From 2af276dfb1722e97b190bd2e646b079a2aa674db Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 30 Jan 2012 20:21:42 +0100 Subject: ARM: 7306/1: vfp: flush thread hwstate before restoring context from sigframe Following execution of a signal handler, we currently restore the VFP context from the ucontext in the signal frame. This involves copying from the user stack into the current thread's vfp_hard_struct and then flushing the new data out to the hardware registers. This is problematic when using a preemptible kernel because we could be context switched whilst updating the vfp_hard_struct. If the current thread has made use of VFP since the last context switch, the VFP notifier will copy from the hardware registers into the vfp_hard_struct, overwriting any data that had been partially copied by the signal code. Disabling preemption across copy_from_user calls is a terrible idea, so instead we move the VFP thread flush *before* we update the vfp_hard_struct. Since the flushing is performed lazily, this has the effect of disabling VFP and clearing the CPU's VFP state pointer, therefore preventing the thread from being updated with stale data on the next context switch. Cc: stable Tested-by: Peter Maydell Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/signal.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'arch/arm/kernel/signal.c') diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 0340224cf73..9e617bd4a14 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -227,6 +227,8 @@ static int restore_vfp_context(struct vfp_sigframe __user *frame) if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) return -EINVAL; + vfp_flush_hwstate(thread); + /* * Copy the floating point registers. There can be unused * registers see asm/hwcap.h for details. @@ -251,9 +253,6 @@ static int restore_vfp_context(struct vfp_sigframe __user *frame) __get_user_error(h->fpinst, &frame->ufp_exc.fpinst, err); __get_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err); - if (!err) - vfp_flush_hwstate(thread); - return err ? -EFAULT : 0; } -- cgit v1.2.3-70-g09d2 From 101d9b0dedbc9e560737d3357104bf09db48eb3e Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Mon, 5 Mar 2012 15:05:34 -0800 Subject: ARM: use set_current_blocked() and block_sigmask() As described in e6fa16ab ("signal: sigprocmask() should do retarget_shared_pending()") the modification of current->blocked is incorrect as we need to check for shared signals we're about to block. Also, use the new helper function introduced in commit 5e6292c0f28f ("signal: add block_sigmask() for adding sigmask to current->blocked") which centralises the code for updating current->blocked after successfully delivering a signal and reduces the amount of duplicate code across architectures. In the past some architectures got this code wrong, so using this helper function should stop that from happening again. Cc: Arnd Bergmann Cc: Dave Martin Cc: Nicolas Pitre Cc: Will Deacon Acked-by: Oleg Nesterov Signed-off-by: Matt Fleming Signed-off-by: Andrew Morton Signed-off-by: Russell King --- arch/arm/kernel/signal.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) (limited to 'arch/arm/kernel/signal.c') diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 0340224cf73..d13e61ac18d 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -66,12 +66,13 @@ const unsigned long syscall_restart_code[2] = { */ asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask) { - mask &= _BLOCKABLE; - spin_lock_irq(¤t->sighand->siglock); + sigset_t blocked; + current->saved_sigmask = current->blocked; - siginitset(¤t->blocked, mask); - recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); + + mask &= _BLOCKABLE; + siginitset(&blocked, mask); + set_current_blocked(&blocked); current->state = TASK_INTERRUPTIBLE; schedule(); @@ -281,10 +282,7 @@ static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); if (err == 0) { sigdelsetmask(&set, ~_BLOCKABLE); - spin_lock_irq(¤t->sighand->siglock); - current->blocked = set; - recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); + set_current_blocked(&set); } __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); @@ -637,13 +635,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, /* * Block the signal if we were successful. */ - spin_lock_irq(&tsk->sighand->siglock); - sigorsets(&tsk->blocked, &tsk->blocked, - &ka->sa.sa_mask); - if (!(ka->sa.sa_flags & SA_NODEFER)) - sigaddset(&tsk->blocked, sig); - recalc_sigpending(); - spin_unlock_irq(&tsk->sighand->siglock); + block_sigmask(ka, sig); return 0; } -- cgit v1.2.3-70-g09d2