3.16.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Maciej W. Rozycki" <macro@xxxxxxxxxxxxxx> commit ed2d72c1eb3643b7c109bdf387563d9b9a30c279 upstream. Respect the FCSR exception mask when interpreting the IEEE 754 exception condition to report with SIGFPE in `si_code', so as not to use one that has been masked where a different one set in parallel caused the FPE hardware exception to trigger. As per the IEEE Std 754 the Inexact exception can happen together with Overflow or Underflow. Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/9703/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- arch/mips/kernel/traps.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -12,6 +12,7 @@ * Copyright (C) 2000, 2001, 2012 MIPS Technologies, Inc. All rights reserved. * Copyright (C) 2014, Imagination Technologies Ltd. */ +#include <linux/bitops.h> #include <linux/bug.h> #include <linux/compiler.h> #include <linux/context_tracking.h> @@ -785,7 +786,15 @@ asmlinkage void do_fpe(struct pt_regs *r process_fpemu_return(sig, fault_addr); goto out; - } else if (fcr31 & FPU_CSR_INV_X) + } + + /* + * Inexact can happen together with Overflow or Underflow. + * Respect the mask to deliver the correct exception. + */ + fcr31 &= (fcr31 & FPU_CSR_ALL_E) << + (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)); + if (fcr31 & FPU_CSR_INV_X) info.si_code = FPE_FLTINV; else if (fcr31 & FPU_CSR_DIV_X) info.si_code = FPE_FLTDIV;
