x86_64: Add support to build kexec-tools with x32 ABI

Summary of changes,

configure.ac: Add test for detect x32 ABI.
purgatory/arch/x86_64/Makefile: Not use mcmodel large when
	x32 ABI is set.
kexec/arch/x86_64/kexec-elf-rel-x86_64.c: When x32 ABI is set
	use ELFCLASS32 instead of ELFCLASS64.
kexec/kexec-syscall.h: Add correct syscall number for x32 ABI.

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

configure.ac

@@ -52,6 +52,15 @@ case $target_cpu in
 		;;
 	ia64|x86_64|alpha|m68k )
 		ARCH="$target_cpu"
+
+		dnl ---Test for x32 ABI in x86_64
+		if test "x$ARCH" = "xx86_64" ; then
+			AC_EGREP_CPP(x32_test,
+			[#if defined(__x86_64__) && defined (__ILP32__)
+				x32_test
+			#endif
+			], SUBARCH='x32', SUBARCH='64')
+		fi
 		;;
 	* )
 		AC_MSG_ERROR([unsupported architecture $target_cpu])

kexec/arch/x86_64/kexec-elf-rel-x86_64.c

@@ -8,7 +8,11 @@ int machine_verify_elf_rel(struct mem_ehdr *ehdr)
 	if (ehdr->ei_data != ELFDATA2LSB) {
 		return 0;
 	}
+#ifdef __ILP32__
+	if (ehdr->ei_class != ELFCLASS32) {
+#else
 	if (ehdr->ei_class != ELFCLASS64) {
+#endif
 		return 0;
 	}
 	if (ehdr->e_machine != EM_X86_64) {

kexec/kexec-syscall.h

@@ -31,8 +31,12 @@
 #define __NR_kexec_load		268
 #endif
 #ifdef __x86_64__
+#ifdef __ILP32__
+#define __NR_kexec_load		528
+#else
 #define __NR_kexec_load		246
 #endif
+#endif
 #ifdef __s390x__
 #define __NR_kexec_load		277
 #endif

purgatory/arch/x86_64/Makefile

@@ -23,4 +23,6 @@ x86_64_PURGATORY_SRCS += purgatory/arch/i386/console-x86.c
 x86_64_PURGATORY_SRCS += purgatory/arch/i386/vga.c
 x86_64_PURGATORY_SRCS += purgatory/arch/i386/pic.c
 
-x86_64_PURGATORY_EXTRA_CFLAGS = -mcmodel=large
+ifeq ($(SUBARCH),64)
+        x86_64_PURGATORY_EXTRA_CFLAGS = -mcmodel=large
+endif