| /* |
| * 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 <asm/cacheflush.h> |
| #include <asm/desc.h> |
| #include <asm/pgtable.h> |
| #include <asm/uaccess.h> |
| #include <asm/alternative.h> |
| |
| void jprobe_return_end(void); |
| |
| DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| |
| #ifdef CONFIG_X86_64 |
| #define stack_addr(regs) ((unsigned long *)regs->sp) |
| #else |
| /* |
| * "®s->sp" looks wrong, but it's correct for x86_32. x86_32 CPUs |
| * don't save the ss and esp registers if the CPU is already in kernel |
| * mode when it traps. So for kprobes, regs->sp and regs->ss are not |
| * the [nonexistent] saved stack pointer and ss register, but rather |
| * the top 8 bytes of the pre-int3 stack. So ®s->sp happens to |
| * point to the top of the pre-int3 stack. |
| */ |
| #define stack_addr(regs) ((unsigned long *)®s->sp) |
| #endif |
| |
| #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. |
| */ |
| static const 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 */ |
| }; |
| static const u32 onebyte_has_modrm[256 / 32] = { |
| /* 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 u32 twobyte_has_modrm[256 / 32] = { |
| /* 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 |
| |
| 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); |
| |
| /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
| static void __kprobes set_jmp_op(void *from, void *to) |
| { |
| struct __arch_jmp_op { |
| char op; |
| s32 raddr; |
| } __attribute__((packed)) * jop; |
| jop = (struct __arch_jmp_op *)from; |
| jop->raddr = (s32)((long)(to) - ((long)(from) + 5)); |
| jop->op = RELATIVEJUMP_INSTRUCTION; |
| } |
| |
| /* |
| * Check for the REX prefix which can only exist on X86_64 |
| * X86_32 always returns 0 |
| */ |
| static int __kprobes is_REX_prefix(kprobe_opcode_t *insn) |
| { |
| #ifdef CONFIG_X86_64 |
| if ((*insn & 0xf0) == 0x40) |
| return 1; |
| #endif |
| return 0; |
| } |
| |
| /* |
| * Returns non-zero if opcode is boostable. |
| * RIP relative instructions are adjusted at copying time in 64 bits mode |
| */ |
| static int __kprobes can_boost(kprobe_opcode_t *opcodes) |
| { |
| kprobe_opcode_t opcode; |
| kprobe_opcode_t *orig_opcodes = opcodes; |
| |
| 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); |
| } |
| } |
| |
| /* |
| * Returns non-zero if opcode modifies the interrupt flag. |
| */ |
| static int __kprobes 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; |
| } |
| |
| /* |
| * on X86_64, 0x40-0x4f are REX prefixes so we need to look |
| * at the next byte instead.. but of course not recurse infinitely |
| */ |
| if (is_REX_prefix(insn)) |
| return is_IF_modifier(++insn); |
| |
| return 0; |
| } |
| |
| /* |
| * 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. |
| */ |
| static void __kprobes fix_riprel(struct kprobe *p) |
| { |
| #ifdef CONFIG_X86_64 |
| u8 *insn = p->ainsn.insn; |
| s64 disp; |
| 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 (is_REX_prefix(insn)) |
| ++insn; |
| |
| if (*insn == 0x0f) { |
| /* Two-byte opcode. */ |
| ++insn; |
| need_modrm = test_bit(*insn, |
| (unsigned long *)twobyte_has_modrm); |
| } else |
| /* One-byte opcode. */ |
| need_modrm = test_bit(*insn, |
| (unsigned long *)onebyte_has_modrm); |
| |
| if (need_modrm) { |
| u8 modrm = *++insn; |
| if ((modrm & 0xc7) == 0x05) { |
| /* %rip+disp32 addressing mode */ |
| /* Displacement follows ModRM byte. */ |
| ++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. |
| */ |
| disp = (u8 *) p->addr + *((s32 *) insn) - |
| (u8 *) p->ainsn.insn; |
| BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ |
| *(s32 *)insn = (s32) disp; |
| } |
| } |
| #endif |
| } |
| |
| static void __kprobes arch_copy_kprobe(struct kprobe *p) |
| { |
| memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
| |
| fix_riprel(p); |
| |
| if (can_boost(p->addr)) |
| p->ainsn.boostable = 0; |
| else |
| p->ainsn.boostable = -1; |
| |
| p->opcode = *p->addr; |
| } |
| |
| int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| { |
| /* 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) |
| { |
| mutex_lock(&kprobe_mutex); |
| free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); |
| 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_flags = kcb->kprobe_old_flags; |
| kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; |
| } |
| |
| 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_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) |
| { |
| __get_cpu_var(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_DEBUGCTLMSR)) |
| wrmsrl(MSR_IA32_DEBUGCTLMSR, 0); |
| } |
| |
| static void __kprobes restore_btf(void) |
| { |
| if (test_thread_flag(TIF_DEBUGCTLMSR)) |
| wrmsrl(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr); |
| } |
| |
| static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
| { |
| 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; |
| } |
| |
| /* Called with kretprobe_lock held */ |
| 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) |
| { |
| #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) |
| if (p->ainsn.boostable == 1 && !p->post_handler) { |
| /* Boost up -- we can execute copied instructions directly */ |
| reset_current_kprobe(); |
| regs->ip = (unsigned long)p->ainsn.insn; |
| preempt_enable_no_resched(); |
| return; |
| } |
| #endif |
| prepare_singlestep(p, regs); |
| kcb->kprobe_status = KPROBE_HIT_SS; |
| } |
| |
| /* |
| * 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: |
| #ifdef CONFIG_X86_64 |
| /* 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->ip = (unsigned long)p->addr; |
| reset_current_kprobe(); |
| preempt_enable_no_resched(); |
| break; |
| #endif |
| case KPROBE_HIT_ACTIVE: |
| save_previous_kprobe(kcb); |
| set_current_kprobe(p, regs, kcb); |
| kprobes_inc_nmissed_count(p); |
| prepare_singlestep(p, regs); |
| kcb->kprobe_status = KPROBE_REENTER; |
| break; |
| case KPROBE_HIT_SS: |
| if (p == kprobe_running()) { |
| regs->flags &= ~TF_MASK; |
| regs->flags |= kcb->kprobe_saved_flags; |
| return 0; |
| } else { |
| /* 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 warning |
| * to highlight this peculiar case. |
| */ |
| } |
| 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 thorough out 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)); |
| 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; |
| return 1; |
| } |
| |
| /* |
| * 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); |
| return 1; |
| } |
| } else if (kprobe_running()) { |
| p = __get_cpu_var(current_kprobe); |
| if (p->break_handler && p->break_handler(p, regs)) { |
| setup_singlestep(p, regs, kcb); |
| 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" |
| /* |
| * Skip cs, ip, orig_ax. |
| * trampoline_handler() will plug in these values |
| */ |
| " subq $24, %rsp\n" |
| " pushq %rdi\n" |
| " pushq %rsi\n" |
| " pushq %rdx\n" |
| " pushq %rcx\n" |
| " pushq %rax\n" |
| " pushq %r8\n" |
| " pushq %r9\n" |
| " pushq %r10\n" |
| " pushq %r11\n" |
| " pushq %rbx\n" |
| " pushq %rbp\n" |
| " pushq %r12\n" |
| " pushq %r13\n" |
| " pushq %r14\n" |
| " pushq %r15\n" |
| " movq %rsp, %rdi\n" |
| " call trampoline_handler\n" |
| /* Replace saved sp with true return address. */ |
| " movq %rax, 152(%rsp)\n" |
| " popq %r15\n" |
| " popq %r14\n" |
| " popq %r13\n" |
| " popq %r12\n" |
| " popq %rbp\n" |
| " popq %rbx\n" |
| " popq %r11\n" |
| " popq %r10\n" |
| " popq %r9\n" |
| " popq %r8\n" |
| " popq %rax\n" |
| " popq %rcx\n" |
| " popq %rdx\n" |
| " popq %rsi\n" |
| " popq %rdi\n" |
| /* Skip orig_ax, ip, cs */ |
| " addq $24, %rsp\n" |
| " popfq\n" |
| #else |
| " pushf\n" |
| /* |
| * Skip cs, ip, orig_ax. |
| * trampoline_handler() will plug in these values |
| */ |
| " subl $12, %esp\n" |
| " pushl %fs\n" |
| " pushl %ds\n" |
| " pushl %es\n" |
| " pushl %eax\n" |
| " pushl %ebp\n" |
| " pushl %edi\n" |
| " pushl %esi\n" |
| " pushl %edx\n" |
| " pushl %ecx\n" |
| " pushl %ebx\n" |
| " movl %esp, %eax\n" |
| " call trampoline_handler\n" |
| /* Move flags to cs */ |
| " movl 52(%esp), %edx\n" |
| " movl %edx, 48(%esp)\n" |
| /* Replace saved flags with true return address. */ |
| " movl %eax, 52(%esp)\n" |
| " popl %ebx\n" |
| " popl %ecx\n" |
| " popl %edx\n" |
| " popl %esi\n" |
| " popl %edi\n" |
| " popl %ebp\n" |
| " popl %eax\n" |
| /* Skip ip, orig_ax, es, ds, fs */ |
| " addl $20, %esp\n" |
| " 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; |
| |
| INIT_HLIST_HEAD(&empty_rp); |
| spin_lock_irqsave(&kretprobe_lock, flags); |
| head = kretprobe_inst_table_head(current); |
| /* fixup registers */ |
| #ifdef CONFIG_X86_64 |
| regs->cs = __KERNEL_CS; |
| #else |
| regs->cs = __KERNEL_CS | get_kernel_rpl(); |
| #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 then 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; |
| |
| if (ri->rp && ri->rp->handler) { |
| __get_cpu_var(current_kprobe) = &ri->rp->kp; |
| get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
| ri->rp->handler(ri, regs); |
| __get_cpu_var(current_kprobe) = NULL; |
| } |
| |
| orig_ret_address = (unsigned long)ri->ret_addr; |
| recycle_rp_inst(ri, &empty_rp); |
| |
| if (orig_ret_address != trampoline_address) |
| /* |
| * This is the real return address. Any other |
| * instances associated with this task are for |
| * other calls deeper on the call stack |
| */ |
| break; |
| } |
| |
| kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| |
| spin_unlock_irqrestore(&kretprobe_lock, 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 the REX prefix*/ |
| if (is_REX_prefix(insn)) |
| 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. |
| */ |
| set_jmp_op((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 thoroughout 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; |
| |
| 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->flags |= kcb->kprobe_saved_flags; |
| trace_hardirqs_fixup_flags(regs->flags); |
| |
| /* 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)) |
| 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_registers(saved_regs); |
| printk(KERN_ERR "Current registers\n"); |
| show_registers(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 0; |
| } |
| |
| int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| { |
| return 0; |
| } |