[tip:,objtool/core] objtool: Fix HOSTCC flag usage

  The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     93eacc15687a491a9cf829f94b6891bf544084f3
Gitweb:        https://git.kernel.org/tip/93eacc15687a491a9cf829f94b6891bf544084f3
Author:        Ian Rogers <irogers@google.com>
AuthorDate:    Thu, 26 Jan 2023 11:06:06 -08:00
Committer:     Josh Poimboeuf <jpoimboe@kernel.org>
CommitterDate: Mon, 30 Jan 2023 16:28:18 -08:00

objtool: Fix HOSTCC flag usage

HOSTCC is always wanted when building objtool. Setting CC to HOSTCC
happens after tools/scripts/Makefile.include is included, meaning
flags (like CFLAGS) are set assuming say CC is gcc, but then it can be
later set to HOSTCC which may be clang. tools/scripts/Makefile.include
is needed for host set up and common macros in objtool's
Makefile. Rather than override the CC variable to HOSTCC, just pass CC
as HOSTCC to the sub-makes of Makefile.build, the libsubcmd builds and
also to the linkage step.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230126190606.40739-4-irogers@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/Makefile | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)
  

Hi,

I just spotted this breaks cross-compiling; details below.

On Wed, Feb 01, 2023 at 04:26:34PM -0000, tip-bot2 for Ian Rogers wrote:
> The following commit has been merged into the objtool/core branch of tip:
> 
> Commit-ID:     93eacc15687a491a9cf829f94b6891bf544084f3
> Gitweb:        https://git.kernel.org/tip/93eacc15687a491a9cf829f94b6891bf544084f3
> Author:        Ian Rogers <irogers@google.com>
> AuthorDate:    Thu, 26 Jan 2023 11:06:06 -08:00
> Committer:     Josh Poimboeuf <jpoimboe@kernel.org>
> CommitterDate: Mon, 30 Jan 2023 16:28:18 -08:00
> 
> objtool: Fix HOSTCC flag usage
> 
> HOSTCC is always wanted when building objtool. Setting CC to HOSTCC
> happens after tools/scripts/Makefile.include is included, meaning
> flags (like CFLAGS) are set assuming say CC is gcc, but then it can be
> later set to HOSTCC which may be clang. tools/scripts/Makefile.include
> is needed for host set up and common macros in objtool's
> Makefile. Rather than override the CC variable to HOSTCC, just pass CC
> as HOSTCC to the sub-makes of Makefile.build, the libsubcmd builds and
> also to the linkage step.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> Link: https://lore.kernel.org/r/20230126190606.40739-4-irogers@google.com
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
>  tools/objtool/Makefile | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> index d54b669..29a8cd7 100644
> --- a/tools/objtool/Makefile
> +++ b/tools/objtool/Makefile
> @@ -2,11 +2,6 @@
>  include ../scripts/Makefile.include
>  include ../scripts/Makefile.arch
>  
> -# always use the host compiler
> -AR	 = $(HOSTAR)
> -CC	 = $(HOSTCC)
> -LD	 = $(HOSTLD)

So as of this change, CC is now the cross-compiler CC ....

> -
>  ifeq ($(srctree),)
>  srctree := $(patsubst %/,%,$(dir $(CURDIR)))
>  srctree := $(patsubst %/,%,$(dir $(srctree)))
> @@ -34,13 +29,18 @@ INCLUDES := -I$(srctree)/tools/include \
>  	    -I$(srctree)/tools/objtool/include \
>  	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
>  	    -I$(LIBSUBCMD_OUTPUT)/include
> +# Note, EXTRA_WARNINGS here was determined for CC and not HOSTCC, it
> +# is passed here to match a legacy behavior.
>  WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
> -CFLAGS   := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
> -LDFLAGS  += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
> +OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
> +OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
>  
>  # Allow old libelf to be used:
>  elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)

... and so as of this patch, this check uses the cross-compiler CC rather than
the HOSTCC (and IIUC the wrong CFLAGS too).

So that probably wants to be `$(HOSTCC) $(OBJTOOL_CFLAGS)` ?

The cross CC might not even have libelf in its header path ...

> -CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
> +OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)

... which means that we might end up setting DLIBELF_USE_DEPRECATED when we
didn't mean to.

I saw this blowing up in some experiments with an arm64 objtool built on
x86_64, and I believe the reverse can also occur (i.e. building for x86_64 on
arm64).

As of this patch, I get a splat:

| [mark@lakrids:~/src/linux]% usekorg 12.1.0 make ARCH=arm64 CROSS_COMPILE=aarch64-linux- tools/objtool/elf.o
|   CALL    scripts/checksyscalls.sh
|   DESCEND objtool
| <stdin>:1:10: fatal error: libelf.h: No such file or directory
| compilation terminated.
|   INSTALL libsubcmd_headers
|   CC      /home/mark/src/linux/tools/objtool/elf.o
| elf.c: In function ‘read_sections’:
| elf.c:273:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations]
|   273 |  if (elf_getshdrnum(elf->elf, &sections_nr)) {
|       |  ^~
| In file included from /usr/include/gelf.h:32,
|                  from /home/mark/src/linux/tools/objtool/include/objtool/elf.h:10,
|                  from elf.c:22:
| /usr/include/libelf.h:310:12: note: declared here
|   310 | extern int elf_getshnum (Elf *__elf, size_t *__dst)
|       |            ^~~~~~~~~~~~
| elf.c:278:2: error: ‘elf_getshstrndx’ is deprecated [-Werror=deprecated-declarations]
|   278 |  if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
|       |  ^~
| In file included from /usr/include/gelf.h:32,
|                  from /home/mark/src/linux/tools/objtool/include/objtool/elf.h:10,
|                  from elf.c:22:
| /usr/include/libelf.h:322:12: note: declared here
|   322 | extern int elf_getshstrndx (Elf *__elf, size_t *__dst)
|       |            ^~~~~~~~~~~~~~~
| cc1: all warnings being treated as errors
| make[3]: *** [/home/mark/src/linux/tools/build/Makefile.build:97: /home/mark/src/linux/tools/objtool/elf.o] Error 1
| make[2]: *** [Makefile:66: /home/mark/src/linux/tools/objtool/objtool-in.o] Error 2
| make[1]: *** [Makefile:73: objtool] Error 2
| make: *** [Makefile:1439: tools/objtool] Error 2

Thanks,
Mark.

> +
> +# Always want host compilation.
> +HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)"
>  
>  AWK = awk
>  MKDIR = mkdir
> @@ -61,12 +61,14 @@ export BUILD_ORC
>  export srctree OUTPUT CFLAGS SRCARCH AWK
>  include $(srctree)/tools/build/Makefile.include
>  
> -$(OBJTOOL_IN): fixdep FORCE
> +$(OBJTOOL_IN): fixdep $(LIBSUBCMD) FORCE
>  	$(Q)$(CONFIG_SHELL) ./sync-check.sh
> -	$(Q)$(MAKE) $(build)=objtool
> +	$(Q)$(MAKE) $(build)=objtool $(HOST_OVERRIDES) CFLAGS="$(OBJTOOL_CFLAGS)" \
> +		LDFLAGS="$(OBJTOOL_LDFLAGS)"
> +
>  
>  $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
> -	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
> +	$(QUIET_LINK)$(HOSTCC) $(OBJTOOL_IN) $(OBJTOOL_LDFLAGS) -o $@
>  
>  
>  $(LIBSUBCMD_OUTPUT):
> @@ -75,6 +77,7 @@ $(LIBSUBCMD_OUTPUT):
>  $(LIBSUBCMD): fixdep $(LIBSUBCMD_OUTPUT) FORCE
>  	$(Q)$(MAKE) -C $(LIBSUBCMD_DIR) O=$(LIBSUBCMD_OUTPUT) \
>  		DESTDIR=$(LIBSUBCMD_OUTPUT) prefix= subdir= \
> +		$(HOST_OVERRIDES) EXTRA_CFLAGS="$(OBJTOOL_CFLAGS)" \
>  		$@ install_headers
>  
>  $(LIBSUBCMD)-clean:
  

On Wed, Feb 01, 2023 at 05:02:16PM +0000, Mark Rutland wrote:
> Hi,
> 
> I just spotted this breaks cross-compiling; details below.

Thanks, we'll fix it up with

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 29a8cd7449bf..83b100c1e7f6 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -36,7 +36,7 @@ OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBE
 OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
 
 # Allow old libelf to be used:
-elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
+elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - | grep elf_getshdr)
 OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
 
 # Always want host compilation.
  

On Wed, Feb 01, 2023 at 09:36:37AM -0800, Josh Poimboeuf wrote:
> On Wed, Feb 01, 2023 at 05:02:16PM +0000, Mark Rutland wrote:
> > Hi,
> > 
> > I just spotted this breaks cross-compiling; details below.
> 
> Thanks, we'll fix it up with
> 
> diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> index 29a8cd7449bf..83b100c1e7f6 100644
> --- a/tools/objtool/Makefile
> +++ b/tools/objtool/Makefile
> @@ -36,7 +36,7 @@ OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBE
>  OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
>  
>  # Allow old libelf to be used:
> -elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
> +elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - | grep elf_getshdr)
>  OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
>  
>  # Always want host compilation.

Profiting off of the occasion to point out that cross-compiling with
CONFIG_DEBUG_INFO_BTF=y is also broken (it builds the resolve_btfids
tool):

I source this script when cross-compiling, which has worked up until now:

#!/bin/bash

export TOPDIR=$(cd "$(dirname "${BASH_SOURCE[0]}" )" && pwd)
export PATH="${TOPDIR}/bin:$PATH"
export ARCH="arm64"
export CROSS_COMPILE="aarch64-none-linux-gnu-"
export SYSROOT="${TOPDIR}/sysroot"
export CC="aarch64-none-linux-gnu-gcc"
export CXX="aarch64-none-linux-gnu-g++"
export LDFLAGS="-L${SYSROOT}/usr/lib -L${SYSROOT}/usr/local/lib"
export CFLAGS="-I${SYSROOT}/usr/include -I${SYSROOT}/usr/local/include"
export CFLAGS="${CFLAGS} -Wno-format-nonliteral"
export KBUILD_OUTPUT="output-arm64"


Before reverting this patch, the build fails like this:

$ make -j 8 Image.gz dtbs modules W=1 C=1
make[1]: Entering directory '/opt/net-next/output-arm64'
  SYNC    include/config/auto.conf.cmd
  GEN     Makefile
  GEN     Makefile
  DESCEND bpf/resolve_btfids
  CC      scripts/mod/empty.o
  CC      scripts/mod/devicetable-offsets.s
  CHECK   ../scripts/mod/empty.c
  INSTALL libsubcmd_headers
  MKELF   scripts/mod/elfconfig.h
  HOSTCC  scripts/mod/modpost.o
  HOSTCC  scripts/mod/file2alias.o
  HOSTCC  scripts/mod/sumversion.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/main.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/rbtree.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/string.o
In file included from /opt/net-next/tools/include/linux/rbtree_augmented.h:19,
                 from ../../lib/rbtree.c:12:
/opt/net-next/tools/include/linux/rbtree.h: In function ‘rb_link_node’:
/opt/net-next/tools/include/linux/rbtree.h:70:42: error: ‘NULL’ undeclared (first use in this function)
   70 |         node->rb_left = node->rb_right = NULL;
      |                                          ^~~~
/opt/net-next/tools/include/linux/rbtree.h:21:1: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
   20 | #include <linux/kernel.h>
  +++ |+#include <stddef.h>
   21 | #include <linux/stddef.h>
/opt/net-next/tools/include/linux/rbtree.h:70:42: note: each undeclared identifier is reported only once for each function it appears in
   70 |         node->rb_left = node->rb_right = NULL;
      |                                          ^~~~
/opt/net-next/tools/include/linux/rbtree.h: At top level:
/opt/net-next/tools/include/linux/rbtree.h:131:43: error: unknown type name ‘bool’
  131 |                                           bool leftmost)
      |                                           ^~~~
/opt/net-next/tools/include/linux/rbtree.h:21:1: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
   20 | #include <linux/kernel.h>
  +++ |+#include <stdbool.h>
   21 | #include <linux/stddef.h>
/opt/net-next/tools/include/linux/rbtree.h:179:15: error: unknown type name ‘bool’
  179 |               bool (*less)(struct rb_node *, const struct rb_node *))
      |               ^~~~
/opt/net-next/tools/include/linux/rbtree.h:179:15: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
/opt/net-next/tools/include/linux/rbtree.h:207:8: error: unknown type name ‘bool’
  207 |        bool (*less)(struct rb_node *, const struct rb_node *))
      |        ^~~~
/opt/net-next/tools/include/linux/rbtree.h:207:8: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
/opt/net-next/tools/include/linux/rbtree.h: In function ‘rb_find_add’:
/opt/net-next/tools/include/linux/rbtree.h:238:34: error: ‘NULL’ undeclared (first use in this function)
  238 |         struct rb_node *parent = NULL;
      |                                  ^~~~
/opt/net-next/tools/include/linux/rbtree.h:238:34: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
/opt/net-next/tools/include/linux/rbtree.h: In function ‘rb_find’:
/opt/net-next/tools/include/linux/rbtree.h:283:16: error: ‘NULL’ undeclared (first use in this function)
  283 |         return NULL;
      |                ^~~~
/opt/net-next/tools/include/linux/rbtree.h:283:16: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
/opt/net-next/tools/include/linux/rbtree.h: In function ‘rb_find_first’:
/opt/net-next/tools/include/linux/rbtree.h:299:33: error: ‘NULL’ undeclared (first use in this function)
  299 |         struct rb_node *match = NULL;
      |                                 ^~~~
/opt/net-next/tools/include/linux/rbtree.h:299:33: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
/opt/net-next/tools/include/linux/rbtree.h: In function ‘rb_next_match’:
/opt/net-next/tools/include/linux/rbtree.h:330:24: error: ‘NULL’ undeclared (first use in this function)
  330 |                 node = NULL;
      |                        ^~~~
/opt/net-next/tools/include/linux/rbtree.h:330:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
In file included from ../../lib/rbtree.c:12:
/opt/net-next/tools/include/linux/rbtree_augmented.h: At top level:
/opt/net-next/tools/include/linux/rbtree_augmented.h:57:57: error: unknown type name ‘bool’
   57 |                            struct rb_root_cached *root, bool newleft,
      |                                                         ^~~~
/opt/net-next/tools/include/linux/rbtree_augmented.h:20:1: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
   19 | #include <linux/rbtree.h>
  +++ |+#include <stdbool.h>
   20 |
/opt/net-next/tools/include/linux/rbtree_augmented.h: In function ‘__rb_erase_augmented’:
/opt/net-next/tools/include/linux/rbtree_augmented.h:208:37: error: ‘NULL’ undeclared (first use in this function)
  208 |                         rebalance = NULL;
      |                                     ^~~~
/opt/net-next/tools/include/linux/rbtree_augmented.h:20:1: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
   19 | #include <linux/rbtree.h>
  +++ |+#include <stddef.h>
   20 |
../../lib/rbtree.c: In function ‘__rb_insert’:
../../lib/rbtree.c:90:16: error: ‘true’ undeclared (first use in this function)
   90 |         while (true) {
      |                ^~~~
../../lib/rbtree.c:14:1: note: ‘true’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
   13 | #include <linux/export.h>
  +++ |+#include <stdbool.h>
   14 |
../../lib/rbtree.c:100:51: error: ‘NULL’ undeclared (first use in this function)
  100 |                         rb_set_parent_color(node, NULL, RB_BLACK);
      |                                                   ^~~~
../../lib/rbtree.c:14:1: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
   13 | #include <linux/export.h>
  +++ |+#include <stddef.h>
   14 |
../../lib/rbtree.c: In function ‘____rb_erase_color’:
../../lib/rbtree.c:230:32: error: ‘NULL’ undeclared (first use in this function)
  230 |         struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
      |                                ^~~~
../../lib/rbtree.c:230:32: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c:232:16: error: ‘true’ undeclared (first use in this function)
  232 |         while (true) {
      |                ^~~~
../../lib/rbtree.c:232:16: note: ‘true’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
../../lib/rbtree.c: In function ‘rb_first’:
../../lib/rbtree.c:468:24: error: ‘NULL’ undeclared (first use in this function)
  468 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:468:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c: In function ‘rb_last’:
../../lib/rbtree.c:480:24: error: ‘NULL’ undeclared (first use in this function)
  480 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:480:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c: In function ‘rb_next’:
../../lib/rbtree.c:491:24: error: ‘NULL’ undeclared (first use in this function)
  491 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:491:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c: In function ‘rb_prev’:
../../lib/rbtree.c:522:24: error: ‘NULL’ undeclared (first use in this function)
  522 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:522:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c: In function ‘rb_next_postorder’:
../../lib/rbtree.c:577:24: error: ‘NULL’ undeclared (first use in this function)
  577 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:577:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/rbtree.c: In function ‘rb_first_postorder’:
../../lib/rbtree.c:594:24: error: ‘NULL’ undeclared (first use in this function)
  594 |                 return NULL;
      |                        ^~~~
../../lib/rbtree.c:594:24: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../../lib/string.c:48:30: error: unknown type name ‘bool’
   48 | int strtobool(const char *s, bool *res)
      |                              ^~~~
../../lib/string.c:21:1: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
   20 | #include <linux/ctype.h>
  +++ |+#include <stdbool.h>
   21 | #include <linux/compiler.h>
../../lib/string.c:172:33: error: unknown type name ‘u8’
  172 | static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
      |                                 ^~
../../lib/string.c:172:44: error: unknown type name ‘u8’
  172 | static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
      |                                            ^~
../../lib/string.c: In function ‘memchr_inv’:
../../lib/string.c:194:9: error: unknown type name ‘u8’
  194 |         u8 value = c;
      |         ^~
../../lib/string.c:195:9: error: unknown type name ‘u64’
  195 |         u64 value64;
      |         ^~~
../../lib/string.c:199:24: warning: implicit declaration of function ‘check_bytes8’ [-Wimplicit-function-declaration]
  199 |                 return check_bytes8(start, value, bytes);
      |                        ^~~~~~~~~~~~
../../lib/string.c:199:24: warning: returning ‘int’ from a function with return type ‘void *’ makes pointer from integer without a cast [-Wint-conversion]
  199 |                 return check_bytes8(start, value, bytes);
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/string.c:204:28: warning: left shift count >= width of type [-Wshift-count-overflow]
  204 |         value64 |= value64 << 32;
      |                            ^~
../../lib/string.c:208:17: error: unknown type name ‘u8’
  208 |                 u8 *r;
      |                 ^~
../../lib/string.c:211:19: warning: assignment to ‘int *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
  211 |                 r = check_bytes8(start, value, prefix);
      |                   ^
../../lib/string.c:221:23: error: ‘u64’ undeclared (first use in this function)
  221 |                 if (*(u64 *)start != value64)
      |                       ^~~
../../lib/string.c:221:23: note: each undeclared identifier is reported only once for each function it appears in
../../lib/string.c:221:28: error: expected expression before ‘)’ token
  221 |                 if (*(u64 *)start != value64)
      |                            ^
../../lib/string.c:222:32: warning: returning ‘int’ from a function with return type ‘void *’ makes pointer from integer without a cast [-Wint-conversion]
  222 |                         return check_bytes8(start, value, 8);
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/string.c:227:16: warning: returning ‘int’ from a function with return type ‘void *’ makes pointer from integer without a cast [-Wint-conversion]
  227 |         return check_bytes8(start, value, bytes % 8);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make[4]: *** [Build:9: /opt/net-next/output-arm64/tools/bpf/resolve_btfids/rbtree.o] Error 1
make[4]: *** Waiting for unfinished jobs....
make[4]: *** [Build:9: /opt/net-next/output-arm64/tools/bpf/resolve_btfids/string.o] Error 1
In file included from main.c:73:
/opt/net-next/tools/include/linux/rbtree.h:131:43: error: unknown type name ‘bool’
  131 |                                           bool leftmost)
      |                                           ^~~~
/opt/net-next/tools/include/linux/rbtree.h:21:1: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
   20 | #include <linux/kernel.h>
  +++ |+#include <stdbool.h>
   21 | #include <linux/stddef.h>
/opt/net-next/tools/include/linux/rbtree.h:179:15: error: unknown type name ‘bool’
  179 |               bool (*less)(struct rb_node *, const struct rb_node *))
      |               ^~~~
/opt/net-next/tools/include/linux/rbtree.h:179:15: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
/opt/net-next/tools/include/linux/rbtree.h:207:8: error: unknown type name ‘bool’
  207 |        bool (*less)(struct rb_node *, const struct rb_node *))
      |        ^~~~
/opt/net-next/tools/include/linux/rbtree.h:207:8: note: ‘bool’ is defined in header ‘<stdbool.h>’; did you forget to ‘#include <stdbool.h>’?
In file included from main.c:75:
/opt/net-next/tools/include/linux/err.h:35:35: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ERR_PTR’
   35 | static inline void * __must_check ERR_PTR(long error_)
      |                                   ^~~~~~~
/opt/net-next/tools/include/linux/err.h:40:33: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘PTR_ERR’
   40 | static inline long __must_check PTR_ERR(__force const void *ptr)
      |                                 ^~~~~~~
/opt/net-next/tools/include/linux/err.h:45:15: error: unknown type name ‘bool’
   45 | static inline bool __must_check IS_ERR(__force const void *ptr)
      |               ^~~~
/opt/net-next/tools/include/linux/err.h:45:33: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘IS_ERR’
   45 | static inline bool __must_check IS_ERR(__force const void *ptr)
      |                                 ^~~~~~
/opt/net-next/tools/include/linux/err.h:50:15: error: unknown type name ‘bool’
   50 | static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
      |               ^~~~
/opt/net-next/tools/include/linux/err.h:50:33: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘IS_ERR_OR_NULL’
   50 | static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
      |                                 ^~~~~~~~~~~~~~
/opt/net-next/tools/include/linux/err.h:55:32: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘PTR_ERR_OR_ZERO’
   55 | static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
      |                                ^~~~~~~~~~~~~~~
/opt/net-next/tools/include/linux/err.h:70:35: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ERR_CAST’
   70 | static inline void * __must_check ERR_CAST(__force const void *ptr)
      |                                   ^~~~~~~~
In file included from main.c:76:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h:208:35: warning: ‘enum btf_func_linkage’ declared inside parameter list will not be visible outside of this definition
 or declaration
  208 |                              enum btf_func_linkage linkage, int proto_type_id);
      |                                   ^~~~~~~~~~~~~~~~
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h: In function ‘btf_kflag’:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h:332:16: warning: implicit declaration of function ‘BTF_INFO_KFLAG’; did you mean ‘BTF_INFO_KIND’? [-Wimplicit-function
-declaration]
  332 |         return BTF_INFO_KFLAG(t->info);
      |                ^~~~~~~~~~~~~~
      |                BTF_INFO_KIND
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h: In function ‘btf_member_bit_offset’:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h:534:24: warning: implicit declaration of function ‘BTF_MEMBER_BIT_OFFSET’ [-Wimplicit-function-declaration]
  534 |         return kflag ? BTF_MEMBER_BIT_OFFSET(m->offset) : m->offset;
      |                        ^~~~~~~~~~~~~~~~~~~~~
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h: In function ‘btf_member_bitfield_size’:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/btf.h:546:24: warning: implicit declaration of function ‘BTF_MEMBER_BITFIELD_SIZE’ [-Wimplicit-function-declaration]
  546 |         return kflag ? BTF_MEMBER_BITFIELD_SIZE(m->offset) : 0;
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~
In file included from main.c:77:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/libbpf.h: At top level:
/opt/gcc-arm-11.2-2022.02-x86_64-aarch64-none-linux-gnu/sysroot/usr/include/bpf/libbpf.h:70:54: warning: ‘enum bpf_link_type’ declared inside parameter list will not be visible outside of this definition
or declaration
   70 | LIBBPF_API const char *libbpf_bpf_link_type_str(enum bpf_link_type t);
      |                                                      ^~~~~~~~~~~~~
In file included from main.c:73:
main.c: In function ‘btf_id__find’:
/opt/net-next/tools/include/linux/rbtree.h:37:37: warning: implicit declaration of function ‘container_of’ [-Wimplicit-function-declaration]
   37 | #define rb_entry(ptr, type, member) container_of(ptr, type, member)
      |                                     ^~~~~~~~~~~~
main.c:174:22: note: in expansion of macro ‘rb_entry’
  174 |                 id = rb_entry(p, struct btf_id, rb_node);
      |                      ^~~~~~~~
main.c:174:34: error: expected expression before ‘struct’
  174 |                 id = rb_entry(p, struct btf_id, rb_node);
      |                                  ^~~~~~
/opt/net-next/tools/include/linux/rbtree.h:37:55: note: in definition of macro ‘rb_entry’
   37 | #define rb_entry(ptr, type, member) container_of(ptr, type, member)
      |                                                       ^~~~
main.c: In function ‘btf_id__add’:
main.c:196:39: error: expected expression before ‘struct’
  196 |                 id = rb_entry(parent, struct btf_id, rb_node);
      |                                       ^~~~~~
/opt/net-next/tools/include/linux/rbtree.h:37:55: note: in definition of macro ‘rb_entry’
   37 | #define rb_entry(ptr, type, member) container_of(ptr, type, member)
      |                                                       ^~~~
main.c: In function ‘__symbols_patch’:
main.c:632:37: error: expected expression before ‘struct’
  632 |                 id = rb_entry(next, struct btf_id, rb_node);
      |                                     ^~~~~~
/opt/net-next/tools/include/linux/rbtree.h:37:55: note: in definition of macro ‘rb_entry’
   37 | #define rb_entry(ptr, type, member) container_of(ptr, type, member)
      |                                                       ^~~~
main.c: In function ‘sets_patch’:
main.c:662:39: error: expected expression before ‘struct’
  662 |                 id   = rb_entry(next, struct btf_id, rb_node);
      |                                       ^~~~~~
/opt/net-next/tools/include/linux/rbtree.h:37:55: note: in definition of macro ‘rb_entry’
   37 | #define rb_entry(ptr, type, member) container_of(ptr, type, member)
      |                                                       ^~~~
In file included from main.c:78:
main.c: In function ‘main’:
/opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/include/subcmd/parse-options.h:118:32: warning: implicit declaration of function ‘BUILD_BUG_ON_ZERO’ [-Wimplicit-function-declaration]
  118 | #define check_vtype(v, type) ( BUILD_BUG_ON_ZERO(!__builtin_types_compatible_p(typeof(v), type)) + v )
      |                                ^~~~~~~~~~~~~~~~~
/opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/include/subcmd/parse-options.h:131:106: note: in expansion of macro ‘check_vtype’
  131 | #define OPT_INCR(s, l, v, h)        { .type = OPTION_INCR, .short_name = (s), .long_name = (l), .value = check_vtype(v, int *), .help = (h) }
      |                                                                                                          ^~~~~~~~~~~
main.c:736:17: note: in expansion of macro ‘OPT_INCR’
  736 |                 OPT_INCR('v', "verbose", &verbose,
      |                 ^~~~~~~~
make[4]: *** [/opt/net-next/tools/build/Makefile.build:97: /opt/net-next/output-arm64/tools/bpf/resolve_btfids/main.o] Error 1
make[3]: *** [Makefile:80: /opt/net-next/output-arm64/tools/bpf/resolve_btfids//resolve_btfids-in.o] Error 2
make[2]: *** [Makefile:76: bpf/resolve_btfids] Error 2
make[1]: *** [/opt/net-next/Makefile:1451: tools/bpf/resolve_btfids] Error 2
make[1]: *** Waiting for unfinished jobs....
  HOSTLD  scripts/mod/modpost
  CC      kernel/bounds.s
  CC      arch/arm64/kernel/asm-offsets.s
  CALL    ../scripts/checksyscalls.sh
make[1]: Leaving directory '/opt/net-next/output-arm64'
make: *** [Makefile:242: __sub-make] Error 2


After reverting:

make -j 8 Image.gz dtbs modules W=1 C=1
make[1]: Entering directory '/opt/net-next/output-arm64'
  GEN     Makefile
  DESCEND bpf/resolve_btfids
  CALL    ../scripts/checksyscalls.sh
  INSTALL libsubcmd_headers
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/exec-cmd.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/help.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/pager.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/parse-options.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/run-command.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/sigchain.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/subcmd-config.o
  LDS     arch/arm64/kernel/vdso/vdso.lds
  CC      arch/arm64/kernel/vdso/vgettimeofday.o
  AS      arch/arm64/kernel/vdso/note.o
  AS      arch/arm64/kernel/vdso/sigreturn.o
  CHECK   ../arch/arm64/kernel/vdso/vgettimeofday.c
../arch/arm64/kernel/vdso/vgettimeofday.c:9:5: warning: symbol '__kernel_clock_gettime' was not declared. Should it be static?
../arch/arm64/kernel/vdso/vgettimeofday.c:15:5: warning: symbol '__kernel_gettimeofday' was not declared. Should it be static?
../arch/arm64/kernel/vdso/vgettimeofday.c:21:5: warning: symbol '__kernel_clock_getres' was not declared. Should it be static?
  LD      arch/arm64/kernel/vdso/vdso.so.dbg
  VDSOSYM include/generated/vdso-offsets.h
  OBJCOPY arch/arm64/kernel/vdso/vdso.so
  LD      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/libsubcmd-in.o
  AR      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/libsubcmd/libsubcmd.a
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/main.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/rbtree.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/zalloc.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/string.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/ctype.o
  CC      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/str_error_r.o
  LD      /opt/net-next/output-arm64/tools/bpf/resolve_btfids/resolve_btfids-in.o
  LINK     resolve_btfids
  (...)

Sadly idk how to fix it. I put this print in tools/bpf/resolve_btfids/Makefile
if it helps:

$(error CC $(CC) HOSTCC $(HOSTCC) HOSTCFLAGS $(HOSTCFLAGS) KBUILD_HOSTCFLAGS $(KBUILD_HOSTLDFLAGS))

which outputs:

Makefile:24: *** CC aarch64-none-linux-gnu-gcc HOSTCC gcc HOSTCFLAGS  KBUILD_HOSTCFLAGS  .  Stop.
  

On Fri, Feb 03, 2023 at 08:25:40PM +0200, Vladimir Oltean wrote:
> On Wed, Feb 01, 2023 at 09:36:37AM -0800, Josh Poimboeuf wrote:
> > On Wed, Feb 01, 2023 at 05:02:16PM +0000, Mark Rutland wrote:
> > > Hi,
> > > 
> > > I just spotted this breaks cross-compiling; details below.
> > 
> > Thanks, we'll fix it up with
> > 
> > diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> > index 29a8cd7449bf..83b100c1e7f6 100644
> > --- a/tools/objtool/Makefile
> > +++ b/tools/objtool/Makefile
> > @@ -36,7 +36,7 @@ OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBE
> >  OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
> >  
> >  # Allow old libelf to be used:
> > -elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
> > +elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - | grep elf_getshdr)
> >  OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
> >  
> >  # Always want host compilation.
> 
> Profiting off of the occasion to point out that cross-compiling with
> CONFIG_DEBUG_INFO_BTF=y is also broken (it builds the resolve_btfids
> tool):

The above patch was for objtool, though I'm guessing you were bitten by
a similar patch for bpf:

  13e07691a16f ("tools/resolve_btfids: Alter how HOSTCC is forced")

It looks like it might have a similar problem we had for objtool.  Does
this fix it?

diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
index daed388aa5d7..fff84cd914cd 100644
--- a/tools/bpf/resolve_btfids/Makefile
+++ b/tools/bpf/resolve_btfids/Makefile
@@ -18,8 +18,8 @@ else
 endif
 
 # always use the host compiler
-HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \
-		  EXTRA_CFLAGS="$(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS)"
+HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)"
+BTF_CFLAGS     := $(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS)
 
 RM      ?= rm
 CROSS_COMPILE =
@@ -53,23 +53,25 @@ $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT):
 
 $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd
 	$(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(SUBCMD_OUT) \
-		    DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
+		    $(HOST_OVERRIDES) EXTRA_CFLAGS="$(BTF_CFLAGS)" \
+		    DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \
 		    $(abspath $@) install_headers
 
 $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUT)
 	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(LIBBPF_OUT)    \
-		    DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
+		    $(HOST_OVERRIDES) EXTRA_CFLAGS="$(BTF_CFLAGS)" \
+		    DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \
 		    $(abspath $@) install_headers
 
 LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
 LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
 
-CFLAGS += -g \
-          -I$(srctree)/tools/include \
-          -I$(srctree)/tools/include/uapi \
-          -I$(LIBBPF_INCLUDE) \
-          -I$(SUBCMD_INCLUDE) \
-          $(LIBELF_FLAGS)
+BTF_CFLAGS += -g \
+              -I$(srctree)/tools/include \
+              -I$(srctree)/tools/include/uapi \
+              -I$(LIBBPF_INCLUDE) \
+              -I$(SUBCMD_INCLUDE) \
+              $(LIBELF_FLAGS)
 
 LIBS = $(LIBELF_LIBS) -lz
 
@@ -77,7 +79,7 @@ export srctree OUTPUT CFLAGS Q
 include $(srctree)/tools/build/Makefile.include
 
 $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT)
-	$(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES)
+	$(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES) CFLAGS="$(BTF_CFLAGS)"
 
 $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)
 	$(call msg,LINK,$@)
  

On Sat, Feb 4, 2023 at 9:05 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>
> On Fri, Feb 03, 2023 at 08:25:40PM +0200, Vladimir Oltean wrote:
> > On Wed, Feb 01, 2023 at 09:36:37AM -0800, Josh Poimboeuf wrote:
> > > On Wed, Feb 01, 2023 at 05:02:16PM +0000, Mark Rutland wrote:
> > > > Hi,
> > > >
> > > > I just spotted this breaks cross-compiling; details below.
> > >
> > > Thanks, we'll fix it up with
> > >
> > > diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> > > index 29a8cd7449bf..83b100c1e7f6 100644
> > > --- a/tools/objtool/Makefile
> > > +++ b/tools/objtool/Makefile
> > > @@ -36,7 +36,7 @@ OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBE
> > >  OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
> > >
> > >  # Allow old libelf to be used:
> > > -elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
> > > +elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - | grep elf_getshdr)
> > >  OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
> > >
> > >  # Always want host compilation.
> >
> > Profiting off of the occasion to point out that cross-compiling with
> > CONFIG_DEBUG_INFO_BTF=y is also broken (it builds the resolve_btfids
> > tool):
>
> The above patch was for objtool, though I'm guessing you were bitten by
> a similar patch for bpf:
>
>   13e07691a16f ("tools/resolve_btfids: Alter how HOSTCC is forced")
>
> It looks like it might have a similar problem we had for objtool.  Does
> this fix it?

Jiri Olsa has been exploring switching to using hostprogs (we need a
hostlibs notion), his patch is:
https://lore.kernel.org/bpf/20230202112839.1131892-1-jolsa@kernel.org/
With this thread giving context:
https://lore.kernel.org/lkml/20230201015015.359535-1-irogers@google.com/
If we have hostprogs and hostlibs then objtool should move to this
approach as changing CC leads to broken CFLAGS and the like.

Thanks,
Ian

> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> index daed388aa5d7..fff84cd914cd 100644
> --- a/tools/bpf/resolve_btfids/Makefile
> +++ b/tools/bpf/resolve_btfids/Makefile
> @@ -18,8 +18,8 @@ else
>  endif
>
>  # always use the host compiler
> -HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \
> -                 EXTRA_CFLAGS="$(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS)"
> +HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)"
> +BTF_CFLAGS     := $(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS)
>
>  RM      ?= rm
>  CROSS_COMPILE =
> @@ -53,23 +53,25 @@ $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT):
>
>  $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd
>         $(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(SUBCMD_OUT) \
> -                   DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
> +                   $(HOST_OVERRIDES) EXTRA_CFLAGS="$(BTF_CFLAGS)" \
> +                   DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \
>                     $(abspath $@) install_headers
>
>  $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUT)
>         $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(LIBBPF_OUT)    \
> -                   DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
> +                   $(HOST_OVERRIDES) EXTRA_CFLAGS="$(BTF_CFLAGS)" \
> +                   DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \
>                     $(abspath $@) install_headers
>
>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>
> -CFLAGS += -g \
> -          -I$(srctree)/tools/include \
> -          -I$(srctree)/tools/include/uapi \
> -          -I$(LIBBPF_INCLUDE) \
> -          -I$(SUBCMD_INCLUDE) \
> -          $(LIBELF_FLAGS)
> +BTF_CFLAGS += -g \
> +              -I$(srctree)/tools/include \
> +              -I$(srctree)/tools/include/uapi \
> +              -I$(LIBBPF_INCLUDE) \
> +              -I$(SUBCMD_INCLUDE) \
> +              $(LIBELF_FLAGS)
>
>  LIBS = $(LIBELF_LIBS) -lz
>
> @@ -77,7 +79,7 @@ export srctree OUTPUT CFLAGS Q
>  include $(srctree)/tools/build/Makefile.include
>
>  $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT)
> -       $(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES)
> +       $(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES) CFLAGS="$(BTF_CFLAGS)"
>
>  $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)
>         $(call msg,LINK,$@)