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Commit f2fb4e4f authored by Stuart Menefy's avatar Stuart Menefy Committed by Paul Mundt
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sh: Conditionally re-enable IRQs in fault path. 



The current kernel behaviour is to reenable interrupts unconditionally
when taking a page fault. This patch changes this to only enable them
if interrupts were previously enabled.

It also fixes a problem seen with this fix in place: the kernel previously
flushed the vsyscall page when handling a signal, which is not only
unncessary, but caused a possible sleep with interrupts disabled.

Signed-off-by: default avatarStuart Menefy <stuart.menefy@st.com>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 068f5914

arch/sh/kernel/signal_32.c

+1 −2
Original line number Diff line number Diff line
@@ -373,6 +373,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, 
		err |= __put_user(OR_R0_R0, &frame->retcode[6]);

		err |= __put_user((__NR_sigreturn), &frame->retcode[7]);

		regs->pr = (unsigned long) frame->retcode;

		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));

	}



	if (err)
@@ -398,8 +399,6 @@ static int setup_frame(int sig, struct k_sigaction *ka, 
	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",

		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);



	flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));



	return 0;



give_sigsegv:

arch/sh/mm/fault_32.c

+8 −4
Original line number Diff line number Diff line
@@ -37,16 +37,12 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	int fault;

	siginfo_t info;



	trace_hardirqs_on();

	local_irq_enable();



#ifdef CONFIG_SH_KGDB

	if (kgdb_nofault && kgdb_bus_err_hook)

		kgdb_bus_err_hook();

#endif



	tsk = current;

	mm = tsk->mm;

	si_code = SEGV_MAPERR;



	if (unlikely(address >= TASK_SIZE)) {
@@ -88,6 +84,14 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
		return;

	}



	/* Only enable interrupts if they were on before the fault */

	if ((regs->sr & SR_IMASK) != SR_IMASK) {

		trace_hardirqs_on();

		local_irq_enable();

	}



	mm = tsk->mm;



	/*

	 * If we're in an interrupt or have no user

	 * context, we must not take the fault..