From 0c9030deaf59d444f9e757ee73d6d81bfe2d3376 Mon Sep 17 00:00:00 2001 From: Leif Lindholm Date: Mon, 12 Dec 2011 19:31:55 +0100 Subject: 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 Reviewed-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/opcodes.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 arch/arm/kernel/opcodes.c (limited to 'arch/arm/kernel/opcodes.c') diff --git a/arch/arm/kernel/opcodes.c b/arch/arm/kernel/opcodes.c new file mode 100644 index 000000000000..f8179c6a817f --- /dev/null +++ b/arch/arm/kernel/opcodes.c @@ -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 +#include + +#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); -- cgit