diff options
Diffstat (limited to 'arch/i386/kernel/kprobes.c')
| -rw-r--r-- | arch/i386/kernel/kprobes.c | 548 |
1 files changed, 0 insertions, 548 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c deleted file mode 100644 index 6345b430b10..00000000000 --- a/arch/i386/kernel/kprobes.c +++ /dev/null @@ -1,548 +0,0 @@ -/* - * Kernel Probes (KProbes) - * arch/i386/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. - * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston - * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi - * <prasanna@in.ibm.com> added function-return probes. - */ - -#include <linux/config.h> -#include <linux/kprobes.h> -#include <linux/ptrace.h> -#include <linux/spinlock.h> -#include <linux/preempt.h> -#include <asm/cacheflush.h> -#include <asm/kdebug.h> -#include <asm/desc.h> - -static struct kprobe *current_kprobe; -static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags; -static struct kprobe *kprobe_prev; -static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev; -static struct pt_regs jprobe_saved_regs; -static long *jprobe_saved_esp; -/* copy of the kernel stack at the probe fire time */ -static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE]; -void jprobe_return_end(void); - -/* - * returns non-zero if opcode modifies the interrupt flag. - */ -static inline int is_IF_modifier(kprobe_opcode_t opcode) -{ - switch (opcode) { - case 0xfa: /* cli */ - case 0xfb: /* sti */ - case 0xcf: /* iret/iretd */ - case 0x9d: /* popf/popfd */ - return 1; - } - return 0; -} - -int __kprobes arch_prepare_kprobe(struct kprobe *p) -{ - return 0; -} - -void __kprobes arch_copy_kprobe(struct kprobe *p) -{ - memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); - p->opcode = *p->addr; -} - -void __kprobes arch_arm_kprobe(struct kprobe *p) -{ - *p->addr = BREAKPOINT_INSTRUCTION; - flush_icache_range((unsigned long) p->addr, - (unsigned long) p->addr + sizeof(kprobe_opcode_t)); -} - -void __kprobes arch_disarm_kprobe(struct kprobe *p) -{ - *p->addr = p->opcode; - flush_icache_range((unsigned long) p->addr, - (unsigned long) p->addr + sizeof(kprobe_opcode_t)); -} - -void __kprobes arch_remove_kprobe(struct kprobe *p) -{ -} - -static inline void save_previous_kprobe(void) -{ - kprobe_prev = current_kprobe; - kprobe_status_prev = kprobe_status; - kprobe_old_eflags_prev = kprobe_old_eflags; - kprobe_saved_eflags_prev = kprobe_saved_eflags; -} - -static inline void restore_previous_kprobe(void) -{ - current_kprobe = kprobe_prev; - kprobe_status = kprobe_status_prev; - kprobe_old_eflags = kprobe_old_eflags_prev; - kprobe_saved_eflags = kprobe_saved_eflags_prev; -} - -static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) -{ - current_kprobe = p; - kprobe_saved_eflags = kprobe_old_eflags - = (regs->eflags & (TF_MASK | IF_MASK)); - if (is_IF_modifier(p->opcode)) - kprobe_saved_eflags &= ~IF_MASK; -} - -static inline void 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->eip = (unsigned long)p->addr; - else - regs->eip = (unsigned long)&p->ainsn.insn; -} - -void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, - struct pt_regs *regs) -{ - unsigned long *sara = (unsigned long *)®s->esp; - struct kretprobe_instance *ri; - - if ((ri = get_free_rp_inst(rp)) != NULL) { - ri->rp = rp; - ri->task = current; - ri->ret_addr = (kprobe_opcode_t *) *sara; - - /* Replace the return addr with trampoline addr */ - *sara = (unsigned long) &kretprobe_trampoline; - - add_rp_inst(ri); - } else { - rp->nmissed++; - } -} - -/* - * Interrupts are disabled on entry as trap3 is an interrupt gate and they - * remain disabled thorough out this function. - */ -static int __kprobes kprobe_handler(struct pt_regs *regs) -{ - struct kprobe *p; - int ret = 0; - kprobe_opcode_t *addr = NULL; - unsigned long *lp; - - /* We're in an interrupt, but this is clear and BUG()-safe. */ - preempt_disable(); - /* Check if the application is using LDT entry for its code segment and - * calculate the address by reading the base address from the LDT entry. - */ - if ((regs->xcs & 4) && (current->mm)) { - lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8) - + (char *) current->mm->context.ldt); - addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip - - sizeof(kprobe_opcode_t)); - } else { - addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t)); - } - /* Check we're not actually recursing */ - if (kprobe_running()) { - /* We *are* holding lock here, so this is safe. - Disarm the probe we just hit, and ignore it. */ - p = get_kprobe(addr); - if (p) { - if (kprobe_status == KPROBE_HIT_SS && - *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { - regs->eflags &= ~TF_MASK; - regs->eflags |= kprobe_saved_eflags; - unlock_kprobes(); - goto no_kprobe; - } - /* We have reentered the kprobe_handler(), since - * another probe was hit while within the handler. - * We here save the original kprobes variables and - * just single step on the instruction of the new probe - * without calling any user handlers. - */ - save_previous_kprobe(); - set_current_kprobe(p, regs); - p->nmissed++; - prepare_singlestep(p, regs); - kprobe_status = KPROBE_REENTER; - return 1; - } else { - p = current_kprobe; - if (p->break_handler && p->break_handler(p, regs)) { - goto ss_probe; - } - } - /* If it's not ours, can't be delete race, (we hold lock). */ - goto no_kprobe; - } - - lock_kprobes(); - p = get_kprobe(addr); - if (!p) { - unlock_kprobes(); - if (regs->eflags & VM_MASK) { - /* We are in virtual-8086 mode. Return 0 */ - goto no_kprobe; - } - - 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->eip -= sizeof(kprobe_opcode_t); - ret = 1; - } - /* Not one of ours: let kernel handle it */ - goto no_kprobe; - } - - kprobe_status = KPROBE_HIT_ACTIVE; - set_current_kprobe(p, regs); - - 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); - 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; - struct hlist_node *node, *tmp; - unsigned long orig_ret_address = 0; - unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; - - 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); - - 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; - } - - BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); - regs->eip = orig_ret_address; - - unlock_kprobes(); - preempt_enable_no_resched(); - - /* - * By returning a non-zero value, we are telling - * kprobe_handler() that we have handled unlocking - * and re-enabling 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 eip 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) -{ - unsigned long *tos = (unsigned long *)®s->esp; - unsigned long next_eip = 0; - unsigned long copy_eip = (unsigned long)&p->ainsn.insn; - unsigned long orig_eip = (unsigned long)p->addr; - - switch (p->ainsn.insn[0]) { - case 0x9c: /* pushfl */ - *tos &= ~(TF_MASK | IF_MASK); - *tos |= kprobe_old_eflags; - break; - case 0xc3: /* ret/lret */ - case 0xcb: - case 0xc2: - case 0xca: - regs->eflags &= ~TF_MASK; - /* eip is already adjusted, no more changes required*/ - return; - case 0xe8: /* call relative - Fix return addr */ - *tos = orig_eip + (*tos - copy_eip); - break; - case 0xff: - if ((p->ainsn.insn[1] & 0x30) == 0x10) { - /* call absolute, indirect */ - /* Fix return addr; eip is correct. */ - next_eip = regs->eip; - *tos = orig_eip + (*tos - copy_eip); - } else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ - ((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ - /* eip is correct. */ - next_eip = regs->eip; - } - break; - case 0xea: /* jmp absolute -- eip is correct */ - next_eip = regs->eip; - break; - default: - break; - } - - regs->eflags &= ~TF_MASK; - if (next_eip) { - regs->eip = next_eip; - } else { - regs->eip = orig_eip + (regs->eip - copy_eip); - } -} - -/* - * Interrupts are disabled on entry as trap1 is an interrupt gate and they - * remain disabled thoroughout this function. And we hold kprobe lock. - */ -static inline int post_kprobe_handler(struct pt_regs *regs) -{ - if (!kprobe_running()) - return 0; - - if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { - kprobe_status = KPROBE_HIT_SSDONE; - current_kprobe->post_handler(current_kprobe, regs, 0); - } - - resume_execution(current_kprobe, regs); - regs->eflags |= kprobe_saved_eflags; - - /*Restore back the original saved kprobes variables and continue. */ - if (kprobe_status == KPROBE_REENTER) { - restore_previous_kprobe(); - goto out; - } - unlock_kprobes(); -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; -} - -/* Interrupts disabled, kprobe_lock held. */ -static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) -{ - if (current_kprobe->fault_handler - && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) - return 1; - - if (kprobe_status & KPROBE_HIT_SS) { - resume_execution(current_kprobe, regs); - regs->eflags |= kprobe_old_eflags; - - unlock_kprobes(); - preempt_enable_no_resched(); - } - return 0; -} - -/* - * Wrapper routine to 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; - switch (val) { - case DIE_INT3: - if (kprobe_handler(args->regs)) - return NOTIFY_STOP; - break; - case DIE_DEBUG: - if (post_kprobe_handler(args->regs)) - return NOTIFY_STOP; - break; - case DIE_GPF: - if (kprobe_running() && - kprobe_fault_handler(args->regs, args->trapnr)) - return NOTIFY_STOP; - break; - case DIE_PAGE_FAULT: - if (kprobe_running() && - kprobe_fault_handler(args->regs, args->trapnr)) - return NOTIFY_STOP; - break; - default: - break; - } - return NOTIFY_DONE; -} - -int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct jprobe *jp = container_of(p, struct jprobe, kp); - unsigned long addr; - - jprobe_saved_regs = *regs; - jprobe_saved_esp = ®s->esp; - addr = (unsigned long)jprobe_saved_esp; - - /* - * TBD: 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(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr)); - regs->eflags &= ~IF_MASK; - regs->eip = (unsigned long)(jp->entry); - return 1; -} - -void __kprobes jprobe_return(void) -{ - preempt_enable_no_resched(); - asm volatile (" xchgl %%ebx,%%esp \n" - " int3 \n" - " .globl jprobe_return_end \n" - " jprobe_return_end: \n" - " nop \n"::"b" - (jprobe_saved_esp):"memory"); -} - -int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) -{ - u8 *addr = (u8 *) (regs->eip - 1); - unsigned long stack_addr = (unsigned long)jprobe_saved_esp; - struct jprobe *jp = container_of(p, struct jprobe, kp); - - if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { - if (®s->esp != jprobe_saved_esp) { - struct pt_regs *saved_regs = - container_of(jprobe_saved_esp, struct pt_regs, esp); - printk("current esp %p does not match saved esp %p\n", - ®s->esp, jprobe_saved_esp); - printk("Saved registers for jprobe %p\n", jp); - show_registers(saved_regs); - printk("Current registers\n"); - show_registers(regs); - BUG(); - } - *regs = jprobe_saved_regs; - memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack, - MIN_STACK_SIZE(stack_addr)); - 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); -} |