[POWERPC] Fixup error handling when emulating a floating point instruction

When we do full FP emulation its possible that we need to post a SIGFPE based
on the results of the emulation.  The previous code ignored this case completely.

Additionally, the Soft_emulate_8xx case had two issues.  One, we should never
generate a SIGFPE since the code only does data movement.  Second, we were
interpreting the return codes incorrectly, it returns 0 on success, 1 on
illop and -EFAULT on a data access error.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index f038caa3c2b92255cc4061e648ceaa855f37f115..dcc6f159fd945070050ece10f77f64df90b70edb 100644 (file)
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -535,34 +535,40 @@ static void emulate_single_step(struct pt_regs *regs)
        }
 }
 
-static void parse_fpe(struct pt_regs *regs)
+static inline int __parse_fpscr(unsigned long fpscr)
 {
-       int code = 0;
-       unsigned long fpscr;
-
-       flush_fp_to_thread(current);
-
-       fpscr = current->thread.fpscr.val;
+       int ret = 0;
 
        /* Invalid operation */
        if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
-               code = FPE_FLTINV;
+               ret = FPE_FLTINV;
 
        /* Overflow */
        else if ((fpscr & FPSCR_OE) && (fpscr & FPSCR_OX))
-               code = FPE_FLTOVF;
+               ret = FPE_FLTOVF;
 
        /* Underflow */
        else if ((fpscr & FPSCR_UE) && (fpscr & FPSCR_UX))
-               code = FPE_FLTUND;
+               ret = FPE_FLTUND;
 
        /* Divide by zero */
        else if ((fpscr & FPSCR_ZE) && (fpscr & FPSCR_ZX))
-               code = FPE_FLTDIV;
+               ret = FPE_FLTDIV;
 
        /* Inexact result */
        else if ((fpscr & FPSCR_XE) && (fpscr & FPSCR_XX))
-               code = FPE_FLTRES;
+               ret = FPE_FLTRES;
+
+       return ret;
+}
+
+static void parse_fpe(struct pt_regs *regs)
+{
+       int code = 0;
+
+       flush_fp_to_thread(current);
+
+       code = __parse_fpscr(current->thread.fpscr.val);
 
        _exception(SIGFPE, regs, code, regs->nip);
 }
@@ -773,10 +779,21 @@ void __kprobes program_check_exception(struct pt_regs *regs)
         * hardware people - not sure if it can happen on any illegal
         * instruction or only on FP instructions, whether there is a
         * pattern to occurences etc. -dgibson 31/Mar/2003 */
-       if (do_mathemu(regs) == 0) {
+       switch (do_mathemu(regs)) {
+       case 0:
                emulate_single_step(regs);
                return;
+       case 1: {
+                       int code = 0;
+                       code = __parse_fpscr(current->thread.fpscr.val);
+                       _exception(SIGFPE, regs, code, regs->nip);
+                       return;
+               }
+       case -EFAULT:
+               _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+               return;
        }
+       /* fall through on any other errors */
 #endif /* CONFIG_MATH_EMULATION */
 
        /* Try to emulate it if we should. */
@@ -892,18 +909,39 @@ void SoftwareEmulation(struct pt_regs *regs)
 
 #ifdef CONFIG_MATH_EMULATION
        errcode = do_mathemu(regs);
+
+       switch (errcode) {
+       case 0:
+               emulate_single_step(regs);
+               return;
+       case 1: {
+                       int code = 0;
+                       code = __parse_fpscr(current->thread.fpscr.val);
+                       _exception(SIGFPE, regs, code, regs->nip);
+                       return;
+               }
+       case -EFAULT:
+               _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+               return;
+       default:
+               _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
+               return;
+       }
+
 #else
        errcode = Soft_emulate_8xx(regs);
-#endif
-       if (errcode) {
-               if (errcode > 0)
-                       _exception(SIGFPE, regs, 0, 0);
-               else if (errcode == -EFAULT)
-                       _exception(SIGSEGV, regs, 0, 0);
-               else
-                       _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-       } else
+       switch (errcode) {
+       case 0:
                emulate_single_step(regs);
+               return;
+       case 1:
+               _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
+               return;
+       case -EFAULT:
+               _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+               return;
+       }
+#endif
 }
 #endif /* CONFIG_8xx */