[PATCH for-next] configure: probe for gcc -m32 integer sizes

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

The hvmloader build on Alpine Linux x86_64 currenly fails:


hvmloader.c: In function 'init_vm86_tss':
hvmloader.c:202:39: error: left shift count >= width of type 
[-Werror=shift-count-overflow]
  202 |                   ((uint64_t)TSS_SIZE << 32) | virt_to_phys(tss));

util.c: In function 'get_cpu_mhz':
util.c:824:15: error: conversion from 'long long unsigned int' to 'uint64_t' 
{aka 'long unsigned int'} changes value from
'4294967296000000' to '0' [-Werror=overflow]
  824 |     cpu_khz = 1000000ull << 32;


The root cause of the issue is that gcc -m32 picks up headers meant for
64-bit builds.

The failures are currently causing problems to the xen-project
gitlab-ci pipeline.

This patch introduces code to detect this kind of errors in the
configure script, and disables with a warning the compilation of
hvmloader if problems are detected.

This patch also updates tools/configure. It has been done by calling
autoreconf -fi.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>


diff --git a/config/Tools.mk.in b/config/Tools.mk.in
index d47936686b..395ed2a6d2 100644
--- a/config/Tools.mk.in
+++ b/config/Tools.mk.in
@@ -51,6 +51,7 @@ CONFIG_OVMF         := @ovmf@
 CONFIG_ROMBIOS      := @rombios@
 CONFIG_SEABIOS      := @seabios@
 CONFIG_IPXE         := @ipxe@
+CONFIG_HVMLOADER    := @hvmloader@
 CONFIG_QEMU_TRAD    := @qemu_traditional@
 CONFIG_QEMU_XEN     := @qemu_xen@
 CONFIG_QEMUU_EXTRA_ARGS:= @EXTRA_QEMUU_CONFIGURE_ARGS@
diff --git a/tools/configure b/tools/configure
index bb5acf9d43..f23a3bb8aa 100755
--- a/tools/configure
+++ b/tools/configure
@@ -687,6 +687,7 @@ INSTALL_DATA
 INSTALL_SCRIPT
 INSTALL_PROGRAM
 SET_MAKE
+hvmloader
 AWK
 IASL
 XGETTEXT
@@ -5279,6 +5280,25 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext 
>&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext 
$LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext 
$LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdint.h>
+#define BUILD_BUG_ON(p) ((void)sizeof(char[1 - 2 * !!(p)]))
+int main() { BUILD_BUG_ON(sizeof(uint64_t) != 8); }
+_ACEOF
+if gcc -m32 -c conftest.c -o /dev/null 2>/dev/null; then :
+  hvmloader=y
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: hvmloader build disabled 
as the compiler cannot build 32bit binaries" >&5
+$as_echo "$as_me: WARNING: hvmloader build disabled as the compiler cannot 
build 32bit binaries" >&2;}
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${MAKE-make} sets 
\$(MAKE)" >&5
 $as_echo_n "checking whether ${MAKE-make} sets \$(MAKE)... " >&6; }
 set x ${MAKE-make}
diff --git a/tools/configure.ac b/tools/configure.ac
index 636e7077be..706c162322 100644
--- a/tools/configure.ac
+++ b/tools/configure.ac
@@ -307,6 +307,12 @@ AC_ARG_VAR([AWK], [Path to awk tool])
 
 # Checks for programs.
 AC_PROG_CC
+AC_LANG(C)
+AC_LANG_CONFTEST([AC_LANG_SOURCE([[#include <stdint.h>
+#define BUILD_BUG_ON(p) ((void)sizeof(char[1 - 2 * !!(p)]))
+int main() { BUILD_BUG_ON(sizeof(uint64_t) != 8); }]])])
+AS_IF([gcc -m32 -c conftest.c -o /dev/null 2>/dev/null], [hvmloader=y], 
[AC_MSG_WARN(hvmloader build disabled due to headers mismatch)])
+AC_SUBST(hvmloader)
 AC_PROG_MAKE_SET
 AC_PROG_INSTALL
 AC_PATH_PROG([FLEX], [flex])
diff --git a/tools/firmware/Makefile b/tools/firmware/Makefile
index 1f27117794..5c395ad738 100644
--- a/tools/firmware/Makefile
+++ b/tools/firmware/Makefile
@@ -13,7 +13,7 @@ SUBDIRS-$(CONFIG_ROMBIOS) += rombios
 SUBDIRS-$(CONFIG_ROMBIOS) += vgabios
 SUBDIRS-$(CONFIG_IPXE) += etherboot
 SUBDIRS-$(CONFIG_PV_SHIM) += xen-dir
-SUBDIRS-y += hvmloader
+SUBDIRS-$(CONFIG_HVMLOADER) += hvmloader
 
 SEABIOSCC ?= $(CC)
 SEABIOSLD ?= $(LD)