core/x86: add compatible 32 register set

Introduced user_regs_struct32.
Other changes mainly are reforming existing code to use the new
register sets union.

For protobuf images - reuse user_x86_regs_entry for both compatible
and native tasks with enum in the beggining that describes register
set type. That's better and simpler, than introducing a new 32-bit
register set for compatible tasks. I tried to do this firstly with
oneof keyword:
https://github.com/0x7f454c46/criu/commit/499c93ae0e2b8ffb8c562f309bb046d77d6b07c0
But protobuf supports oneof keyword only from recent version 2.6.0,
so I tried to rework it into enum + 2 register sets:
https://github.com/0x7f454c46/criu/commit/aab4489bd4e0b1360b6e05614c2fce3ff2a52eb7

But that did not work either because restorer pie takes gpregs as
thread_restore_args parameter and UserRegsEntry shouldn't contain
pointers, but structure objects. This may be fixed by redefining
UserRegsEntry not as typedef for UserX86RegsEntry, but containing
needed objects, than treat it right for restorer - but that's
more complicated that reusing user_x86_regs_entry.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/arch/x86/include/asm/dump.h

@@ -5,6 +5,9 @@ extern int get_task_regs(pid_t pid, user_regs_struct_t regs, CoreEntry *core);
 extern int arch_alloc_thread_info(CoreEntry *core);
 extern void arch_free_thread_info(CoreEntry *core);
 
+#define ARCH_HAS_GET_REGS
+extern int ptrace_get_regs(pid_t pid, user_regs_struct_t *regs);
+extern int ptrace_set_regs(pid_t pid, user_regs_struct_t *regs);
 
 #define core_put_tls(core, tls)
 

criu/arch/x86/include/asm/infect-types.h

@@ -11,34 +11,78 @@
 #define SIGMAX_OLD		31
 
 typedef struct {
-	unsigned long	r15;
-	unsigned long	r14;
-	unsigned long	r13;
-	unsigned long	r12;
-	unsigned long	bp;
-	unsigned long	bx;
-	unsigned long	r11;
-	unsigned long	r10;
-	unsigned long	r9;
-	unsigned long	r8;
-	unsigned long	ax;
-	unsigned long	cx;
-	unsigned long	dx;
-	unsigned long	si;
-	unsigned long	di;
-	unsigned long	orig_ax;
-	unsigned long	ip;
-	unsigned long	cs;
-	unsigned long	flags;
-	unsigned long	sp;
-	unsigned long	ss;
-	unsigned long	fs_base;
-	unsigned long	gs_base;
-	unsigned long	ds;
-	unsigned long	es;
-	unsigned long	fs;
-	unsigned long	gs;
+	uint64_t	r15;
+	uint64_t	r14;
+	uint64_t	r13;
+	uint64_t	r12;
+	uint64_t	bp;
+	uint64_t	bx;
+	uint64_t	r11;
+	uint64_t	r10;
+	uint64_t	r9;
+	uint64_t	r8;
+	uint64_t	ax;
+	uint64_t	cx;
+	uint64_t	dx;
+	uint64_t	si;
+	uint64_t	di;
+	uint64_t	orig_ax;
+	uint64_t	ip;
+	uint64_t	cs;
+	uint64_t	flags;
+	uint64_t	sp;
+	uint64_t	ss;
+	uint64_t	fs_base;
+	uint64_t	gs_base;
+	uint64_t	ds;
+	uint64_t	es;
+	uint64_t	fs;
+	uint64_t	gs;
+} user_regs_struct64;
+
+typedef struct {
+	uint32_t	bx;
+	uint32_t	cx;
+	uint32_t	dx;
+	uint32_t	si;
+	uint32_t	di;
+	uint32_t	bp;
+	uint32_t	ax;
+	uint32_t	ds;
+	uint32_t	es;
+	uint32_t	fs;
+	uint32_t	gs;
+	uint32_t	orig_ax;
+	uint32_t	ip;
+	uint32_t	cs;
+	uint32_t	flags;
+	uint32_t	sp;
+	uint32_t	ss;
+} user_regs_struct32;
+
+#ifdef CONFIG_X86_64
+typedef struct {
+	union {
+		user_regs_struct64 native;
+		user_regs_struct32 compat;
+	};
+	bool is_native;
 } user_regs_struct_t;
+#define get_user_reg(pregs, name) (((pregs)->is_native) ?	\
+		((pregs)->native.name) :			\
+		((pregs)->compat.name))
+#define set_user_reg(pregs, name, val) (((pregs)->is_native) ?	\
+		((pregs)->native.name = val) :			\
+		((pregs)->compat.name = val))
+#else
+typedef struct {
+	union {
+		user_regs_struct32 native;
+	};
+} user_regs_struct_t;
+#define get_user_reg(pregs, name) ((pregs)->native.name)
+#define set_user_reg(pregs, name, val) ((pregs)->native.name = val)
+#endif
 
 #if 0
 typedef struct {
@@ -74,9 +118,9 @@ static inline unsigned long task_size(void) { return TASK_SIZE; }
 typedef uint64_t auxv_t;
 typedef uint32_t tls_t;
 
-#define REG_RES(regs) ((regs).ax)
-#define REG_IP(regs)  ((regs).ip)
-#define REG_SYSCALL_NR(regs)	((regs).orig_ax)
+#define REG_RES(regs)		get_user_reg(&regs, ax)
+#define REG_IP(regs)		get_user_reg(&regs, ip)
+#define REG_SYSCALL_NR(regs)	get_user_reg(&regs, orig_ax)
 
 #define AT_VECTOR_SIZE 44
 

criu/parasite-syscall.c

@@ -69,6 +69,7 @@ unsigned long get_exec_start(struct vm_area_list *vmas)
 	return 0;
 }
 
+#ifndef ARCH_HAS_GET_REGS
 static inline int ptrace_get_regs(int pid, user_regs_struct_t *regs)
 {
 	struct iovec iov;
@@ -86,6 +87,7 @@ static inline int ptrace_set_regs(int pid, user_regs_struct_t *regs)
 	iov.iov_len = sizeof(user_regs_struct_t);
 	return ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &iov);
 }
+#endif
 
 static int get_thread_ctx(int pid, struct thread_ctx *ctx)
 {

images/core-x86.proto

@@ -2,6 +2,12 @@ syntax = "proto2";
 
 import "opts.proto";
 
+enum user_x86_regs_case_t {
+	NATIVE = 1;
+	COMPAT = 2;
+}
+
+/* Reusing entry for both 64 and 32 bits register sets */
 message user_x86_regs_entry {
 	required uint64			r15		=  1;
 	required uint64			r14		=  2;
@@ -30,6 +36,7 @@ message user_x86_regs_entry {
 	required uint64			es		= 25;
 	required uint64			fs		= 26;
 	required uint64			gs		= 27;
+	optional user_x86_regs_case_t	gpregs_case	= 28 [default = NATIVE];
 }
 
 message user_x86_xsave_entry {