+++ /dev/null
-/*
- * arch/arm/kernel/kprobes.c
- *
- * Kprobes on ARM
- *
- * Abhishek Sagar <sagar.abhishek@gmail.com>
- * Copyright (C) 2006, 2007 Motorola Inc.
- *
- * Nicolas Pitre <nico@marvell.com>
- * Copyright (C) 2007 Marvell Ltd.
- *
- * 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.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- */
-
-#include <linux/kernel.h>
-#include <linux/kprobes.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/stop_machine.h>
-#include <linux/stringify.h>
-#include <asm/traps.h>
-#include <asm/opcodes.h>
-#include <asm/cacheflush.h>
-#include <linux/percpu.h>
-#include <linux/bug.h>
-
-#include "kprobes.h"
-#include "probes-arm.h"
-#include "probes-thumb.h"
-#include "patch.h"
-
-#define MIN_STACK_SIZE(addr) \
- min((unsigned long)MAX_STACK_SIZE, \
- (unsigned long)current_thread_info() + THREAD_START_SP - (addr))
-
-#define flush_insns(addr, size) \
- flush_icache_range((unsigned long)(addr), \
- (unsigned long)(addr) + \
- (size))
-
-/* Used as a marker in ARM_pc to note when we're in a jprobe. */
-#define JPROBE_MAGIC_ADDR 0xffffffff
-
-DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
-DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-
-
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
-{
- kprobe_opcode_t insn;
- kprobe_opcode_t tmp_insn[MAX_INSN_SIZE];
- unsigned long addr = (unsigned long)p->addr;
- bool thumb;
- kprobe_decode_insn_t *decode_insn;
- const union decode_action *actions;
- int is;
-
- if (in_exception_text(addr))
- return -EINVAL;
-
-#ifdef CONFIG_THUMB2_KERNEL
- thumb = true;
- addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */
- insn = __mem_to_opcode_thumb16(((u16 *)addr)[0]);
- if (is_wide_instruction(insn)) {
- u16 inst2 = __mem_to_opcode_thumb16(((u16 *)addr)[1]);
- insn = __opcode_thumb32_compose(insn, inst2);
- decode_insn = thumb32_probes_decode_insn;
- actions = kprobes_t32_actions;
- } else {
- decode_insn = thumb16_probes_decode_insn;
- actions = kprobes_t16_actions;
- }
-#else /* !CONFIG_THUMB2_KERNEL */
- thumb = false;
- if (addr & 0x3)
- return -EINVAL;
- insn = __mem_to_opcode_arm(*p->addr);
- decode_insn = arm_probes_decode_insn;
- actions = kprobes_arm_actions;
-#endif
-
- p->opcode = insn;
- p->ainsn.insn = tmp_insn;
-
- switch ((*decode_insn)(insn, &p->ainsn, true, actions)) {
- case INSN_REJECTED: /* not supported */
- return -EINVAL;
-
- case INSN_GOOD: /* instruction uses slot */
- p->ainsn.insn = get_insn_slot();
- if (!p->ainsn.insn)
- return -ENOMEM;
- for (is = 0; is < MAX_INSN_SIZE; ++is)
- p->ainsn.insn[is] = tmp_insn[is];
- flush_insns(p->ainsn.insn,
- sizeof(p->ainsn.insn[0]) * MAX_INSN_SIZE);
- p->ainsn.insn_fn = (probes_insn_fn_t *)
- ((uintptr_t)p->ainsn.insn | thumb);
- break;
-
- case INSN_GOOD_NO_SLOT: /* instruction doesn't need insn slot */
- p->ainsn.insn = NULL;
- break;
- }
-
- return 0;
-}
-
-void __kprobes arch_arm_kprobe(struct kprobe *p)
-{
- unsigned int brkp;
- void *addr;
-
- if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
- /* Remove any Thumb flag */
- addr = (void *)((uintptr_t)p->addr & ~1);
-
- if (is_wide_instruction(p->opcode))
- brkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION;
- else
- brkp = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION;
- } else {
- kprobe_opcode_t insn = p->opcode;
-
- addr = p->addr;
- brkp = KPROBE_ARM_BREAKPOINT_INSTRUCTION;
-
- if (insn >= 0xe0000000)
- brkp |= 0xe0000000; /* Unconditional instruction */
- else
- brkp |= insn & 0xf0000000; /* Copy condition from insn */
- }
-
- patch_text(addr, brkp);
-}
-
-/*
- * The actual disarming is done here on each CPU and synchronized using
- * stop_machine. This synchronization is necessary on SMP to avoid removing
- * a probe between the moment the 'Undefined Instruction' exception is raised
- * and the moment the exception handler reads the faulting instruction from
- * memory. It is also needed to atomically set the two half-words of a 32-bit
- * Thumb breakpoint.
- */
-int __kprobes __arch_disarm_kprobe(void *p)
-{
- struct kprobe *kp = p;
- void *addr = (void *)((uintptr_t)kp->addr & ~1);
-
- __patch_text(addr, kp->opcode);
-
- return 0;
-}
-
-void __kprobes arch_disarm_kprobe(struct kprobe *p)
-{
- stop_machine(__arch_disarm_kprobe, p, cpu_online_mask);
-}
-
-void __kprobes arch_remove_kprobe(struct kprobe *p)
-{
- if (p->ainsn.insn) {
- free_insn_slot(p->ainsn.insn, 0);
- p->ainsn.insn = NULL;
- }
-}
-
-static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
- kcb->prev_kprobe.kp = kprobe_running();
- kcb->prev_kprobe.status = kcb->kprobe_status;
-}
-
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
- __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
- kcb->kprobe_status = kcb->prev_kprobe.status;
-}
-
-static void __kprobes set_current_kprobe(struct kprobe *p)
-{
- __this_cpu_write(current_kprobe, p);
-}
-
-static void __kprobes
-singlestep_skip(struct kprobe *p, struct pt_regs *regs)
-{
-#ifdef CONFIG_THUMB2_KERNEL
- regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
- if (is_wide_instruction(p->opcode))
- regs->ARM_pc += 4;
- else
- regs->ARM_pc += 2;
-#else
- regs->ARM_pc += 4;
-#endif
-}
-
-static inline void __kprobes
-singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
-{
- p->ainsn.insn_singlestep(p->opcode, &p->ainsn, regs);
-}
-
-/*
- * Called with IRQs disabled. IRQs must remain disabled from that point
- * all the way until processing this kprobe is complete. The current
- * kprobes implementation cannot process more than one nested level of
- * kprobe, and that level is reserved for user kprobe handlers, so we can't
- * risk encountering a new kprobe in an interrupt handler.
- */
-void __kprobes kprobe_handler(struct pt_regs *regs)
-{
- struct kprobe *p, *cur;
- struct kprobe_ctlblk *kcb;
-
- kcb = get_kprobe_ctlblk();
- cur = kprobe_running();
-
-#ifdef CONFIG_THUMB2_KERNEL
- /*
- * First look for a probe which was registered using an address with
- * bit 0 set, this is the usual situation for pointers to Thumb code.
- * If not found, fallback to looking for one with bit 0 clear.
- */
- p = get_kprobe((kprobe_opcode_t *)(regs->ARM_pc | 1));
- if (!p)
- p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc);
-
-#else /* ! CONFIG_THUMB2_KERNEL */
- p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc);
-#endif
-
- if (p) {
- if (cur) {
- /* Kprobe is pending, so we're recursing. */
- switch (kcb->kprobe_status) {
- case KPROBE_HIT_ACTIVE:
- case KPROBE_HIT_SSDONE:
- /* A pre- or post-handler probe got us here. */
- kprobes_inc_nmissed_count(p);
- save_previous_kprobe(kcb);
- set_current_kprobe(p);
- kcb->kprobe_status = KPROBE_REENTER;
- singlestep(p, regs, kcb);
- restore_previous_kprobe(kcb);
- break;
- default:
- /* impossible cases */
- BUG();
- }
- } else if (p->ainsn.insn_check_cc(regs->ARM_cpsr)) {
- /* Probe hit and conditional execution check ok. */
- set_current_kprobe(p);
- kcb->kprobe_status = KPROBE_HIT_ACTIVE;
-
- /*
- * If we have no pre-handler or it returned 0, we
- * continue with normal processing. If we have a
- * pre-handler and it returned non-zero, it prepped
- * for calling the break_handler below on re-entry,
- * so get out doing nothing more here.
- */
- if (!p->pre_handler || !p->pre_handler(p, regs)) {
- kcb->kprobe_status = KPROBE_HIT_SS;
- singlestep(p, regs, kcb);
- if (p->post_handler) {
- kcb->kprobe_status = KPROBE_HIT_SSDONE;
- p->post_handler(p, regs, 0);
- }
- reset_current_kprobe();
- }
- } else {
- /*
- * Probe hit but conditional execution check failed,
- * so just skip the instruction and continue as if
- * nothing had happened.
- */
- singlestep_skip(p, regs);
- }
- } else if (cur) {
- /* We probably hit a jprobe. Call its break handler. */
- if (cur->break_handler && cur->break_handler(cur, regs)) {
- kcb->kprobe_status = KPROBE_HIT_SS;
- singlestep(cur, regs, kcb);
- if (cur->post_handler) {
- kcb->kprobe_status = KPROBE_HIT_SSDONE;
- cur->post_handler(cur, regs, 0);
- }
- }
- reset_current_kprobe();
- } else {
- /*
- * The probe was removed and a race is in progress.
- * There is nothing we can do about it. Let's restart
- * the instruction. By the time we can restart, the
- * real instruction will be there.
- */
- }
-}
-
-static int __kprobes kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
-{
- unsigned long flags;
- local_irq_save(flags);
- kprobe_handler(regs);
- local_irq_restore(flags);
- return 0;
-}
-
-int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
-{
- struct kprobe *cur = kprobe_running();
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- switch (kcb->kprobe_status) {
- case KPROBE_HIT_SS:
- case KPROBE_REENTER:
- /*
- * We are here because the instruction being single
- * stepped caused a page fault. We reset the current
- * kprobe and the PC to point back to the probe address
- * and allow the page fault handler to continue as a
- * normal page fault.
- */
- regs->ARM_pc = (long)cur->addr;
- if (kcb->kprobe_status == KPROBE_REENTER) {
- restore_previous_kprobe(kcb);
- } else {
- reset_current_kprobe();
- }
- break;
-
- case KPROBE_HIT_ACTIVE:
- case KPROBE_HIT_SSDONE:
- /*
- * We increment the nmissed count for accounting,
- * we can also use npre/npostfault count for accounting
- * these specific fault cases.
- */
- kprobes_inc_nmissed_count(cur);
-
- /*
- * We come here because instructions in the pre/post
- * handler caused the page_fault, this could happen
- * if handler tries to access user space by
- * copy_from_user(), get_user() etc. Let the
- * user-specified handler try to fix it.
- */
- if (cur->fault_handler && cur->fault_handler(cur, regs, fsr))
- return 1;
- break;
-
- default:
- break;
- }
-
- return 0;
-}
-
-int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
- unsigned long val, void *data)
-{
- /*
- * notify_die() is currently never called on ARM,
- * so this callback is currently empty.
- */
- return NOTIFY_DONE;
-}
-
-/*
- * When a retprobed function returns, trampoline_handler() is called,
- * calling the kretprobe's handler. We construct a struct pt_regs to
- * give a view of registers r0-r11 to the user return-handler. This is
- * not a complete pt_regs structure, but that should be plenty sufficient
- * for kretprobe handlers which should normally be interested in r0 only
- * anyway.
- */
-void __naked __kprobes kretprobe_trampoline(void)
-{
- __asm__ __volatile__ (
- "stmdb sp!, {r0 - r11} \n\t"
- "mov r0, sp \n\t"
- "bl trampoline_handler \n\t"
- "mov lr, r0 \n\t"
- "ldmia sp!, {r0 - r11} \n\t"
-#ifdef CONFIG_THUMB2_KERNEL
- "bx lr \n\t"
-#else
- "mov pc, lr \n\t"
-#endif
- : : : "memory");
-}
-
-/* Called from kretprobe_trampoline */
-static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
-{
- struct kretprobe_instance *ri = NULL;
- struct hlist_head *head, empty_rp;
- struct hlist_node *tmp;
- unsigned long flags, orig_ret_address = 0;
- unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
-
- INIT_HLIST_HEAD(&empty_rp);
- kretprobe_hash_lock(current, &head, &flags);
-
- /*
- * It is possible to have multiple instances associated with a given
- * task either because multiple functions in the call path have
- * a return probe installed on them, and/or more than one return
- * probe was registered for a target function.
- *
- * We can handle this because:
- * - instances are always inserted at the head of the list
- * - when multiple return probes are registered for the same
- * function, the first instance's ret_addr will point to the
- * real return address, and all the rest will point to
- * kretprobe_trampoline
- */
- hlist_for_each_entry_safe(ri, tmp, head, hlist) {
- if (ri->task != current)
- /* another task is sharing our hash bucket */
- continue;
-
- if (ri->rp && ri->rp->handler) {
- __this_cpu_write(current_kprobe, &ri->rp->kp);
- get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
- ri->rp->handler(ri, regs);
- __this_cpu_write(current_kprobe, NULL);
- }
-
- orig_ret_address = (unsigned long)ri->ret_addr;
- recycle_rp_inst(ri, &empty_rp);
-
- if (orig_ret_address != trampoline_address)
- /*
- * This is the real return address. Any other
- * instances associated with this task are for
- * other calls deeper on the call stack
- */
- break;
- }
-
- kretprobe_assert(ri, orig_ret_address, trampoline_address);
- kretprobe_hash_unlock(current, &flags);
-
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
-
- return (void *)orig_ret_address;
-}
-
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
- struct pt_regs *regs)
-{
- ri->ret_addr = (kprobe_opcode_t *)regs->ARM_lr;
-
- /* Replace the return addr with trampoline addr. */
- regs->ARM_lr = (unsigned long)&kretprobe_trampoline;
-}
-
-int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct jprobe *jp = container_of(p, struct jprobe, kp);
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
- long sp_addr = regs->ARM_sp;
- long cpsr;
-
- kcb->jprobe_saved_regs = *regs;
- memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr));
- regs->ARM_pc = (long)jp->entry;
-
- cpsr = regs->ARM_cpsr | PSR_I_BIT;
-#ifdef CONFIG_THUMB2_KERNEL
- /* Set correct Thumb state in cpsr */
- if (regs->ARM_pc & 1)
- cpsr |= PSR_T_BIT;
- else
- cpsr &= ~PSR_T_BIT;
-#endif
- regs->ARM_cpsr = cpsr;
-
- preempt_disable();
- return 1;
-}
-
-void __kprobes jprobe_return(void)
-{
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- __asm__ __volatile__ (
- /*
- * Setup an empty pt_regs. Fill SP and PC fields as
- * they're needed by longjmp_break_handler.
- *
- * We allocate some slack between the original SP and start of
- * our fabricated regs. To be precise we want to have worst case
- * covered which is STMFD with all 16 regs so we allocate 2 *
- * sizeof(struct_pt_regs)).
- *
- * This is to prevent any simulated instruction from writing
- * over the regs when they are accessing the stack.
- */
-#ifdef CONFIG_THUMB2_KERNEL
- "sub r0, %0, %1 \n\t"
- "mov sp, r0 \n\t"
-#else
- "sub sp, %0, %1 \n\t"
-#endif
- "ldr r0, ="__stringify(JPROBE_MAGIC_ADDR)"\n\t"
- "str %0, [sp, %2] \n\t"
- "str r0, [sp, %3] \n\t"
- "mov r0, sp \n\t"
- "bl kprobe_handler \n\t"
-
- /*
- * Return to the context saved by setjmp_pre_handler
- * and restored by longjmp_break_handler.
- */
-#ifdef CONFIG_THUMB2_KERNEL
- "ldr lr, [sp, %2] \n\t" /* lr = saved sp */
- "ldrd r0, r1, [sp, %5] \n\t" /* r0,r1 = saved lr,pc */
- "ldr r2, [sp, %4] \n\t" /* r2 = saved psr */
- "stmdb lr!, {r0, r1, r2} \n\t" /* push saved lr and */
- /* rfe context */
- "ldmia sp, {r0 - r12} \n\t"
- "mov sp, lr \n\t"
- "ldr lr, [sp], #4 \n\t"
- "rfeia sp! \n\t"
-#else
- "ldr r0, [sp, %4] \n\t"
- "msr cpsr_cxsf, r0 \n\t"
- "ldmia sp, {r0 - pc} \n\t"
-#endif
- :
- : "r" (kcb->jprobe_saved_regs.ARM_sp),
- "I" (sizeof(struct pt_regs) * 2),
- "J" (offsetof(struct pt_regs, ARM_sp)),
- "J" (offsetof(struct pt_regs, ARM_pc)),
- "J" (offsetof(struct pt_regs, ARM_cpsr)),
- "J" (offsetof(struct pt_regs, ARM_lr))
- : "memory", "cc");
-}
-
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
- long stack_addr = kcb->jprobe_saved_regs.ARM_sp;
- long orig_sp = regs->ARM_sp;
- struct jprobe *jp = container_of(p, struct jprobe, kp);
-
- if (regs->ARM_pc == JPROBE_MAGIC_ADDR) {
- if (orig_sp != stack_addr) {
- struct pt_regs *saved_regs =
- (struct pt_regs *)kcb->jprobe_saved_regs.ARM_sp;
- printk("current sp %lx does not match saved sp %lx\n",
- orig_sp, stack_addr);
- printk("Saved registers for jprobe %p\n", jp);
- show_regs(saved_regs);
- printk("Current registers\n");
- show_regs(regs);
- BUG();
- }
- *regs = kcb->jprobe_saved_regs;
- memcpy((void *)stack_addr, kcb->jprobes_stack,
- MIN_STACK_SIZE(stack_addr));
- preempt_enable_no_resched();
- return 1;
- }
- return 0;
-}
-
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
-{
- return 0;
-}
-
-#ifdef CONFIG_THUMB2_KERNEL
-
-static struct undef_hook kprobes_thumb16_break_hook = {
- .instr_mask = 0xffff,
- .instr_val = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION,
- .cpsr_mask = MODE_MASK,
- .cpsr_val = SVC_MODE,
- .fn = kprobe_trap_handler,
-};
-
-static struct undef_hook kprobes_thumb32_break_hook = {
- .instr_mask = 0xffffffff,
- .instr_val = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION,
- .cpsr_mask = MODE_MASK,
- .cpsr_val = SVC_MODE,
- .fn = kprobe_trap_handler,
-};
-
-#else /* !CONFIG_THUMB2_KERNEL */
-
-static struct undef_hook kprobes_arm_break_hook = {
- .instr_mask = 0x0fffffff,
- .instr_val = KPROBE_ARM_BREAKPOINT_INSTRUCTION,
- .cpsr_mask = MODE_MASK,
- .cpsr_val = SVC_MODE,
- .fn = kprobe_trap_handler,
-};
-
-#endif /* !CONFIG_THUMB2_KERNEL */
-
-int __init arch_init_kprobes()
-{
- arm_probes_decode_init();
-#ifdef CONFIG_THUMB2_KERNEL
- register_undef_hook(&kprobes_thumb16_break_hook);
- register_undef_hook(&kprobes_thumb32_break_hook);
-#else
- register_undef_hook(&kprobes_arm_break_hook);
-#endif
- return 0;
-}
projects / firefly-linux-kernel-4.4.55.git / blobdiff