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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/kernel/opcodes.c
*
* A32 condition code lookup feature moved from nwfpe/fpopcode.c
*/
#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);
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