From 0d071fa3772b85fe5d81032fbc011c623570d2fc Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 27 Jul 2015 12:58:20 -0700 Subject: [PATCH] MIPS: Indicate FP mode in sigcontext sc_used_math The sc_used_math field of struct sigcontext & its variants has traditionally been used as a boolean value indicating only whether or not floating point context is saved within the sigcontext. With various supported FP modes & the ability to switch between them this information will no longer be enough to decode the meaning of the data stored in the sc_fpregs fields of struct sigcontext. To make that possible 3 bits are defined within sc_used_math: - Bit 0 (USED_FP) represents whether FP was used, essentially providing the boolean flag which sc_used_math as a whole provided previously. - Bit 1 (USED_FR1) provides the value of the Status.FR bit at the time the FP context was saved. - Bit 2 (USED_HYBRID_FPRS) indicates whether the FP context was saved under the hybrid FPR scheme. Essentially, when set the odd singles are located in bits 63:32 of the preceding even indexed sc_fpregs element. Any userland that tests whether the sc_used_math field is zero or non-zero will continue to function as expected. Having said that, I could not find any userland which uses the sc_used_math field at all. [ralf@linux-mips.org: Fixed rejects.] Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Cc: Guenter Roeck Cc: Matthew Fortune Cc: Michael Ellerman Cc: linux-kernel@vger.kernel.org Cc: Richard Weinberger Cc: Andy Lutomirski Cc: Maciej W. Rozycki Patchwork: https://patchwork.linux-mips.org/patch/10794/ Signed-off-by: Ralf Baechle --- arch/mips/include/uapi/asm/sigcontext.h | 9 +++++++++ arch/mips/kernel/signal.c | 15 +++++++++++---- 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/mips/include/uapi/asm/sigcontext.h b/arch/mips/include/uapi/asm/sigcontext.h index 9081d88ae44f..28f51bb47046 100644 --- a/arch/mips/include/uapi/asm/sigcontext.h +++ b/arch/mips/include/uapi/asm/sigcontext.h @@ -12,6 +12,15 @@ #include #include +/* scalar FP context was used */ +#define USED_FP (1 << 0) + +/* the value of Status.FR when context was saved */ +#define USED_FR1 (1 << 1) + +/* FR=1, but with odd singles in bits 63:32 of preceding even double */ +#define USED_HYBRID_FPRS (1 << 2) + #if _MIPS_SIM == _MIPS_SIM_ABI32 /* diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c index 08f521567d64..9cb75e9519c5 100644 --- a/arch/mips/kernel/signal.c +++ b/arch/mips/kernel/signal.c @@ -133,9 +133,16 @@ int protected_save_fp_context(void __user *sc) unsigned int used; int err; - used = !!used_math(); + used = used_math() ? USED_FP : 0; + if (used) { + if (!test_thread_flag(TIF_32BIT_FPREGS)) + used |= USED_FR1; + if (test_thread_flag(TIF_HYBRID_FPREGS)) + used |= USED_HYBRID_FPRS; + } + err = __put_user(used, used_math); - if (err || !used) + if (err || !(used & USED_FP)) return err; /* @@ -177,13 +184,13 @@ int protected_restore_fp_context(void __user *sc) int err, sig, tmp __maybe_unused; err = __get_user(used, used_math); - conditional_used_math(used); + conditional_used_math(used & USED_FP); /* * The signal handler may have used FPU; give it up if the program * doesn't want it following sigreturn. */ - if (err || !used) { + if (err || !(used & USED_FP)) { lose_fpu(0); return err; }