objtool: Allow AR to be overridden with HOSTAR

Currently, this Makefile hardcodes GNU ar, meaning that if it is not
available, there is no way to supply a different one and the build will
fail.

  $ make AR=llvm-ar CC=clang LD=ld.lld HOSTAR=llvm-ar HOSTCC=clang \
         HOSTLD=ld.lld HOSTLDFLAGS=-fuse-ld=lld defconfig modules_prepare
  ...
    AR       /out/tools/objtool/libsubcmd.a
  /bin/sh: 1: ar: not found
  ...

Follow the logic of HOST{CC,LD} and allow the user to specify a
different ar tool via HOSTAR (which is used elsewhere in other
tools/ Makefiles).

Signed-off-by: Nathan Chancellor <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Reviewed-by: Mukesh Ojha <[email protected]>
Cc: <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/80822a9353926c38fd7a152991c6292491a9d0e8.1558028966.git.jpoimboe@redhat.com
Link: https://github.com/ClangBuiltLinux/linux/issues/481
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 53f8be0f4a1f763e613b649aeac98399bd34eb69..88158239622bce38a7f27fb718123b8a62e03d09 100644 (file)
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -7,11 +7,12 @@ ARCH := x86
 endif
 
 # always use the host compiler
+HOSTAR ?= ar
 HOSTCC ?= gcc
 HOSTLD ?= ld
+AR      = $(HOSTAR)
 CC      = $(HOSTCC)
 LD      = $(HOSTLD)
-AR      = ar
 
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(CURDIR)))