dump: Be more specific about inability to dump 32bit tasks on x86

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/arm/crtools.c

@@ -46,12 +46,12 @@ void parasite_setup_regs(unsigned long new_ip, user_regs_struct_t *regs)
 	regs->ARM_cpsr &= PSR_f | PSR_s | PSR_x | PSR_T_BIT | MODE32_BIT;
 }
 
-int task_in_compat_mode(pid_t pid)
+bool arch_can_dump_task(pid_t pid)
 {
 	/*
 	 * TODO: Add proper check here
 	 */
-	return 0;
+	return true;
 }
 
 int syscall_seized(struct parasite_ctl *ctl, int nr, unsigned long *ret,

arch/x86/crtools.c

@@ -46,7 +46,7 @@ void parasite_setup_regs(unsigned long new_ip, user_regs_struct_t *regs)
 	regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF | X86_EFLAGS_IF);
 }
 
-int task_in_compat_mode(pid_t pid)
+static int task_in_compat_mode(pid_t pid)
 {
 	unsigned long cs, ds;
 
@@ -68,6 +68,16 @@ int task_in_compat_mode(pid_t pid)
 	return cs != 0x33 || ds == 0x2b;
 }
 
+bool arch_can_dump_task(pid_t pid)
+{
+	if (task_in_compat_mode(pid)) {
+		pr_err("Can't dump task %d running in 32-bit mode\n", pid);
+		return false;
+	}
+
+	return true;
+}
+
 int syscall_seized(struct parasite_ctl *ctl, int nr, unsigned long *ret,
 		unsigned long arg1,
 		unsigned long arg2,

include/parasite-syscall.h

@@ -74,6 +74,6 @@ int syscall_seized(struct parasite_ctl *ctl, int nr, unsigned long *ret,
 		unsigned long arg6);
 
 extern int __parasite_execute(struct parasite_ctl *ctl, pid_t pid, user_regs_struct_t *regs);
-extern int task_in_compat_mode(pid_t pid);
+extern bool arch_can_dump_task(pid_t pid);
 
 #endif /* __CR_PARASITE_SYSCALL_H__ */

parasite-syscall.c

@@ -767,10 +767,8 @@ struct parasite_ctl *parasite_prep_ctl(pid_t pid, struct vm_area_list *vma_area_
 	struct parasite_ctl *ctl = NULL;
 	struct vma_area *vma_area;
 
-	if (task_in_compat_mode(pid)) {
-		pr_err("Can't checkpoint task running in compat mode\n");
+	if (!arch_can_dump_task(pid))
 		goto err;
-	}
 
 	/*
 	 * Control block early setup.