diff options
Diffstat (limited to 'arch/powerpc/math-emu')
| -rw-r--r-- | arch/powerpc/math-emu/math_efp.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/arch/powerpc/math-emu/math_efp.c b/arch/powerpc/math-emu/math_efp.c index a73f0884d358..59835c625dc6 100644 --- a/arch/powerpc/math-emu/math_efp.c +++ b/arch/powerpc/math-emu/math_efp.c @@ -630,9 +630,27 @@ update_ccr: regs->ccr |= (IR << ((7 - ((speinsn >> 23) & 0x7)) << 2)); update_regs: - __FPU_FPSCR &= ~FP_EX_MASK; + /* + * If the "invalid" exception sticky bit was set by the + * processor for non-finite input, but was not set before the + * instruction being emulated, clear it. Likewise for the + * "underflow" bit, which may have been set by the processor + * for exact underflow, not just inexact underflow when the + * flag should be set for IEEE 754 semantics. Other sticky + * exceptions will only be set by the processor when they are + * correct according to IEEE 754 semantics, and we must not + * clear sticky bits that were already set before the emulated + * instruction as they represent the user-visible sticky + * exception status. "inexact" traps to kernel are not + * required for IEEE semantics and are not enabled by default, + * so the "inexact" sticky bit may have been set by a previous + * instruction without the kernel being aware of it. + */ + __FPU_FPSCR + &= ~(FP_EX_INVALID | FP_EX_UNDERFLOW) | current->thread.spefscr_last; __FPU_FPSCR |= (FP_CUR_EXCEPTIONS & FP_EX_MASK); mtspr(SPRN_SPEFSCR, __FPU_FPSCR); + current->thread.spefscr_last = __FPU_FPSCR; current->thread.evr[fc] = vc.wp[0]; regs->gpr[fc] = vc.wp[1]; |