[PATCH 6/7] uml: cleanup unprofile expression and build infrastructure

[Paolo 'Blaisorblade' Giarrusso]

From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@xxxxxxxx>

*) Rather than duplicate in various buggy ways the application of
CFLAGS_NO_HARDENING and UNPROFILE (which apply to the same files), centralize it
in Makefile.rules. UNPROFILE_OBJS mustn't be listed in USER_OBJS but are
compiled as such.

I've also verified that unprofile didn't work in the current form, because we
set _c_flags directly (using CFLAGS and not USER_CFLAGS, which is wrong), which
is normally used by c_flags, but we also override c_flags for all USER_OBJS, and
there we don't call unprofile.

Instead it only worked for unmap.o, the only one which wasn't a USER_OBJ.

We need to set c_flags (which is not a public Kbuild API) to clear a lot of
compilation flags like -nostdinc which Kbuild forces on everything.

*) Rather than $(CFLAGS_$(notdir $@)), which expands to CFLAGS_anObj.s when
building "anObj.s", use $(CFLAGS_$(*F).o) which always accesses
CFLAGS_anObj.o, like done by Kbuild.

*) Make c_flags apply to all targets having the same basename, rather than
listing .s, .i, .lst and .o, with the use (which I tested) of
	$(USER_OBJS:.o=.%): c_flags = ...

and of
 -      $(obj)/unmap.c: _c_flags = ...
 +      $(obj)/unmap.%: _c_flags = ...

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@xxxxxxxx>
---

 arch/um/kernel/skas/Makefile   |    9 ++-------
 arch/um/scripts/Makefile.rules |   12 ++++++++++--
 arch/um/sys-i386/Makefile      |   10 +++++-----
 arch/um/sys-x86_64/Makefile    |   10 +++++-----
 4 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile
index ad84296..ea3a8e4 100644
--- a/arch/um/kernel/skas/Makefile
+++ b/arch/um/kernel/skas/Makefile
@@ -6,16 +6,11 @@
 obj-y := clone.o exec_kern.o mem.o mmu.o process_kern.o \
 	syscall.o tlb.o uaccess.o
 
-USER_OBJS := clone.o
-
-include arch/um/scripts/Makefile.rules
-
 # clone.o is in the stub, so it can't be built with profiling
 # GCC hardened also auto-enables -fpic, but we need %ebx so it can't work ->
 # disable it
 
 CFLAGS_clone.o := $(CFLAGS_NO_HARDENING)
+UNPROFILE_OBJS := clone.o
 
-# since we're setting c_flags we _must_ add $(CFLAGS_$(*F).o).
-
-$(obj)/clone.o : c_flags = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) $(CFLAGS_$(*F).o)
+include arch/um/scripts/Makefile.rules
diff --git a/arch/um/scripts/Makefile.rules b/arch/um/scripts/Makefile.rules
index 5e7a9c3..1347dc6 100644
--- a/arch/um/scripts/Makefile.rules
+++ b/arch/um/scripts/Makefile.rules
@@ -7,11 +7,19 @@ USER_SINGLE_OBJS := \
 USER_OBJS += $(filter %_user.o,$(obj-y) $(obj-m)  $(USER_SINGLE_OBJS))
 USER_OBJS := $(foreach file,$(USER_OBJS),$(obj)/$(file))
 
-$(USER_OBJS) $(USER_OBJS:.o=.i) $(USER_OBJS:.o=.s) $(USER_OBJS:.o=.lst): \
-	c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) $(CFLAGS_$(notdir $@))
+$(USER_OBJS:.o=.%): \
+	c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) $(CFLAGS_$(*F).o)
 $(USER_OBJS) : CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ \
 	-Dunix -D__unix__ -D__$(SUBARCH)__
 
+# These are like USER_OBJS but filter USER_CFLAGS through unprofile instead of
+# using it directly.
+UNPROFILE_OBJS := $(foreach file,$(UNPROFILE_OBJS),$(obj)/$(file))
+
+$(UNPROFILE_OBJS:.o=.%): \
+	c_flags = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) $(CFLAGS_$(*F).o)
+$(UNPROFILE_OBJS) : CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ \
+	-Dunix -D__unix__ -D__$(SUBARCH)__
 
 # The stubs and unmap.o can't try to call mcount or update basic block data
 define unprofile
diff --git a/arch/um/sys-i386/Makefile b/arch/um/sys-i386/Makefile
index 3734c3e..374d61a 100644
--- a/arch/um/sys-i386/Makefile
+++ b/arch/um/sys-i386/Makefile
@@ -8,16 +8,16 @@ subarch-obj-y = lib/bitops.o kernel/sema
 subarch-obj-$(CONFIG_HIGHMEM) += mm/highmem.o
 subarch-obj-$(CONFIG_MODULES) += kernel/module.o
 
-USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o stub_segv.o
+USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o
 
 USER_OBJS += user-offsets.s
 extra-y += user-offsets.s
 
-CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)
-
 extra-$(CONFIG_MODE_TT) += unmap.o
 
+UNPROFILE_OBJS := stub_segv.o
+CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)
+
 include arch/um/scripts/Makefile.rules
 
-$(obj)/stub_segv.o $(obj)/unmap.o: \
-	_c_flags = $(call unprofile,$(CFLAGS))
+$(obj)/unmap.%: _c_flags = $(call unprofile,$(CFLAGS))
diff --git a/arch/um/sys-x86_64/Makefile b/arch/um/sys-x86_64/Makefile
index 6d3b29c..c19794d 100644
--- a/arch/um/sys-x86_64/Makefile
+++ b/arch/um/sys-x86_64/Makefile
@@ -16,16 +16,16 @@ subarch-obj-$(CONFIG_MODULES) += kernel/
 
 ldt-y = ../sys-i386/ldt.o
 
-USER_OBJS := ptrace_user.o sigcontext.o stub_segv.o
+USER_OBJS := ptrace_user.o sigcontext.o
 
 USER_OBJS += user-offsets.s
 extra-y += user-offsets.s
 
-CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)
-
 extra-$(CONFIG_MODE_TT) += unmap.o
 
+UNPROFILE_OBJS := stub_segv.o
+CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING)
+
 include arch/um/scripts/Makefile.rules
 
-$(obj)/stub_segv.o $(obj)/unmap.o: \
-	_c_flags = $(call unprofile,$(CFLAGS))
+$(obj)/unmap.%: _c_flags = $(call unprofile,$(CFLAGS))
-
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