#include <linux/kernel.h>
#include <linux/kprobes.h>
-#include <asm/system_info.h>
-#include <linux/types.h>
-#include <linux/stddef.h>
-#include <linux/bug.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)
{
kprobe_opcode_t insn = p->opcode;
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;
- }
- }
- }
projects / cascardo / linux.git / blobdiff