diff options
Diffstat (limited to 'arch/arm/kernel/uprobes-arm.c')
| -rw-r--r-- | arch/arm/kernel/uprobes-arm.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c new file mode 100644 index 000000000000..d3b655ff17da --- /dev/null +++ b/arch/arm/kernel/uprobes-arm.c @@ -0,0 +1,234 @@ +/* + * Copyright (C) 2012 Rabin Vincent <rabin at rab.in> + * + * 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 <linux/kernel.h> +#include <linux/types.h> +#include <linux/stddef.h> +#include <linux/wait.h> +#include <linux/uprobes.h> +#include <linux/module.h> + +#include "probes.h" +#include "probes-arm.h" +#include "uprobes.h" + +static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs) +{ + probes_opcode_t insn = __mem_to_opcode_arm(*pinsn); + probes_opcode_t temp; + probes_opcode_t mask; + int freereg; + u32 free = 0xffff; + u32 regs; + + for (regs = oregs; regs; regs >>= 4, insn >>= 4) { + if ((regs & 0xf) == REG_TYPE_NONE) + continue; + + free &= ~(1 << (insn & 0xf)); + } + + /* No PC, no problem */ + if (free & (1 << 15)) + return 15; + + if (!free) + return -1; + + /* + * fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would + * pick LR instead of R1. + */ + freereg = free = fls(free) - 1; + + temp = __mem_to_opcode_arm(*pinsn); + insn = temp; + regs = oregs; + mask = 0xf; + + for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) { + if ((regs & 0xf) == REG_TYPE_NONE) + continue; + + if ((temp & 0xf) != 15) + continue; + + insn &= ~mask; + insn |= free & mask; + } + + *pinsn = __opcode_to_mem_arm(insn); + return freereg; +} + +static void uprobe_set_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + autask->backup = regs->uregs[pcreg]; + regs->uregs[pcreg] = regs->ARM_pc + 8; +} + +static void uprobe_unset_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + /* PC will be taken care of by common code */ + regs->uregs[auprobe->pcreg] = autask->backup; +} + +static void uprobe_aluwrite_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + alu_write_pc(regs->uregs[pcreg], regs); + regs->uregs[pcreg] = autask->backup; +} + +static void uprobe_write_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + load_write_pc(regs->uregs[pcreg], regs); + regs->uregs[pcreg] = autask->backup; +} + +enum probes_insn +decode_pc_ro(probes_opcode_t insn, struct arch_probes_insn *asi, + const struct decode_header *d) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + struct decode_emulate *decode = (struct decode_emulate *) d; + u32 regs = decode->header.type_regs.bits >> DECODE_TYPE_BITS; + int reg; + + reg = uprobes_substitute_pc(&auprobe->ixol[0], regs); + if (reg == 15) + return INSN_GOOD; + + if (reg == -1) + return INSN_REJECTED; + + auprobe->pcreg = reg; + auprobe->prehandler = uprobe_set_pc; + auprobe->posthandler = uprobe_unset_pc; + + return INSN_GOOD; +} + +enum probes_insn +decode_wb_pc(probes_opcode_t insn, struct arch_probes_insn *asi, + const struct decode_header *d, bool alu) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + enum probes_insn ret = decode_pc_ro(insn, asi, d); + + if (((insn >> 12) & 0xf) == 15) + auprobe->posthandler = alu ? uprobe_aluwrite_pc + : uprobe_write_pc; + + return ret; +} + +enum probes_insn +decode_rd12rn16rm0rs8_rwflags(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *d) +{ + return decode_wb_pc(insn, asi, d, true); +} + +enum probes_insn +decode_ldr(probes_opcode_t insn, struct arch_probes_insn *asi, + const struct decode_header *d) +{ + return decode_wb_pc(insn, asi, d, false); +} + +enum probes_insn +uprobe_decode_ldmstm(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *d) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + unsigned reglist = insn & 0xffff; + int rn = (insn >> 16) & 0xf; + int lbit = insn & (1 << 20); + unsigned used = reglist | (1 << rn); + + if (rn == 15) + return INSN_REJECTED; + + if (!(used & (1 << 15))) + return INSN_GOOD; + + if (used & (1 << 14)) + return INSN_REJECTED; + + /* Use LR instead of PC */ + insn ^= 0xc000; + + auprobe->pcreg = 14; + auprobe->ixol[0] = __opcode_to_mem_arm(insn); + + auprobe->prehandler = uprobe_set_pc; + if (lbit) + auprobe->posthandler = uprobe_write_pc; + else + auprobe->posthandler = uprobe_unset_pc; + + return INSN_GOOD; +} + +const union decode_action uprobes_probes_actions[] = { + [PROBES_EMULATE_NONE] = {.handler = probes_simulate_nop}, + [PROBES_SIMULATE_NOP] = {.handler = probes_simulate_nop}, + [PROBES_PRELOAD_IMM] = {.handler = probes_simulate_nop}, + [PROBES_PRELOAD_REG] = {.handler = probes_simulate_nop}, + [PROBES_BRANCH_IMM] = {.handler = simulate_blx1}, + [PROBES_MRS] = {.handler = simulate_mrs}, + [PROBES_BRANCH_REG] = {.handler = simulate_blx2bx}, + [PROBES_CLZ] = {.handler = probes_simulate_nop}, + [PROBES_SATURATING_ARITHMETIC] = {.handler = probes_simulate_nop}, + [PROBES_MUL1] = {.handler = probes_simulate_nop}, + [PROBES_MUL2] = {.handler = probes_simulate_nop}, + [PROBES_SWP] = {.handler = probes_simulate_nop}, + [PROBES_LDRSTRD] = {.decoder = decode_pc_ro}, + [PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro}, + [PROBES_LOAD] = {.decoder = decode_ldr}, + [PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro}, + [PROBES_STORE] = {.decoder = decode_pc_ro}, + [PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp}, + [PROBES_DATA_PROCESSING_REG] = { + .decoder = decode_rd12rn16rm0rs8_rwflags}, + [PROBES_DATA_PROCESSING_IMM] = { + .decoder = decode_rd12rn16rm0rs8_rwflags}, + [PROBES_MOV_HALFWORD] = {.handler = probes_simulate_nop}, + [PROBES_SEV] = {.handler = probes_simulate_nop}, + [PROBES_WFE] = {.handler = probes_simulate_nop}, + [PROBES_SATURATE] = {.handler = probes_simulate_nop}, + [PROBES_REV] = {.handler = probes_simulate_nop}, + [PROBES_MMI] = {.handler = probes_simulate_nop}, + [PROBES_PACK] = {.handler = probes_simulate_nop}, + [PROBES_EXTEND] = {.handler = probes_simulate_nop}, + [PROBES_EXTEND_ADD] = {.handler = probes_simulate_nop}, + [PROBES_MUL_ADD_LONG] = {.handler = probes_simulate_nop}, + [PROBES_MUL_ADD] = {.handler = probes_simulate_nop}, + [PROBES_BITFIELD] = {.handler = probes_simulate_nop}, + [PROBES_BRANCH] = {.handler = simulate_bbl}, + [PROBES_LDMSTM] = {.decoder = uprobe_decode_ldmstm} +}; |