powerpc/math_emu/efp: No need to round if the result is exact

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/powerpc/math-emu/math_efp.c b/arch/powerpc/math-emu/math_efp.c
index 10fda0f13a00..96dbbae1a590 100644
--- a/arch/powerpc/math-emu/math_efp.c
+++ b/arch/powerpc/math-emu/math_efp.c
@@ -676,13 +676,20 @@ int speround_handler(struct pt_regs *regs)
         type = insn_type(speinsn & 0x7ff);
         if (type == XCR) return -ENOSYS;
 
+        __FPU_FPSCR = mfspr(SPRN_SPEFSCR);
+        pr_debug("speinsn:%08lx spefscr:%08lx\n", speinsn, __FPU_FPSCR);
+
+        /* No need to round if the result is exact */
+        if (!(__FPU_FPSCR & FP_EX_INEXACT))
+                return 0;
+
         fc = (speinsn >> 21) & 0x1f;
         s_lo = regs->gpr[fc] & SIGN_BIT_S;
         s_hi = current->thread.evr[fc] & SIGN_BIT_S;
         fgpr.wp[0] = current->thread.evr[fc];
         fgpr.wp[1] = regs->gpr[fc];
 
-        __FPU_FPSCR = mfspr(SPRN_SPEFSCR);
+        pr_debug("round fgpr: %08x  %08x\n", fgpr.wp[0], fgpr.wp[1]);
 
         switch ((speinsn >> 5) & 0x7) {
         /* Since SPE instructions on E500 core can handle round to nearest
@@ -722,6 +729,8 @@ int speround_handler(struct pt_regs *regs)
         current->thread.evr[fc] = fgpr.wp[0];
         regs->gpr[fc] = fgpr.wp[1];
 
+        pr_debug("  to fgpr: %08x  %08x\n", fgpr.wp[0], fgpr.wp[1]);
+
         return 0;
 }