLAGS then manually having to re-add them. Seems also that __stack_chk_fail references are generated when using CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.

Fixes 8fc5b4d4121c ("purgatory: core purgatory functionality")
Reported-by Vaibhav Rustagi <[email protected]>
Suggested-by Peter Zijlstra <[email protected]>
Suggested-by Thomas Gleixner <[email protected]>
Signed-off-by Nick Desaulniers <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Tested-by Vaibhav Rustagi <[email protected]>
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here
arch/x86/purgatory/Makefile +21 -5
index 91ef244026d2..8901a1f89cf5 100644
@@ -20,11 +20,34 @@ KCOV_INSTRUMENT := n
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not
-# sure how to relocate those. Like kexec-tools, use custom flags.
-
-KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large
-KBUILD_CFLAGS += -m$(BITS)
-KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
+# sure how to relocate those.
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_sha256.o         += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_purgatory.o      += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_string.o         += $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_kexec-purgatory.o        += $(CC_FLAGS_FTRACE)
+endif
+
+ifdef CONFIG_STACKPROTECTOR
+CFLAGS_REMOVE_sha256.o         += -fstack-protector
+CFLAGS_REMOVE_purgatory.o      += -fstack-protector
+CFLAGS_REMOVE_string.o         += -fstack-protector
+CFLAGS_REMOVE_kexec-purgatory.o        += -fstack-protector
+endif
+
+ifdef CONFIG_STACKPROTECTOR_STRONG
+CFLAGS_REMOVE_sha256.o         += -fstack-protector-strong
+CFLAGS_REMOVE_purgatory.o      += -fstack-protector-strong
+CFLAGS_REMOVE_string.o         += -fstack-protector-strong
+CFLAGS_REMOVE_kexec-purgatory.o        += -fstack-protector-strong
+endif

arch/x86/purgatory/Makefile KCOV_INSTRUMENT := n · line 53

Quoted 10 lines
arch/x86/purgatory/Makefile +7 -0
+
+ifdef CONFIG_RETPOLINE
+CFLAGS_REMOVE_sha256.o         += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_purgatory.o      += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_string.o         += $(RETPOLINE_CFLAGS)
+CFLAGS_REMOVE_kexec-purgatory.o        += $(RETPOLINE_CFLAGS)
+endif
 
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
                $(call if_changed,ld)

--
Thanks,
~Nick Desaulniers