Commit 59e4f3b4 authored by Russell King (Oracle)'s avatar Russell King (Oracle)
Browse files

ARM: ensure interrupts are enabled in __do_user_fault() 



__do_user_fault() may be called from fault handling paths where the
interrupts are enabled or disabled. E.g. do_page_fault() calls this
with interrupts enabled, whereas do_sect_fault()->do_bad_area()
will call this with interrupts disabled. Since this is a userspace
fault, we know that interrupts were enabled in the parent context,
so call local_irq_enable() here to give a consistent interrupt state.

This is necessary for force_sig_info() when PREEMPT_RT is enabled.

Reported-by: default avatarYadi.hu <yadi.hu@windriver.com>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
parent 05f7e89a

arch/arm/mm/fault.c

+5 −1
Original line number Diff line number Diff line
@@ -190,7 +190,8 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 


/*

 * Something tried to access memory that isn't in our memory map..

 * User mode accesses just cause a SIGSEGV

 * User mode accesses just cause a SIGSEGV. Ensure interrupts are enabled

 * for preempt RT.

 */

static void

__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
@@ -198,6 +199,8 @@ __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig, 
{

	struct task_struct *tsk = current;



	local_irq_enable();



#ifdef CONFIG_DEBUG_USER

	if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||

	    ((user_debug & UDBG_BUS)  && (sig == SIGBUS))) {
@@ -268,6 +271,7 @@ do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr, 
		 * should not be faulting in kernel space, which includes the

		 * vector/khelper page. Handle the branch predictor hardening

		 * while interrupts are still disabled, then send a SIGSEGV.

		 * Note that __do_user_fault() will enable interrupts.

		 */

		harden_branch_predictor();

		__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);