1 /* 2 * linux/arch/arm/kernel/opcodes.c 3 * 4 * A32 condition code lookup feature moved from nwfpe/fpopcode.c 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11 #include <linux/module.h> 12 #include <asm/opcodes.h> 13 14 #define ARM_OPCODE_CONDITION_UNCOND 0xf 15 16 /* 17 * condition code lookup table 18 * index into the table is test code: EQ, NE, ... LT, GT, AL, NV 19 * 20 * bit position in short is condition code: NZCV 21 */ 22 static const unsigned short cc_map[16] = { 23 0xF0F0, /* EQ == Z set */ 24 0x0F0F, /* NE */ 25 0xCCCC, /* CS == C set */ 26 0x3333, /* CC */ 27 0xFF00, /* MI == N set */ 28 0x00FF, /* PL */ 29 0xAAAA, /* VS == V set */ 30 0x5555, /* VC */ 31 0x0C0C, /* HI == C set && Z clear */ 32 0xF3F3, /* LS == C clear || Z set */ 33 0xAA55, /* GE == (N==V) */ 34 0x55AA, /* LT == (N!=V) */ 35 0x0A05, /* GT == (!Z && (N==V)) */ 36 0xF5FA, /* LE == (Z || (N!=V)) */ 37 0xFFFF, /* AL always */ 38 0 /* NV */ 39 }; 40 41 /* 42 * Returns: 43 * ARM_OPCODE_CONDTEST_FAIL - if condition fails 44 * ARM_OPCODE_CONDTEST_PASS - if condition passes (including AL) 45 * ARM_OPCODE_CONDTEST_UNCOND - if NV condition, or separate unconditional 46 * opcode space from v5 onwards 47 * 48 * Code that tests whether a conditional instruction would pass its condition 49 * check should check that return value == ARM_OPCODE_CONDTEST_PASS. 50 * 51 * Code that tests if a condition means that the instruction would be executed 52 * (regardless of conditional or unconditional) should instead check that the 53 * return value != ARM_OPCODE_CONDTEST_FAIL. 54 */ 55 asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr) 56 { 57 u32 cc_bits = opcode >> 28; 58 u32 psr_cond = psr >> 28; 59 unsigned int ret; 60 61 if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) { 62 if ((cc_map[cc_bits] >> (psr_cond)) & 1) 63 ret = ARM_OPCODE_CONDTEST_PASS; 64 else 65 ret = ARM_OPCODE_CONDTEST_FAIL; 66 } else { 67 ret = ARM_OPCODE_CONDTEST_UNCOND; 68 } 69 70 return ret; 71 } 72 EXPORT_SYMBOL_GPL(arm_check_condition); 73