1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (c) 2010 Cavium Networks, Inc. 7 */ 8 9 #include <linux/jump_label.h> 10 #include <linux/kernel.h> 11 #include <linux/memory.h> 12 #include <linux/mutex.h> 13 #include <linux/types.h> 14 #include <linux/cpu.h> 15 16 #include <asm/cacheflush.h> 17 #include <asm/inst.h> 18 19 /* 20 * Define parameters for the standard MIPS and the microMIPS jump 21 * instruction encoding respectively: 22 * 23 * - the ISA bit of the target, either 0 or 1 respectively, 24 * 25 * - the amount the jump target address is shifted right to fit in the 26 * immediate field of the machine instruction, either 2 or 1, 27 * 28 * - the mask determining the size of the jump region relative to the 29 * delay-slot instruction, either 256MB or 128MB, 30 * 31 * - the jump target alignment, either 4 or 2 bytes. 32 */ 33 #define J_ISA_BIT IS_ENABLED(CONFIG_CPU_MICROMIPS) 34 #define J_RANGE_SHIFT (2 - J_ISA_BIT) 35 #define J_RANGE_MASK ((1ul << (26 + J_RANGE_SHIFT)) - 1) 36 #define J_ALIGN_MASK ((1ul << J_RANGE_SHIFT) - 1) 37 38 void arch_jump_label_transform(struct jump_entry *e, 39 enum jump_label_type type) 40 { 41 union mips_instruction *insn_p; 42 union mips_instruction insn; 43 long offset; 44 45 insn_p = (union mips_instruction *)msk_isa16_mode(e->code); 46 47 /* Target must have the right alignment and ISA must be preserved. */ 48 BUG_ON((e->target & J_ALIGN_MASK) != J_ISA_BIT); 49 50 if (type == JUMP_LABEL_JMP) { 51 if (!IS_ENABLED(CONFIG_CPU_MICROMIPS) && MIPS_ISA_REV >= 6) { 52 offset = e->target - ((unsigned long)insn_p + 4); 53 offset >>= 2; 54 55 /* 56 * The branch offset must fit in the instruction's 26 57 * bit field. 58 */ 59 WARN_ON((offset >= (long)BIT(25)) || 60 (offset < -(long)BIT(25))); 61 62 insn.j_format.opcode = bc6_op; 63 insn.j_format.target = offset; 64 } else { 65 /* 66 * Jump only works within an aligned region its delay 67 * slot is in. 68 */ 69 WARN_ON((e->target & ~J_RANGE_MASK) != 70 ((e->code + 4) & ~J_RANGE_MASK)); 71 72 insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op; 73 insn.j_format.target = e->target >> J_RANGE_SHIFT; 74 } 75 } else { 76 insn.word = 0; /* nop */ 77 } 78 79 mutex_lock(&text_mutex); 80 if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) { 81 insn_p->halfword[0] = insn.word >> 16; 82 insn_p->halfword[1] = insn.word; 83 } else 84 *insn_p = insn; 85 86 flush_icache_range((unsigned long)insn_p, 87 (unsigned long)insn_p + sizeof(*insn_p)); 88 89 mutex_unlock(&text_mutex); 90 } 91 92 #ifdef CONFIG_MODULES 93 void jump_label_apply_nops(struct module *mod) 94 { 95 struct jump_entry *iter_start = mod->jump_entries; 96 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 97 struct jump_entry *iter; 98 99 /* if the module doesn't have jump label entries, just return */ 100 if (iter_start == iter_stop) 101 return; 102 103 for (iter = iter_start; iter < iter_stop; iter++) { 104 /* Only write NOPs for arch_branch_static(). */ 105 if (jump_label_init_type(iter) == JUMP_LABEL_NOP) 106 arch_jump_label_transform(iter, JUMP_LABEL_NOP); 107 } 108 } 109 #endif 110