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Commit c1f438f5 authored by Catalin Marinas's avatar Catalin Marinas Committed by Russell King
Browse files

[ARM] 4581/1: Fix the conditional execution of the NWFPE instructions 



Starting with ARMv7-A, conditional execution of undefined instructions
can trigger an exception even if the condition check fails. This patch
modifies the NWFPE support to check the condition before emulating the
instruction.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent ec6b1482

arch/arm/nwfpe/entry.S

+14 −11
Original line number Diff line number Diff line
@@ -70,13 +70,24 @@ floating point instructions. GCC attempts to group floating point 
instructions to allow the emulator to spread the cost of the trap over

several floating point instructions.  */



#include <asm/asm-offsets.h>



	.globl	nwfpe_enter

nwfpe_enter:

	mov	r4, lr			@ save the failure-return addresses

	mov	sl, sp			@ we access the registers via 'sl'



	ldr	r5, [sp, #60]		@ get contents of PC;

	ldr	r5, [sp, #S_PC]		@ get contents of PC;

	mov	r6, r0			@ save the opcode

emulate:

	ldr	r1, [sp, #S_PSR]	@ fetch the PSR

	bl	checkCondition		@ check the condition

	cmp	r0, #0			@ r0 = 0 ==> condition failed



	@ if condition code failed to match, next insn

	beq	next			@ get the next instruction;



	mov	r0, r6			@ prepare for EmulateAll()

	bl	EmulateAll		@ emulate the instruction

	cmp	r0, #0			@ was emulation successful

	moveq	pc, r4			@ no, return failure
@@ -91,18 +102,10 @@ next: 
	teqne	r2, #0x0E000000

	movne	pc, r9			@ return ok if not a fp insn



	str	r5, [sp, #60]		@ update PC copy in regs

	str	r5, [sp, #S_PC]		@ update PC copy in regs



	mov	r0, r6			@ save a copy

	ldr	r1, [sp, #64]		@ fetch the condition codes

	bl	checkCondition		@ check the condition

	cmp	r0, #0			@ r0 = 0 ==> condition failed



	@ if condition code failed to match, next insn

	beq	next			@ get the next instruction;



	mov	r0, r6			@ prepare for EmulateAll()

	b	emulate			@ if r0 != 0, goto EmulateAll

	b	emulate			@ check condition and emulate



	@ We need to be prepared for the instructions at .Lx1 and .Lx2 

	@ to fault.  Emit the appropriate exception gunk to fix things up.