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authorPaul Burton <paul.burton@imgtec.com>2015-07-27 12:58:20 -0700
committerRalf Baechle <ralf@linux-mips.org>2015-09-03 12:07:56 +0200
commit0d071fa3772b85fe5d81032fbc011c623570d2fc (patch)
tree0d477af57f1e9d81aa2437dc5fc0b25032a8fd8f /arch/mips/kernel/signal.c
parent6a24432cf9cfb6e071fb3566144a3a5ace9d3c0d (diff)
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 <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Guenter Roeck <linux@roeck-us.net> Cc: Matthew Fortune <matthew.fortune@imgtec.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linux-kernel@vger.kernel.org Cc: Richard Weinberger <richard@nod.at> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Maciej W. Rozycki <macro@codesourcery.com> Patchwork: https://patchwork.linux-mips.org/patch/10794/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/signal.c')
-rw-r--r--arch/mips/kernel/signal.c15
1 files changed, 11 insertions, 4 deletions
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;
}