arch: x86-32 -- Be able to build 32bit CRIU

After this patch one can run ARCH="ia32" make to build
32bit version on CRIU on 64bit host. Note this is only
build procedure which tuned up, the CRIU itself is not
yet ready to make a checkpoint/restore cycle -- a lot
of additional code is needed and here we rather put
stubs simply to make build procedure run.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -59,6 +59,16 @@ ifeq ($(ARCH),x86_64)
 	LDARCH       := i386:x86-64
 	VDSO         := y
 endif
+ifeq ($(ARCH),ia32)
+	SRCARCH      := x86
+	DEFINES      := -DCONFIG_X86_32
+	LDARCH       := i386
+	ldflags-y    += -m elf_i386
+	VDSO         := y
+	USERCFLAGS   += -m32
+	PROTOUFIX    := y
+	export PROTOUFIX ldflags-y
+endif
 
 ifeq ($(shell echo $(ARCH) | sed -e 's/arm.*/arm/'),arm)
 	ARMV         := $(shell echo $(ARCH) | sed -nr 's/armv([[:digit:]]).*/\1/p; t; i7')

arch/x86/include/asm/restore.h

@@ -5,6 +5,7 @@
 
 #include "protobuf/core.pb-c.h"
 
+#ifdef CONFIG_X86_64
 #define JUMP_TO_RESTORER_BLOB(new_sp, restore_task_exec_start,		\
 			      task_args)				\
 	asm volatile(							\
@@ -18,6 +19,14 @@
 		       "g"(restore_task_exec_start),			\
 		       "g"(task_args)					\
 		     : "rsp", "rdi", "rsi", "rbx", "rax", "memory")
+#else /* CONFIG_X86_64 */
+#define JUMP_TO_RESTORER_BLOB(new_sp, restore_task_exec_start,		\
+			      task_args)				\
+	(void)new_sp;							\
+	(void)restore_task_exec_start;					\
+	(void)task_args;						\
+	;
+#endif /* CONFIG_X86_64 */
 
 #define core_get_tls(pcore, ptls)
 

arch/x86/include/asm/restorer.h

@@ -72,7 +72,7 @@ struct rt_sigframe {
 	fpu_state_t		fpu_state;
 };
 
-
+#ifdef CONFIG_X86_64
 #define ARCH_RT_SIGRETURN(new_sp)					\
 	asm volatile(							\
 		     "movq %0, %%rax				    \n"	\
@@ -129,6 +129,35 @@ struct rt_sigframe {
 		     :						\
 		     : "r"(ret)					\
 		     : "memory")
+#else /* CONFIG_X86_64 */
+#define ARCH_RT_SIGRETURN(new_sp)					\
+	asm volatile(							\
+		     "movl %0, %%eax				    \n"	\
+		     "movl %%eax, %%esp				    \n"	\
+		     "movl $"__stringify(__NR_rt_sigreturn)", %%eax \n" \
+		     "int $0x80					    \n"	\
+		     :							\
+		     : "r"(new_sp)					\
+		     : "eax","esp","memory")
+
+#define RUN_CLONE_RESTORE_FN(ret, clone_flags, new_sp, parent_tid,      \
+			     thread_args, clone_restore_fn)             \
+	(void)ret;							\
+	(void)clone_flags;						\
+	(void)new_sp;							\
+	(void)parent_tid;						\
+	(void)thread_args;						\
+	(void)clone_restore_fn;						\
+	;
+#define ARCH_FAIL_CORE_RESTORE					\
+	asm volatile(						\
+		     "movl %0, %%esp			    \n"	\
+		     "xorl %%eax, %%eax			    \n"	\
+		     "jmp *%%eax			    \n"	\
+		     :						\
+		     : "r"(ret)					\
+		     : "memory")
+#endif /* CONFIG_X86_64 */
 
 #define RT_SIGFRAME_UC(rt_sigframe) rt_sigframe->uc
 #define RT_SIGFRAME_REGIP(rt_sigframe) (rt_sigframe)->uc.uc_mcontext.rip

arch/x86/restorer.c

@@ -11,6 +11,7 @@
 
 int restore_nonsigframe_gpregs(UserX86RegsEntry *r)
 {
+#ifdef CONFIG_X86_64
 	long ret;
 	unsigned long fsgs_base;
 
@@ -27,6 +28,6 @@ int restore_nonsigframe_gpregs(UserX86RegsEntry *r)
 		pr_info("SET_GS fail %ld\n", ret);
 		return -1;
 	}
-
+#endif
 	return 0;
 }

arch/x86/vdso-pie.c

@@ -26,6 +26,7 @@
 #endif
 #define LOG_PREFIX "vdso: "
 
+#ifdef CONFIG_X86_64
 typedef struct {
 	u16	movabs;
 	u64	imm64;
@@ -438,3 +439,31 @@ int vdso_proxify(char *who, struct vdso_symtable *sym_rt,
 	sys_mprotect((void *)vdso_rt_parked_at,  vdso_vma_size(sym_rt), VDSO_PROT);
 	return 0;
 }
+
+#else /* CONFIG_X86_64 */
+
+int vdso_redirect_calls(void *base_to, void *base_from,
+			struct vdso_symtable *to,
+			struct vdso_symtable *from)
+{
+	return 0;
+}
+
+int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t)
+{
+	return 0;
+}
+
+int vdso_do_park(struct vdso_symtable *sym_rt, unsigned long park_at, unsigned long park_size)
+{
+	return 0;
+}
+
+int vdso_proxify(char *who, struct vdso_symtable *sym_rt,
+		 unsigned long vdso_rt_parked_at, size_t index,
+		 VmaEntry *vmas, size_t nr_vmas)
+{
+	return 0;
+}
+
+#endif /* CONFIG_X86_64 */