obj-$(CONFIG_IOMMU) += pci-gart.o aperture_64.o
obj-$(CONFIG_CALGARY_IOMMU) += pci-calgary_64.o tce_64.o
obj-$(CONFIG_SWIOTLB) += pci-swiotlb_64.o
-obj-$(CONFIG_KPROBES) += kprobes.o
+obj-$(CONFIG_KPROBES) += kprobes_64.o
obj-$(CONFIG_X86_PM_TIMER) += pmtimer_64.o
obj-$(CONFIG_X86_VSMP) += vsmp_64.o
obj-$(CONFIG_K8_NB) += k8.o
+++ /dev/null
-/*
- * Kernel Probes (KProbes)
- * arch/x86_64/kernel/kprobes.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright (C) IBM Corporation, 2002, 2004
- *
- * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
- * Probes initial implementation ( includes contributions from
- * Rusty Russell).
- * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
- * interface to access function arguments.
- * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi
- * <prasanna@in.ibm.com> adapted for x86_64
- * 2005-Mar Roland McGrath <roland@redhat.com>
- * Fixed to handle %rip-relative addressing mode correctly.
- * 2005-May Rusty Lynch <rusty.lynch@intel.com>
- * Added function return probes functionality
- */
-
-#include <linux/kprobes.h>
-#include <linux/ptrace.h>
-#include <linux/string.h>
-#include <linux/slab.h>
-#include <linux/preempt.h>
-#include <linux/module.h>
-#include <linux/kdebug.h>
-
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
-#include <asm/alternative.h>
-
-void jprobe_return_end(void);
-static void __kprobes arch_copy_kprobe(struct kprobe *p);
-
-DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
-DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-
-/*
- * returns non-zero if opcode modifies the interrupt flag.
- */
-static __always_inline int is_IF_modifier(kprobe_opcode_t *insn)
-{
- switch (*insn) {
- case 0xfa: /* cli */
- case 0xfb: /* sti */
- case 0xcf: /* iret/iretd */
- case 0x9d: /* popf/popfd */
- return 1;
- }
-
- if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf)
- return 1;
- return 0;
-}
-
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
-{
- /* insn: must be on special executable page on x86_64. */
- p->ainsn.insn = get_insn_slot();
- if (!p->ainsn.insn) {
- return -ENOMEM;
- }
- arch_copy_kprobe(p);
- return 0;
-}
-
-/*
- * Determine if the instruction uses the %rip-relative addressing mode.
- * If it does, return the address of the 32-bit displacement word.
- * If not, return null.
- */
-static s32 __kprobes *is_riprel(u8 *insn)
-{
-#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
- (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
- (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
- (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
- (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
- << (row % 64))
- static const u64 onebyte_has_modrm[256 / 64] = {
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- /* ------------------------------- */
- W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */
- W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */
- W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */
- W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */
- W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */
- W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */
- W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */
- W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */
- W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */
- W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */
- W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */
- W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */
- W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */
- W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */
- W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */
- W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */
- /* ------------------------------- */
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- };
- static const u64 twobyte_has_modrm[256 / 64] = {
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- /* ------------------------------- */
- W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */
- W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */
- W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */
- W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */
- W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */
- W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */
- W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */
- W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */
- W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */
- W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */
- W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */
- W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */
- W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */
- W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */
- W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */
- W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */
- /* ------------------------------- */
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- };
-#undef W
- int need_modrm;
-
- /* Skip legacy instruction prefixes. */
- while (1) {
- switch (*insn) {
- case 0x66:
- case 0x67:
- case 0x2e:
- case 0x3e:
- case 0x26:
- case 0x64:
- case 0x65:
- case 0x36:
- case 0xf0:
- case 0xf3:
- case 0xf2:
- ++insn;
- continue;
- }
- break;
- }
-
- /* Skip REX instruction prefix. */
- if ((*insn & 0xf0) == 0x40)
- ++insn;
-
- if (*insn == 0x0f) { /* Two-byte opcode. */
- ++insn;
- need_modrm = test_bit(*insn, twobyte_has_modrm);
- } else { /* One-byte opcode. */
- need_modrm = test_bit(*insn, onebyte_has_modrm);
- }
-
- if (need_modrm) {
- u8 modrm = *++insn;
- if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */
- /* Displacement follows ModRM byte. */
- return (s32 *) ++insn;
- }
- }
-
- /* No %rip-relative addressing mode here. */
- return NULL;
-}
-
-static void __kprobes arch_copy_kprobe(struct kprobe *p)
-{
- s32 *ripdisp;
- memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE);
- ripdisp = is_riprel(p->ainsn.insn);
- if (ripdisp) {
- /*
- * The copied instruction uses the %rip-relative
- * addressing mode. Adjust the displacement for the
- * difference between the original location of this
- * instruction and the location of the copy that will
- * actually be run. The tricky bit here is making sure
- * that the sign extension happens correctly in this
- * calculation, since we need a signed 32-bit result to
- * be sign-extended to 64 bits when it's added to the
- * %rip value and yield the same 64-bit result that the
- * sign-extension of the original signed 32-bit
- * displacement would have given.
- */
- s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn;
- BUG_ON((s64) (s32) disp != disp); /* Sanity check. */
- *ripdisp = disp;
- }
- p->opcode = *p->addr;
-}
-
-void __kprobes arch_arm_kprobe(struct kprobe *p)
-{
- text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
-}
-
-void __kprobes arch_disarm_kprobe(struct kprobe *p)
-{
- text_poke(p->addr, &p->opcode, 1);
-}
-
-void __kprobes arch_remove_kprobe(struct kprobe *p)
-{
- mutex_lock(&kprobe_mutex);
- free_insn_slot(p->ainsn.insn, 0);
- mutex_unlock(&kprobe_mutex);
-}
-
-static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
- kcb->prev_kprobe.kp = kprobe_running();
- kcb->prev_kprobe.status = kcb->kprobe_status;
- kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags;
- kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags;
-}
-
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
- __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
- kcb->kprobe_status = kcb->prev_kprobe.status;
- kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags;
- kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags;
-}
-
-static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
- struct kprobe_ctlblk *kcb)
-{
- __get_cpu_var(current_kprobe) = p;
- kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags
- = (regs->eflags & (TF_MASK | IF_MASK));
- if (is_IF_modifier(p->ainsn.insn))
- kcb->kprobe_saved_rflags &= ~IF_MASK;
-}
-
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
-{
- regs->eflags |= TF_MASK;
- regs->eflags &= ~IF_MASK;
- /*single step inline if the instruction is an int3*/
- if (p->opcode == BREAKPOINT_INSTRUCTION)
- regs->rip = (unsigned long)p->addr;
- else
- regs->rip = (unsigned long)p->ainsn.insn;
-}
-
-/* Called with kretprobe_lock held */
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
- struct pt_regs *regs)
-{
- unsigned long *sara = (unsigned long *)regs->rsp;
-
- ri->ret_addr = (kprobe_opcode_t *) *sara;
- /* Replace the return addr with trampoline addr */
- *sara = (unsigned long) &kretprobe_trampoline;
-}
-
-int __kprobes kprobe_handler(struct pt_regs *regs)
-{
- struct kprobe *p;
- int ret = 0;
- kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t));
- struct kprobe_ctlblk *kcb;
-
- /*
- * We don't want to be preempted for the entire
- * duration of kprobe processing
- */
- preempt_disable();
- kcb = get_kprobe_ctlblk();
-
- /* Check we're not actually recursing */
- if (kprobe_running()) {
- p = get_kprobe(addr);
- if (p) {
- if (kcb->kprobe_status == KPROBE_HIT_SS &&
- *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
- regs->eflags &= ~TF_MASK;
- regs->eflags |= kcb->kprobe_saved_rflags;
- goto no_kprobe;
- } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) {
- /* TODO: Provide re-entrancy from
- * post_kprobes_handler() and avoid exception
- * stack corruption while single-stepping on
- * the instruction of the new probe.
- */
- arch_disarm_kprobe(p);
- regs->rip = (unsigned long)p->addr;
- reset_current_kprobe();
- ret = 1;
- } else {
- /* We have reentered the kprobe_handler(), since
- * another probe was hit while within the
- * handler. We here save the original kprobe
- * variables and just single step on instruction
- * of the new probe without calling any user
- * handlers.
- */
- save_previous_kprobe(kcb);
- set_current_kprobe(p, regs, kcb);
- kprobes_inc_nmissed_count(p);
- prepare_singlestep(p, regs);
- kcb->kprobe_status = KPROBE_REENTER;
- return 1;
- }
- } else {
- if (*addr != BREAKPOINT_INSTRUCTION) {
- /* The breakpoint instruction was removed by
- * another cpu right after we hit, no further
- * handling of this interrupt is appropriate
- */
- regs->rip = (unsigned long)addr;
- ret = 1;
- goto no_kprobe;
- }
- p = __get_cpu_var(current_kprobe);
- if (p->break_handler && p->break_handler(p, regs)) {
- goto ss_probe;
- }
- }
- goto no_kprobe;
- }
-
- p = get_kprobe(addr);
- if (!p) {
- if (*addr != BREAKPOINT_INSTRUCTION) {
- /*
- * The breakpoint instruction was removed right
- * after we hit it. Another cpu has removed
- * either a probepoint or a debugger breakpoint
- * at this address. In either case, no further
- * handling of this interrupt is appropriate.
- * Back up over the (now missing) int3 and run
- * the original instruction.
- */
- regs->rip = (unsigned long)addr;
- ret = 1;
- }
- /* Not one of ours: let kernel handle it */
- goto no_kprobe;
- }
-
- set_current_kprobe(p, regs, kcb);
- kcb->kprobe_status = KPROBE_HIT_ACTIVE;
-
- if (p->pre_handler && p->pre_handler(p, regs))
- /* handler has already set things up, so skip ss setup */
- return 1;
-
-ss_probe:
- prepare_singlestep(p, regs);
- kcb->kprobe_status = KPROBE_HIT_SS;
- return 1;
-
-no_kprobe:
- preempt_enable_no_resched();
- return ret;
-}
-
-/*
- * For function-return probes, init_kprobes() establishes a probepoint
- * here. When a retprobed function returns, this probe is hit and
- * trampoline_probe_handler() runs, calling the kretprobe's handler.
- */
- void kretprobe_trampoline_holder(void)
- {
- asm volatile ( ".global kretprobe_trampoline\n"
- "kretprobe_trampoline: \n"
- "nop\n");
- }
-
-/*
- * Called when we hit the probe point at kretprobe_trampoline
- */
-int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct kretprobe_instance *ri = NULL;
- struct hlist_head *head, empty_rp;
- struct hlist_node *node, *tmp;
- unsigned long flags, orig_ret_address = 0;
- unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
-
- INIT_HLIST_HEAD(&empty_rp);
- spin_lock_irqsave(&kretprobe_lock, flags);
- head = kretprobe_inst_table_head(current);
-
- /*
- * It is possible to have multiple instances associated with a given
- * task either because an multiple functions in the call path
- * have a return probe installed on them, and/or more then one return
- * 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, node, tmp, head, hlist) {
- if (ri->task != current)
- /* another task is sharing our hash bucket */
- continue;
-
- if (ri->rp && ri->rp->handler)
- ri->rp->handler(ri, regs);
-
- 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);
- regs->rip = orig_ret_address;
-
- reset_current_kprobe();
- spin_unlock_irqrestore(&kretprobe_lock, flags);
- preempt_enable_no_resched();
-
- hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
- /*
- * By returning a non-zero value, we are telling
- * kprobe_handler() that we don't want the post_handler
- * to run (and have re-enabled preemption)
- */
- return 1;
-}
-
-/*
- * Called after single-stepping. p->addr is the address of the
- * instruction whose first byte has been replaced by the "int 3"
- * instruction. To avoid the SMP problems that can occur when we
- * temporarily put back the original opcode to single-step, we
- * single-stepped a copy of the instruction. The address of this
- * copy is p->ainsn.insn.
- *
- * This function prepares to return from the post-single-step
- * interrupt. We have to fix up the stack as follows:
- *
- * 0) Except in the case of absolute or indirect jump or call instructions,
- * the new rip is relative to the copied instruction. We need to make
- * it relative to the original instruction.
- *
- * 1) If the single-stepped instruction was pushfl, then the TF and IF
- * flags are set in the just-pushed eflags, and may need to be cleared.
- *
- * 2) If the single-stepped instruction was a call, the return address
- * that is atop the stack is the address following the copied instruction.
- * We need to make it the address following the original instruction.
- */
-static void __kprobes resume_execution(struct kprobe *p,
- struct pt_regs *regs, struct kprobe_ctlblk *kcb)
-{
- unsigned long *tos = (unsigned long *)regs->rsp;
- unsigned long next_rip = 0;
- unsigned long copy_rip = (unsigned long)p->ainsn.insn;
- unsigned long orig_rip = (unsigned long)p->addr;
- kprobe_opcode_t *insn = p->ainsn.insn;
-
- /*skip the REX prefix*/
- if (*insn >= 0x40 && *insn <= 0x4f)
- insn++;
-
- switch (*insn) {
- case 0x9c: /* pushfl */
- *tos &= ~(TF_MASK | IF_MASK);
- *tos |= kcb->kprobe_old_rflags;
- break;
- case 0xc3: /* ret/lret */
- case 0xcb:
- case 0xc2:
- case 0xca:
- regs->eflags &= ~TF_MASK;
- /* rip is already adjusted, no more changes required*/
- return;
- case 0xe8: /* call relative - Fix return addr */
- *tos = orig_rip + (*tos - copy_rip);
- break;
- case 0xff:
- if ((insn[1] & 0x30) == 0x10) {
- /* call absolute, indirect */
- /* Fix return addr; rip is correct. */
- next_rip = regs->rip;
- *tos = orig_rip + (*tos - copy_rip);
- } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
- ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
- /* rip is correct. */
- next_rip = regs->rip;
- }
- break;
- case 0xea: /* jmp absolute -- rip is correct */
- next_rip = regs->rip;
- break;
- default:
- break;
- }
-
- regs->eflags &= ~TF_MASK;
- if (next_rip) {
- regs->rip = next_rip;
- } else {
- regs->rip = orig_rip + (regs->rip - copy_rip);
- }
-}
-
-int __kprobes post_kprobe_handler(struct pt_regs *regs)
-{
- struct kprobe *cur = kprobe_running();
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- if (!cur)
- return 0;
-
- if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
- kcb->kprobe_status = KPROBE_HIT_SSDONE;
- cur->post_handler(cur, regs, 0);
- }
-
- resume_execution(cur, regs, kcb);
- regs->eflags |= kcb->kprobe_saved_rflags;
-
- /* Restore the original saved kprobes variables and continue. */
- if (kcb->kprobe_status == KPROBE_REENTER) {
- restore_previous_kprobe(kcb);
- goto out;
- }
- reset_current_kprobe();
-out:
- preempt_enable_no_resched();
-
- /*
- * if somebody else is singlestepping across a probe point, eflags
- * will have TF set, in which case, continue the remaining processing
- * of do_debug, as if this is not a probe hit.
- */
- if (regs->eflags & TF_MASK)
- return 0;
-
- return 1;
-}
-
-int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
-{
- struct kprobe *cur = kprobe_running();
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
- const struct exception_table_entry *fixup;
-
- 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 rip points back to the probe address
- * and allow the page fault handler to continue as a
- * normal page fault.
- */
- regs->rip = (unsigned long)cur->addr;
- regs->eflags |= kcb->kprobe_old_rflags;
- if (kcb->kprobe_status == KPROBE_REENTER)
- restore_previous_kprobe(kcb);
- else
- reset_current_kprobe();
- preempt_enable_no_resched();
- break;
- case KPROBE_HIT_ACTIVE:
- case KPROBE_HIT_SSDONE:
- /*
- * We increment the nmissed count for accounting,
- * we can also use npre/npostfault count for accouting
- * 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 first.
- */
- if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
- return 1;
-
- /*
- * In case the user-specified fault handler returned
- * zero, try to fix up.
- */
- fixup = search_exception_tables(regs->rip);
- if (fixup) {
- regs->rip = fixup->fixup;
- return 1;
- }
-
- /*
- * fixup() could not handle it,
- * Let do_page_fault() fix it.
- */
- break;
- default:
- break;
- }
- return 0;
-}
-
-/*
- * Wrapper routine for handling exceptions.
- */
-int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
- unsigned long val, void *data)
-{
- struct die_args *args = (struct die_args *)data;
- int ret = NOTIFY_DONE;
-
- if (args->regs && user_mode(args->regs))
- return ret;
-
- switch (val) {
- case DIE_INT3:
- if (kprobe_handler(args->regs))
- ret = NOTIFY_STOP;
- break;
- case DIE_DEBUG:
- if (post_kprobe_handler(args->regs))
- ret = NOTIFY_STOP;
- break;
- case DIE_GPF:
- case DIE_PAGE_FAULT:
- /* kprobe_running() needs smp_processor_id() */
- preempt_disable();
- if (kprobe_running() &&
- kprobe_fault_handler(args->regs, args->trapnr))
- ret = NOTIFY_STOP;
- preempt_enable();
- break;
- default:
- break;
- }
- return ret;
-}
-
-int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct jprobe *jp = container_of(p, struct jprobe, kp);
- unsigned long addr;
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- kcb->jprobe_saved_regs = *regs;
- kcb->jprobe_saved_rsp = (long *) regs->rsp;
- addr = (unsigned long)(kcb->jprobe_saved_rsp);
- /*
- * As Linus pointed out, gcc assumes that the callee
- * owns the argument space and could overwrite it, e.g.
- * tailcall optimization. So, to be absolutely safe
- * we also save and restore enough stack bytes to cover
- * the argument area.
- */
- memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
- MIN_STACK_SIZE(addr));
- regs->eflags &= ~IF_MASK;
- regs->rip = (unsigned long)(jp->entry);
- return 1;
-}
-
-void __kprobes jprobe_return(void)
-{
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- asm volatile (" xchg %%rbx,%%rsp \n"
- " int3 \n"
- " .globl jprobe_return_end \n"
- " jprobe_return_end: \n"
- " nop \n"::"b"
- (kcb->jprobe_saved_rsp):"memory");
-}
-
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
- u8 *addr = (u8 *) (regs->rip - 1);
- unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp);
- struct jprobe *jp = container_of(p, struct jprobe, kp);
-
- if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
- if ((long *)regs->rsp != kcb->jprobe_saved_rsp) {
- struct pt_regs *saved_regs =
- container_of(kcb->jprobe_saved_rsp,
- struct pt_regs, rsp);
- printk("current rsp %p does not match saved rsp %p\n",
- (long *)regs->rsp, kcb->jprobe_saved_rsp);
- printk("Saved registers for jprobe %p\n", jp);
- show_registers(saved_regs);
- printk("Current registers\n");
- show_registers(regs);
- BUG();
- }
- *regs = kcb->jprobe_saved_regs;
- memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
- MIN_STACK_SIZE(stack_addr));
- preempt_enable_no_resched();
- return 1;
- }
- return 0;
-}
-
-static struct kprobe trampoline_p = {
- .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
- .pre_handler = trampoline_probe_handler
-};
-
-int __init arch_init_kprobes(void)
-{
- return register_kprobe(&trampoline_p);
-}
-
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
-{
- if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
- return 1;
-
- return 0;
-}
--- /dev/null
+/*
+ * Kernel Probes (KProbes)
+ * arch/x86_64/kernel/kprobes.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ *
+ * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ * Probes initial implementation ( includes contributions from
+ * Rusty Russell).
+ * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
+ * interface to access function arguments.
+ * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi
+ * <prasanna@in.ibm.com> adapted for x86_64
+ * 2005-Mar Roland McGrath <roland@redhat.com>
+ * Fixed to handle %rip-relative addressing mode correctly.
+ * 2005-May Rusty Lynch <rusty.lynch@intel.com>
+ * Added function return probes functionality
+ */
+
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/preempt.h>
+#include <linux/module.h>
+#include <linux/kdebug.h>
+
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/alternative.h>
+
+void jprobe_return_end(void);
+static void __kprobes arch_copy_kprobe(struct kprobe *p);
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+/*
+ * returns non-zero if opcode modifies the interrupt flag.
+ */
+static __always_inline int is_IF_modifier(kprobe_opcode_t *insn)
+{
+ switch (*insn) {
+ case 0xfa: /* cli */
+ case 0xfb: /* sti */
+ case 0xcf: /* iret/iretd */
+ case 0x9d: /* popf/popfd */
+ return 1;
+ }
+
+ if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf)
+ return 1;
+ return 0;
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ /* insn: must be on special executable page on x86_64. */
+ p->ainsn.insn = get_insn_slot();
+ if (!p->ainsn.insn) {
+ return -ENOMEM;
+ }
+ arch_copy_kprobe(p);
+ return 0;
+}
+
+/*
+ * Determine if the instruction uses the %rip-relative addressing mode.
+ * If it does, return the address of the 32-bit displacement word.
+ * If not, return null.
+ */
+static s32 __kprobes *is_riprel(u8 *insn)
+{
+#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
+ (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
+ (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
+ (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
+ (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
+ << (row % 64))
+ static const u64 onebyte_has_modrm[256 / 64] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ------------------------------- */
+ W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */
+ W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */
+ W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */
+ W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */
+ W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */
+ W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */
+ W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */
+ W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */
+ W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */
+ W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */
+ W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */
+ W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */
+ W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */
+ W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */
+ W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */
+ W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */
+ /* ------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ };
+ static const u64 twobyte_has_modrm[256 / 64] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ------------------------------- */
+ W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */
+ W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */
+ W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */
+ W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */
+ W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */
+ W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */
+ W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */
+ W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */
+ W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */
+ W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */
+ W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */
+ W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */
+ W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */
+ W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */
+ W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */
+ W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */
+ /* ------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ };
+#undef W
+ int need_modrm;
+
+ /* Skip legacy instruction prefixes. */
+ while (1) {
+ switch (*insn) {
+ case 0x66:
+ case 0x67:
+ case 0x2e:
+ case 0x3e:
+ case 0x26:
+ case 0x64:
+ case 0x65:
+ case 0x36:
+ case 0xf0:
+ case 0xf3:
+ case 0xf2:
+ ++insn;
+ continue;
+ }
+ break;
+ }
+
+ /* Skip REX instruction prefix. */
+ if ((*insn & 0xf0) == 0x40)
+ ++insn;
+
+ if (*insn == 0x0f) { /* Two-byte opcode. */
+ ++insn;
+ need_modrm = test_bit(*insn, twobyte_has_modrm);
+ } else { /* One-byte opcode. */
+ need_modrm = test_bit(*insn, onebyte_has_modrm);
+ }
+
+ if (need_modrm) {
+ u8 modrm = *++insn;
+ if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */
+ /* Displacement follows ModRM byte. */
+ return (s32 *) ++insn;
+ }
+ }
+
+ /* No %rip-relative addressing mode here. */
+ return NULL;
+}
+
+static void __kprobes arch_copy_kprobe(struct kprobe *p)
+{
+ s32 *ripdisp;
+ memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE);
+ ripdisp = is_riprel(p->ainsn.insn);
+ if (ripdisp) {
+ /*
+ * The copied instruction uses the %rip-relative
+ * addressing mode. Adjust the displacement for the
+ * difference between the original location of this
+ * instruction and the location of the copy that will
+ * actually be run. The tricky bit here is making sure
+ * that the sign extension happens correctly in this
+ * calculation, since we need a signed 32-bit result to
+ * be sign-extended to 64 bits when it's added to the
+ * %rip value and yield the same 64-bit result that the
+ * sign-extension of the original signed 32-bit
+ * displacement would have given.
+ */
+ s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn;
+ BUG_ON((s64) (s32) disp != disp); /* Sanity check. */
+ *ripdisp = disp;
+ }
+ p->opcode = *p->addr;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ text_poke(p->addr, &p->opcode, 1);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ mutex_lock(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn, 0);
+ mutex_unlock(&kprobe_mutex);
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+ kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags;
+ kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags;
+ kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = p;
+ kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags
+ = (regs->eflags & (TF_MASK | IF_MASK));
+ if (is_IF_modifier(p->ainsn.insn))
+ kcb->kprobe_saved_rflags &= ~IF_MASK;
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+ regs->eflags |= TF_MASK;
+ regs->eflags &= ~IF_MASK;
+ /*single step inline if the instruction is an int3*/
+ if (p->opcode == BREAKPOINT_INSTRUCTION)
+ regs->rip = (unsigned long)p->addr;
+ else
+ regs->rip = (unsigned long)p->ainsn.insn;
+}
+
+/* Called with kretprobe_lock held */
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ unsigned long *sara = (unsigned long *)regs->rsp;
+
+ ri->ret_addr = (kprobe_opcode_t *) *sara;
+ /* Replace the return addr with trampoline addr */
+ *sara = (unsigned long) &kretprobe_trampoline;
+}
+
+int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ int ret = 0;
+ kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t));
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
+
+ /* Check we're not actually recursing */
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
+ *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+ regs->eflags &= ~TF_MASK;
+ regs->eflags |= kcb->kprobe_saved_rflags;
+ goto no_kprobe;
+ } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) {
+ /* TODO: Provide re-entrancy from
+ * post_kprobes_handler() and avoid exception
+ * stack corruption while single-stepping on
+ * the instruction of the new probe.
+ */
+ arch_disarm_kprobe(p);
+ regs->rip = (unsigned long)p->addr;
+ reset_current_kprobe();
+ ret = 1;
+ } else {
+ /* We have reentered the kprobe_handler(), since
+ * another probe was hit while within the
+ * handler. We here save the original kprobe
+ * variables and just single step on instruction
+ * of the new probe without calling any user
+ * handlers.
+ */
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kprobes_inc_nmissed_count(p);
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_REENTER;
+ return 1;
+ }
+ } else {
+ if (*addr != BREAKPOINT_INSTRUCTION) {
+ /* The breakpoint instruction was removed by
+ * another cpu right after we hit, no further
+ * handling of this interrupt is appropriate
+ */
+ regs->rip = (unsigned long)addr;
+ ret = 1;
+ goto no_kprobe;
+ }
+ p = __get_cpu_var(current_kprobe);
+ if (p->break_handler && p->break_handler(p, regs)) {
+ goto ss_probe;
+ }
+ }
+ goto no_kprobe;
+ }
+
+ p = get_kprobe(addr);
+ if (!p) {
+ if (*addr != BREAKPOINT_INSTRUCTION) {
+ /*
+ * The breakpoint instruction was removed right
+ * after we hit it. Another cpu has removed
+ * either a probepoint or a debugger breakpoint
+ * at this address. In either case, no further
+ * handling of this interrupt is appropriate.
+ * Back up over the (now missing) int3 and run
+ * the original instruction.
+ */
+ regs->rip = (unsigned long)addr;
+ ret = 1;
+ }
+ /* Not one of ours: let kernel handle it */
+ goto no_kprobe;
+ }
+
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+ if (p->pre_handler && p->pre_handler(p, regs))
+ /* handler has already set things up, so skip ss setup */
+ return 1;
+
+ss_probe:
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+/*
+ * For function-return probes, init_kprobes() establishes a probepoint
+ * here. When a retprobed function returns, this probe is hit and
+ * trampoline_probe_handler() runs, calling the kretprobe's handler.
+ */
+ void kretprobe_trampoline_holder(void)
+ {
+ asm volatile ( ".global kretprobe_trampoline\n"
+ "kretprobe_trampoline: \n"
+ "nop\n");
+ }
+
+/*
+ * Called when we hit the probe point at kretprobe_trampoline
+ */
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri = NULL;
+ struct hlist_head *head, empty_rp;
+ struct hlist_node *node, *tmp;
+ unsigned long flags, orig_ret_address = 0;
+ unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
+
+ INIT_HLIST_HEAD(&empty_rp);
+ spin_lock_irqsave(&kretprobe_lock, flags);
+ head = kretprobe_inst_table_head(current);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because an multiple functions in the call path
+ * have a return probe installed on them, and/or more then one return
+ * 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, node, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler)
+ ri->rp->handler(ri, regs);
+
+ 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);
+ regs->rip = orig_ret_address;
+
+ reset_current_kprobe();
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ preempt_enable_no_resched();
+
+ hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+ hlist_del(&ri->hlist);
+ kfree(ri);
+ }
+ /*
+ * By returning a non-zero value, we are telling
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
+ */
+ return 1;
+}
+
+/*
+ * Called after single-stepping. p->addr is the address of the
+ * instruction whose first byte has been replaced by the "int 3"
+ * instruction. To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction. The address of this
+ * copy is p->ainsn.insn.
+ *
+ * This function prepares to return from the post-single-step
+ * interrupt. We have to fix up the stack as follows:
+ *
+ * 0) Except in the case of absolute or indirect jump or call instructions,
+ * the new rip is relative to the copied instruction. We need to make
+ * it relative to the original instruction.
+ *
+ * 1) If the single-stepped instruction was pushfl, then the TF and IF
+ * flags are set in the just-pushed eflags, and may need to be cleared.
+ *
+ * 2) If the single-stepped instruction was a call, the return address
+ * that is atop the stack is the address following the copied instruction.
+ * We need to make it the address following the original instruction.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+ struct pt_regs *regs, struct kprobe_ctlblk *kcb)
+{
+ unsigned long *tos = (unsigned long *)regs->rsp;
+ unsigned long next_rip = 0;
+ unsigned long copy_rip = (unsigned long)p->ainsn.insn;
+ unsigned long orig_rip = (unsigned long)p->addr;
+ kprobe_opcode_t *insn = p->ainsn.insn;
+
+ /*skip the REX prefix*/
+ if (*insn >= 0x40 && *insn <= 0x4f)
+ insn++;
+
+ switch (*insn) {
+ case 0x9c: /* pushfl */
+ *tos &= ~(TF_MASK | IF_MASK);
+ *tos |= kcb->kprobe_old_rflags;
+ break;
+ case 0xc3: /* ret/lret */
+ case 0xcb:
+ case 0xc2:
+ case 0xca:
+ regs->eflags &= ~TF_MASK;
+ /* rip is already adjusted, no more changes required*/
+ return;
+ case 0xe8: /* call relative - Fix return addr */
+ *tos = orig_rip + (*tos - copy_rip);
+ break;
+ case 0xff:
+ if ((insn[1] & 0x30) == 0x10) {
+ /* call absolute, indirect */
+ /* Fix return addr; rip is correct. */
+ next_rip = regs->rip;
+ *tos = orig_rip + (*tos - copy_rip);
+ } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
+ ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
+ /* rip is correct. */
+ next_rip = regs->rip;
+ }
+ break;
+ case 0xea: /* jmp absolute -- rip is correct */
+ next_rip = regs->rip;
+ break;
+ default:
+ break;
+ }
+
+ regs->eflags &= ~TF_MASK;
+ if (next_rip) {
+ regs->rip = next_rip;
+ } else {
+ regs->rip = orig_rip + (regs->rip - copy_rip);
+ }
+}
+
+int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (!cur)
+ return 0;
+
+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ cur->post_handler(cur, regs, 0);
+ }
+
+ resume_execution(cur, regs, kcb);
+ regs->eflags |= kcb->kprobe_saved_rflags;
+
+ /* Restore the original saved kprobes variables and continue. */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
+ goto out;
+ }
+ reset_current_kprobe();
+out:
+ preempt_enable_no_resched();
+
+ /*
+ * if somebody else is singlestepping across a probe point, eflags
+ * will have TF set, in which case, continue the remaining processing
+ * of do_debug, as if this is not a probe hit.
+ */
+ if (regs->eflags & TF_MASK)
+ return 0;
+
+ return 1;
+}
+
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ const struct exception_table_entry *fixup;
+
+ 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 rip points back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->rip = (unsigned long)cur->addr;
+ regs->eflags |= kcb->kprobe_old_rflags;
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else
+ reset_current_kprobe();
+ preempt_enable_no_resched();
+ break;
+ case KPROBE_HIT_ACTIVE:
+ case KPROBE_HIT_SSDONE:
+ /*
+ * We increment the nmissed count for accounting,
+ * we can also use npre/npostfault count for accouting
+ * 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 first.
+ */
+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+ return 1;
+
+ /*
+ * In case the user-specified fault handler returned
+ * zero, try to fix up.
+ */
+ fixup = search_exception_tables(regs->rip);
+ if (fixup) {
+ regs->rip = fixup->fixup;
+ return 1;
+ }
+
+ /*
+ * fixup() could not handle it,
+ * Let do_page_fault() fix it.
+ */
+ break;
+ default:
+ break;
+ }
+ return 0;
+}
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ if (args->regs && user_mode(args->regs))
+ return ret;
+
+ switch (val) {
+ case DIE_INT3:
+ if (kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_DEBUG:
+ if (post_kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_GPF:
+ case DIE_PAGE_FAULT:
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
+ if (kprobe_running() &&
+ kprobe_fault_handler(args->regs, args->trapnr))
+ ret = NOTIFY_STOP;
+ preempt_enable();
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct jprobe *jp = container_of(p, struct jprobe, kp);
+ unsigned long addr;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ kcb->jprobe_saved_regs = *regs;
+ kcb->jprobe_saved_rsp = (long *) regs->rsp;
+ addr = (unsigned long)(kcb->jprobe_saved_rsp);
+ /*
+ * As Linus pointed out, gcc assumes that the callee
+ * owns the argument space and could overwrite it, e.g.
+ * tailcall optimization. So, to be absolutely safe
+ * we also save and restore enough stack bytes to cover
+ * the argument area.
+ */
+ memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
+ MIN_STACK_SIZE(addr));
+ regs->eflags &= ~IF_MASK;
+ regs->rip = (unsigned long)(jp->entry);
+ return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ asm volatile (" xchg %%rbx,%%rsp \n"
+ " int3 \n"
+ " .globl jprobe_return_end \n"
+ " jprobe_return_end: \n"
+ " nop \n"::"b"
+ (kcb->jprobe_saved_rsp):"memory");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ u8 *addr = (u8 *) (regs->rip - 1);
+ unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp);
+ struct jprobe *jp = container_of(p, struct jprobe, kp);
+
+ if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
+ if ((long *)regs->rsp != kcb->jprobe_saved_rsp) {
+ struct pt_regs *saved_regs =
+ container_of(kcb->jprobe_saved_rsp,
+ struct pt_regs, rsp);
+ printk("current rsp %p does not match saved rsp %p\n",
+ (long *)regs->rsp, kcb->jprobe_saved_rsp);
+ printk("Saved registers for jprobe %p\n", jp);
+ show_registers(saved_regs);
+ printk("Current registers\n");
+ show_registers(regs);
+ BUG();
+ }
+ *regs = kcb->jprobe_saved_regs;
+ memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
+ MIN_STACK_SIZE(stack_addr));
+ preempt_enable_no_resched();
+ return 1;
+ }
+ return 0;
+}
+
+static struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+ return register_kprobe(&trampoline_p);
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+ if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+ return 1;
+
+ return 0;
+}
projects / openwrt / staging / blogic.git / commitdiff