[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>

1 files changed, 37 insertions, 52 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
@@ -675,35 +675,24 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
         force_sig_info(SIGFPE, &info, current);
 }
 
-asmlinkage void do_bp(struct pt_regs *regs)
+static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
+        const char *str)
 {
-        unsigned int opcode, bcode;
         siginfo_t info;
-
-        if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
-                goto out_sigsegv;
-
-        /*
-         * There is the ancient bug in the MIPS assemblers that the break
-         * code starts left to bit 16 instead to bit 6 in the opcode.
-         * Gas is bug-compatible, but not always, grrr...
-         * We handle both cases with a simple heuristics.  --macro
-         */
-        bcode = ((opcode >> 6) & ((1 << 20) - 1));
-        if (bcode < (1 << 10))
-                bcode <<= 10;
+        char b[40];
 
         /*
-         * (A short test says that IRIX 5.3 sends SIGTRAP for all break
-         * insns, even for break codes that indicate arithmetic failures.
-         * Weird ...)
+         * 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 (bcode) {
-        case BRK_OVERFLOW << 10:
-        case BRK_DIVZERO << 10:
-                die_if_kernel("Break instruction in kernel code", regs);
-                if (bcode == (BRK_DIVZERO << 10))
+        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;
@@ -713,12 +702,34 @@ asmlinkage void do_bp(struct pt_regs *regs)
                 force_sig_info(SIGFPE, &info, current);
                 break;
         case BRK_BUG:
-                die("Kernel bug detected", regs);
+                die_if_kernel("Kernel bug detected", regs);
+                force_sig(SIGTRAP, current);
                 break;
         default:
-                die_if_kernel("Break instruction in kernel code", regs);
+                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;
+
+        if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
+                goto out_sigsegv;
+
+        /*
+         * There is the ancient bug in the MIPS assemblers that the break
+         * code starts left to bit 16 instead to bit 6 in the opcode.
+         * Gas is bug-compatible, but not always, grrr...
+         * We handle both cases with a simple heuristics.  --macro
+         */
+        bcode = ((opcode >> 6) & ((1 << 20) - 1));
+        if (bcode >= (1 << 10))
+                bcode >>= 10;
+
+        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: