start_thread() (called for execve(2)) clears the TIF_USEDFPU flag without atomically disabling the FPU. With a preemptive kernel, an unfortunately timed preemption after this could result in another task (or KVM guest) being scheduled in with the FPU still enabled, since lose_fpu_inatomic() only turns it off if TIF_USEDFPU is set. Use lose_fpu(0) instead of the separate FPU / MSA management, which should do the right thing (drop FPU properly and atomically without saving state) and will be more future proof. Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx> Reviewed-by: Paul Burton <paul.burton@xxxxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx --- arch/mips/kernel/process.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index f2975d4d1e44..eddd5fd6fdfa 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -65,12 +65,10 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); status |= KU_USER; regs->cp0_status = status; + lose_fpu(0); + clear_thread_flag(TIF_MSA_CTX_LIVE); clear_used_math(); - clear_fpu_owner(); init_dsp(); - clear_thread_flag(TIF_USEDMSA); - clear_thread_flag(TIF_MSA_CTX_LIVE); - disable_msa(); regs->cp0_epc = pc; regs->regs[29] = sp; } -- 2.4.10
