exit: Add and use make_task_dead.

There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

arch/alpha/kernel/traps.c

@@ -190,7 +190,7 @@ die_if_kernel(char * str, struct pt_regs *regs, long err, unsigned long *r9_15)
 		local_irq_enable();
 		while (1);
 	}
-	do_exit(SIGSEGV);
+	make_task_dead(SIGSEGV);
 }
 
 #ifndef CONFIG_MATHEMU
@@ -575,7 +575,7 @@ do_entUna(void * va, unsigned long opcode, unsigned long reg,
 
 	printk("Bad unaligned kernel access at %016lx: %p %lx %lu\n",
 		pc, va, opcode, reg);
-	do_exit(SIGSEGV);
+	make_task_dead(SIGSEGV);
 
 got_exception:
 	/* Ok, we caught the exception, but we don't want it.  Is there
@@ -630,7 +630,7 @@ got_exception:
 		local_irq_enable();
 		while (1);
 	}
-	do_exit(SIGSEGV);
+	make_task_dead(SIGSEGV);
 }
 
 /*

arch/alpha/mm/fault.c

@@ -204,7 +204,7 @@ retry:
 	printk(KERN_ALERT "Unable to handle kernel paging request at "
 	       "virtual address %016lx\n", address);
 	die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
-	do_exit(SIGKILL);
+	make_task_dead(SIGKILL);
 
 	/* We ran out of memory, or some other thing happened to us that
 	   made us unable to handle the page fault gracefully.  */

arch/arm/kernel/traps.c

@@ -333,7 +333,7 @@ static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 	if (panic_on_oops)
 		panic("Fatal exception");
 	if (signr)
-		do_exit(signr);
+		make_task_dead(signr);
 }
 
 /*

arch/arm/mm/fault.c

@@ -111,7 +111,7 @@ static void die_kernel_fault(const char *msg, struct mm_struct *mm,
 	show_pte(KERN_ALERT, mm, addr);
 	die("Oops", regs, fsr);
 	bust_spinlocks(0);
-	do_exit(SIGKILL);
+	make_task_dead(SIGKILL);
 }
 
 /*

arch/arm64/kernel/traps.c

@@ -235,7 +235,7 @@ void die(const char *str, struct pt_regs *regs, int err)
 	raw_spin_unlock_irqrestore(&die_lock, flags);
 
 	if (ret != NOTIFY_STOP)
-		do_exit(SIGSEGV);
+		make_task_dead(SIGSEGV);
 }
 
 static void arm64_show_signal(int signo, const char *str)

arch/arm64/mm/fault.c

@@ -302,7 +302,7 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
 	show_pte(addr);
 	die("Oops", regs, esr);
 	bust_spinlocks(0);
-	do_exit(SIGKILL);
+	make_task_dead(SIGKILL);
 }
 
 #ifdef CONFIG_KASAN_HW_TAGS

arch/csky/abiv1/alignment.c

@@ -294,7 +294,7 @@ bad_area:
 				__func__, opcode, rz, rx, imm, addr);
 		show_regs(regs);
 		bust_spinlocks(0);
-		do_exit(SIGKILL);
+		make_dead_task(SIGKILL);
 	}
 
 	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr);

arch/csky/kernel/traps.c

@@ -109,7 +109,7 @@ void die(struct pt_regs *regs, const char *str)
 	if (panic_on_oops)
 		panic("Fatal exception");
 	if (ret != NOTIFY_STOP)
-		do_exit(SIGSEGV);
+		make_dead_task(SIGSEGV);
 }
 
 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)

arch/csky/mm/fault.c

@@ -67,7 +67,7 @@ static inline void no_context(struct pt_regs *regs, unsigned long addr)
 	pr_alert("Unable to handle kernel paging request at virtual "
 		 "addr 0x%08lx, pc: 0x%08lx\n", addr, regs->pc);
 	die(regs, "Oops");
-	do_exit(SIGKILL);
+	make_task_dead(SIGKILL);
 }
 
 static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault)

arch/h8300/kernel/traps.c

@@ -106,7 +106,7 @@ void die(const char *str, struct pt_regs *fp, unsigned long err)
 	dump(fp);
 
 	spin_unlock_irq(&die_lock);
-	do_exit(SIGSEGV);
+	make_dead_task(SIGSEGV);
 }
 
 static int kstack_depth_to_print = 24;

arch/h8300/mm/fault.c

@@ -51,7 +51,7 @@ asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address,
 	printk(" at virtual address %08lx\n", address);
 	if (!user_mode(regs))
 		die("Oops", regs, error_code);
-	do_exit(SIGKILL);
+	make_dead_task(SIGKILL);
 
 	return 1;
 }

arch/hexagon/kernel/traps.c

@@ -214,7 +214,7 @@ int die(const char *str, struct pt_regs *regs, long err)
 		panic("Fatal exception");
 
 	oops_exit();
-	do_exit(err);
+	make_dead_task(err);
 	return 0;
 }
 

arch/ia64/kernel/mca_drv.c

@@ -176,7 +176,7 @@ mca_handler_bh(unsigned long paddr, void *iip, unsigned long ipsr)
 	spin_unlock(&mca_bh_lock);
 
 	/* This process is about to be killed itself */
-	do_exit(SIGKILL);
+	make_task_dead(SIGKILL);
 }
 
 /**

arch/ia64/kernel/traps.c

@@ -85,7 +85,7 @@ die (const char *str, struct pt_regs *regs, long err)
 	if (panic_on_oops)
 		panic("Fatal exception");
 
-  	do_exit(SIGSEGV);
+	make_task_dead(SIGSEGV);
 	return 0;
 }
 

arch/ia64/mm/fault.c

@@ -259,7 +259,7 @@ retry:
 		regs = NULL;
 	bust_spinlocks(0);
 	if (regs)
-		do_exit(SIGKILL);
+		make_task_dead(SIGKILL);
 	return;
 
   out_of_memory:

arch/m68k/kernel/traps.c

@@ -1131,7 +1131,7 @@ void die_if_kernel (char *str, struct pt_regs *fp, int nr)
 	pr_crit("%s: %08x\n", str, nr);
 	show_registers(fp);
 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-	do_exit(SIGSEGV);
+	make_task_dead(SIGSEGV);
 }
 
 asmlinkage void set_esp0(unsigned long ssp)

arch/m68k/mm/fault.c

@@ -48,7 +48,7 @@ int send_fault_sig(struct pt_regs *regs)
 			pr_alert("Unable to handle kernel access");
 		pr_cont(" at virtual address %p\n", addr);
 		die_if_kernel("Oops", regs, 0 /*error_code*/);
-		do_exit(SIGKILL);
+		make_task_dead(SIGKILL);
 	}
 
 	return 1;

arch/microblaze/kernel/exceptions.c

@@ -44,10 +44,10 @@ void die(const char *str, struct pt_regs *fp, long err)
 	pr_warn("Oops: %s, sig: %ld\n", str, err);
 	show_regs(fp);
 	spin_unlock_irq(&die_lock);
-	/* do_exit() should take care of panic'ing from an interrupt
+	/* make_task_dead() should take care of panic'ing from an interrupt
 	 * context so we don't handle it here
 	 */
-	do_exit(err);
+	make_task_dead(err);
 }
 
 /* for user application debugging */

arch/mips/kernel/traps.c

@@ -422,7 +422,7 @@ void __noreturn die(const char *str, struct pt_regs *regs)
 	if (regs && kexec_should_crash(current))
 		crash_kexec(regs);
 
-	do_exit(sig);
+	make_task_dead(sig);
 }
 
 extern struct exception_table_entry __start___dbe_table[];

arch/nds32/kernel/fpu.c

@@ -223,7 +223,7 @@ inline void handle_fpu_exception(struct pt_regs *regs)
 		}
 	} else if (fpcsr & FPCSR_mskRIT) {
 		if (!user_mode(regs))
-			do_exit(SIGILL);
+			make_task_dead(SIGILL);
 		si_signo = SIGILL;
 	}