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Commit b5c8f0fd authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Michael Ellerman
Browse files

powerpc/mm: Rework mm_fault_error() 



First, handle the normal retry failure in do_page_fault itself,
since it's a simple return statement. That allows us to remove
the "continue" special return code from mm_fault_error().

Once that's done, we can have an implementation much closer to
x86 where we only call mm_fault_error() if VM_FAULT_ERROR is set
and directly return.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c3350602

arch/powerpc/mm/fault.c

+28 −38
Original line number Diff line number Diff line
@@ -147,10 +147,6 @@ static noinline int bad_area(struct pt_regs *regs, unsigned long address) 
	return __bad_area(regs, address, SEGV_MAPERR);

}



#define MM_FAULT_RETURN		0

#define MM_FAULT_CONTINUE	-1

#define MM_FAULT_ERR(sig)	(sig)



static int do_sigbus(struct pt_regs *regs, unsigned long address,

		     unsigned int fault)

{
@@ -158,7 +154,7 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address, 
	unsigned int lsb = 0;



	if (!user_mode(regs))

		return MM_FAULT_ERR(SIGBUS);

		return SIGBUS;



	current->thread.trap_nr = BUS_ADRERR;

	info.si_signo = SIGBUS;
@@ -179,25 +175,17 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address, 
#endif

	info.si_addr_lsb = lsb;

	force_sig_info(SIGBUS, &info, current);

	return MM_FAULT_RETURN;

	return 0;

}



static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)

{

	/*

	 * Pagefault was interrupted by SIGKILL. We have no reason to

	 * continue the pagefault.

	 * Kernel page fault interrupted by SIGKILL. We have no reason to

	 * continue processing.

	 */

	if (fatal_signal_pending(current)) {

		/* Coming from kernel, we need to deal with uaccess fixups */

		if (user_mode(regs))

			return MM_FAULT_RETURN;

		return MM_FAULT_ERR(SIGKILL);

	}



	/* No fault: be happy */

	if (!(fault & VM_FAULT_ERROR))

		return MM_FAULT_CONTINUE;

	if (fatal_signal_pending(current) && !user_mode(regs))

		return SIGKILL;



	/* Out of memory */

	if (fault & VM_FAULT_OOM) {
@@ -206,17 +194,18 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault) 
		 * made us unable to handle the page fault gracefully.

		 */

		if (!user_mode(regs))

			return MM_FAULT_ERR(SIGKILL);

			return SIGSEGV;

		pagefault_out_of_memory();

		return MM_FAULT_RETURN;

	}



	if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE))

	} else {

		if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|

			     VM_FAULT_HWPOISON_LARGE))

			return do_sigbus(regs, addr, fault);



	/* We don't understand the fault code, this is fatal */

		else if (fault & VM_FAULT_SIGSEGV)

			return bad_area_nosemaphore(regs, addr);

		else

			BUG();

	return MM_FAULT_CONTINUE;

	}

	return 0;

}



/* Is this a bad kernel fault ? */
@@ -274,7 +263,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
	int is_user = user_mode(regs);

	int is_write = page_fault_is_write(error_code);

	int fault;

	int rc = 0, store_update_sp = 0;

	int store_update_sp = 0;



#ifdef CONFIG_PPC_ICSWX

	/*
@@ -283,7 +272,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
	 * look at it

	 */

	if (error_code & ICSWX_DSI_UCT) {

		rc = acop_handle_fault(regs, address, error_code);

		int rc = acop_handle_fault(regs, address, error_code);

		if (rc)

			return rc;

	}
@@ -492,18 +481,19 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
			if (!fatal_signal_pending(current))

				goto retry;

		}

		/* We will enter mm_fault_error() below */

	} else

		up_read(&current->mm->mmap_sem);



	if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {

		if (fault & VM_FAULT_SIGSEGV)

			return bad_area_nosemaphore(regs, address);

		rc = mm_fault_error(regs, address, fault);

		if (rc >= MM_FAULT_RETURN)

			return rc;

		/*

		 * User mode? Just return to handle the fatal exception otherwise

		 * return to bad_page_fault

		 */

		return is_user ? 0 : SIGBUS;

	}



	up_read(&current->mm->mmap_sem);



	if (unlikely(fault & VM_FAULT_ERROR))

		return mm_fault_error(regs, address, fault);



	/*

	 * Major/minor page fault accounting.

	 */