235 lines
6.2 KiB
C
235 lines
6.2 KiB
C
/*
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* Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/stddef.h>
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#include <linux/wait.h>
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#include <linux/uprobes.h>
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#include <linux/module.h>
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#include "probes.h"
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#include "probes-arm.h"
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#include "uprobes.h"
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static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs)
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{
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probes_opcode_t insn = __mem_to_opcode_arm(*pinsn);
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probes_opcode_t temp;
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probes_opcode_t mask;
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int freereg;
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u32 free = 0xffff;
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u32 regs;
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for (regs = oregs; regs; regs >>= 4, insn >>= 4) {
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if ((regs & 0xf) == REG_TYPE_NONE)
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continue;
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free &= ~(1 << (insn & 0xf));
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}
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/* No PC, no problem */
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if (free & (1 << 15))
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return 15;
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if (!free)
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return -1;
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/*
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* fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would
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* pick LR instead of R1.
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*/
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freereg = free = fls(free) - 1;
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temp = __mem_to_opcode_arm(*pinsn);
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insn = temp;
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regs = oregs;
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mask = 0xf;
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for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) {
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if ((regs & 0xf) == REG_TYPE_NONE)
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continue;
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if ((temp & 0xf) != 15)
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continue;
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insn &= ~mask;
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insn |= free & mask;
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}
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*pinsn = __opcode_to_mem_arm(insn);
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return freereg;
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}
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static void uprobe_set_pc(struct arch_uprobe *auprobe,
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struct arch_uprobe_task *autask,
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struct pt_regs *regs)
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{
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u32 pcreg = auprobe->pcreg;
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autask->backup = regs->uregs[pcreg];
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regs->uregs[pcreg] = regs->ARM_pc + 8;
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}
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static void uprobe_unset_pc(struct arch_uprobe *auprobe,
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struct arch_uprobe_task *autask,
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struct pt_regs *regs)
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{
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/* PC will be taken care of by common code */
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regs->uregs[auprobe->pcreg] = autask->backup;
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}
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static void uprobe_aluwrite_pc(struct arch_uprobe *auprobe,
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struct arch_uprobe_task *autask,
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struct pt_regs *regs)
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{
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u32 pcreg = auprobe->pcreg;
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alu_write_pc(regs->uregs[pcreg], regs);
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regs->uregs[pcreg] = autask->backup;
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}
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static void uprobe_write_pc(struct arch_uprobe *auprobe,
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struct arch_uprobe_task *autask,
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struct pt_regs *regs)
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{
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u32 pcreg = auprobe->pcreg;
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load_write_pc(regs->uregs[pcreg], regs);
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regs->uregs[pcreg] = autask->backup;
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}
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enum probes_insn
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decode_pc_ro(probes_opcode_t insn, struct arch_probes_insn *asi,
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const struct decode_header *d)
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{
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struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
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asi);
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struct decode_emulate *decode = (struct decode_emulate *) d;
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u32 regs = decode->header.type_regs.bits >> DECODE_TYPE_BITS;
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int reg;
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reg = uprobes_substitute_pc(&auprobe->ixol[0], regs);
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if (reg == 15)
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return INSN_GOOD;
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if (reg == -1)
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return INSN_REJECTED;
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auprobe->pcreg = reg;
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auprobe->prehandler = uprobe_set_pc;
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auprobe->posthandler = uprobe_unset_pc;
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return INSN_GOOD;
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}
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enum probes_insn
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decode_wb_pc(probes_opcode_t insn, struct arch_probes_insn *asi,
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const struct decode_header *d, bool alu)
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{
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struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
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asi);
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enum probes_insn ret = decode_pc_ro(insn, asi, d);
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if (((insn >> 12) & 0xf) == 15)
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auprobe->posthandler = alu ? uprobe_aluwrite_pc
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: uprobe_write_pc;
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return ret;
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}
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enum probes_insn
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decode_rd12rn16rm0rs8_rwflags(probes_opcode_t insn,
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struct arch_probes_insn *asi,
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const struct decode_header *d)
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{
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return decode_wb_pc(insn, asi, d, true);
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}
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enum probes_insn
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decode_ldr(probes_opcode_t insn, struct arch_probes_insn *asi,
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const struct decode_header *d)
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{
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return decode_wb_pc(insn, asi, d, false);
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}
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enum probes_insn
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uprobe_decode_ldmstm(probes_opcode_t insn,
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struct arch_probes_insn *asi,
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const struct decode_header *d)
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{
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struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
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asi);
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unsigned reglist = insn & 0xffff;
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int rn = (insn >> 16) & 0xf;
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int lbit = insn & (1 << 20);
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unsigned used = reglist | (1 << rn);
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if (rn == 15)
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return INSN_REJECTED;
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if (!(used & (1 << 15)))
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return INSN_GOOD;
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if (used & (1 << 14))
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return INSN_REJECTED;
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/* Use LR instead of PC */
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insn ^= 0xc000;
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auprobe->pcreg = 14;
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auprobe->ixol[0] = __opcode_to_mem_arm(insn);
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auprobe->prehandler = uprobe_set_pc;
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if (lbit)
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auprobe->posthandler = uprobe_write_pc;
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else
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auprobe->posthandler = uprobe_unset_pc;
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return INSN_GOOD;
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}
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const union decode_action uprobes_probes_actions[] = {
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[PROBES_EMULATE_NONE] = {.handler = probes_simulate_nop},
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[PROBES_SIMULATE_NOP] = {.handler = probes_simulate_nop},
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[PROBES_PRELOAD_IMM] = {.handler = probes_simulate_nop},
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[PROBES_PRELOAD_REG] = {.handler = probes_simulate_nop},
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[PROBES_BRANCH_IMM] = {.handler = simulate_blx1},
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[PROBES_MRS] = {.handler = simulate_mrs},
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[PROBES_BRANCH_REG] = {.handler = simulate_blx2bx},
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[PROBES_CLZ] = {.handler = probes_simulate_nop},
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[PROBES_SATURATING_ARITHMETIC] = {.handler = probes_simulate_nop},
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[PROBES_MUL1] = {.handler = probes_simulate_nop},
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[PROBES_MUL2] = {.handler = probes_simulate_nop},
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[PROBES_SWP] = {.handler = probes_simulate_nop},
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[PROBES_LDRSTRD] = {.decoder = decode_pc_ro},
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[PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro},
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[PROBES_LOAD] = {.decoder = decode_ldr},
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[PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro},
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[PROBES_STORE] = {.decoder = decode_pc_ro},
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[PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
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[PROBES_DATA_PROCESSING_REG] = {
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.decoder = decode_rd12rn16rm0rs8_rwflags},
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[PROBES_DATA_PROCESSING_IMM] = {
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.decoder = decode_rd12rn16rm0rs8_rwflags},
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[PROBES_MOV_HALFWORD] = {.handler = probes_simulate_nop},
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[PROBES_SEV] = {.handler = probes_simulate_nop},
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[PROBES_WFE] = {.handler = probes_simulate_nop},
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[PROBES_SATURATE] = {.handler = probes_simulate_nop},
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[PROBES_REV] = {.handler = probes_simulate_nop},
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[PROBES_MMI] = {.handler = probes_simulate_nop},
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[PROBES_PACK] = {.handler = probes_simulate_nop},
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[PROBES_EXTEND] = {.handler = probes_simulate_nop},
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[PROBES_EXTEND_ADD] = {.handler = probes_simulate_nop},
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[PROBES_MUL_ADD_LONG] = {.handler = probes_simulate_nop},
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[PROBES_MUL_ADD] = {.handler = probes_simulate_nop},
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[PROBES_BITFIELD] = {.handler = probes_simulate_nop},
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[PROBES_BRANCH] = {.handler = simulate_bbl},
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[PROBES_LDMSTM] = {.decoder = uprobe_decode_ldmstm}
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};
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