ARM: 9425/1: vfp: Use vfp_state_hold() in vfp_support_entry().

vfp_entry() is invoked from exception handler and is fully preemptible.
It uses local_bh_disable() to remain uninterrupted while checking the
VFP state.
This is not working on PREEMPT_RT because local_bh_disable()
synchronizes the relevant section but the context remains fully
preemptible.

Use vfp_state_hold() for uninterrupted access.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 1726db0..28dafae 100644 (file)
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -708,7 +708,7 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger)
        if (!user_mode(regs))
                return vfp_kmode_exception(regs, trigger);
 
-       local_bh_disable();
+       vfp_state_hold();
        fpexc = fmrx(FPEXC);
 
        /*
@@ -787,7 +787,7 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger)
                        if (!(fpscr & FPSCR_IXE)) {
                                if (!(fpscr & FPSCR_LENGTH_MASK)) {
                                        pr_debug("not VFP\n");
-                                       local_bh_enable();
+                                       vfp_state_release();
                                        return -ENOEXEC;
                                }
                                fpexc |= FPEXC_DEX;
@@ -797,7 +797,7 @@ bounce:             regs->ARM_pc += 4;
                VFP_bounce(trigger, fpexc, regs);
        }
 
-       local_bh_enable();
+       vfp_state_release();
        return 0;
 }