diff options
Diffstat (limited to 'arch/arm/kernel/kprobes-common.c')
| -rw-r--r-- | arch/arm/kernel/kprobes-common.c | 469 |
1 files changed, 30 insertions, 439 deletions
diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c index 18a76282970..c311ed94ff1 100644 --- a/arch/arm/kernel/kprobes-common.c +++ b/arch/arm/kernel/kprobes-common.c @@ -13,178 +13,14 @@ #include <linux/kernel.h> #include <linux/kprobes.h> -#include <asm/system_info.h> #include "kprobes.h" -#ifndef find_str_pc_offset - -/* - * For STR and STM instructions, an ARM core may choose to use either - * a +8 or a +12 displacement from the current instruction's address. - * Whichever value is chosen for a given core, it must be the same for - * both instructions and may not change. This function measures it. - */ - -int str_pc_offset; - -void __init find_str_pc_offset(void) -{ - int addr, scratch, ret; - - __asm__ ( - "sub %[ret], pc, #4 \n\t" - "str pc, %[addr] \n\t" - "ldr %[scr], %[addr] \n\t" - "sub %[ret], %[scr], %[ret] \n\t" - : [ret] "=r" (ret), [scr] "=r" (scratch), [addr] "+m" (addr)); - - str_pc_offset = ret; -} - -#endif /* !find_str_pc_offset */ - - -#ifndef test_load_write_pc_interworking - -bool load_write_pc_interworks; - -void __init test_load_write_pc_interworking(void) -{ - int arch = cpu_architecture(); - BUG_ON(arch == CPU_ARCH_UNKNOWN); - load_write_pc_interworks = arch >= CPU_ARCH_ARMv5T; -} - -#endif /* !test_load_write_pc_interworking */ - - -#ifndef test_alu_write_pc_interworking - -bool alu_write_pc_interworks; - -void __init test_alu_write_pc_interworking(void) -{ - int arch = cpu_architecture(); - BUG_ON(arch == CPU_ARCH_UNKNOWN); - alu_write_pc_interworks = arch >= CPU_ARCH_ARMv7; -} - -#endif /* !test_alu_write_pc_interworking */ - - -void __init arm_kprobe_decode_init(void) -{ - find_str_pc_offset(); - test_load_write_pc_interworking(); - test_alu_write_pc_interworking(); -} - - -static unsigned long __kprobes __check_eq(unsigned long cpsr) -{ - return cpsr & PSR_Z_BIT; -} - -static unsigned long __kprobes __check_ne(unsigned long cpsr) -{ - return (~cpsr) & PSR_Z_BIT; -} - -static unsigned long __kprobes __check_cs(unsigned long cpsr) -{ - return cpsr & PSR_C_BIT; -} - -static unsigned long __kprobes __check_cc(unsigned long cpsr) -{ - return (~cpsr) & PSR_C_BIT; -} - -static unsigned long __kprobes __check_mi(unsigned long cpsr) -{ - return cpsr & PSR_N_BIT; -} - -static unsigned long __kprobes __check_pl(unsigned long cpsr) -{ - return (~cpsr) & PSR_N_BIT; -} - -static unsigned long __kprobes __check_vs(unsigned long cpsr) -{ - return cpsr & PSR_V_BIT; -} - -static unsigned long __kprobes __check_vc(unsigned long cpsr) -{ - return (~cpsr) & PSR_V_BIT; -} - -static unsigned long __kprobes __check_hi(unsigned long cpsr) -{ - cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ - return cpsr & PSR_C_BIT; -} - -static unsigned long __kprobes __check_ls(unsigned long cpsr) -{ - cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ - return (~cpsr) & PSR_C_BIT; -} - -static unsigned long __kprobes __check_ge(unsigned long cpsr) -{ - cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ - return (~cpsr) & PSR_N_BIT; -} - -static unsigned long __kprobes __check_lt(unsigned long cpsr) -{ - cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ - return cpsr & PSR_N_BIT; -} - -static unsigned long __kprobes __check_gt(unsigned long cpsr) -{ - unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ - temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */ - return (~temp) & PSR_N_BIT; -} - -static unsigned long __kprobes __check_le(unsigned long cpsr) -{ - unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ - temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */ - return temp & PSR_N_BIT; -} - -static unsigned long __kprobes __check_al(unsigned long cpsr) -{ - return true; -} - -kprobe_check_cc * const kprobe_condition_checks[16] = { - &__check_eq, &__check_ne, &__check_cs, &__check_cc, - &__check_mi, &__check_pl, &__check_vs, &__check_vc, - &__check_hi, &__check_ls, &__check_ge, &__check_lt, - &__check_gt, &__check_le, &__check_al, &__check_al -}; - - -void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs) -{ -} - -void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs) -{ - p->ainsn.insn_fn(); -} - -static void __kprobes simulate_ldm1stm1(struct kprobe *p, struct pt_regs *regs) +static void __kprobes simulate_ldm1stm1(probes_opcode_t insn, + struct arch_probes_insn *asi, + struct pt_regs *regs) { - kprobe_opcode_t insn = p->opcode; int rn = (insn >> 16) & 0xf; int lbit = insn & (1 << 20); int wbit = insn & (1 << 21); @@ -223,24 +59,31 @@ static void __kprobes simulate_ldm1stm1(struct kprobe *p, struct pt_regs *regs) } } -static void __kprobes simulate_stm1_pc(struct kprobe *p, struct pt_regs *regs) +static void __kprobes simulate_stm1_pc(probes_opcode_t insn, + struct arch_probes_insn *asi, + struct pt_regs *regs) { - regs->ARM_pc = (long)p->addr + str_pc_offset; - simulate_ldm1stm1(p, regs); - regs->ARM_pc = (long)p->addr + 4; + unsigned long addr = regs->ARM_pc - 4; + + regs->ARM_pc = (long)addr + str_pc_offset; + simulate_ldm1stm1(insn, asi, regs); + regs->ARM_pc = (long)addr + 4; } -static void __kprobes simulate_ldm1_pc(struct kprobe *p, struct pt_regs *regs) +static void __kprobes simulate_ldm1_pc(probes_opcode_t insn, + struct arch_probes_insn *asi, + struct pt_regs *regs) { - simulate_ldm1stm1(p, regs); + simulate_ldm1stm1(insn, asi, regs); load_write_pc(regs->ARM_pc, regs); } static void __kprobes -emulate_generic_r0_12_noflags(struct kprobe *p, struct pt_regs *regs) +emulate_generic_r0_12_noflags(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) { register void *rregs asm("r1") = regs; - register void *rfn asm("lr") = p->ainsn.insn_fn; + register void *rfn asm("lr") = asi->insn_fn; __asm__ __volatile__ ( "stmdb sp!, {%[regs], r11} \n\t" @@ -264,22 +107,27 @@ emulate_generic_r0_12_noflags(struct kprobe *p, struct pt_regs *regs) } static void __kprobes -emulate_generic_r2_14_noflags(struct kprobe *p, struct pt_regs *regs) +emulate_generic_r2_14_noflags(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) { - emulate_generic_r0_12_noflags(p, (struct pt_regs *)(regs->uregs+2)); + emulate_generic_r0_12_noflags(insn, asi, + (struct pt_regs *)(regs->uregs+2)); } static void __kprobes -emulate_ldm_r3_15(struct kprobe *p, struct pt_regs *regs) +emulate_ldm_r3_15(probes_opcode_t insn, + struct arch_probes_insn *asi, struct pt_regs *regs) { - emulate_generic_r0_12_noflags(p, (struct pt_regs *)(regs->uregs+3)); + emulate_generic_r0_12_noflags(insn, asi, + (struct pt_regs *)(regs->uregs+3)); load_write_pc(regs->ARM_pc, regs); } -enum kprobe_insn __kprobes -kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi) +enum probes_insn __kprobes +kprobe_decode_ldmstm(probes_opcode_t insn, struct arch_probes_insn *asi, + const struct decode_header *h) { - kprobe_insn_handler_t *handler = 0; + probes_insn_handler_t *handler = 0; unsigned reglist = insn & 0xffff; int is_ldm = insn & 0x100000; int rn = (insn >> 16) & 0xf; @@ -319,260 +167,3 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi) return INSN_GOOD_NO_SLOT; } - -/* - * Prepare an instruction slot to receive an instruction for emulating. - * This is done by placing a subroutine return after the location where the - * instruction will be placed. We also modify ARM instructions to be - * unconditional as the condition code will already be checked before any - * emulation handler is called. - */ -static kprobe_opcode_t __kprobes -prepare_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi, - bool thumb) -{ -#ifdef CONFIG_THUMB2_KERNEL - if (thumb) { - u16 *thumb_insn = (u16 *)asi->insn; - thumb_insn[1] = 0x4770; /* Thumb bx lr */ - thumb_insn[2] = 0x4770; /* Thumb bx lr */ - return insn; - } - asi->insn[1] = 0xe12fff1e; /* ARM bx lr */ -#else - asi->insn[1] = 0xe1a0f00e; /* mov pc, lr */ -#endif - /* Make an ARM instruction unconditional */ - if (insn < 0xe0000000) - insn = (insn | 0xe0000000) & ~0x10000000; - return insn; -} - -/* - * Write a (probably modified) instruction into the slot previously prepared by - * prepare_emulated_insn - */ -static void __kprobes -set_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi, - bool thumb) -{ -#ifdef CONFIG_THUMB2_KERNEL - if (thumb) { - u16 *ip = (u16 *)asi->insn; - if (is_wide_instruction(insn)) - *ip++ = insn >> 16; - *ip++ = insn; - return; - } -#endif - asi->insn[0] = insn; -} - -/* - * When we modify the register numbers encoded in an instruction to be emulated, - * the new values come from this define. For ARM and 32-bit Thumb instructions - * this gives... - * - * bit position 16 12 8 4 0 - * ---------------+---+---+---+---+---+ - * register r2 r0 r1 -- r3 - */ -#define INSN_NEW_BITS 0x00020103 - -/* Each nibble has same value as that at INSN_NEW_BITS bit 16 */ -#define INSN_SAMEAS16_BITS 0x22222222 - -/* - * Validate and modify each of the registers encoded in an instruction. - * - * Each nibble in regs contains a value from enum decode_reg_type. For each - * non-zero value, the corresponding nibble in pinsn is validated and modified - * according to the type. - */ -static bool __kprobes decode_regs(kprobe_opcode_t* pinsn, u32 regs) -{ - kprobe_opcode_t insn = *pinsn; - kprobe_opcode_t mask = 0xf; /* Start at least significant nibble */ - - for (; regs != 0; regs >>= 4, mask <<= 4) { - - kprobe_opcode_t new_bits = INSN_NEW_BITS; - - switch (regs & 0xf) { - - case REG_TYPE_NONE: - /* Nibble not a register, skip to next */ - continue; - - case REG_TYPE_ANY: - /* Any register is allowed */ - break; - - case REG_TYPE_SAMEAS16: - /* Replace register with same as at bit position 16 */ - new_bits = INSN_SAMEAS16_BITS; - break; - - case REG_TYPE_SP: - /* Only allow SP (R13) */ - if ((insn ^ 0xdddddddd) & mask) - goto reject; - break; - - case REG_TYPE_PC: - /* Only allow PC (R15) */ - if ((insn ^ 0xffffffff) & mask) - goto reject; - break; - - case REG_TYPE_NOSP: - /* Reject SP (R13) */ - if (((insn ^ 0xdddddddd) & mask) == 0) - goto reject; - break; - - case REG_TYPE_NOSPPC: - case REG_TYPE_NOSPPCX: - /* Reject SP and PC (R13 and R15) */ - if (((insn ^ 0xdddddddd) & 0xdddddddd & mask) == 0) - goto reject; - break; - - case REG_TYPE_NOPCWB: - if (!is_writeback(insn)) - break; /* No writeback, so any register is OK */ - /* fall through... */ - case REG_TYPE_NOPC: - case REG_TYPE_NOPCX: - /* Reject PC (R15) */ - if (((insn ^ 0xffffffff) & mask) == 0) - goto reject; - break; - } - - /* Replace value of nibble with new register number... */ - insn &= ~mask; - insn |= new_bits & mask; - } - - *pinsn = insn; - return true; - -reject: - return false; -} - -static const int decode_struct_sizes[NUM_DECODE_TYPES] = { - [DECODE_TYPE_TABLE] = sizeof(struct decode_table), - [DECODE_TYPE_CUSTOM] = sizeof(struct decode_custom), - [DECODE_TYPE_SIMULATE] = sizeof(struct decode_simulate), - [DECODE_TYPE_EMULATE] = sizeof(struct decode_emulate), - [DECODE_TYPE_OR] = sizeof(struct decode_or), - [DECODE_TYPE_REJECT] = sizeof(struct decode_reject) -}; - -/* - * kprobe_decode_insn operates on data tables in order to decode an ARM - * architecture instruction onto which a kprobe has been placed. - * - * These instruction decoding tables are a concatenation of entries each - * of which consist of one of the following structs: - * - * decode_table - * decode_custom - * decode_simulate - * decode_emulate - * decode_or - * decode_reject - * - * Each of these starts with a struct decode_header which has the following - * fields: - * - * type_regs - * mask - * value - * - * The least significant DECODE_TYPE_BITS of type_regs contains a value - * from enum decode_type, this indicates which of the decode_* structs - * the entry contains. The value DECODE_TYPE_END indicates the end of the - * table. - * - * When the table is parsed, each entry is checked in turn to see if it - * matches the instruction to be decoded using the test: - * - * (insn & mask) == value - * - * If no match is found before the end of the table is reached then decoding - * fails with INSN_REJECTED. - * - * When a match is found, decode_regs() is called to validate and modify each - * of the registers encoded in the instruction; the data it uses to do this - * is (type_regs >> DECODE_TYPE_BITS). A validation failure will cause decoding - * to fail with INSN_REJECTED. - * - * Once the instruction has passed the above tests, further processing - * depends on the type of the table entry's decode struct. - * - */ -int __kprobes -kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi, - const union decode_item *table, bool thumb) -{ - const struct decode_header *h = (struct decode_header *)table; - const struct decode_header *next; - bool matched = false; - - insn = prepare_emulated_insn(insn, asi, thumb); - - for (;; h = next) { - enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; - u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; - - if (type == DECODE_TYPE_END) - return INSN_REJECTED; - - next = (struct decode_header *) - ((uintptr_t)h + decode_struct_sizes[type]); - - if (!matched && (insn & h->mask.bits) != h->value.bits) - continue; - - if (!decode_regs(&insn, regs)) - return INSN_REJECTED; - - switch (type) { - - case DECODE_TYPE_TABLE: { - struct decode_table *d = (struct decode_table *)h; - next = (struct decode_header *)d->table.table; - break; - } - - case DECODE_TYPE_CUSTOM: { - struct decode_custom *d = (struct decode_custom *)h; - return (*d->decoder.decoder)(insn, asi); - } - - case DECODE_TYPE_SIMULATE: { - struct decode_simulate *d = (struct decode_simulate *)h; - asi->insn_handler = d->handler.handler; - return INSN_GOOD_NO_SLOT; - } - - case DECODE_TYPE_EMULATE: { - struct decode_emulate *d = (struct decode_emulate *)h; - asi->insn_handler = d->handler.handler; - set_emulated_insn(insn, asi, thumb); - return INSN_GOOD; - } - - case DECODE_TYPE_OR: - matched = true; - break; - - case DECODE_TYPE_REJECT: - default: - return INSN_REJECTED; - } - } - } |