MIPS: Set trap_no field in thread_struct on exception.

This reverts commit 7281cd22973008a782860e48ed8d85d00204168c and adds
actual functionality to use the field.

arch/mips/include/asm/processor.h

@@ -275,6 +275,7 @@ struct thread_struct {
 	unsigned long cp0_badvaddr;	/* Last user fault */
 	unsigned long cp0_baduaddr;	/* Last kernel fault accessing USEG */
 	unsigned long error_code;
+	unsigned long trap_nr;
 #ifdef CONFIG_CPU_CAVIUM_OCTEON
 	struct octeon_cop2_state cp2 __attribute__ ((__aligned__(128)));
 	struct octeon_cvmseg_state cvmseg __attribute__ ((__aligned__(128)));
@@ -341,6 +342,7 @@ struct thread_struct {
 	.cp0_badvaddr		= 0,				\
 	.cp0_baduaddr		= 0,				\
 	.error_code		= 0,				\
+	.trap_nr		= 0,				\
 	/*							\
 	 * Platform specific cop2 registers(null if no COP2)	\
 	 */							\

arch/mips/kernel/asm-offsets.c

@@ -128,6 +128,7 @@ void output_thread_defines(void)
 	       thread.cp0_baduaddr);
 	OFFSET(THREAD_ECODE, task_struct, \
 	       thread.error_code);
+	OFFSET(THREAD_TRAPNO, task_struct, thread.trap_nr);
 	BLANK();
 }
 

arch/mips/kernel/traps.c

@@ -370,11 +370,6 @@ void show_registers(struct pt_regs *regs)
 	set_fs(old_fs);
 }
 
-static int regs_to_trapnr(struct pt_regs *regs)
-{
-	return (regs->cp0_cause >> 2) & 0x1f;
-}
-
 static DEFINE_RAW_SPINLOCK(die_lock);
 
 void __noreturn die(const char *str, struct pt_regs *regs)
@@ -384,7 +379,7 @@ void __noreturn die(const char *str, struct pt_regs *regs)
 
 	oops_enter();
 
-	if (notify_die(DIE_OOPS, str, regs, 0, regs_to_trapnr(regs),
+	if (notify_die(DIE_OOPS, str, regs, 0, current->thread.trap_nr,
 		       SIGSEGV) == NOTIFY_STOP)
 		sig = 0;
 
@@ -470,7 +465,7 @@ asmlinkage void do_be(struct pt_regs *regs)
 	printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n",
 	       data ? "Data" : "Instruction",
 	       field, regs->cp0_epc, field, regs->regs[31]);
-	if (notify_die(DIE_OOPS, "bus error", regs, 0, regs_to_trapnr(regs),
+	if (notify_die(DIE_OOPS, "bus error", regs, 0, current->thread.trap_nr,
 		       SIGBUS) == NOTIFY_STOP)
 		goto out;
 
@@ -826,7 +821,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 	int sig;
 
 	prev_state = exception_enter();
-	if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs),
+	if (notify_die(DIE_FP, "FP exception", regs, 0, current->thread.trap_nr,
 		       SIGFPE) == NOTIFY_STOP)
 		goto out;
 
@@ -882,11 +877,12 @@ void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
 	char b[40];
 
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
-	if (kgdb_ll_trap(DIE_TRAP, str, regs, code, regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
+	if (kgdb_ll_trap(DIE_TRAP, str, regs, code, current->thread.trap_nr,
+			 SIGTRAP) == NOTIFY_STOP)
 		return;
 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 
-	if (notify_die(DIE_TRAP, str, regs, code, regs_to_trapnr(regs),
+	if (notify_die(DIE_TRAP, str, regs, code, current->thread.trap_nr,
 		       SIGTRAP) == NOTIFY_STOP)
 		return;
 
@@ -948,6 +944,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
 		set_fs(KERNEL_DS);
 
 	prev_state = exception_enter();
+	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 	if (get_isa16_mode(regs->cp0_epc)) {
 		u16 instr[2];
 
@@ -989,13 +986,13 @@ asmlinkage void do_bp(struct pt_regs *regs)
 	switch (bcode) {
 	case BRK_KPROBE_BP:
 		if (notify_die(DIE_BREAK, "debug", regs, bcode,
-			       regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
+			       current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
 			goto out;
 		else
 			break;
 	case BRK_KPROBE_SSTEPBP:
 		if (notify_die(DIE_SSTEPBP, "single_step", regs, bcode,
-			       regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
+			       current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
 			goto out;
 		else
 			break;
@@ -1028,6 +1025,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
 		set_fs(get_ds());
 
 	prev_state = exception_enter();
+	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 	if (get_isa16_mode(regs->cp0_epc)) {
 		if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
 		    __get_user(instr[1], (u16 __user *)(epc + 2)))
@@ -1094,8 +1092,9 @@ asmlinkage void do_ri(struct pt_regs *regs)
 no_r2_instr:
 
 	prev_state = exception_enter();
+	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 
-	if (notify_die(DIE_RI, "RI Fault", regs, 0, regs_to_trapnr(regs),
+	if (notify_die(DIE_RI, "RI Fault", regs, 0, current->thread.trap_nr,
 		       SIGILL) == NOTIFY_STOP)
 		goto out;
 
@@ -1444,8 +1443,9 @@ asmlinkage void do_msa_fpe(struct pt_regs *regs, unsigned int msacsr)
 	enum ctx_state prev_state;
 
 	prev_state = exception_enter();
+	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 	if (notify_die(DIE_MSAFP, "MSA FP exception", regs, 0,
-		       regs_to_trapnr(regs), SIGFPE) == NOTIFY_STOP)
+		       current->thread.trap_nr, SIGFPE) == NOTIFY_STOP)
 		goto out;
 
 	/* Clear MSACSR.Cause before enabling interrupts */

arch/mips/mm/fault.c

@@ -57,12 +57,10 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
 
 #ifdef CONFIG_KPROBES
 	/*
-	 * This is to notify the fault handler of the kprobes.	The
-	 * exception code is redundant as it is also carried in REGS,
-	 * but we pass it anyhow.
+	 * This is to notify the fault handler of the kprobes.
 	 */
 	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
-		       (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
+		       current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
 		return;
 #endif
 
@@ -224,6 +222,7 @@ bad_area_nosemaphore:
 			print_vma_addr(" ", regs->regs[31]);
 			pr_info("\n");
 		}
+		current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 		info.si_signo = SIGSEGV;
 		info.si_errno = 0;
 		/* info.si_code has been set above */
@@ -282,6 +281,7 @@ do_sigbus:
 		       field, (unsigned long) regs->cp0_epc,
 		       field, (unsigned long) regs->regs[31]);
 #endif
+	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 	tsk->thread.cp0_badvaddr = address;
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;