HOSTCFLAGS and HOSTLDFLAGS from the environment

PATCH In review Laura Abbott 3 participants 10 messages Mar 29, 2018 – Apr 6, 2018

Subsystems (3)

Documentation Kbuild objtool

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Laura Abbott

author

2018-03-29 00:48 UTC #0 lore raw

cover HOSTCFLAGS and HOSTLDFLAGS from the environment

Hi,

Someone noted that scripts/tools userspace binaries packaged as part of the Fedora kernel were not picking up the recommended compiler flags
(https://src.fedoraproject.org/rpms/redhat-rpm-config/blob/master/f/buildflags.md)
This series lets the host ld and C flags be set on the command line similar to the kernel flags:

make AFLAGS_HOSTCFLAGS="%{build_cflags}" AFLAGS_HOSTLDFLAGS="%{build_ldflags}"

There's one more annoying case I didn't quite figure out with tools/objtool/fixdep since that's linked with ld directly but this covers the initial set of reports.

Thanks,
Laura

Laura Abbott (3):
kbuild: Support HOSTLDFLAGS
objtool: Support HOSTCFLAGS and HOSTLDFLAGS
kbuild: Allow passing additional HOSTCFLAGS and HOSTLDFLAGS

 Documentation/kbuild/kbuild.txt | 9 +++++++++
 Makefile                        | 3 +++
 scripts/Makefile.host           | 6 +++---
 tools/build/Makefile.build      | 2 +-
 tools/objtool/Makefile          | 5 +++--
 5 files changed, 19 insertions(+), 6 deletions(-)

Signature · 1 line

2.16.2

Laura Abbott

author

2018-03-29 00:48 UTC #1 lore raw

PATCH 1/3 kbuild: Support HOSTLDFLAGS

In addition to HOSTCFLAGS, there's HOSTLDFLAGS. Ensure these get passed to calls to build host binaries.

Signed-off-by Laura Abbott <[email protected]>

---
 scripts/Makefile.host      | 6 +++---
 tools/build/Makefile.build | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

scripts/Makefile.host +3 -3

index e6dc6ae2d7c4..a3a0e2282a56 100644
@@ -84,7 +84,7 @@ hostcxx_flags  = -Wp,-MD,$(depfile) $(__hostcxx_flags)
 # Create executable from a single .c file
 # host-csingle -> Executable
 quiet_cmd_host-csingle 	= HOSTCC  $@
-      cmd_host-csingle	= $(HOSTCC) $(hostc_flags) -o $@ $< \
+      cmd_host-csingle	= $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -o $@ $< \
 	  	$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
 $(host-csingle): $(obj)/%: $(src)/%.c FORCE
 	$(call if_changed_dep,host-csingle)

@@ -102,7 +102,7 @@ $(call multi_depend, $(host-cmulti), , -objs)
 # Create .o file from a single .c file
 # host-cobjs -> .o
 quiet_cmd_host-cobjs	= HOSTCC  $@
-      cmd_host-cobjs	= $(HOSTCC) $(hostc_flags) -c -o $@ $<
+      cmd_host-cobjs	= $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -c -o $@ $<
 $(host-cobjs): $(obj)/%.o: $(src)/%.c FORCE
 	$(call if_changed_dep,host-cobjs)

@@ -126,7 +126,7 @@ $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
 # Compile .c file, create position independent .o file
 # host-cshobjs -> .o
 quiet_cmd_host-cshobjs	= HOSTCC  -fPIC $@
-      cmd_host-cshobjs	= $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
+      cmd_host-cshobjs	= $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -fPIC -c -o $@ $<
 $(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
 	$(call if_changed_dep,host-cshobjs)

tools/build/Makefile.build +1 -1

index cd72016c3cfa..cab55f0d90e1 100644
@@ -64,7 +64,7 @@ quiet_cmd_cc_o_c = CC       $@
       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
 quiet_cmd_host_cc_o_c = HOSTCC   $@
-      cmd_host_cc_o_c = $(HOSTCC) $(host_c_flags) -c -o $@ $<
+      cmd_host_cc_o_c = $(HOSTCC) $(HOSTLDFLAGS) $(host_c_flags) -c -o $@ $<
 
 quiet_cmd_cxx_o_c = CXX      $@
       cmd_cxx_o_c = $(CXX) $(cxx_flags) -c -o $@ $<

Signature · 1 line

2.16.2

Masahiro Yamada

2018-04-05 05:14 UTC #2 lore raw

Re: [PATCH 1/3] kbuild: Support HOSTLDFLAGS

2018-03-29 9:48 GMT+09:00 Laura Abbott <[email protected]>:

Quoted 15 lines

In addition to HOSTCFLAGS, there's HOSTLDFLAGS. Ensure these get passed to calls to build host binaries.
Signed-off-by Laura Abbott <[email protected]>
---
 scripts/Makefile.host      | 6 +++---
 tools/build/Makefile.build | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)
scripts/Makefile.host +0 -0
index e6dc6ae2d7c4..a3a0e2282a56 100644

scripts/Makefile.host hostcxx_flags = -Wp,-MD,$(depfile) $(__hostcxx_flags) · line 90

Quoted 8 lines

scripts/Makefile.host +1 -1

@@ -84,7 +84,7 @@ hostcxx_flags  = -Wp,-MD,$(depfile) $(__hostcxx_flags)
 # Create executable from a single .c file
 # host-csingle -> Executable
 quiet_cmd_host-csingle         = HOSTCC  $@
-      cmd_host-csingle = $(HOSTCC) $(hostc_flags) -o $@ $< \
+      cmd_host-csingle = $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -o $@ $< \
                $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
 $(host-csingle): $(obj)/%: $(src)/%.c FORCE
        $(call if_changed_dep,host-csingle)

This hunk is correct, but Robin posted this.
https://patchwork.kernel.org/patch/10243073/

Somehow it fell into a crack, and I missed to pick it up. I will apply it lately.

scripts/Makefile.host $(call multi_depend, $(host-cmulti), , -objs) · line 108

Quoted 9 lines

scripts/Makefile.host +1 -1

@@ -102,7 +102,7 @@ $(call multi_depend, $(host-cmulti), , -objs)
 # Create .o file from a single .c file
 # host-cobjs -> .o
 quiet_cmd_host-cobjs   = HOSTCC  $@
-      cmd_host-cobjs   = $(HOSTCC) $(hostc_flags) -c -o $@ $<
+      cmd_host-cobjs   = $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -c -o $@ $<
 $(host-cobjs): $(obj)/%.o: $(src)/%.c FORCE
        $(call if_changed_dep,host-cobjs)

This does not involve the link stage.
You should not do this.

Quoted 22 lines

scripts/Makefile.host +1 -1

@@ -126,7 +126,7 @@ $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
 # Compile .c file, create position independent .o file
 # host-cshobjs -> .o
 quiet_cmd_host-cshobjs = HOSTCC  -fPIC $@
-      cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
+      cmd_host-cshobjs = $(HOSTCC) $(HOSTLDFLAGS) $(hostc_flags) -fPIC -c -o $@ $<
 $(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
        $(call if_changed_dep,host-cshobjs)

tools/build/Makefile.build +1 -1

index cd72016c3cfa..cab55f0d90e1 100644
@@ -64,7 +64,7 @@ quiet_cmd_cc_o_c = CC       $@
       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
 quiet_cmd_host_cc_o_c = HOSTCC   $@
-      cmd_host_cc_o_c = $(HOSTCC) $(host_c_flags) -c -o $@ $<
+      cmd_host_cc_o_c = $(HOSTCC) $(HOSTLDFLAGS) $(host_c_flags) -c -o $@ $<
 
 quiet_cmd_cxx_o_c = CXX      $@
       cmd_cxx_o_c = $(CXX) $(cxx_flags) -c -o $@ $<

Signature · 2 lines

Best Regards
Masahiro Yamada

Laura Abbott

author

2018-03-29 00:48 UTC #3 lore raw

PATCH 2/3 objtool: Support HOSTCFLAGS and HOSTLDFLAGS

In reply to Laura Abbott

It may be useful to compile host programs with different flags (e.g. hardening). Ensure that objtool picks up the appropriate flags.

Signed-off-by Laura Abbott <[email protected]>

---
 tools/objtool/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

tools/objtool/Makefile +3 -2

index e6acc281dd37..0ff3bcac1ca9 100644
@@ -31,8 +31,9 @@ INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
 	    -I$(srctree)/tools/objtool/arch/$(ARCH)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
-CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
-LDFLAGS  += -lelf $(LIBSUBCMD)
+CFLAGS   += -Wall -Werror $(WARNINGS) $(HOSTCFLAGS) -fomit-frame-pointer -O2 -g \
+	    $(INCLUDES)
+LDFLAGS  += -lelf $(LIBSUBCMD) $(HOSTLDFLAGS)
 
 # Allow old libelf to be used:
 elfshdr := $(shell echo '\#include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)

Signature · 1 line

2.16.2

Masahiro Yamada

2018-04-05 04:43 UTC #4 lore raw

Re: [PATCH 2/3] objtool: Support HOSTCFLAGS and HOSTLDFLAGS

2018-03-29 9:48 GMT+09:00 Laura Abbott <[email protected]>:

Quoted 5 lines

It may be useful to compile host programs with different flags (e.g. hardening). Ensure that objtool picks up the appropriate flags.
Signed-off-by Laura Abbott <[email protected]>
---

I saw some similar patches before.

I thought they are fixing this way
https://patchwork.kernel.org/patch/10251259/

but, I am not tacking the progress.

Quoted 26 lines

 tools/objtool/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

tools/objtool/Makefile +3 -3

index e6acc281dd37..0ff3bcac1ca9 100644
@@ -31,8 +31,9 @@ INCLUDES := -I$(srctree)/tools/include \
            -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
            -I$(srctree)/tools/objtool/arch/$(ARCH)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
-CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
-LDFLAGS  += -lelf $(LIBSUBCMD)
+CFLAGS   += -Wall -Werror $(WARNINGS) $(HOSTCFLAGS) -fomit-frame-pointer -O2 -g \
+           $(INCLUDES)
+LDFLAGS  += -lelf $(LIBSUBCMD) $(HOSTLDFLAGS)
 
 # Allow old libelf to be used:
 elfshdr := $(shell echo '\#include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
--

2.16.2

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Signature · 2 lines

Best Regards
Masahiro Yamada

Laura Abbott

author

2018-04-05 22:01 UTC #5 lore raw

Re: [PATCH 2/3] objtool: Support HOSTCFLAGS and HOSTLDFLAGS

Quoted 8 lines · Masahiro Yamada

2018-03-29 9:48 GMT+09:00 Laura Abbott <[email protected]>:
Quoted 5 lines
It may be useful to compile host programs with different flags (e.g. hardening). Ensure that objtool picks up the appropriate flags.
Signed-off-by Laura Abbott <[email protected]>
---

Quoted 9 lines

I saw some similar patches before.
I thought they are fixing this way
https://patchwork.kernel.org/patch/10251259/
but, I am not tacking the progress.

That looks like a different issue since it's still not going to pick up the HOST{C,LD}FLAGS.

Quoted 30 lines

Quoted 27 lines

  tools/objtool/Makefile | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

tools/objtool/Makefile +3 -3

index e6acc281dd37..0ff3bcac1ca9 100644
@@ -31,8 +31,9 @@ INCLUDES := -I$(srctree)/tools/include \
             -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
             -I$(srctree)/tools/objtool/arch/$(ARCH)/include
  WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
-CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
-LDFLAGS  += -lelf $(LIBSUBCMD)
+CFLAGS   += -Wall -Werror $(WARNINGS) $(HOSTCFLAGS) -fomit-frame-pointer -O2 -g \
+           $(INCLUDES)
+LDFLAGS  += -lelf $(LIBSUBCMD) $(HOSTLDFLAGS)
 
  # Allow old libelf to be used:
  elfshdr := $(shell echo '\#include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
--

2.16.2

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Josh Poimboeuf

2018-04-06 17:27 UTC #6 lore raw

Re: [PATCH 2/3] objtool: Support HOSTCFLAGS and HOSTLDFLAGS

In reply to Laura Abbott

Quoted 13 lines · Laura Abbott

It may be useful to compile host programs with different flags (e.g. hardening). Ensure that objtool picks up the appropriate flags.
Signed-off-by Laura Abbott <[email protected]>
---
 tools/objtool/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
tools/objtool/Makefile +0 -0
index e6acc281dd37..0ff3bcac1ca9 100644

tools/objtool/Makefile INCLUDES := -I$(srctree)/tools/include \ · line 35

Quoted 7 lines

tools/objtool/Makefile +2 -2

@@ -31,8 +31,9 @@ INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
 	    -I$(srctree)/tools/objtool/arch/$(ARCH)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
-CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
-LDFLAGS  += -lelf $(LIBSUBCMD)
+CFLAGS   += -Wall -Werror $(WARNINGS) $(HOSTCFLAGS) -fomit-frame-pointer -O2 -g \
+	    $(INCLUDES)

HOSTCFLAGS already has '-Wall', '-fomit-frame-pointer', and '-O2', so we can remove the setting of those in CFLAGS here.

Signature · 1 line

Josh

Laura Abbott

author

2018-03-29 00:48 UTC #7 lore raw

PATCH 3/3 kbuild: Allow passing additional HOSTCFLAGS and HOSTLDFLAGS

In reply to Laura Abbott

Similar to AFLAGS_KBUILD, there may be uses (e.g. hardening) for passing in additional flags to host programs. Allow these to be passed in from the environment.

Signed-off-by Laura Abbott <[email protected]>

---
 Documentation/kbuild/kbuild.txt | 9 +++++++++
 Makefile                        | 3 +++
 2 files changed, 12 insertions(+)

Documentation/kbuild/kbuild.txt +9 -0

index ac2363ea05c5..3751a4bc8596 100644
@@ -24,6 +24,15 @@ KAFLAGS
 --------------------------------------------------
 Additional options to the assembler (for built-in and modules).
 
+AFLAGS_HOSTCFLAGS
+--------------------------------------------------
+Additional options passed to the compiler when building host programs.
+
+AFLAGS_HOSTLDFLAGS
+--------------------------------------------------
+Additional options passed to the linker (through the compiler) when buidling
+host programs.
+
 AFLAGS_MODULE
 --------------------------------------------------
 Additional module specific options to use for $(AS).

Makefile +3 -0

index 7ba478ab8c82..2cab3f8d489c 100644
@@ -367,6 +367,9 @@ HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS)
 HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS)
 HOST_LOADLIBES := $(HOST_LFS_LIBS)
 
+HOSTCFLAGS  += $(AFLAGS_HOSTCFLAGS)
+HOSTLDFLAGS  += $(AFLAGS_HOSTLDFLAGS)
+
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as
 LD		= $(CROSS_COMPILE)ld

Signature · 1 line

2.16.2

Masahiro Yamada

2018-04-05 05:00 UTC #8 lore raw

Re: [PATCH 3/3] kbuild: Allow passing additional HOSTCFLAGS and HOSTLDFLAGS

2018-03-29 9:48 GMT+09:00 Laura Abbott <[email protected]>:

Quoted 18 lines

Similar to AFLAGS_KBUILD, there may be uses (e.g. hardening) for passing in additional flags to host programs. Allow these to be passed in from the environment.
Signed-off-by Laura Abbott <[email protected]>
---
 Documentation/kbuild/kbuild.txt | 9 +++++++++
 Makefile                        | 3 +++
 2 files changed, 12 insertions(+)
Documentation/kbuild/kbuild.txt +0 -0
index ac2363ea05c5..3751a4bc8596 100644
@@ -24,6 +24,15 @@ KAFLAGS
 --------------------------------------------------
 Additional options to the assembler (for built-in and modules).

Documentation/kbuild/kbuild.txt KAFLAGS · line 35

Quoted 10 lines

Documentation/kbuild/kbuild.txt +9 -0

 
+AFLAGS_HOSTCFLAGS
+--------------------------------------------------
+Additional options passed to the compiler when building host programs.
+
+AFLAGS_HOSTLDFLAGS
+--------------------------------------------------
+Additional options passed to the linker (through the compiler) when buidling
+host programs.
+

I am afraid you misunderstood the meaning of 'AFLAGS'.

AFLAGS is not 'Additional flags', but 'Assembler flags' that are used for compiling *.S files.

AFLAGS for host programs is weird.

I see similar proposals from different people.

I replied like follows:
https://lkml.org/lkml/2018/2/28/178

However, Robin seems busy lately.

I will wait a bit, then
if nobody does this, I may do it.

Quoted 24 lines

Documentation/kbuild/kbuild.txt +0 -0
 AFLAGS_MODULE
 --------------------------------------------------
 Additional module specific options to use for $(AS).
Makefile +3 -1
index 7ba478ab8c82..2cab3f8d489c 100644
@@ -367,6 +367,9 @@ HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS)
 HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS)
 HOST_LOADLIBES := $(HOST_LFS_LIBS)
 
+HOSTCFLAGS  += $(AFLAGS_HOSTCFLAGS)
+HOSTLDFLAGS  += $(AFLAGS_HOSTLDFLAGS)
+
 # Make variables (CC, etc...)
 AS             = $(CROSS_COMPILE)as
 LD             = $(CROSS_COMPILE)ld
--
2.16.2
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Signature · 2 lines

Best Regards
Masahiro Yamada

Laura Abbott

author

2018-04-05 21:51 UTC #9 lore raw

Re: [PATCH 3/3] kbuild: Allow passing additional HOSTCFLAGS and HOSTLDFLAGS

Quoted 42 lines · Masahiro Yamada

2018-03-29 9:48 GMT+09:00 Laura Abbott <[email protected]>:
Quoted 18 lines
Similar to AFLAGS_KBUILD, there may be uses (e.g. hardening) for passing in additional flags to host programs. Allow these to be passed in from the environment.
Signed-off-by Laura Abbott <[email protected]>
---
  Documentation/kbuild/kbuild.txt | 9 +++++++++
  Makefile                        | 3 +++
  2 files changed, 12 insertions(+)
Documentation/kbuild/kbuild.txt +0 -0
index ac2363ea05c5..3751a4bc8596 100644
@@ -24,6 +24,15 @@ KAFLAGS
  --------------------------------------------------
  Additional options to the assembler (for built-in and modules).
Documentation/kbuild/kbuild.txt KAFLAGS · line 35
Quoted 10 lines
Documentation/kbuild/kbuild.txt +9 -0
 
+AFLAGS_HOSTCFLAGS
+--------------------------------------------------
+Additional options passed to the compiler when building host programs.
+
+AFLAGS_HOSTLDFLAGS
+--------------------------------------------------
+Additional options passed to the linker (through the compiler) when buidling
+host programs.
+
I am afraid you misunderstood the meaning of 'AFLAGS'.
AFLAGS is not 'Additional flags', but 'Assembler flags' that are used for compiling *.S files.
AFLAGS for host programs is weird.
I see similar proposals from different people.

Quoted 8 lines

I replied like follows:
https://lkml.org/lkml/2018/2/28/178
However, Robin seems busy lately.
I will wait a bit, then
if nobody does this, I may do it.

Thanks for the pointer. I'll keep an eye out for those patches.

Quoted 30 lines

Quoted 27 lines
Documentation/kbuild/kbuild.txt +0 -0
  AFLAGS_MODULE
  --------------------------------------------------
  Additional module specific options to use for $(AS).
Makefile +3 -1
index 7ba478ab8c82..2cab3f8d489c 100644
@@ -367,6 +367,9 @@ HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS)
  HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS)
  HOST_LOADLIBES := $(HOST_LFS_LIBS)
 
+HOSTCFLAGS  += $(AFLAGS_HOSTCFLAGS)
+HOSTLDFLAGS  += $(AFLAGS_HOSTLDFLAGS)
+
  # Make variables (CC, etc...)
  AS             = $(CROSS_COMPILE)as
  LD             = $(CROSS_COMPILE)ld
--
2.16.2
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