From df2700519c84ee8ee1e5ea165725c651f6d4d1a4 Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Sun, 20 Apr 2008 16:28:54 +0100
Subject: [PATCH] [MIPS] Fix handling of trap and breakpoint instructions

With fixes and cleanups from Atsushi Nemoto (anemo@mba.ocn.ne.jp).

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
 arch/mips/kernel/traps.c | 97 +++++++++++++++++-----------------------
 1 file changed, 41 insertions(+), 56 deletions(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 88185cd40c3b..cb8b0e2c7954 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -675,10 +675,46 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 	force_sig_info(SIGFPE, &info, current);
 }
 
+static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
+	const char *str)
+{
+	siginfo_t info;
+	char b[40];
+
+	/*
+	 * A short test says that IRIX 5.3 sends SIGTRAP for all trap
+	 * insns, even for trap and break codes that indicate arithmetic
+	 * failures.  Weird ...
+	 * But should we continue the brokenness???  --macro
+	 */
+	switch (code) {
+	case BRK_OVERFLOW:
+	case BRK_DIVZERO:
+		scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
+		die_if_kernel(b, regs);
+		if (code == BRK_DIVZERO)
+			info.si_code = FPE_INTDIV;
+		else
+			info.si_code = FPE_INTOVF;
+		info.si_signo = SIGFPE;
+		info.si_errno = 0;
+		info.si_addr = (void __user *) regs->cp0_epc;
+		force_sig_info(SIGFPE, &info, current);
+		break;
+	case BRK_BUG:
+		die_if_kernel("Kernel bug detected", regs);
+		force_sig(SIGTRAP, current);
+		break;
+	default:
+		scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
+		die_if_kernel(b, regs);
+		force_sig(SIGTRAP, current);
+	}
+}
+
 asmlinkage void do_bp(struct pt_regs *regs)
 {
 	unsigned int opcode, bcode;
-	siginfo_t info;
 
 	if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
 		goto out_sigsegv;
@@ -690,35 +726,10 @@ asmlinkage void do_bp(struct pt_regs *regs)
 	 * We handle both cases with a simple heuristics.  --macro
 	 */
 	bcode = ((opcode >> 6) & ((1 << 20) - 1));
-	if (bcode < (1 << 10))
-		bcode <<= 10;
+	if (bcode >= (1 << 10))
+		bcode >>= 10;
 
-	/*
-	 * (A short test says that IRIX 5.3 sends SIGTRAP for all break
-	 * insns, even for break codes that indicate arithmetic failures.
-	 * Weird ...)
-	 * But should we continue the brokenness???  --macro
-	 */
-	switch (bcode) {
-	case BRK_OVERFLOW << 10:
-	case BRK_DIVZERO << 10:
-		die_if_kernel("Break instruction in kernel code", regs);
-		if (bcode == (BRK_DIVZERO << 10))
-			info.si_code = FPE_INTDIV;
-		else
-			info.si_code = FPE_INTOVF;
-		info.si_signo = SIGFPE;
-		info.si_errno = 0;
-		info.si_addr = (void __user *) regs->cp0_epc;
-		force_sig_info(SIGFPE, &info, current);
-		break;
-	case BRK_BUG:
-		die("Kernel bug detected", regs);
-		break;
-	default:
-		die_if_kernel("Break instruction in kernel code", regs);
-		force_sig(SIGTRAP, current);
-	}
+	do_trap_or_bp(regs, bcode, "Break");
 	return;
 
 out_sigsegv:
@@ -728,7 +739,6 @@ out_sigsegv:
 asmlinkage void do_tr(struct pt_regs *regs)
 {
 	unsigned int opcode, tcode = 0;
-	siginfo_t info;
 
 	if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
 		goto out_sigsegv;
@@ -737,32 +747,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
 	if (!(opcode & OPCODE))
 		tcode = ((opcode >> 6) & ((1 << 10) - 1));
 
-	/*
-	 * (A short test says that IRIX 5.3 sends SIGTRAP for all trap
-	 * insns, even for trap codes that indicate arithmetic failures.
-	 * Weird ...)
-	 * But should we continue the brokenness???  --macro
-	 */
-	switch (tcode) {
-	case BRK_OVERFLOW:
-	case BRK_DIVZERO:
-		die_if_kernel("Trap instruction in kernel code", regs);
-		if (tcode == BRK_DIVZERO)
-			info.si_code = FPE_INTDIV;
-		else
-			info.si_code = FPE_INTOVF;
-		info.si_signo = SIGFPE;
-		info.si_errno = 0;
-		info.si_addr = (void __user *) regs->cp0_epc;
-		force_sig_info(SIGFPE, &info, current);
-		break;
-	case BRK_BUG:
-		die("Kernel bug detected", regs);
-		break;
-	default:
-		die_if_kernel("Trap instruction in kernel code", regs);
-		force_sig(SIGTRAP, current);
-	}
+	do_trap_or_bp(regs, tcode, "Trap");
 	return;
 
 out_sigsegv: