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Commit 709b973c authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Michael Ellerman
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powerpc/fscr: Enable interrupts earlier before calling get_user() 



The function get_user() can sleep while trying to fetch instruction
from user address space and causes the following warning from the
scheduler.

BUG: sleeping function called from invalid context

Though interrupts get enabled back but it happens bit later after
get_user() is called. This change moves enabling these interrupts
earlier covering the function get_user(). While at this, lets check
for kernel mode and crash as this interrupt should not have been
triggered from the kernel context.

Signed-off-by: default avatarAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 501a78cb

arch/powerpc/kernel/traps.c

+17 −15
Original line number Diff line number Diff line
@@ -1613,6 +1613,22 @@ void facility_unavailable_exception(struct pt_regs *regs) 
		value = mfspr(SPRN_FSCR);



	status = value >> 56;

	if ((hv || status >= 2) &&

	    (status < ARRAY_SIZE(facility_strings)) &&

	    facility_strings[status])

		facility = facility_strings[status];



	/* We should not have taken this interrupt in kernel */

	if (!user_mode(regs)) {

		pr_emerg("Facility '%s' unavailable (%d) exception in kernel mode at %lx\n",

			 facility, status, regs->nip);

		die("Unexpected facility unavailable exception", regs, SIGABRT);

	}



	/* We restore the interrupt state now */

	if (!arch_irq_disabled_regs(regs))

		local_irq_enable();



	if (status == FSCR_DSCR_LG) {

		/*

		 * User is accessing the DSCR register using the problem
@@ -1679,25 +1695,11 @@ void facility_unavailable_exception(struct pt_regs *regs) 
		return;

	}



	if ((hv || status >= 2) &&

	    (status < ARRAY_SIZE(facility_strings)) &&

	    facility_strings[status])

		facility = facility_strings[status];



	/* We restore the interrupt state now */

	if (!arch_irq_disabled_regs(regs))

		local_irq_enable();



	pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at 0x%lx, MSR=%lx\n",

		hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr);



out:

	if (user_mode(regs)) {

	_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

		return;

	}



	die("Unexpected facility unavailable exception", regs, SIGABRT);

}

#endif