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Diffstat (limited to 'arch/x86/kernel/kprobes.c')
| -rw-r--r-- | arch/x86/kernel/kprobes.c | 1064 |
1 files changed, 0 insertions, 1064 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c deleted file mode 100644 index 18114bf..0000000 --- a/arch/x86/kernel/kprobes.c +++ /dev/null @@ -1,1064 +0,0 @@ -/* - * Kernel Probes (KProbes) - * - * 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 <jkenisto@us.ibm.com> and Prasanna S Panchamukhi - * <prasanna@in.ibm.com> adapted for x86_64 from i386. - * 2005-Mar Roland McGrath <roland@redhat.com> - * Fixed to handle %rip-relative addressing mode correctly. - * 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. - * 2005-May Rusty Lynch <rusty.lynch@intel.com> - * Added function return probes functionality - * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added - * kprobe-booster and kretprobe-booster for i386. - * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster - * and kretprobe-booster for x86-64 - * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven - * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> - * unified x86 kprobes code. - */ -#include <linux/kprobes.h> -#include <linux/ptrace.h> -#include <linux/string.h> -#include <linux/slab.h> -#include <linux/hardirq.h> -#include <linux/preempt.h> -#include <linux/module.h> -#include <linux/kdebug.h> -#include <linux/kallsyms.h> -#include <linux/ftrace.h> - -#include <asm/cacheflush.h> -#include <asm/desc.h> -#include <asm/pgtable.h> -#include <asm/uaccess.h> -#include <asm/alternative.h> -#include <asm/insn.h> -#include <asm/debugreg.h> - -#include "kprobes-common.h" - -void jprobe_return_end(void); - -DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; -DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); - -#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) - -#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 % 32)) - /* - * Undefined/reserved opcodes, conditional jump, Opcode Extension - * Groups, and some special opcodes can not boost. - * This is non-const and volatile to keep gcc from statically - * optimizing it out, as variable_test_bit makes gcc think only - * *(unsigned long*) is used. - */ -static volatile u32 twobyte_is_boostable[256 / 32] = { - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ - /* ---------------------------------------------- */ - W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ - W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ - W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ - W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ - W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ - W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ - W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ - W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ - W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ - W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ - W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ - W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ - W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ - W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ - W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ - W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ - /* ----------------------------------------------- */ - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ -}; -#undef W - -struct kretprobe_blackpoint kretprobe_blacklist[] = { - {"__switch_to", }, /* This function switches only current task, but - doesn't switch kernel stack.*/ - {NULL, NULL} /* Terminator */ -}; - -const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); - -static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) -{ - struct __arch_relative_insn { - u8 op; - s32 raddr; - } __attribute__((packed)) *insn; - - insn = (struct __arch_relative_insn *)from; - insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); - insn->op = op; -} - -/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ -void __kprobes synthesize_reljump(void *from, void *to) -{ - __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); -} - -/* Insert a call instruction at address 'from', which calls address 'to'.*/ -void __kprobes synthesize_relcall(void *from, void *to) -{ - __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); -} - -/* - * Skip the prefixes of the instruction. - */ -static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn) -{ - insn_attr_t attr; - - attr = inat_get_opcode_attribute((insn_byte_t)*insn); - while (inat_is_legacy_prefix(attr)) { - insn++; - attr = inat_get_opcode_attribute((insn_byte_t)*insn); - } -#ifdef CONFIG_X86_64 - if (inat_is_rex_prefix(attr)) - insn++; -#endif - return insn; -} - -/* - * Returns non-zero if opcode is boostable. - * RIP relative instructions are adjusted at copying time in 64 bits mode - */ -int __kprobes can_boost(kprobe_opcode_t *opcodes) -{ - kprobe_opcode_t opcode; - kprobe_opcode_t *orig_opcodes = opcodes; - - if (search_exception_tables((unsigned long)opcodes)) - return 0; /* Page fault may occur on this address. */ - -retry: - if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) - return 0; - opcode = *(opcodes++); - - /* 2nd-byte opcode */ - if (opcode == 0x0f) { - if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) - return 0; - return test_bit(*opcodes, - (unsigned long *)twobyte_is_boostable); - } - - switch (opcode & 0xf0) { -#ifdef CONFIG_X86_64 - case 0x40: - goto retry; /* REX prefix is boostable */ -#endif - case 0x60: - if (0x63 < opcode && opcode < 0x67) - goto retry; /* prefixes */ - /* can't boost Address-size override and bound */ - return (opcode != 0x62 && opcode != 0x67); - case 0x70: - return 0; /* can't boost conditional jump */ - case 0xc0: - /* can't boost software-interruptions */ - return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; - case 0xd0: - /* can boost AA* and XLAT */ - return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); - case 0xe0: - /* can boost in/out and absolute jmps */ - return ((opcode & 0x04) || opcode == 0xea); - case 0xf0: - if ((opcode & 0x0c) == 0 && opcode != 0xf1) - goto retry; /* lock/rep(ne) prefix */ - /* clear and set flags are boostable */ - return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); - default: - /* segment override prefixes are boostable */ - if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) - goto retry; /* prefixes */ - /* CS override prefix and call are not boostable */ - return (opcode != 0x2e && opcode != 0x9a); - } -} - -static unsigned long -__recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) -{ - struct kprobe *kp; - - kp = get_kprobe((void *)addr); - /* There is no probe, return original address */ - if (!kp) - return addr; - - /* - * Basically, kp->ainsn.insn has an original instruction. - * However, RIP-relative instruction can not do single-stepping - * at different place, __copy_instruction() tweaks the displacement of - * that instruction. In that case, we can't recover the instruction - * from the kp->ainsn.insn. - * - * On the other hand, kp->opcode has a copy of the first byte of - * the probed instruction, which is overwritten by int3. And - * the instruction at kp->addr is not modified by kprobes except - * for the first byte, we can recover the original instruction - * from it and kp->opcode. - */ - memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); - buf[0] = kp->opcode; - return (unsigned long)buf; -} - -/* - * Recover the probed instruction at addr for further analysis. - * Caller must lock kprobes by kprobe_mutex, or disable preemption - * for preventing to release referencing kprobes. - */ -unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) -{ - unsigned long __addr; - - __addr = __recover_optprobed_insn(buf, addr); - if (__addr != addr) - return __addr; - - return __recover_probed_insn(buf, addr); -} - -/* Check if paddr is at an instruction boundary */ -static int __kprobes can_probe(unsigned long paddr) -{ - unsigned long addr, __addr, offset = 0; - struct insn insn; - kprobe_opcode_t buf[MAX_INSN_SIZE]; - - if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) - return 0; - - /* Decode instructions */ - addr = paddr - offset; - while (addr < paddr) { - /* - * Check if the instruction has been modified by another - * kprobe, in which case we replace the breakpoint by the - * original instruction in our buffer. - * Also, jump optimization will change the breakpoint to - * relative-jump. Since the relative-jump itself is - * normally used, we just go through if there is no kprobe. - */ - __addr = recover_probed_instruction(buf, addr); - kernel_insn_init(&insn, (void *)__addr); - insn_get_length(&insn); - - /* - * Another debugging subsystem might insert this breakpoint. - * In that case, we can't recover it. - */ - if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) - return 0; - addr += insn.length; - } - - return (addr == paddr); -} - -/* - * Returns non-zero if opcode modifies the interrupt flag. - */ -static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) -{ - /* Skip prefixes */ - insn = skip_prefixes(insn); - - switch (*insn) { - case 0xfa: /* cli */ - case 0xfb: /* sti */ - case 0xcf: /* iret/iretd */ - case 0x9d: /* popf/popfd */ - return 1; - } - - return 0; -} - -/* - * Copy an instruction and adjust the displacement 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. - * Only applicable to 64-bit x86. - */ -int __kprobes __copy_instruction(u8 *dest, u8 *src) -{ - struct insn insn; - kprobe_opcode_t buf[MAX_INSN_SIZE]; - - kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src)); - insn_get_length(&insn); - /* Another subsystem puts a breakpoint, failed to recover */ - if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) - return 0; - memcpy(dest, insn.kaddr, insn.length); - -#ifdef CONFIG_X86_64 - if (insn_rip_relative(&insn)) { - s64 newdisp; - u8 *disp; - kernel_insn_init(&insn, dest); - insn_get_displacement(&insn); - /* - * 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. - */ - newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest; - BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */ - disp = (u8 *) dest + insn_offset_displacement(&insn); - *(s32 *) disp = (s32) newdisp; - } -#endif - return insn.length; -} - -static void __kprobes arch_copy_kprobe(struct kprobe *p) -{ - /* Copy an instruction with recovering if other optprobe modifies it.*/ - __copy_instruction(p->ainsn.insn, p->addr); - - /* - * __copy_instruction can modify the displacement of the instruction, - * but it doesn't affect boostable check. - */ - if (can_boost(p->ainsn.insn)) - p->ainsn.boostable = 0; - else - p->ainsn.boostable = -1; - - /* Also, displacement change doesn't affect the first byte */ - p->opcode = p->ainsn.insn[0]; -} - -int __kprobes arch_prepare_kprobe(struct kprobe *p) -{ - if (alternatives_text_reserved(p->addr, p->addr)) - return -EINVAL; - - if (!can_probe((unsigned long)p->addr)) - return -EILSEQ; - /* insn: must be on special executable page on x86. */ - p->ainsn.insn = get_insn_slot(); - if (!p->ainsn.insn) - return -ENOMEM; - arch_copy_kprobe(p); - return 0; -} - -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) -{ - if (p->ainsn.insn) { - free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); - 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; - kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; - kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; -} - -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; - kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; - kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; -} - -static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, - struct kprobe_ctlblk *kcb) -{ - __this_cpu_write(current_kprobe, p); - kcb->kprobe_saved_flags = kcb->kprobe_old_flags - = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); - if (is_IF_modifier(p->ainsn.insn)) - kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; -} - -static void __kprobes clear_btf(void) -{ - if (test_thread_flag(TIF_BLOCKSTEP)) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl &= ~DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); - } -} - -static void __kprobes restore_btf(void) -{ - if (test_thread_flag(TIF_BLOCKSTEP)) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl |= DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); - } -} - -void __kprobes -arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) -{ - unsigned long *sara = stack_addr(regs); - - ri->ret_addr = (kprobe_opcode_t *) *sara; - - /* Replace the return addr with trampoline addr */ - *sara = (unsigned long) &kretprobe_trampoline; -} - -static void __kprobes -setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter) -{ - if (setup_detour_execution(p, regs, reenter)) - return; - -#if !defined(CONFIG_PREEMPT) - if (p->ainsn.boostable == 1 && !p->post_handler) { - /* Boost up -- we can execute copied instructions directly */ - if (!reenter) - reset_current_kprobe(); - /* - * Reentering boosted probe doesn't reset current_kprobe, - * nor set current_kprobe, because it doesn't use single - * stepping. - */ - regs->ip = (unsigned long)p->ainsn.insn; - preempt_enable_no_resched(); - return; - } -#endif - if (reenter) { - save_previous_kprobe(kcb); - set_current_kprobe(p, regs, kcb); - kcb->kprobe_status = KPROBE_REENTER; - } else - kcb->kprobe_status = KPROBE_HIT_SS; - /* Prepare real single stepping */ - clear_btf(); - regs->flags |= X86_EFLAGS_TF; - regs->flags &= ~X86_EFLAGS_IF; - /* single step inline if the instruction is an int3 */ - if (p->opcode == BREAKPOINT_INSTRUCTION) - regs->ip = (unsigned long)p->addr; - else - regs->ip = (unsigned long)p->ainsn.insn; -} - -/* - * We have reentered the kprobe_handler(), since another probe was hit while - * within the handler. We save the original kprobes variables and just single - * step on the instruction of the new probe without calling any user handlers. - */ -static int __kprobes -reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) -{ - switch (kcb->kprobe_status) { - case KPROBE_HIT_SSDONE: - case KPROBE_HIT_ACTIVE: - kprobes_inc_nmissed_count(p); - setup_singlestep(p, regs, kcb, 1); - break; - case KPROBE_HIT_SS: - /* A probe has been hit in the codepath leading up to, or just - * after, single-stepping of a probed instruction. This entire - * codepath should strictly reside in .kprobes.text section. - * Raise a BUG or we'll continue in an endless reentering loop - * and eventually a stack overflow. - */ - printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", - p->addr); - dump_kprobe(p); - BUG(); - default: - /* impossible cases */ - WARN_ON(1); - return 0; - } - - return 1; -} - -/* - * Interrupts are disabled on entry as trap3 is an interrupt gate and they - * remain disabled throughout this function. - */ -static int __kprobes kprobe_handler(struct pt_regs *regs) -{ - kprobe_opcode_t *addr; - struct kprobe *p; - struct kprobe_ctlblk *kcb; - - addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); - /* - * We don't want to be preempted for the entire - * duration of kprobe processing. We conditionally - * re-enable preemption at the end of this function, - * and also in reenter_kprobe() and setup_singlestep(). - */ - preempt_disable(); - - kcb = get_kprobe_ctlblk(); - p = get_kprobe(addr); - - if (p) { - if (kprobe_running()) { - if (reenter_kprobe(p, regs, kcb)) - return 1; - } else { - set_current_kprobe(p, regs, kcb); - 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 - * for jprobe processing, so get out doing nothing - * more here. - */ - if (!p->pre_handler || !p->pre_handler(p, regs)) - setup_singlestep(p, regs, kcb, 0); - return 1; - } - } else 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->ip = (unsigned long)addr; - preempt_enable_no_resched(); - return 1; - } else if (kprobe_running()) { - p = __this_cpu_read(current_kprobe); - if (p->break_handler && p->break_handler(p, regs)) { - if (!skip_singlestep(p, regs, kcb)) - setup_singlestep(p, regs, kcb, 0); - return 1; - } - } /* else: not a kprobe fault; let the kernel handle it */ - - preempt_enable_no_resched(); - return 0; -} - -/* - * When a retprobed function returns, this code saves registers and - * calls trampoline_handler() runs, which calls the kretprobe's handler. - */ -static void __used __kprobes kretprobe_trampoline_holder(void) -{ - asm volatile ( - ".global kretprobe_trampoline\n" - "kretprobe_trampoline: \n" -#ifdef CONFIG_X86_64 - /* We don't bother saving the ss register */ - " pushq %rsp\n" - " pushfq\n" - SAVE_REGS_STRING - " movq %rsp, %rdi\n" - " call trampoline_handler\n" - /* Replace saved sp with true return address. */ - " movq %rax, 152(%rsp)\n" - RESTORE_REGS_STRING - " popfq\n" -#else - " pushf\n" - SAVE_REGS_STRING - " movl %esp, %eax\n" - " call trampoline_handler\n" - /* Move flags to cs */ - " movl 56(%esp), %edx\n" - " movl %edx, 52(%esp)\n" - /* Replace saved flags with true return address. */ - " movl %eax, 56(%esp)\n" - RESTORE_REGS_STRING - " popf\n" -#endif - " ret\n"); -} - -/* - * 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 *node, *tmp; - unsigned long flags, orig_ret_address = 0; - unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; - kprobe_opcode_t *correct_ret_addr = NULL; - - INIT_HLIST_HEAD(&empty_rp); - kretprobe_hash_lock(current, &head, &flags); - /* fixup registers */ -#ifdef CONFIG_X86_64 - regs->cs = __KERNEL_CS; -#else - regs->cs = __KERNEL_CS | get_kernel_rpl(); - regs->gs = 0; -#endif - regs->ip = trampoline_address; - regs->orig_ax = ~0UL; - - /* - * It is possible to have multiple instances associated with a given - * task either because multiple functions in the call path have - * return probes installed on them, and/or more than one - * return probe was registered for a target function. - * - * We can handle this because: - * - instances are always pushed into the head of the list - * - when multiple return probes are registered for the same - * function, the (chronologically) first instance's ret_addr - * will be 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; - - orig_ret_address = (unsigned long)ri->ret_addr; - - 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); - - correct_ret_addr = ri->ret_addr; - hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { - if (ri->task != current) - /* another task is sharing our hash bucket */ - continue; - - orig_ret_address = (unsigned long)ri->ret_addr; - if (ri->rp && ri->rp->handler) { - __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; - ri->ret_addr = correct_ret_addr; - ri->rp->handler(ri, regs); - __this_cpu_write(current_kprobe, NULL); - } - - 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_hash_unlock(current, &flags); - - hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } - return (void *)orig_ret_address; -} - -/* - * 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 ip 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 flags, 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. - * - * If this is the first time we've single-stepped the instruction at - * this probepoint, and the instruction is boostable, boost it: add a - * jump instruction after the copied instruction, that jumps to the next - * instruction after the probepoint. - */ -static void __kprobes -resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) -{ - unsigned long *tos = stack_addr(regs); - unsigned long copy_ip = (unsigned long)p->ainsn.insn; - unsigned long orig_ip = (unsigned long)p->addr; - kprobe_opcode_t *insn = p->ainsn.insn; - - /* Skip prefixes */ - insn = skip_prefixes(insn); - - regs->flags &= ~X86_EFLAGS_TF; - switch (*insn) { - case 0x9c: /* pushfl */ - *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); - *tos |= kcb->kprobe_old_flags; - break; - case 0xc2: /* iret/ret/lret */ - case 0xc3: - case 0xca: - case 0xcb: - case 0xcf: - case 0xea: /* jmp absolute -- ip is correct */ - /* ip is already adjusted, no more changes required */ - p->ainsn.boostable = 1; - goto no_change; - case 0xe8: /* call relative - Fix return addr */ - *tos = orig_ip + (*tos - copy_ip); - break; -#ifdef CONFIG_X86_32 - case 0x9a: /* call absolute -- same as call absolute, indirect */ - *tos = orig_ip + (*tos - copy_ip); - goto no_change; -#endif - case 0xff: - if ((insn[1] & 0x30) == 0x10) { - /* - * call absolute, indirect - * Fix return addr; ip is correct. - * But this is not boostable - */ - *tos = orig_ip + (*tos - copy_ip); - goto no_change; - } else if (((insn[1] & 0x31) == 0x20) || - ((insn[1] & 0x31) == 0x21)) { - /* - * jmp near and far, absolute indirect - * ip is correct. And this is boostable - */ - p->ainsn.boostable = 1; - goto no_change; - } - default: - break; - } - - if (p->ainsn.boostable == 0) { - if ((regs->ip > copy_ip) && - (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { - /* - * These instructions can be executed directly if it - * jumps back to correct address. - */ - synthesize_reljump((void *)regs->ip, - (void *)orig_ip + (regs->ip - copy_ip)); - p->ainsn.boostable = 1; - } else { - p->ainsn.boostable = -1; - } - } - - regs->ip += orig_ip - copy_ip; - -no_change: - restore_btf(); -} - -/* - * Interrupts are disabled on entry as trap1 is an interrupt gate and they - * remain disabled throughout this function. - */ -static 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; - - resume_execution(cur, regs, kcb); - regs->flags |= kcb->kprobe_saved_flags; - - if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { - kcb->kprobe_status = KPROBE_HIT_SSDONE; - cur->post_handler(cur, regs, 0); - } - - /* Restore back 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, flags - * will have TF set, in which case, continue the remaining processing - * of do_debug, as if this is not a probe hit. - */ - if (regs->flags & X86_EFLAGS_TF) - 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(); - - 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 ip points back to the probe address - * and allow the page fault handler to continue as a - * normal page fault. - */ - regs->ip = (unsigned long)cur->addr; - regs->flags |= kcb->kprobe_old_flags; - 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 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 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. - */ - if (fixup_exception(regs)) - return 1; - - /* - * fixup routine 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 = data; - int ret = NOTIFY_DONE; - - if (args->regs && user_mode_vm(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)) { - /* - * Reset the BS bit in dr6 (pointed by args->err) to - * denote completion of processing - */ - (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; - ret = NOTIFY_STOP; - } - break; - case DIE_GPF: - /* - * To be potentially processing a kprobe fault and to - * trust the result from kprobe_running(), we have - * be non-preemptible. - */ - if (!preemptible() && kprobe_running() && - kprobe_fault_handler(args->regs, args->trapnr)) - ret = NOTIFY_STOP; - 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_sp = stack_addr(regs); - addr = (unsigned long)(kcb->jprobe_saved_sp); - - /* - * 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->flags &= ~X86_EFLAGS_IF; - trace_hardirqs_off(); - regs->ip = (unsigned long)(jp->entry); - return 1; -} - -void __kprobes jprobe_return(void) -{ - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - - asm volatile ( -#ifdef CONFIG_X86_64 - " xchg %%rbx,%%rsp \n" -#else - " xchgl %%ebx,%%esp \n" -#endif - " int3 \n" - " .globl jprobe_return_end\n" - " jprobe_return_end: \n" - " nop \n"::"b" - (kcb->jprobe_saved_sp):"memory"); -} - -int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - u8 *addr = (u8 *) (regs->ip - 1); - struct jprobe *jp = container_of(p, struct jprobe, kp); - - if ((addr > (u8 *) jprobe_return) && - (addr < (u8 *) jprobe_return_end)) { - if (stack_addr(regs) != kcb->jprobe_saved_sp) { - struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; - printk(KERN_ERR - "current sp %p does not match saved sp %p\n", - stack_addr(regs), kcb->jprobe_saved_sp); - printk(KERN_ERR "Saved registers for jprobe %p\n", jp); - show_regs(saved_regs); - printk(KERN_ERR "Current registers\n"); - show_regs(regs); - BUG(); - } - *regs = kcb->jprobe_saved_regs; - memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), - kcb->jprobes_stack, - MIN_STACK_SIZE(kcb->jprobe_saved_sp)); - preempt_enable_no_resched(); - return 1; - } - return 0; -} - -int __init arch_init_kprobes(void) -{ - return arch_init_optprobes(); -} - -int __kprobes arch_trampoline_kprobe(struct kprobe *p) -{ - return 0; -} |
