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Commit f3d96e69 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Michael Ellerman
Browse files

powerpc/mm: Overhaul handling of bad page faults 



A bad page fault is when the HW signals an error such as a bad
copy/paste, an AMO error, or some other type of error that will
not be fixed by updating the PTE.

Use a helper page_fault_is_bad() to check for bad page faults thus
removing the per-processor family open-coding in __do_page_fault()
and trigger a SIGBUS rather than a SIGSEGV which is more appropriate.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent e6c8290a

arch/powerpc/mm/fault.c

+14 −18
Original line number Diff line number Diff line
@@ -188,8 +188,16 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault) 
 */

#if (defined(CONFIG_4xx) || defined(CONFIG_BOOKE))

#define page_fault_is_write(__err)	((__err) & ESR_DST)

#define page_fault_is_bad(__err)	(0)

#else

#define page_fault_is_write(__err)	((__err) & DSISR_ISSTORE)

#if defined(CONFIG_8xx)

#define page_fault_is_bad(__err)	((__err) & 0x10000000)

#elif defined(CONFIG_PPC64)

#define page_fault_is_bad(__err)	((__err) & DSISR_BAD_FAULT_64S)

#else

#define page_fault_is_bad(__err)	((__err) & DSISR_BAD_FAULT_32S)

#endif

#endif



/*
@@ -237,25 +245,13 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
	if (unlikely(debugger_fault_handler(regs)))

		goto bail;



#if defined(CONFIG_6xx)

	if (error_code & 0x95700000) {

		/* an error such as lwarx to I/O controller space,

		   address matching DABR, eciwx, etc. */

		code = SEGV_ACCERR;

		goto bad_area_nosemaphore;

	}

#endif /* CONFIG_6xx */

#if defined(CONFIG_8xx)

        /* The MPC8xx seems to always set 0x80000000, which is

         * "undefined".  Of those that can be set, this is the only

         * one which seems bad.

         */

	if (error_code & 0x10000000) {

                /* Guarded storage error. */

		code = SEGV_ACCERR;

		goto bad_area_nosemaphore;

	if (unlikely(page_fault_is_bad(error_code))) {

		if (is_user)

			_exception(SIGBUS, regs, BUS_OBJERR, address);

		else

			rc = SIGBUS;

		goto bail;

	}

#endif /* CONFIG_8xx */



	/*

	 * The kernel should never take an execute fault nor should it