Commit 5567b1ee authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s: fix hash page fault interrupt handler 



The early bad fault or key fault test in do_hash_fault() ends up calling
into ___do_page_fault without having gone through an interrupt handler
wrapper (except the initial _RAW one). This can end up calling local irq
functions while the interrupt has not been reconciled, which will likely
cause crashes and it trips up on a later patch that adds more assertions.

pkey_exec_prot from selftests causes this path to be executed.

There is no real reason to run the in_nmi() test should be performed
before the key fault check. In fact if a perf interrupt in the hash
fault code did a stack walk that was made to take a key fault somehow
then running ___do_page_fault could possibly cause another hash fault
causing problems. Move the in_nmi() test first, and then do everything
else inside the regular interrupt handler function.

Fixes: 3a96570f ("powerpc: convert interrupt handlers to use wrappers")
Reported-by: default avatarSachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Tested-by: default avatarSachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210630074621.2109197-2-npiggin@gmail.com
parent fc499986

arch/powerpc/mm/book3s64/hash_utils.c

+11 −13
Original line number Diff line number Diff line
@@ -1522,8 +1522,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap, 
}

EXPORT_SYMBOL_GPL(hash_page);



DECLARE_INTERRUPT_HANDLER_RET(__do_hash_fault);

DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)

DECLARE_INTERRUPT_HANDLER(__do_hash_fault);

DEFINE_INTERRUPT_HANDLER(__do_hash_fault)

{

	unsigned long ea = regs->dar;

	unsigned long dsisr = regs->dsisr;
@@ -1533,6 +1533,11 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault) 
	unsigned int region_id;

	long err;



	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {

		hash__do_page_fault(regs);

		return;

	}



	region_id = get_region_id(ea);

	if ((region_id == VMALLOC_REGION_ID) || (region_id == IO_REGION_ID))

		mm = &init_mm;
@@ -1571,9 +1576,10 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault) 
			bad_page_fault(regs, SIGBUS);

		}

		err = 0;

	}



	return err;

	} else if (err) {

		hash__do_page_fault(regs);

	}

}



/*
@@ -1582,13 +1588,6 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault) 
 */

DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)

{

	unsigned long dsisr = regs->dsisr;



	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {

		hash__do_page_fault(regs);

		return 0;

	}



	/*

	 * If we are in an "NMI" (e.g., an interrupt when soft-disabled), then

	 * don't call hash_page, just fail the fault. This is required to
@@ -1607,8 +1606,7 @@ DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault) 
		return 0;

	}



	if (__do_hash_fault(regs))

		hash__do_page_fault(regs);

	__do_hash_fault(regs);



	return 0;

}