[MIPS] Use conditional traps for BUG_ON on MIPS II and better.

This shaves of around 4kB and a few cycles for the average kernel that
has CONFIG_BUG enabled.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 22 insertions, 6 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 0ae19e1fa867..2a932cada244 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -669,8 +669,6 @@ asmlinkage void do_bp(struct pt_regs *regs)
         unsigned int opcode, bcode;
         siginfo_t info;
 
-        die_if_kernel("Break instruction in kernel code", regs);
-
         if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                 goto out_sigsegv;
 
@@ -693,6 +691,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
         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
@@ -702,7 +701,11 @@ asmlinkage void do_bp(struct pt_regs *regs)
                 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);
         }
 
@@ -715,8 +718,6 @@ asmlinkage void do_tr(struct pt_regs *regs)
         unsigned int opcode, tcode = 0;
         siginfo_t info;
 
-        die_if_kernel("Trap instruction in kernel code", regs);
-
         if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                 goto out_sigsegv;
 
@@ -733,6 +734,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
         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
@@ -742,7 +744,11 @@ asmlinkage void do_tr(struct pt_regs *regs)
                 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);
         }
 
diff --git a/include/asm-mips/bug.h b/include/asm-mips/bug.h
index 7b4739dc8f3f..4d560a533940 100644
--- a/include/asm-mips/bug.h
+++ b/include/asm-mips/bug.h
@@ -1,6 +1,7 @@
 #ifndef __ASM_BUG_H
 #define __ASM_BUG_H
 
+#include <asm/sgidefs.h>
 
 #ifdef CONFIG_BUG
 
@@ -13,6 +14,17 @@ do {									\
 
 #define HAVE_ARCH_BUG
 
+#if (_MIPS_ISA > _MIPS_ISA_MIPS1)
+
+#define BUG_ON(condition)                                               \
+do {                                                                    \
+        __asm__ __volatile__("tne $0, %0" : : "r" (condition));         \
+} while (0)
+
+#define HAVE_ARCH_BUG_ON
+
+#endif /* _MIPS_ISA > _MIPS_ISA_MIPS1 */
+
 #endif
 
 #include <asm-generic/bug.h>
diff --git a/include/asm-mips/ptrace.h b/include/asm-mips/ptrace.h
index 5f3a9075cd28..30bf555faeaa 100644
--- a/include/asm-mips/ptrace.h
+++ b/include/asm-mips/ptrace.h
@@ -80,8 +80,6 @@ struct pt_regs {
 #define instruction_pointer(regs) ((regs)->cp0_epc)
 #define profile_pc(regs) instruction_pointer(regs)
 
-extern void show_regs(struct pt_regs *);
-
 extern asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit);
 
 #endif