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Commit c433ec04 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Michael Ellerman
Browse files

powerpc/mm: Pre-filter SRR1 bits before do_page_fault() 



By filtering the relevant SRR1 bits in the assembly rather than
in do_page_fault() itself, we avoid a conditional branch (since we
already come from different path for data and instruction faults).

This will allow more simplifications later

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 7afad422

arch/powerpc/kernel/head_32.S

+1 −1
Original line number Diff line number Diff line
@@ -409,7 +409,7 @@ InstructionAccess: 
	mr	r4,r12			/* SRR0 is fault address */

	bl	hash_page

1:	mr	r4,r12

	mr	r5,r9

	andis.	r5,r9,0x4820		/* Filter relevant SRR1 bits */

	EXC_XFER_LITE(0x400, handle_page_fault)



/* External interrupt */

arch/powerpc/kernel/head_8xx.S

+2 −2
Original line number Diff line number Diff line
@@ -569,8 +569,8 @@ _ENTRY(DTLBMiss_jmp) 
InstructionTLBError:

	EXCEPTION_PROLOG

	mr	r4,r12

	mr	r5,r9

	andis.	r10,r5,0x4000

	andis.	r5,r9,0x4820		/* Filter relevant SRR1 bits */

	andis.	r10,r9,0x4000

	beq+	1f

	tlbie	r4

itlbie:

arch/powerpc/mm/fault.c

+2 −12
Original line number Diff line number Diff line
@@ -203,22 +203,12 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	int code = SEGV_MAPERR;

	int is_write = 0;

	int trap = TRAP(regs);

 	int is_exec = trap == 0x400;

 	int is_exec = TRAP(regs) == 0x400;

	int is_user = user_mode(regs);

	int fault;

	int rc = 0, store_update_sp = 0;



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

	/*

	 * Fortunately the bit assignments in SRR1 for an instruction

	 * fault and DSISR for a data fault are mostly the same for the

	 * bits we are interested in.  But there are some bits which

	 * indicate errors in DSISR but can validly be set in SRR1.

	 */

	if (is_exec)

		error_code &= 0x48200000;

	else

	is_write = error_code & DSISR_ISSTORE;

#else

	is_write = error_code & ESR_DST;