diff options
Diffstat (limited to 'arch/x86/kernel/kprobes/core.c')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 1350 |
1 files changed, 677 insertions, 673 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 211bce445522..c1fac3a9fecc 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1,20 +1,7 @@ +// SPDX-License-Identifier: GPL-2.0-or-later /* * 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 @@ -45,28 +32,35 @@ #include <linux/slab.h> #include <linux/hardirq.h> #include <linux/preempt.h> -#include <linux/module.h> +#include <linux/sched/debug.h> +#include <linux/perf_event.h> +#include <linux/extable.h> #include <linux/kdebug.h> #include <linux/kallsyms.h> +#include <linux/kgdb.h> #include <linux/ftrace.h> - +#include <linux/kasan.h> +#include <linux/objtool.h> +#include <linux/vmalloc.h> +#include <linux/pgtable.h> +#include <linux/set_memory.h> +#include <linux/cfi.h> +#include <linux/execmem.h> + +#include <asm/text-patching.h> #include <asm/cacheflush.h> #include <asm/desc.h> -#include <asm/pgtable.h> -#include <asm/uaccess.h> +#include <linux/uaccess.h> #include <asm/alternative.h> #include <asm/insn.h> #include <asm/debugreg.h> +#include <asm/ibt.h> #include "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) | \ @@ -84,7 +78,7 @@ 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(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 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 */ @@ -112,106 +106,97 @@ struct kretprobe_blackpoint kretprobe_blacklist[] = { const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); -static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) +static nokprobe_inline void +__synthesize_relative_insn(void *dest, void *from, void *to, u8 op) { struct __arch_relative_insn { u8 op; s32 raddr; } __packed *insn; - insn = (struct __arch_relative_insn *)from; + insn = (struct __arch_relative_insn *)dest; 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) +void synthesize_reljump(void *dest, void *from, void *to) { - __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); + __synthesize_relative_insn(dest, from, to, JMP32_INSN_OPCODE); } +NOKPROBE_SYMBOL(synthesize_reljump); /* Insert a call instruction at address 'from', which calls address 'to'.*/ -void __kprobes synthesize_relcall(void *from, void *to) +void synthesize_relcall(void *dest, 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; + __synthesize_relative_insn(dest, from, to, CALL_INSN_OPCODE); } +NOKPROBE_SYMBOL(synthesize_relcall); /* - * Returns non-zero if opcode is boostable. + * Returns non-zero if INSN is boostable. * RIP relative instructions are adjusted at copying time in 64 bits mode */ -int __kprobes can_boost(kprobe_opcode_t *opcodes) +bool can_boost(struct insn *insn, void *addr) { kprobe_opcode_t opcode; - kprobe_opcode_t *orig_opcodes = opcodes; + insn_byte_t prefix; - 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++); + if (search_exception_tables((unsigned long)addr)) + return false; /* Page fault may occur on this address. */ /* 2nd-byte opcode */ - if (opcode == 0x0f) { - if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) - return 0; - return test_bit(*opcodes, + if (insn->opcode.nbytes == 2) + return test_bit(insn->opcode.bytes[1], (unsigned long *)twobyte_is_boostable); + + if (insn->opcode.nbytes != 1) + return false; + + for_each_insn_prefix(insn, prefix) { + insn_attr_t attr; + + attr = inat_get_opcode_attribute(prefix); + /* Can't boost Address-size override prefix and CS override prefix */ + if (prefix == 0x2e || inat_is_address_size_prefix(attr)) + return false; } - 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)); + opcode = insn->opcode.bytes[0]; + + switch (opcode) { + case 0x62: /* bound */ + case 0x70 ... 0x7f: /* Conditional jumps */ + case 0x9a: /* Call far */ + case 0xcc ... 0xce: /* software exceptions */ + case 0xd6: /* (UD) */ + case 0xd8 ... 0xdf: /* ESC */ + case 0xe0 ... 0xe3: /* LOOP*, JCXZ */ + case 0xe8 ... 0xe9: /* near Call, JMP */ + case 0xeb: /* Short JMP */ + case 0xf0 ... 0xf4: /* LOCK/REP, HLT */ + /* ... are not boostable */ + return false; + case 0xc0 ... 0xc1: /* Grp2 */ + case 0xd0 ... 0xd3: /* Grp2 */ + /* + * AMD uses nnn == 110 as SHL/SAL, but Intel makes it reserved. + */ + return X86_MODRM_REG(insn->modrm.bytes[0]) != 0b110; + case 0xf6 ... 0xf7: /* Grp3 */ + /* AMD uses nnn == 001 as TEST, but Intel makes it reserved. */ + return X86_MODRM_REG(insn->modrm.bytes[0]) != 0b001; + case 0xfe: /* Grp4 */ + /* Only INC and DEC are boostable */ + return X86_MODRM_REG(insn->modrm.bytes[0]) == 0b000 || + X86_MODRM_REG(insn->modrm.bytes[0]) == 0b001; + case 0xff: /* Grp5 */ + /* Only INC, DEC, and indirect JMP are boostable */ + return X86_MODRM_REG(insn->modrm.bytes[0]) == 0b000 || + X86_MODRM_REG(insn->modrm.bytes[0]) == 0b001 || + X86_MODRM_REG(insn->modrm.bytes[0]) == 0b100; 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); + return true; } } @@ -219,27 +204,44 @@ static unsigned long __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) { struct kprobe *kp; + bool faddr; kp = get_kprobe((void *)addr); - /* There is no probe, return original address */ - if (!kp) + faddr = ftrace_location(addr) == addr; + /* + * Use the current code if it is not modified by Kprobe + * and it cannot be modified by ftrace. + */ + if (!kp && !faddr) 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. + * 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, in case on normal Kprobe, 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. * - * 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. + * In case of Kprobes using ftrace, we do not have a copy of + * the original instruction. In fact, the ftrace location might + * be modified at anytime and even could be in an inconsistent state. + * Fortunately, we know that the original code is the ideal 5-byte + * long NOP. */ - memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); - buf[0] = kp->opcode; + if (copy_from_kernel_nofault(buf, (void *)addr, + MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) + return 0UL; + + if (faddr) + memcpy(buf, x86_nops[5], 5); + else + buf[0] = kp->opcode; return (unsigned long)buf; } @@ -247,6 +249,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) * 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. + * Returns zero if the instruction can not get recovered (or access failed). */ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) { @@ -259,15 +262,36 @@ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long add return __recover_probed_insn(buf, addr); } -/* Check if paddr is at an instruction boundary */ -static int __kprobes can_probe(unsigned long paddr) +/* Check if insn is INT or UD */ +static inline bool is_exception_insn(struct insn *insn) +{ + /* UD uses 0f escape */ + if (insn->opcode.bytes[0] == 0x0f) { + /* UD0 / UD1 / UD2 */ + return insn->opcode.bytes[1] == 0xff || + insn->opcode.bytes[1] == 0xb9 || + insn->opcode.bytes[1] == 0x0b; + } + + /* INT3 / INT n / INTO / INT1 */ + return insn->opcode.bytes[0] == 0xcc || + insn->opcode.bytes[0] == 0xcd || + insn->opcode.bytes[0] == 0xce || + insn->opcode.bytes[0] == 0xf1; +} + +/* + * Check if paddr is at an instruction boundary and that instruction can + * be probed + */ +static bool 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; + return false; /* Decode instructions */ addr = paddr - offset; @@ -281,65 +305,127 @@ static int __kprobes can_probe(unsigned long paddr) * 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); + if (!__addr) + return false; + + if (insn_decode_kernel(&insn, (void *)__addr) < 0) + return false; +#ifdef CONFIG_KGDB /* - * Another debugging subsystem might insert this breakpoint. - * In that case, we can't recover it. + * If there is a dynamically installed kgdb sw breakpoint, + * this function should not be probed. */ - if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) - return 0; + if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && + kgdb_has_hit_break(addr)) + return false; +#endif addr += insn.length; } - return (addr == paddr); + /* Check if paddr is at an instruction boundary */ + if (addr != paddr) + return false; + + __addr = recover_probed_instruction(buf, addr); + if (!__addr) + return false; + + if (insn_decode_kernel(&insn, (void *)__addr) < 0) + return false; + + /* INT and UD are special and should not be kprobed */ + if (is_exception_insn(&insn)) + return false; + + if (IS_ENABLED(CONFIG_CFI)) { + /* + * The compiler generates the following instruction sequence + * for indirect call checks and cfi.c decodes this; + * + * movl -<id>, %r10d ; 6 bytes + * addl -4(%reg), %r10d ; 4 bytes + * je .Ltmp1 ; 2 bytes + * ud2 ; <- regs->ip + * .Ltmp1: + * + * Also, these movl and addl are used for showing expected + * type. So those must not be touched. + */ + if (insn.opcode.value == 0xBA) + offset = 12; + else if (insn.opcode.value == 0x3) + offset = 6; + else + goto out; + + /* This movl/addl is used for decoding CFI. */ + if (is_cfi_trap(addr + offset)) + return false; + } + +out: + return true; } -/* - * Returns non-zero if opcode modifies the interrupt flag. - */ -static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) +/* If x86 supports IBT (ENDBR) it must be skipped. */ +kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, + bool *on_func_entry) { - /* Skip prefixes */ - insn = skip_prefixes(insn); + if (is_endbr((u32 *)addr)) { + *on_func_entry = !offset || offset == 4; + if (*on_func_entry) + offset = 4; - switch (*insn) { - case 0xfa: /* cli */ - case 0xfb: /* sti */ - case 0xcf: /* iret/iretd */ - case 0x9d: /* popf/popfd */ - return 1; + } else { + *on_func_entry = !offset; } - return 0; + return (kprobe_opcode_t *)(addr + offset); } /* - * 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. + * Copy an instruction with recovering modified instruction by kprobes + * and adjust the displacement if the instruction uses the %rip-relative + * addressing mode. Note that since @real will be the final place of copied + * instruction, displacement must be adjust by @real, not @dest. + * This returns the length of copied instruction, or 0 if it has an error. */ -int __kprobes __copy_instruction(u8 *dest, u8 *src) +int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn) { - struct insn insn; kprobe_opcode_t buf[MAX_INSN_SIZE]; + unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src); + int ret; + + if (!recovered_insn || !insn) + return 0; + + /* This can access kernel text if given address is not recovered */ + if (copy_from_kernel_nofault(dest, (void *)recovered_insn, + MAX_INSN_SIZE)) + return 0; + + ret = insn_decode_kernel(insn, dest); + if (ret < 0) + return 0; + + /* We can not probe force emulate prefixed instruction */ + if (insn_has_emulate_prefix(insn)) + return 0; - 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) + if (insn->opcode.bytes[0] == INT3_INSN_OPCODE) + return 0; + + /* We should not singlestep on the exception masking instructions */ + if (insn_masking_exception(insn)) return 0; - memcpy(dest, insn.kaddr, insn.length); #ifdef CONFIG_X86_64 - if (insn_rip_relative(&insn)) { + /* Only x86_64 has RIP relative instructions */ + 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 @@ -352,80 +438,383 @@ int __kprobes __copy_instruction(u8 *dest, u8 *src) * extension of the original signed 32-bit displacement would * have given. */ - newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest; + newdisp = (u8 *) src + (s64) insn->displacement.value + - (u8 *) real; if ((s64) (s32) newdisp != newdisp) { pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp); - pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value); return 0; } - disp = (u8 *) dest + insn_offset_displacement(&insn); + disp = (u8 *) dest + insn_offset_displacement(insn); *(s32 *) disp = (s32) newdisp; } #endif - return insn.length; + return insn->length; } -static int __kprobes arch_copy_kprobe(struct kprobe *p) +/* Prepare reljump or int3 right after instruction */ +static int prepare_singlestep(kprobe_opcode_t *buf, struct kprobe *p, + struct insn *insn) { - int ret; + int len = insn->length; + + if (!IS_ENABLED(CONFIG_PREEMPTION) && + !p->post_handler && can_boost(insn, p->addr) && + MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) { + /* + * These instructions can be executed directly if it + * jumps back to correct address. + */ + synthesize_reljump(buf + len, p->ainsn.insn + len, + p->addr + insn->length); + len += JMP32_INSN_SIZE; + p->ainsn.boostable = 1; + } else { + /* Otherwise, put an int3 for trapping singlestep */ + if (MAX_INSN_SIZE - len < INT3_INSN_SIZE) + return -ENOSPC; + + buf[len] = INT3_INSN_OPCODE; + len += INT3_INSN_SIZE; + } + + return len; +} + +/* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */ + +static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs) +{ + switch (p->ainsn.opcode) { + case 0xfa: /* cli */ + regs->flags &= ~(X86_EFLAGS_IF); + break; + case 0xfb: /* sti */ + regs->flags |= X86_EFLAGS_IF; + break; + case 0x9c: /* pushf */ + int3_emulate_push(regs, regs->flags); + break; + case 0x9d: /* popf */ + regs->flags = int3_emulate_pop(regs); + break; + } + regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; +} +NOKPROBE_SYMBOL(kprobe_emulate_ifmodifiers); + +static void kprobe_emulate_ret(struct kprobe *p, struct pt_regs *regs) +{ + int3_emulate_ret(regs); +} +NOKPROBE_SYMBOL(kprobe_emulate_ret); + +static void kprobe_emulate_call(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long func = regs->ip - INT3_INSN_SIZE + p->ainsn.size; + + func += p->ainsn.rel32; + int3_emulate_call(regs, func); +} +NOKPROBE_SYMBOL(kprobe_emulate_call); + +static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; + + ip += p->ainsn.rel32; + int3_emulate_jmp(regs, ip); +} +NOKPROBE_SYMBOL(kprobe_emulate_jmp); + +static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; + + int3_emulate_jcc(regs, p->ainsn.jcc.type, ip, p->ainsn.rel32); +} +NOKPROBE_SYMBOL(kprobe_emulate_jcc); + +static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; + bool match; + + if (p->ainsn.loop.type != 3) { /* LOOP* */ + if (p->ainsn.loop.asize == 32) + match = ((*(u32 *)®s->cx)--) != 0; +#ifdef CONFIG_X86_64 + else if (p->ainsn.loop.asize == 64) + match = ((*(u64 *)®s->cx)--) != 0; +#endif + else + match = ((*(u16 *)®s->cx)--) != 0; + } else { /* JCXZ */ + if (p->ainsn.loop.asize == 32) + match = *(u32 *)(®s->cx) == 0; +#ifdef CONFIG_X86_64 + else if (p->ainsn.loop.asize == 64) + match = *(u64 *)(®s->cx) == 0; +#endif + else + match = *(u16 *)(®s->cx) == 0; + } + + if (p->ainsn.loop.type == 0) /* LOOPNE */ + match = match && !(regs->flags & X86_EFLAGS_ZF); + else if (p->ainsn.loop.type == 1) /* LOOPE */ + match = match && (regs->flags & X86_EFLAGS_ZF); + + if (match) + ip += p->ainsn.rel32; + int3_emulate_jmp(regs, ip); +} +NOKPROBE_SYMBOL(kprobe_emulate_loop); + +static const int addrmode_regoffs[] = { + offsetof(struct pt_regs, ax), + offsetof(struct pt_regs, cx), + offsetof(struct pt_regs, dx), + offsetof(struct pt_regs, bx), + offsetof(struct pt_regs, sp), + offsetof(struct pt_regs, bp), + offsetof(struct pt_regs, si), + offsetof(struct pt_regs, di), +#ifdef CONFIG_X86_64 + offsetof(struct pt_regs, r8), + offsetof(struct pt_regs, r9), + offsetof(struct pt_regs, r10), + offsetof(struct pt_regs, r11), + offsetof(struct pt_regs, r12), + offsetof(struct pt_regs, r13), + offsetof(struct pt_regs, r14), + offsetof(struct pt_regs, r15), +#endif +}; + +static void kprobe_emulate_call_indirect(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg]; + + int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + p->ainsn.size); + int3_emulate_jmp(regs, regs_get_register(regs, offs)); +} +NOKPROBE_SYMBOL(kprobe_emulate_call_indirect); + +static void kprobe_emulate_jmp_indirect(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg]; + + int3_emulate_jmp(regs, regs_get_register(regs, offs)); +} +NOKPROBE_SYMBOL(kprobe_emulate_jmp_indirect); + +static int prepare_emulation(struct kprobe *p, struct insn *insn) +{ + insn_byte_t opcode = insn->opcode.bytes[0]; + + switch (opcode) { + case 0xfa: /* cli */ + case 0xfb: /* sti */ + case 0x9c: /* pushfl */ + case 0x9d: /* popf/popfd */ + /* + * IF modifiers must be emulated since it will enable interrupt while + * int3 single stepping. + */ + p->ainsn.emulate_op = kprobe_emulate_ifmodifiers; + p->ainsn.opcode = opcode; + break; + case 0xc2: /* ret/lret */ + case 0xc3: + case 0xca: + case 0xcb: + p->ainsn.emulate_op = kprobe_emulate_ret; + break; + case 0x9a: /* far call absolute -- segment is not supported */ + case 0xea: /* far jmp absolute -- segment is not supported */ + case 0xcc: /* int3 */ + case 0xcf: /* iret -- in-kernel IRET is not supported */ + return -EOPNOTSUPP; + break; + case 0xe8: /* near call relative */ + p->ainsn.emulate_op = kprobe_emulate_call; + if (insn->immediate.nbytes == 2) + p->ainsn.rel32 = *(s16 *)&insn->immediate.value; + else + p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + break; + case 0xeb: /* short jump relative */ + case 0xe9: /* near jump relative */ + p->ainsn.emulate_op = kprobe_emulate_jmp; + if (insn->immediate.nbytes == 1) + p->ainsn.rel32 = *(s8 *)&insn->immediate.value; + else if (insn->immediate.nbytes == 2) + p->ainsn.rel32 = *(s16 *)&insn->immediate.value; + else + p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + break; + case 0x70 ... 0x7f: + /* 1 byte conditional jump */ + p->ainsn.emulate_op = kprobe_emulate_jcc; + p->ainsn.jcc.type = opcode & 0xf; + p->ainsn.rel32 = insn->immediate.value; + break; + case 0x0f: + opcode = insn->opcode.bytes[1]; + if ((opcode & 0xf0) == 0x80) { + /* 2 bytes Conditional Jump */ + p->ainsn.emulate_op = kprobe_emulate_jcc; + p->ainsn.jcc.type = opcode & 0xf; + if (insn->immediate.nbytes == 2) + p->ainsn.rel32 = *(s16 *)&insn->immediate.value; + else + p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + } else if (opcode == 0x01 && + X86_MODRM_REG(insn->modrm.bytes[0]) == 0 && + X86_MODRM_MOD(insn->modrm.bytes[0]) == 3) { + /* VM extensions - not supported */ + return -EOPNOTSUPP; + } + break; + case 0xe0: /* Loop NZ */ + case 0xe1: /* Loop */ + case 0xe2: /* Loop */ + case 0xe3: /* J*CXZ */ + p->ainsn.emulate_op = kprobe_emulate_loop; + p->ainsn.loop.type = opcode & 0x3; + p->ainsn.loop.asize = insn->addr_bytes * 8; + p->ainsn.rel32 = *(s8 *)&insn->immediate.value; + break; + case 0xff: + /* + * Since the 0xff is an extended group opcode, the instruction + * is determined by the MOD/RM byte. + */ + opcode = insn->modrm.bytes[0]; + switch (X86_MODRM_REG(opcode)) { + case 0b010: /* FF /2, call near, absolute indirect */ + p->ainsn.emulate_op = kprobe_emulate_call_indirect; + break; + case 0b100: /* FF /4, jmp near, absolute indirect */ + p->ainsn.emulate_op = kprobe_emulate_jmp_indirect; + break; + case 0b011: /* FF /3, call far, absolute indirect */ + case 0b101: /* FF /5, jmp far, absolute indirect */ + return -EOPNOTSUPP; + } + + if (!p->ainsn.emulate_op) + break; + + if (insn->addr_bytes != sizeof(unsigned long)) + return -EOPNOTSUPP; /* Don't support different size */ + if (X86_MODRM_MOD(opcode) != 3) + return -EOPNOTSUPP; /* TODO: support memory addressing */ + + p->ainsn.indirect.reg = X86_MODRM_RM(opcode); +#ifdef CONFIG_X86_64 + if (X86_REX_B(insn->rex_prefix.value)) + p->ainsn.indirect.reg += 8; +#endif + break; + default: + break; + } + p->ainsn.size = insn->length; + + return 0; +} + +static int arch_copy_kprobe(struct kprobe *p) +{ + struct insn insn; + kprobe_opcode_t buf[MAX_INSN_SIZE]; + int ret, len; /* Copy an instruction with recovering if other optprobe modifies it.*/ - ret = __copy_instruction(p->ainsn.insn, p->addr); - if (!ret) + len = __copy_instruction(buf, p->addr, p->ainsn.insn, &insn); + if (!len) return -EINVAL; - /* - * __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; + /* Analyze the opcode and setup emulate functions */ + ret = prepare_emulation(p, &insn); + if (ret < 0) + return ret; - /* Check whether the instruction modifies Interrupt Flag or not */ - p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); + /* Add int3 for single-step or booster jmp */ + len = prepare_singlestep(buf, p, &insn); + if (len < 0) + return len; /* Also, displacement change doesn't affect the first byte */ - p->opcode = p->ainsn.insn[0]; + p->opcode = buf[0]; + + p->ainsn.tp_len = len; + perf_event_text_poke(p->ainsn.insn, NULL, 0, buf, len); + + /* OK, write back the instruction(s) into ROX insn buffer */ + text_poke(p->ainsn.insn, buf, len); return 0; } -int __kprobes arch_prepare_kprobe(struct kprobe *p) +int arch_prepare_kprobe(struct kprobe *p) { + int ret; + if (alternatives_text_reserved(p->addr, p->addr)) return -EINVAL; if (!can_probe((unsigned long)p->addr)) return -EILSEQ; + + memset(&p->ainsn, 0, sizeof(p->ainsn)); + /* insn: must be on special executable page on x86. */ p->ainsn.insn = get_insn_slot(); if (!p->ainsn.insn) return -ENOMEM; - return arch_copy_kprobe(p); + ret = arch_copy_kprobe(p); + if (ret) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; + } + + return ret; } -void __kprobes arch_arm_kprobe(struct kprobe *p) +void arch_arm_kprobe(struct kprobe *p) { - text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); + u8 int3 = INT3_INSN_OPCODE; + + text_poke(p->addr, &int3, 1); + smp_text_poke_sync_each_cpu(); + perf_event_text_poke(p->addr, &p->opcode, 1, &int3, 1); } -void __kprobes arch_disarm_kprobe(struct kprobe *p) +void arch_disarm_kprobe(struct kprobe *p) { + u8 int3 = INT3_INSN_OPCODE; + + perf_event_text_poke(p->addr, &int3, 1, &p->opcode, 1); text_poke(p->addr, &p->opcode, 1); + smp_text_poke_sync_each_cpu(); } -void __kprobes arch_remove_kprobe(struct kprobe *p) +void arch_remove_kprobe(struct kprobe *p) { if (p->ainsn.insn) { - free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); + /* Record the perf event before freeing the slot */ + perf_event_text_poke(p->ainsn.insn, p->ainsn.insn, + p->ainsn.tp_len, NULL, 0); + free_insn_slot(p->ainsn.insn, p->ainsn.boostable); p->ainsn.insn = NULL; } } -static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) +static nokprobe_inline void +save_previous_kprobe(struct kprobe_ctlblk *kcb) { kcb->prev_kprobe.kp = kprobe_running(); kcb->prev_kprobe.status = kcb->kprobe_status; @@ -433,7 +822,8 @@ static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; } -static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) +static nokprobe_inline void +restore_previous_kprobe(struct kprobe_ctlblk *kcb) { __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); kcb->kprobe_status = kcb->prev_kprobe.status; @@ -441,55 +831,43 @@ static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) 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) +static nokprobe_inline void +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 (p->ainsn.if_modifier) - 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); - } + = (regs->flags & X86_EFLAGS_IF); } -static void __kprobes restore_btf(void) +static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) { - if (test_thread_flag(TIF_BLOCKSTEP)) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl |= DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); + /* Restore back the original saved kprobes variables and continue. */ + if (kcb->kprobe_status == KPROBE_REENTER) { + /* This will restore both kcb and current_kprobe */ + restore_previous_kprobe(kcb); + } else { + /* + * Always update the kcb status because + * reset_curent_kprobe() doesn't update kcb. + */ + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (cur->post_handler) + cur->post_handler(cur, regs, 0); + reset_current_kprobe(); } } +NOKPROBE_SYMBOL(kprobe_post_process); -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) +static void 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) { +#if !defined(CONFIG_PREEMPTION) + if (p->ainsn.boostable) { /* Boost up -- we can execute copied instructions directly */ if (!reenter) reset_current_kprobe(); @@ -499,7 +877,6 @@ setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *k * stepping. */ regs->ip = (unsigned long)p->ainsn.insn; - preempt_enable_no_resched(); return; } #endif @@ -509,40 +886,73 @@ setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *k kcb->kprobe_status = KPROBE_REENTER; } else kcb->kprobe_status = KPROBE_HIT_SS; - /* Prepare real single stepping */ - clear_btf(); - regs->flags |= X86_EFLAGS_TF; + + if (p->ainsn.emulate_op) { + p->ainsn.emulate_op(p, regs); + kprobe_post_process(p, regs, kcb); + return; + } + + /* Disable interrupt, and set ip register on trampoline */ 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; + regs->ip = (unsigned long)p->ainsn.insn; +} +NOKPROBE_SYMBOL(setup_singlestep); + +/* + * Called after single-stepping. p->addr is the address of the + * instruction whose first byte has been replaced by the "int3" + * 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. We also doesn't use trap, but "int3" again + * right after the copied instruction. + * Different from the trap single-step, "int3" single-step can not + * handle the instruction which changes the ip register, e.g. jmp, + * call, conditional jmp, and the instructions which changes the IF + * flags because interrupt must be disabled around the single-stepping. + * Such instructions are software emulated, but others are single-stepped + * using "int3". + * + * When the 2nd "int3" handled, the regs->ip and regs->flags needs to + * be adjusted, so that we can resume execution on correct code. + */ +static void resume_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + unsigned long copy_ip = (unsigned long)p->ainsn.insn; + unsigned long orig_ip = (unsigned long)p->addr; + + /* Restore saved interrupt flag and ip register */ + regs->flags |= kcb->kprobe_saved_flags; + /* Note that regs->ip is executed int3 so must be a step back */ + regs->ip += (orig_ip - copy_ip) - INT3_INSN_SIZE; } +NOKPROBE_SYMBOL(resume_singlestep); /* * 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) +static int 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: + case KPROBE_HIT_SS: kprobes_inc_nmissed_count(p); setup_singlestep(p, regs, kcb, 1); break; - case KPROBE_HIT_SS: + case KPROBE_REENTER: /* 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); + pr_err("Unrecoverable kprobe detected.\n"); dump_kprobe(p); BUG(); default: @@ -553,25 +963,33 @@ reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb return 1; } +NOKPROBE_SYMBOL(reenter_kprobe); + +static nokprobe_inline int kprobe_is_ss(struct kprobe_ctlblk *kcb) +{ + return (kcb->kprobe_status == KPROBE_HIT_SS || + kcb->kprobe_status == KPROBE_REENTER); +} /* * 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) +int kprobe_int3_handler(struct pt_regs *regs) { kprobe_opcode_t *addr; struct kprobe *p; struct kprobe_ctlblk *kcb; + if (user_mode(regs)) + return 0; + 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(). + * We don't want to be preempted for the entire duration of kprobe + * processing. Since int3 and debug trap disables irqs and we clear + * IF while singlestepping, it must be no preemptible. */ - preempt_disable(); kcb = get_kprobe_ctlblk(); p = get_kprobe(addr); @@ -587,319 +1005,40 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) /* * 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. + * pre-handler and it returned non-zero, that means + * user handler setup registers to exit to another + * instruction, we must skip the single stepping. */ if (!p->pre_handler || !p->pre_handler(p, regs)) setup_singlestep(p, regs, kcb, 0); + else + reset_current_kprobe(); 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); + } else if (kprobe_is_ss(kcb)) { + p = kprobe_running(); + if ((unsigned long)p->ainsn.insn < regs->ip && + (unsigned long)p->ainsn.insn + MAX_INSN_SIZE > regs->ip) { + /* Most provably this is the second int3 for singlestep */ + resume_singlestep(p, regs, kcb); + kprobe_post_process(p, regs, kcb); return 1; } } /* else: not a kprobe fault; let the kernel handle it */ - preempt_enable_no_resched(); return 0; } +NOKPROBE_SYMBOL(kprobe_int3_handler); -/* - * 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 *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, 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, 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, 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) +int kprobe_fault_handler(struct pt_regs *regs, int trapnr) { 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: + if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) { + /* This must happen on single-stepping */ + WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS && + kcb->kprobe_status != KPROBE_REENTER); /* * We are here because the instruction being single * stepped caused a page fault. We reset the current @@ -908,170 +1047,35 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) * normal page fault. */ regs->ip = (unsigned long)cur->addr; + + /* + * If the IF flag was set before the kprobe hit, + * don't touch it: + */ 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"); + return 0; } +NOKPROBE_SYMBOL(kprobe_fault_handler); -int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +int __init arch_populate_kprobe_blacklist(void) { - 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; + return kprobe_add_area_blacklist((unsigned long)__entry_text_start, + (unsigned long)__entry_text_end); } int __init arch_init_kprobes(void) { - return arch_init_optprobes(); + return 0; } -int __kprobes arch_trampoline_kprobe(struct kprobe *p) +int arch_trampoline_kprobe(struct kprobe *p) { return 0; } |