powerpc: Introduce function emulate_math()

There are two invocations of do_mathemu() in traps.c. And the codes
in these two places are almost the same. Introduce a locale function
to eliminate the duplication. With this change we can also make sure
that in program_check_exception() the PPC_WARN_EMULATED is invoked for
the correctly emulated math instructions.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 34 insertions, 45 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 82df498069bc..e6fac2102b06 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1055,11 +1055,41 @@ int is_valid_bugaddr(unsigned long addr)
         return is_kernel_addr(addr);
 }
 
+#ifdef CONFIG_MATH_EMULATION
+static int emulate_math(struct pt_regs *regs)
+{
+        int ret;
+        extern int do_mathemu(struct pt_regs *regs);
+
+        ret = do_mathemu(regs);
+        if (ret >= 0)
+                PPC_WARN_EMULATED(math, regs);
+
+        switch (ret) {
+        case 0:
+                emulate_single_step(regs);
+                return 0;
+        case 1: {
+                        int code = 0;
+                        code = __parse_fpscr(current->thread.fpscr.val);
+                        _exception(SIGFPE, regs, code, regs->nip);
+                        return 0;
+                }
+        case -EFAULT:
+                _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+                return 0;
+        }
+
+        return -1;
+}
+#else
+static inline int emulate_math(struct pt_regs *regs) { return -1; }
+#endif
+
 void __kprobes program_check_exception(struct pt_regs *regs)
 {
         enum ctx_state prev_state = exception_enter();
         unsigned int reason = get_reason(regs);
-        extern int do_mathemu(struct pt_regs *regs);
 
         /* We can now get here via a FP Unavailable exception if the core
          * has no FPU, in that case the reason flags will be 0 */
@@ -1125,7 +1155,6 @@ void __kprobes program_check_exception(struct pt_regs *regs)
         if (!arch_irq_disabled_regs(regs))
                 local_irq_enable();
 
-#ifdef CONFIG_MATH_EMULATION
         /* (reason & REASON_ILLEGAL) would be the obvious thing here,
          * but there seems to be a hardware bug on the 405GP (RevD)
          * that means ESR is sometimes set incorrectly - either to
@@ -1134,22 +1163,8 @@ void __kprobes program_check_exception(struct pt_regs *regs)
          * instruction or only on FP instructions, whether there is a
          * pattern to occurrences etc. -dgibson 31/Mar/2003
          */
-        switch (do_mathemu(regs)) {
-        case 0:
-                emulate_single_step(regs);
-                goto bail;
-        case 1: {
-                        int code = 0;
-                        code = __parse_fpscr(current->thread.fpscr.val);
-                        _exception(SIGFPE, regs, code, regs->nip);
-                        goto bail;
-                }
-        case -EFAULT:
-                _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
+        if (!emulate_math(regs))
                 goto bail;
-        }
-        /* fall through on any other errors */
-#endif /* CONFIG_MATH_EMULATION */
 
         /* Try to emulate it if we should. */
         if (reason & (REASON_ILLEGAL | REASON_PRIVILEGED)) {
@@ -1428,11 +1443,6 @@ void performance_monitor_exception(struct pt_regs *regs)
 #ifdef CONFIG_8xx
 void SoftwareEmulation(struct pt_regs *regs)
 {
-        extern int do_mathemu(struct pt_regs *);
-#if defined(CONFIG_MATH_EMULATION)
-        int errcode;
-#endif
-
         CHECK_FULL_REGS(regs);
 
         if (!user_mode(regs)) {
@@ -1440,31 +1450,10 @@ void SoftwareEmulation(struct pt_regs *regs)
                 die("Kernel Mode Software FPU Emulation", regs, SIGFPE);
         }
 
-#ifdef CONFIG_MATH_EMULATION
-        errcode = do_mathemu(regs);
-        if (errcode >= 0)
-                PPC_WARN_EMULATED(math, 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);
+        if (!emulate_math(regs))
                 return;
-        default:
-                _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-                return;
-        }
-#else
+
         _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-#endif
 }
 #endif /* CONFIG_8xx */