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ARM: 7206/1: Add generic ARM instruction set condition code checks. 

This patch breaks the ARM condition checking code out of nwfpe/fpopcode.{ch}
into a standalone file for opcode operations. It also modifies the code
somewhat for coding style adherence, and adds some temporary variables for
increased readability.

Signed-off-by: Leif Lindholm <leif.lindholm@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Leif Lindholm 2011-12-12 19:31:55 +01:00 committed by Russell King
parent 9904f7933b
commit 0c9030deaf
3 changed files with 93 additions and 1 deletions
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20
arch/arm/include/asm/opcodes.h Normal file
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@ -0,0 +1,20 @@
/*
* arch/arm/include/asm/opcodes.h
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_ARM_OPCODES_H
#define __ASM_ARM_OPCODES_H
#ifndef __ASSEMBLY__
extern asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
#endif
#define ARM_OPCODE_CONDTEST_FAIL 0
#define ARM_OPCODE_CONDTEST_PASS 1
#define ARM_OPCODE_CONDTEST_UNCOND 2
#endif /* __ASM_ARM_OPCODES_H */

2
arch/arm/kernel/Makefile
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@ -13,7 +13,7 @@ CFLAGS_REMOVE_return_address.o = -pg
# Object file lists.
obj-y := elf.o entry-armv.o entry-common.o irq.o \
obj-y := elf.o entry-armv.o entry-common.o irq.o opcodes.o \
process.o ptrace.o return_address.o setup.o signal.o \
sys_arm.o stacktrace.o time.o traps.o

72
arch/arm/kernel/opcodes.c Normal file
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@ -0,0 +1,72 @@
/*
* linux/arch/arm/kernel/opcodes.c
*
* A32 condition code lookup feature moved from nwfpe/fpopcode.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <asm/opcodes.h>
#define ARM_OPCODE_CONDITION_UNCOND 0xf
/*
* condition code lookup table
* index into the table is test code: EQ, NE, ... LT, GT, AL, NV
*
* bit position in short is condition code: NZCV
*/
static const unsigned short cc_map[16] = {
0xF0F0, /* EQ == Z set */
0x0F0F, /* NE */
0xCCCC, /* CS == C set */
0x3333, /* CC */
0xFF00, /* MI == N set */
0x00FF, /* PL */
0xAAAA, /* VS == V set */
0x5555, /* VC */
0x0C0C, /* HI == C set && Z clear */
0xF3F3, /* LS == C clear || Z set */
0xAA55, /* GE == (N==V) */
0x55AA, /* LT == (N!=V) */
0x0A05, /* GT == (!Z && (N==V)) */
0xF5FA, /* LE == (Z || (N!=V)) */
0xFFFF, /* AL always */
0 /* NV */
};
/*
* Returns:
* ARM_OPCODE_CONDTEST_FAIL - if condition fails
* ARM_OPCODE_CONDTEST_PASS - if condition passes (including AL)
* ARM_OPCODE_CONDTEST_UNCOND - if NV condition, or separate unconditional
* opcode space from v5 onwards
*
* Code that tests whether a conditional instruction would pass its condition
* check should check that return value == ARM_OPCODE_CONDTEST_PASS.
*
* Code that tests if a condition means that the instruction would be executed
* (regardless of conditional or unconditional) should instead check that the
* return value != ARM_OPCODE_CONDTEST_FAIL.
*/
asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr)
{
u32 cc_bits = opcode >> 28;
u32 psr_cond = psr >> 28;
unsigned int ret;
if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) {
if ((cc_map[cc_bits] >> (psr_cond)) & 1)
ret = ARM_OPCODE_CONDTEST_PASS;
else
ret = ARM_OPCODE_CONDTEST_FAIL;
} else {
ret = ARM_OPCODE_CONDTEST_UNCOND;
}
return ret;
}
EXPORT_SYMBOL_GPL(arm_check_condition);