x86/restorer: add sigreturn to compat mode

Do pure 32-bit sigreturn.
Change code selector, do 0x80 rt_sigreturn.
We should have here remapped 32-bit vDSO, all should be fine.

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
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/aarch64/include/asm/sigframe.h

@@ -32,7 +32,7 @@ struct rt_sigframe {
 	uint64_t			lr;
 };
 
-#define ARCH_RT_SIGRETURN(new_sp)						\
+#define ARCH_RT_SIGRETURN(new_sp, rt_sigframe)					\
 	asm volatile(								\
 			"mov sp, %0					\n"	\
 			"mov x8, #"__stringify(__NR_rt_sigreturn)"	\n"	\

criu/arch/arm/include/asm/sigframe.h

@@ -64,7 +64,7 @@ struct rt_sigframe {
 };
 
 
-#define ARCH_RT_SIGRETURN(new_sp)					\
+#define ARCH_RT_SIGRETURN(new_sp, rt_sigframe)				\
 	asm volatile(							\
 		     "mov sp, %0				    \n"	\
 		     "mov r7,  #"__stringify(__NR_rt_sigreturn)"  \n" \

criu/arch/ppc64/include/asm/sigframe.h

@@ -43,7 +43,7 @@ struct rt_sigframe {
         char				abigap[USER_REDZONE_SIZE];
 } __attribute__((aligned(16)));
 
-#define ARCH_RT_SIGRETURN(new_sp)				\
+#define ARCH_RT_SIGRETURN(new_sp, rt_sigframe)			\
         asm volatile(						\
 		"mr 1, %0 \n"					\
 		"li 0, "__stringify(__NR_rt_sigreturn)" \n"	\

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

@@ -174,7 +174,9 @@ struct rt_sigframe {
  */
 #define RT_SIGFRAME_OFFSET(rt_sigframe)	((rt_sigframe->is_native) ? 8 : 4 )
 
-#define ARCH_RT_SIGRETURN(new_sp)					\
+#define USER32_CS		0x23
+
+#define ARCH_RT_SIGRETURN_NATIVE(new_sp)				\
 	asm volatile(							\
 		     "movq %0, %%rax				    \n"	\
 		     "movq %%rax, %%rsp				    \n"	\
@@ -183,6 +185,28 @@ struct rt_sigframe {
 		     :							\
 		     : "r"(new_sp)					\
 		     : "rax","rsp","memory")
+#define ARCH_RT_SIGRETURN_COMPAT(new_sp)				\
+	asm volatile(							\
+		"pushq $"__stringify(USER32_CS)"		\n"	\
+		"pushq $1f					\n"	\
+		"lretq						\n"	\
+		"1:						\n"	\
+		".code32					\n"	\
+		"movl %%edi, %%esp				\n"	\
+		"movl $"__stringify(__NR32_rt_sigreturn)",%%eax	\n"	\
+		"int $0x80					\n"	\
+		".code64					\n"	\
+		:							\
+		: "rdi"(new_sp)						\
+		: "eax","esp","memory")
+
+#define ARCH_RT_SIGRETURN(new_sp, rt_sigframe)				\
+do {									\
+	if ((rt_sigframe)->is_native)					\
+		ARCH_RT_SIGRETURN_NATIVE(new_sp);			\
+	else								\
+		ARCH_RT_SIGRETURN_COMPAT(new_sp);			\
+} while (0)
 #else /* CONFIG_X86_64 */
 #define RT_SIGFRAME_UC(rt_sigframe) (&rt_sigframe->uc)
 #define RT_SIGFRAME_OFFSET(rt_sigframe)	4
@@ -191,7 +215,7 @@ struct rt_sigframe {
 #define RT_SIGFRAME_FPU(rt_sigframe) (&(rt_sigframe)->fpu_state)
 #define RT_SIGFRAME_HAS_FPU(rt_sigframe) (RT_SIGFRAME_FPU(rt_sigframe)->has_fpu)
 
-#define ARCH_RT_SIGRETURN(new_sp)					\
+#define ARCH_RT_SIGRETURN(new_sp, rt_sigframe)				\
 	asm volatile(							\
 		     "movl %0, %%eax				    \n"	\
 		     "movl %%eax, %%esp				    \n"	\

criu/pie/parasite.c

@@ -659,7 +659,7 @@ static int __parasite_daemon_wait_msg(struct ctl_msg *m)
 
 static noinline void fini_sigreturn(unsigned long new_sp)
 {
-	ARCH_RT_SIGRETURN(new_sp);
+	ARCH_RT_SIGRETURN(new_sp, sigframe);
 }
 
 static void parasite_cleanup(void)

criu/pie/restorer.c

@@ -424,9 +424,10 @@ static int restore_thread_common(struct thread_restore_args *args)
 	return 0;
 }
 
-static void noinline rst_sigreturn(unsigned long new_sp)
+static void noinline rst_sigreturn(unsigned long new_sp,
+		struct rt_sigframe *sigframe)
 {
-	ARCH_RT_SIGRETURN(new_sp);
+	ARCH_RT_SIGRETURN(new_sp, sigframe);
 }
 
 /*
@@ -485,7 +486,7 @@ long __export_restore_thread(struct thread_restore_args *args)
 	futex_dec_and_wake(&thread_inprogress);
 
 	new_sp = (long)rt_sigframe + RT_SIGFRAME_OFFSET(rt_sigframe);
-	rst_sigreturn(new_sp);
+	rst_sigreturn(new_sp, rt_sigframe);
 
 core_restore_end:
 	pr_err("Restorer abnormal termination for %ld\n", sys_getpid());
@@ -1449,7 +1450,7 @@ long __export_restore_task(struct task_restore_args *args)
 	 * pure assembly since we don't need any additional
 	 * code insns from gcc.
 	 */
-	rst_sigreturn(new_sp);
+	rst_sigreturn(new_sp, rt_sigframe);
 
 core_restore_end:
 	futex_abort_and_wake(&task_entries_local->nr_in_progress);