diff options
Diffstat (limited to 'arch/arm/probes/kprobes/actions-arm.c')
| -rw-r--r-- | arch/arm/probes/kprobes/actions-arm.c | 336 |
1 files changed, 336 insertions, 0 deletions
diff --git a/arch/arm/probes/kprobes/actions-arm.c b/arch/arm/probes/kprobes/actions-arm.c new file mode 100644 index 000000000..c12bb1bed --- /dev/null +++ b/arch/arm/probes/kprobes/actions-arm.c @@ -0,0 +1,336 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * arch/arm/probes/kprobes/actions-arm.c + * + * Copyright (C) 2006, 2007 Motorola Inc. + */ + +/* + * We do not have hardware single-stepping on ARM, This + * effort is further complicated by the ARM not having a + * "next PC" register. Instructions that change the PC + * can't be safely single-stepped in a MP environment, so + * we have a lot of work to do: + * + * In the prepare phase: + * *) If it is an instruction that does anything + * with the CPU mode, we reject it for a kprobe. + * (This is out of laziness rather than need. The + * instructions could be simulated.) + * + * *) Otherwise, decode the instruction rewriting its + * registers to take fixed, ordered registers and + * setting a handler for it to run the instruction. + * + * In the execution phase by an instruction's handler: + * + * *) If the PC is written to by the instruction, the + * instruction must be fully simulated in software. + * + * *) Otherwise, a modified form of the instruction is + * directly executed. Its handler calls the + * instruction in insn[0]. In insn[1] is a + * "mov pc, lr" to return. + * + * Before calling, load up the reordered registers + * from the original instruction's registers. If one + * of the original input registers is the PC, compute + * and adjust the appropriate input register. + * + * After call completes, copy the output registers to + * the original instruction's original registers. + * + * We don't use a real breakpoint instruction since that + * would have us in the kernel go from SVC mode to SVC + * mode losing the link register. Instead we use an + * undefined instruction. To simplify processing, the + * undefined instruction used for kprobes must be reserved + * exclusively for kprobes use. + * + * TODO: ifdef out some instruction decoding based on architecture. + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/ptrace.h> + +#include "../decode-arm.h" +#include "core.h" +#include "checkers.h" + +#if __LINUX_ARM_ARCH__ >= 6 +#define BLX(reg) "blx "reg" \n\t" +#else +#define BLX(reg) "mov lr, pc \n\t" \ + "mov pc, "reg" \n\t" +#endif + +static void __kprobes +emulate_ldrdstrd(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + unsigned long pc = regs->ARM_pc + 4; + int rt = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + + register unsigned long rtv asm("r0") = regs->uregs[rt]; + register unsigned long rt2v asm("r1") = regs->uregs[rt+1]; + register unsigned long rnv asm("r2") = (rn == 15) ? pc + : regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + + __asm__ __volatile__ ( + BLX("%[fn]") + : "=r" (rtv), "=r" (rt2v), "=r" (rnv) + : "0" (rtv), "1" (rt2v), "2" (rnv), "r" (rmv), + [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rt] = rtv; + regs->uregs[rt+1] = rt2v; + if (is_writeback(insn)) + regs->uregs[rn] = rnv; +} + +static void __kprobes +emulate_ldr(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + unsigned long pc = regs->ARM_pc + 4; + int rt = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + + register unsigned long rtv asm("r0"); + register unsigned long rnv asm("r2") = (rn == 15) ? pc + : regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + + __asm__ __volatile__ ( + BLX("%[fn]") + : "=r" (rtv), "=r" (rnv) + : "1" (rnv), "r" (rmv), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + if (rt == 15) + load_write_pc(rtv, regs); + else + regs->uregs[rt] = rtv; + + if (is_writeback(insn)) + regs->uregs[rn] = rnv; +} + +static void __kprobes +emulate_str(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + unsigned long rtpc = regs->ARM_pc - 4 + str_pc_offset; + unsigned long rnpc = regs->ARM_pc + 4; + int rt = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + + register unsigned long rtv asm("r0") = (rt == 15) ? rtpc + : regs->uregs[rt]; + register unsigned long rnv asm("r2") = (rn == 15) ? rnpc + : regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + + __asm__ __volatile__ ( + BLX("%[fn]") + : "=r" (rnv) + : "r" (rtv), "0" (rnv), "r" (rmv), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + if (is_writeback(insn)) + regs->uregs[rn] = rnv; +} + +static void __kprobes +emulate_rd12rn16rm0rs8_rwflags(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + unsigned long pc = regs->ARM_pc + 4; + int rd = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + int rs = (insn >> 8) & 0xf; + + register unsigned long rdv asm("r0") = regs->uregs[rd]; + register unsigned long rnv asm("r2") = (rn == 15) ? pc + : regs->uregs[rn]; + register unsigned long rmv asm("r3") = (rm == 15) ? pc + : regs->uregs[rm]; + register unsigned long rsv asm("r1") = regs->uregs[rs]; + unsigned long cpsr = regs->ARM_cpsr; + + __asm__ __volatile__ ( + "msr cpsr_fs, %[cpsr] \n\t" + BLX("%[fn]") + "mrs %[cpsr], cpsr \n\t" + : "=r" (rdv), [cpsr] "=r" (cpsr) + : "0" (rdv), "r" (rnv), "r" (rmv), "r" (rsv), + "1" (cpsr), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + if (rd == 15) + alu_write_pc(rdv, regs); + else + regs->uregs[rd] = rdv; + regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK); +} + +static void __kprobes +emulate_rd12rn16rm0_rwflags_nopc(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + int rd = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + + register unsigned long rdv asm("r0") = regs->uregs[rd]; + register unsigned long rnv asm("r2") = regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + unsigned long cpsr = regs->ARM_cpsr; + + __asm__ __volatile__ ( + "msr cpsr_fs, %[cpsr] \n\t" + BLX("%[fn]") + "mrs %[cpsr], cpsr \n\t" + : "=r" (rdv), [cpsr] "=r" (cpsr) + : "0" (rdv), "r" (rnv), "r" (rmv), + "1" (cpsr), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rd] = rdv; + regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK); +} + +static void __kprobes +emulate_rd16rn12rm0rs8_rwflags_nopc(probes_opcode_t insn, + struct arch_probes_insn *asi, + struct pt_regs *regs) +{ + int rd = (insn >> 16) & 0xf; + int rn = (insn >> 12) & 0xf; + int rm = insn & 0xf; + int rs = (insn >> 8) & 0xf; + + register unsigned long rdv asm("r2") = regs->uregs[rd]; + register unsigned long rnv asm("r0") = regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + register unsigned long rsv asm("r1") = regs->uregs[rs]; + unsigned long cpsr = regs->ARM_cpsr; + + __asm__ __volatile__ ( + "msr cpsr_fs, %[cpsr] \n\t" + BLX("%[fn]") + "mrs %[cpsr], cpsr \n\t" + : "=r" (rdv), [cpsr] "=r" (cpsr) + : "0" (rdv), "r" (rnv), "r" (rmv), "r" (rsv), + "1" (cpsr), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rd] = rdv; + regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK); +} + +static void __kprobes +emulate_rd12rm0_noflags_nopc(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) +{ + int rd = (insn >> 12) & 0xf; + int rm = insn & 0xf; + + register unsigned long rdv asm("r0") = regs->uregs[rd]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + + __asm__ __volatile__ ( + BLX("%[fn]") + : "=r" (rdv) + : "0" (rdv), "r" (rmv), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rd] = rdv; +} + +static void __kprobes +emulate_rdlo12rdhi16rn0rm8_rwflags_nopc(probes_opcode_t insn, + struct arch_probes_insn *asi, + struct pt_regs *regs) +{ + int rdlo = (insn >> 12) & 0xf; + int rdhi = (insn >> 16) & 0xf; + int rn = insn & 0xf; + int rm = (insn >> 8) & 0xf; + + register unsigned long rdlov asm("r0") = regs->uregs[rdlo]; + register unsigned long rdhiv asm("r2") = regs->uregs[rdhi]; + register unsigned long rnv asm("r3") = regs->uregs[rn]; + register unsigned long rmv asm("r1") = regs->uregs[rm]; + unsigned long cpsr = regs->ARM_cpsr; + + __asm__ __volatile__ ( + "msr cpsr_fs, %[cpsr] \n\t" + BLX("%[fn]") + "mrs %[cpsr], cpsr \n\t" + : "=r" (rdlov), "=r" (rdhiv), [cpsr] "=r" (cpsr) + : "0" (rdlov), "1" (rdhiv), "r" (rnv), "r" (rmv), + "2" (cpsr), [fn] "r" (asi->insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rdlo] = rdlov; + regs->uregs[rdhi] = rdhiv; + regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK); +} + +const union decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = { + [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 = emulate_rd12rm0_noflags_nopc}, + [PROBES_SATURATING_ARITHMETIC] = { + .handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_MUL1] = {.handler = emulate_rdlo12rdhi16rn0rm8_rwflags_nopc}, + [PROBES_MUL2] = {.handler = emulate_rd16rn12rm0rs8_rwflags_nopc}, + [PROBES_SWP] = {.handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_LDRSTRD] = {.handler = emulate_ldrdstrd}, + [PROBES_LOAD_EXTRA] = {.handler = emulate_ldr}, + [PROBES_LOAD] = {.handler = emulate_ldr}, + [PROBES_STORE_EXTRA] = {.handler = emulate_str}, + [PROBES_STORE] = {.handler = emulate_str}, + [PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp}, + [PROBES_DATA_PROCESSING_REG] = { + .handler = emulate_rd12rn16rm0rs8_rwflags}, + [PROBES_DATA_PROCESSING_IMM] = { + .handler = emulate_rd12rn16rm0rs8_rwflags}, + [PROBES_MOV_HALFWORD] = {.handler = emulate_rd12rm0_noflags_nopc}, + [PROBES_SEV] = {.handler = probes_emulate_none}, + [PROBES_WFE] = {.handler = probes_simulate_nop}, + [PROBES_SATURATE] = {.handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_REV] = {.handler = emulate_rd12rm0_noflags_nopc}, + [PROBES_MMI] = {.handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_PACK] = {.handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_EXTEND] = {.handler = emulate_rd12rm0_noflags_nopc}, + [PROBES_EXTEND_ADD] = {.handler = emulate_rd12rn16rm0_rwflags_nopc}, + [PROBES_MUL_ADD_LONG] = { + .handler = emulate_rdlo12rdhi16rn0rm8_rwflags_nopc}, + [PROBES_MUL_ADD] = {.handler = emulate_rd16rn12rm0rs8_rwflags_nopc}, + [PROBES_BITFIELD] = {.handler = emulate_rd12rm0_noflags_nopc}, + [PROBES_BRANCH] = {.handler = simulate_bbl}, + [PROBES_LDMSTM] = {.decoder = kprobe_decode_ldmstm} +}; + +const struct decode_checker *kprobes_arm_checkers[] = {arm_stack_checker, arm_regs_checker, NULL}; |