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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Kernel Probes (KProbes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2004
19 *
20 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
21 * Probes initial implementation ( includes contributions from
22 * Rusty Russell).
23 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
24 * interface to access function arguments.
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010025 * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
26 * <prasanna@in.ibm.com> adapted for x86_64 from i386.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 * 2005-Mar Roland McGrath <roland@redhat.com>
28 * Fixed to handle %rip-relative addressing mode correctly.
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010029 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
30 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
31 * <prasanna@in.ibm.com> added function-return probes.
32 * 2005-May Rusty Lynch <rusty.lynch@intel.com>
33 * Added function return probes functionality
34 * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
35 * kprobe-booster and kretprobe-booster for i386.
Masami Hiramatsuda07ab02008-01-30 13:31:21 +010036 * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
37 * and kretprobe-booster for x86-64
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010038 * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
39 * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
40 * unified x86 kprobes code.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 */
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <linux/kprobes.h>
44#include <linux/ptrace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/string.h>
46#include <linux/slab.h>
Quentin Barnesb506a9d2008-01-30 13:32:32 +010047#include <linux/hardirq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <linux/preempt.h>
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -080049#include <linux/module.h>
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -070050#include <linux/kdebug.h>
Masami Hiramatsub46b3d72009-08-13 16:34:28 -040051#include <linux/kallsyms.h>
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070052
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +010053#include <asm/cacheflush.h>
54#include <asm/desc.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070055#include <asm/pgtable.h>
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -080056#include <asm/uaccess.h>
Andi Kleen19d36cc2007-07-22 11:12:31 +020057#include <asm/alternative.h>
Masami Hiramatsub46b3d72009-08-13 16:34:28 -040058#include <asm/insn.h>
K.Prasad62edab92009-06-01 23:47:06 +053059#include <asm/debugreg.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Linus Torvalds1da177e2005-04-16 15:20:36 -070061void jprobe_return_end(void);
62
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -080063DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
64DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
H. Peter Anvin98272ed2009-10-12 14:14:10 -070066#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +010067
68#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
69 (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
70 (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
71 (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
72 (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
73 << (row % 32))
74 /*
75 * Undefined/reserved opcodes, conditional jump, Opcode Extension
76 * Groups, and some special opcodes can not boost.
77 */
78static const u32 twobyte_is_boostable[256 / 32] = {
79 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
80 /* ---------------------------------------------- */
81 W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */
82 W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */
83 W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */
84 W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
85 W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
86 W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */
87 W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */
88 W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
89 W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */
90 W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
91 W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */
92 W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */
93 W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
94 W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */
95 W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */
96 W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */
97 /* ----------------------------------------------- */
98 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
99};
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100100#undef W
101
Masami Hiramatsuf438d912007-10-16 01:27:49 -0700102struct kretprobe_blackpoint kretprobe_blacklist[] = {
103 {"__switch_to", }, /* This function switches only current task, but
104 doesn't switch kernel stack.*/
105 {NULL, NULL} /* Terminator */
106};
107const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
108
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100109/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100110static void __kprobes set_jmp_op(void *from, void *to)
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100111{
112 struct __arch_jmp_op {
113 char op;
114 s32 raddr;
115 } __attribute__((packed)) * jop;
116 jop = (struct __arch_jmp_op *)from;
117 jop->raddr = (s32)((long)(to) - ((long)(from) + 5));
118 jop->op = RELATIVEJUMP_INSTRUCTION;
119}
120
121/*
Harvey Harrison99309272008-01-30 13:32:14 +0100122 * Check for the REX prefix which can only exist on X86_64
123 * X86_32 always returns 0
124 */
125static int __kprobes is_REX_prefix(kprobe_opcode_t *insn)
126{
127#ifdef CONFIG_X86_64
128 if ((*insn & 0xf0) == 0x40)
129 return 1;
130#endif
131 return 0;
132}
133
134/*
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100135 * Returns non-zero if opcode is boostable.
136 * RIP relative instructions are adjusted at copying time in 64 bits mode
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100137 */
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100138static int __kprobes can_boost(kprobe_opcode_t *opcodes)
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100139{
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100140 kprobe_opcode_t opcode;
141 kprobe_opcode_t *orig_opcodes = opcodes;
142
Jaswinder Singh Rajputcde5edb2009-03-18 17:37:45 +0530143 if (search_exception_tables((unsigned long)opcodes))
Masami Hiramatsu30390882009-03-16 18:57:22 -0400144 return 0; /* Page fault may occur on this address. */
145
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100146retry:
147 if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
148 return 0;
149 opcode = *(opcodes++);
150
151 /* 2nd-byte opcode */
152 if (opcode == 0x0f) {
153 if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
154 return 0;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100155 return test_bit(*opcodes,
156 (unsigned long *)twobyte_is_boostable);
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100157 }
158
159 switch (opcode & 0xf0) {
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100160#ifdef CONFIG_X86_64
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100161 case 0x40:
162 goto retry; /* REX prefix is boostable */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100163#endif
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100164 case 0x60:
165 if (0x63 < opcode && opcode < 0x67)
166 goto retry; /* prefixes */
167 /* can't boost Address-size override and bound */
168 return (opcode != 0x62 && opcode != 0x67);
169 case 0x70:
170 return 0; /* can't boost conditional jump */
171 case 0xc0:
172 /* can't boost software-interruptions */
173 return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
174 case 0xd0:
175 /* can boost AA* and XLAT */
176 return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
177 case 0xe0:
178 /* can boost in/out and absolute jmps */
179 return ((opcode & 0x04) || opcode == 0xea);
180 case 0xf0:
181 if ((opcode & 0x0c) == 0 && opcode != 0xf1)
182 goto retry; /* lock/rep(ne) prefix */
183 /* clear and set flags are boostable */
184 return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
185 default:
186 /* segment override prefixes are boostable */
187 if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
188 goto retry; /* prefixes */
189 /* CS override prefix and call are not boostable */
190 return (opcode != 0x2e && opcode != 0x9a);
191 }
192}
193
Masami Hiramatsub46b3d72009-08-13 16:34:28 -0400194/* Recover the probed instruction at addr for further analysis. */
195static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
196{
197 struct kprobe *kp;
198 kp = get_kprobe((void *)addr);
199 if (!kp)
200 return -EINVAL;
201
202 /*
203 * Basically, kp->ainsn.insn has an original instruction.
204 * However, RIP-relative instruction can not do single-stepping
205 * at different place, fix_riprel() tweaks the displacement of
206 * that instruction. In that case, we can't recover the instruction
207 * from the kp->ainsn.insn.
208 *
209 * On the other hand, kp->opcode has a copy of the first byte of
210 * the probed instruction, which is overwritten by int3. And
211 * the instruction at kp->addr is not modified by kprobes except
212 * for the first byte, we can recover the original instruction
213 * from it and kp->opcode.
214 */
215 memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
216 buf[0] = kp->opcode;
217 return 0;
218}
219
220/* Dummy buffers for kallsyms_lookup */
221static char __dummy_buf[KSYM_NAME_LEN];
222
223/* Check if paddr is at an instruction boundary */
224static int __kprobes can_probe(unsigned long paddr)
225{
226 int ret;
227 unsigned long addr, offset = 0;
228 struct insn insn;
229 kprobe_opcode_t buf[MAX_INSN_SIZE];
230
231 if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf))
232 return 0;
233
234 /* Decode instructions */
235 addr = paddr - offset;
236 while (addr < paddr) {
237 kernel_insn_init(&insn, (void *)addr);
238 insn_get_opcode(&insn);
239
240 /*
241 * Check if the instruction has been modified by another
242 * kprobe, in which case we replace the breakpoint by the
243 * original instruction in our buffer.
244 */
245 if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
246 ret = recover_probed_instruction(buf, addr);
247 if (ret)
248 /*
249 * Another debugging subsystem might insert
250 * this breakpoint. In that case, we can't
251 * recover it.
252 */
253 return 0;
254 kernel_insn_init(&insn, buf);
255 }
256 insn_get_length(&insn);
257 addr += insn.length;
258 }
259
260 return (addr == paddr);
261}
262
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263/*
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100264 * Returns non-zero if opcode modifies the interrupt flag.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 */
Andrew Morton86454192007-11-26 20:42:19 +0100266static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
268 switch (*insn) {
269 case 0xfa: /* cli */
270 case 0xfb: /* sti */
271 case 0xcf: /* iret/iretd */
272 case 0x9d: /* popf/popfd */
273 return 1;
274 }
Harvey Harrison99309272008-01-30 13:32:14 +0100275
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100276 /*
Harvey Harrison99309272008-01-30 13:32:14 +0100277 * on X86_64, 0x40-0x4f are REX prefixes so we need to look
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100278 * at the next byte instead.. but of course not recurse infinitely
279 */
Harvey Harrison99309272008-01-30 13:32:14 +0100280 if (is_REX_prefix(insn))
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100281 return is_IF_modifier(++insn);
Harvey Harrison99309272008-01-30 13:32:14 +0100282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 return 0;
284}
285
286/*
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100287 * Adjust the displacement if the instruction uses the %rip-relative
288 * addressing mode.
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100289 * If it does, Return the address of the 32-bit displacement word.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 * If not, return null.
Harvey Harrison31f80e42008-01-30 13:32:16 +0100291 * Only applicable to 64-bit x86.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 */
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100293static void __kprobes fix_riprel(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294{
Harvey Harrison31f80e42008-01-30 13:32:16 +0100295#ifdef CONFIG_X86_64
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400296 struct insn insn;
297 kernel_insn_init(&insn, p->ainsn.insn);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400299 if (insn_rip_relative(&insn)) {
300 s64 newdisp;
301 u8 *disp;
302 insn_get_displacement(&insn);
303 /*
304 * The copied instruction uses the %rip-relative addressing
305 * mode. Adjust the displacement for the difference between
306 * the original location of this instruction and the location
307 * of the copy that will actually be run. The tricky bit here
308 * is making sure that the sign extension happens correctly in
309 * this calculation, since we need a signed 32-bit result to
310 * be sign-extended to 64 bits when it's added to the %rip
311 * value and yield the same 64-bit result that the sign-
312 * extension of the original signed 32-bit displacement would
313 * have given.
314 */
315 newdisp = (u8 *) p->addr + (s64) insn.displacement.value -
316 (u8 *) p->ainsn.insn;
317 BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
318 disp = (u8 *) p->ainsn.insn + insn_offset_displacement(&insn);
319 *(s32 *) disp = (s32) newdisp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 }
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100321#endif
Harvey Harrison31f80e42008-01-30 13:32:16 +0100322}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800324static void __kprobes arch_copy_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100326 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
Harvey Harrison31f80e42008-01-30 13:32:16 +0100327
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100328 fix_riprel(p);
Harvey Harrison31f80e42008-01-30 13:32:16 +0100329
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100330 if (can_boost(p->addr))
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100331 p->ainsn.boostable = 0;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100332 else
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100333 p->ainsn.boostable = -1;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100334
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700335 p->opcode = *p->addr;
336}
337
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100338int __kprobes arch_prepare_kprobe(struct kprobe *p)
339{
Masami Hiramatsub46b3d72009-08-13 16:34:28 -0400340 if (!can_probe((unsigned long)p->addr))
341 return -EILSEQ;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100342 /* insn: must be on special executable page on x86. */
343 p->ainsn.insn = get_insn_slot();
344 if (!p->ainsn.insn)
345 return -ENOMEM;
346 arch_copy_kprobe(p);
347 return 0;
348}
349
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700350void __kprobes arch_arm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700351{
Andi Kleen19d36cc2007-07-22 11:12:31 +0200352 text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700353}
354
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700355void __kprobes arch_disarm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700356{
Andi Kleen19d36cc2007-07-22 11:12:31 +0200357 text_poke(p->addr, &p->opcode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358}
359
Ananth N Mavinakayanahalli0498b632006-01-09 20:52:46 -0800360void __kprobes arch_remove_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361{
Masami Hiramatsu12941562009-01-06 14:41:50 -0800362 if (p->ainsn.insn) {
363 free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
364 p->ainsn.insn = NULL;
365 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366}
367
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700368static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700369{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800370 kcb->prev_kprobe.kp = kprobe_running();
371 kcb->prev_kprobe.status = kcb->kprobe_status;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100372 kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags;
373 kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700374}
375
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700376static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700377{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800378 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
379 kcb->kprobe_status = kcb->prev_kprobe.status;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100380 kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags;
381 kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700382}
383
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700384static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800385 struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700386{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800387 __get_cpu_var(current_kprobe) = p;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100388 kcb->kprobe_saved_flags = kcb->kprobe_old_flags
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100389 = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700390 if (is_IF_modifier(p->ainsn.insn))
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100391 kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700392}
393
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100394static void __kprobes clear_btf(void)
Roland McGrath1ecc7982008-01-30 13:30:54 +0100395{
396 if (test_thread_flag(TIF_DEBUGCTLMSR))
Jan Beulich5b0e5082008-03-10 13:11:17 +0000397 update_debugctlmsr(0);
Roland McGrath1ecc7982008-01-30 13:30:54 +0100398}
399
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100400static void __kprobes restore_btf(void)
Roland McGrath1ecc7982008-01-30 13:30:54 +0100401{
402 if (test_thread_flag(TIF_DEBUGCTLMSR))
Jan Beulich5b0e5082008-03-10 13:11:17 +0000403 update_debugctlmsr(current->thread.debugctlmsr);
Roland McGrath1ecc7982008-01-30 13:30:54 +0100404}
405
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700406static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407{
Roland McGrath1ecc7982008-01-30 13:30:54 +0100408 clear_btf();
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100409 regs->flags |= X86_EFLAGS_TF;
410 regs->flags &= ~X86_EFLAGS_IF;
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100411 /* single step inline if the instruction is an int3 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 if (p->opcode == BREAKPOINT_INSTRUCTION)
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100413 regs->ip = (unsigned long)p->addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 else
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100415 regs->ip = (unsigned long)p->ainsn.insn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416}
417
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700418void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700419 struct pt_regs *regs)
Rusty Lynch73649da2005-06-23 00:09:23 -0700420{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100421 unsigned long *sara = stack_addr(regs);
Rusty Lynch73649da2005-06-23 00:09:23 -0700422
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700423 ri->ret_addr = (kprobe_opcode_t *) *sara;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100424
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700425 /* Replace the return addr with trampoline addr */
426 *sara = (unsigned long) &kretprobe_trampoline;
Rusty Lynch73649da2005-06-23 00:09:23 -0700427}
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100428
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100429static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
430 struct kprobe_ctlblk *kcb)
431{
Masami Hiramatsu5a4ccaf2009-01-06 21:15:32 +0100432#if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER)
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100433 if (p->ainsn.boostable == 1 && !p->post_handler) {
434 /* Boost up -- we can execute copied instructions directly */
435 reset_current_kprobe();
436 regs->ip = (unsigned long)p->ainsn.insn;
437 preempt_enable_no_resched();
438 return;
439 }
440#endif
441 prepare_singlestep(p, regs);
442 kcb->kprobe_status = KPROBE_HIT_SS;
443}
444
Harvey Harrison40102d42008-01-30 13:32:02 +0100445/*
446 * We have reentered the kprobe_handler(), since another probe was hit while
447 * within the handler. We save the original kprobes variables and just single
448 * step on the instruction of the new probe without calling any user handlers.
449 */
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100450static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
451 struct kprobe_ctlblk *kcb)
Harvey Harrison40102d42008-01-30 13:32:02 +0100452{
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100453 switch (kcb->kprobe_status) {
454 case KPROBE_HIT_SSDONE:
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100455 case KPROBE_HIT_ACTIVE:
Abhishek Sagarfb8830e2008-01-30 13:33:13 +0100456 save_previous_kprobe(kcb);
457 set_current_kprobe(p, regs, kcb);
458 kprobes_inc_nmissed_count(p);
459 prepare_singlestep(p, regs);
460 kcb->kprobe_status = KPROBE_REENTER;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100461 break;
462 case KPROBE_HIT_SS:
Masami Hiramatsue9afe9e2009-08-27 13:22:58 -0400463 /* A probe has been hit in the codepath leading up to, or just
464 * after, single-stepping of a probed instruction. This entire
465 * codepath should strictly reside in .kprobes.text section.
466 * Raise a BUG or we'll continue in an endless reentering loop
467 * and eventually a stack overflow.
468 */
469 printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n",
470 p->addr);
471 dump_kprobe(p);
472 BUG();
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100473 default:
474 /* impossible cases */
475 WARN_ON(1);
Abhishek Sagarfb8830e2008-01-30 13:33:13 +0100476 return 0;
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100477 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100478
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100479 return 1;
Harvey Harrison40102d42008-01-30 13:32:02 +0100480}
Rusty Lynch73649da2005-06-23 00:09:23 -0700481
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100482/*
483 * Interrupts are disabled on entry as trap3 is an interrupt gate and they
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200484 * remain disabled throughout this function.
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100485 */
486static int __kprobes kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100488 kprobe_opcode_t *addr;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100489 struct kprobe *p;
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800490 struct kprobe_ctlblk *kcb;
491
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100492 addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100493 if (*addr != BREAKPOINT_INSTRUCTION) {
494 /*
495 * The breakpoint instruction was removed right
496 * after we hit it. Another cpu has removed
497 * either a probepoint or a debugger breakpoint
498 * at this address. In either case, no further
499 * handling of this interrupt is appropriate.
500 * Back up over the (now missing) int3 and run
501 * the original instruction.
502 */
503 regs->ip = (unsigned long)addr;
504 return 1;
505 }
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100506
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800507 /*
508 * We don't want to be preempted for the entire
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100509 * duration of kprobe processing. We conditionally
510 * re-enable preemption at the end of this function,
511 * and also in reenter_kprobe() and setup_singlestep().
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800512 */
513 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100515 kcb = get_kprobe_ctlblk();
Harvey Harrisonb9760152008-01-30 13:32:19 +0100516 p = get_kprobe(addr);
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100517
Harvey Harrisonb9760152008-01-30 13:32:19 +0100518 if (p) {
Harvey Harrisonb9760152008-01-30 13:32:19 +0100519 if (kprobe_running()) {
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100520 if (reenter_kprobe(p, regs, kcb))
521 return 1;
Harvey Harrisonb9760152008-01-30 13:32:19 +0100522 } else {
523 set_current_kprobe(p, regs, kcb);
524 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100525
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 /*
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100527 * If we have no pre-handler or it returned 0, we
528 * continue with normal processing. If we have a
529 * pre-handler and it returned non-zero, it prepped
530 * for calling the break_handler below on re-entry
531 * for jprobe processing, so get out doing nothing
532 * more here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 */
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100534 if (!p->pre_handler || !p->pre_handler(p, regs))
535 setup_singlestep(p, regs, kcb);
536 return 1;
Harvey Harrisonb9760152008-01-30 13:32:19 +0100537 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100538 } else if (kprobe_running()) {
539 p = __get_cpu_var(current_kprobe);
540 if (p->break_handler && p->break_handler(p, regs)) {
541 setup_singlestep(p, regs, kcb);
542 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100544 } /* else: not a kprobe fault; let the kernel handle it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800546 preempt_enable_no_resched();
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100547 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548}
549
550/*
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100551 * When a retprobed function returns, this code saves registers and
552 * calls trampoline_handler() runs, which calls the kretprobe's handler.
Rusty Lynch73649da2005-06-23 00:09:23 -0700553 */
Harvey Harrisonf1452d42008-02-14 15:23:53 -0800554static void __used __kprobes kretprobe_trampoline_holder(void)
Harvey Harrison10175792008-01-30 13:33:01 +0100555{
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100556 asm volatile (
557 ".global kretprobe_trampoline\n"
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100558 "kretprobe_trampoline: \n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100559#ifdef CONFIG_X86_64
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100560 /* We don't bother saving the ss register */
561 " pushq %rsp\n"
562 " pushfq\n"
563 /*
564 * Skip cs, ip, orig_ax.
565 * trampoline_handler() will plug in these values
566 */
567 " subq $24, %rsp\n"
568 " pushq %rdi\n"
569 " pushq %rsi\n"
570 " pushq %rdx\n"
571 " pushq %rcx\n"
572 " pushq %rax\n"
573 " pushq %r8\n"
574 " pushq %r9\n"
575 " pushq %r10\n"
576 " pushq %r11\n"
577 " pushq %rbx\n"
578 " pushq %rbp\n"
579 " pushq %r12\n"
580 " pushq %r13\n"
581 " pushq %r14\n"
582 " pushq %r15\n"
583 " movq %rsp, %rdi\n"
584 " call trampoline_handler\n"
585 /* Replace saved sp with true return address. */
586 " movq %rax, 152(%rsp)\n"
587 " popq %r15\n"
588 " popq %r14\n"
589 " popq %r13\n"
590 " popq %r12\n"
591 " popq %rbp\n"
592 " popq %rbx\n"
593 " popq %r11\n"
594 " popq %r10\n"
595 " popq %r9\n"
596 " popq %r8\n"
597 " popq %rax\n"
598 " popq %rcx\n"
599 " popq %rdx\n"
600 " popq %rsi\n"
601 " popq %rdi\n"
602 /* Skip orig_ax, ip, cs */
603 " addq $24, %rsp\n"
604 " popfq\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100605#else
606 " pushf\n"
607 /*
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400608 * Skip cs, ip, orig_ax and gs.
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100609 * trampoline_handler() will plug in these values
610 */
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400611 " subl $16, %esp\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100612 " pushl %fs\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100613 " pushl %es\n"
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400614 " pushl %ds\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100615 " pushl %eax\n"
616 " pushl %ebp\n"
617 " pushl %edi\n"
618 " pushl %esi\n"
619 " pushl %edx\n"
620 " pushl %ecx\n"
621 " pushl %ebx\n"
622 " movl %esp, %eax\n"
623 " call trampoline_handler\n"
624 /* Move flags to cs */
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400625 " movl 56(%esp), %edx\n"
626 " movl %edx, 52(%esp)\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100627 /* Replace saved flags with true return address. */
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400628 " movl %eax, 56(%esp)\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100629 " popl %ebx\n"
630 " popl %ecx\n"
631 " popl %edx\n"
632 " popl %esi\n"
633 " popl %edi\n"
634 " popl %ebp\n"
635 " popl %eax\n"
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400636 /* Skip ds, es, fs, gs, orig_ax and ip */
637 " addl $24, %esp\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100638 " popf\n"
639#endif
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100640 " ret\n");
Harvey Harrison10175792008-01-30 13:33:01 +0100641}
Rusty Lynch73649da2005-06-23 00:09:23 -0700642
643/*
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100644 * Called from kretprobe_trampoline
Rusty Lynch73649da2005-06-23 00:09:23 -0700645 */
Harvey Harrisonf1452d42008-02-14 15:23:53 -0800646static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
Rusty Lynch73649da2005-06-23 00:09:23 -0700647{
bibo,mao62c27be2006-10-02 02:17:33 -0700648 struct kretprobe_instance *ri = NULL;
bibo,mao99219a32006-10-02 02:17:35 -0700649 struct hlist_head *head, empty_rp;
bibo,mao62c27be2006-10-02 02:17:33 -0700650 struct hlist_node *node, *tmp;
Ananth N Mavinakayanahalli991a51d2005-11-07 01:00:14 -0800651 unsigned long flags, orig_ret_address = 0;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100652 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
Rusty Lynch73649da2005-06-23 00:09:23 -0700653
bibo,mao99219a32006-10-02 02:17:35 -0700654 INIT_HLIST_HEAD(&empty_rp);
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700655 kretprobe_hash_lock(current, &head, &flags);
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100656 /* fixup registers */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100657#ifdef CONFIG_X86_64
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100658 regs->cs = __KERNEL_CS;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100659#else
660 regs->cs = __KERNEL_CS | get_kernel_rpl();
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400661 regs->gs = 0;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100662#endif
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100663 regs->ip = trampoline_address;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100664 regs->orig_ax = ~0UL;
Rusty Lynch73649da2005-06-23 00:09:23 -0700665
Rusty Lynchba8af122005-06-27 15:17:10 -0700666 /*
667 * It is possible to have multiple instances associated with a given
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100668 * task either because multiple functions in the call path have
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200669 * return probes installed on them, and/or more than one
Rusty Lynchba8af122005-06-27 15:17:10 -0700670 * return probe was registered for a target function.
671 *
672 * We can handle this because:
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100673 * - instances are always pushed into the head of the list
Rusty Lynchba8af122005-06-27 15:17:10 -0700674 * - when multiple return probes are registered for the same
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100675 * function, the (chronologically) first instance's ret_addr
676 * will be the real return address, and all the rest will
677 * point to kretprobe_trampoline.
Rusty Lynchba8af122005-06-27 15:17:10 -0700678 */
679 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
bibo,mao62c27be2006-10-02 02:17:33 -0700680 if (ri->task != current)
Rusty Lynchba8af122005-06-27 15:17:10 -0700681 /* another task is sharing our hash bucket */
bibo,mao62c27be2006-10-02 02:17:33 -0700682 continue;
Rusty Lynch73649da2005-06-23 00:09:23 -0700683
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100684 if (ri->rp && ri->rp->handler) {
685 __get_cpu_var(current_kprobe) = &ri->rp->kp;
686 get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
Rusty Lynchba8af122005-06-27 15:17:10 -0700687 ri->rp->handler(ri, regs);
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100688 __get_cpu_var(current_kprobe) = NULL;
689 }
Rusty Lynch73649da2005-06-23 00:09:23 -0700690
Rusty Lynchba8af122005-06-27 15:17:10 -0700691 orig_ret_address = (unsigned long)ri->ret_addr;
bibo,mao99219a32006-10-02 02:17:35 -0700692 recycle_rp_inst(ri, &empty_rp);
Rusty Lynchba8af122005-06-27 15:17:10 -0700693
694 if (orig_ret_address != trampoline_address)
695 /*
696 * This is the real return address. Any other
697 * instances associated with this task are for
698 * other calls deeper on the call stack
699 */
700 break;
Rusty Lynch73649da2005-06-23 00:09:23 -0700701 }
Rusty Lynchba8af122005-06-27 15:17:10 -0700702
Ananth N Mavinakayanahalli0f95b7f2007-05-08 00:28:27 -0700703 kretprobe_assert(ri, orig_ret_address, trampoline_address);
Rusty Lynchba8af122005-06-27 15:17:10 -0700704
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700705 kretprobe_hash_unlock(current, &flags);
Rusty Lynchba8af122005-06-27 15:17:10 -0700706
bibo,mao99219a32006-10-02 02:17:35 -0700707 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
708 hlist_del(&ri->hlist);
709 kfree(ri);
710 }
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100711 return (void *)orig_ret_address;
Rusty Lynch73649da2005-06-23 00:09:23 -0700712}
713
714/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 * Called after single-stepping. p->addr is the address of the
716 * instruction whose first byte has been replaced by the "int 3"
717 * instruction. To avoid the SMP problems that can occur when we
718 * temporarily put back the original opcode to single-step, we
719 * single-stepped a copy of the instruction. The address of this
720 * copy is p->ainsn.insn.
721 *
722 * This function prepares to return from the post-single-step
723 * interrupt. We have to fix up the stack as follows:
724 *
725 * 0) Except in the case of absolute or indirect jump or call instructions,
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100726 * the new ip is relative to the copied instruction. We need to make
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 * it relative to the original instruction.
728 *
729 * 1) If the single-stepped instruction was pushfl, then the TF and IF
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100730 * flags are set in the just-pushed flags, and may need to be cleared.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 *
732 * 2) If the single-stepped instruction was a call, the return address
733 * that is atop the stack is the address following the copied instruction.
734 * We need to make it the address following the original instruction.
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100735 *
736 * If this is the first time we've single-stepped the instruction at
737 * this probepoint, and the instruction is boostable, boost it: add a
738 * jump instruction after the copied instruction, that jumps to the next
739 * instruction after the probepoint.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800741static void __kprobes resume_execution(struct kprobe *p,
742 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100744 unsigned long *tos = stack_addr(regs);
745 unsigned long copy_ip = (unsigned long)p->ainsn.insn;
746 unsigned long orig_ip = (unsigned long)p->addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 kprobe_opcode_t *insn = p->ainsn.insn;
748
749 /*skip the REX prefix*/
Harvey Harrison99309272008-01-30 13:32:14 +0100750 if (is_REX_prefix(insn))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 insn++;
752
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100753 regs->flags &= ~X86_EFLAGS_TF;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 switch (*insn) {
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100755 case 0x9c: /* pushfl */
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100756 *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100757 *tos |= kcb->kprobe_old_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 break;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100759 case 0xc2: /* iret/ret/lret */
760 case 0xc3:
Prasanna S Panchamukhi0b9e2ca2005-05-05 16:15:40 -0700761 case 0xca:
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100762 case 0xcb:
763 case 0xcf:
764 case 0xea: /* jmp absolute -- ip is correct */
765 /* ip is already adjusted, no more changes required */
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100766 p->ainsn.boostable = 1;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100767 goto no_change;
768 case 0xe8: /* call relative - Fix return addr */
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100769 *tos = orig_ip + (*tos - copy_ip);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 break;
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100771#ifdef CONFIG_X86_32
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100772 case 0x9a: /* call absolute -- same as call absolute, indirect */
773 *tos = orig_ip + (*tos - copy_ip);
774 goto no_change;
775#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 case 0xff:
Satoshi Oshimadc49e342006-05-20 15:00:21 -0700777 if ((insn[1] & 0x30) == 0x10) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100778 /*
779 * call absolute, indirect
780 * Fix return addr; ip is correct.
781 * But this is not boostable
782 */
783 *tos = orig_ip + (*tos - copy_ip);
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100784 goto no_change;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100785 } else if (((insn[1] & 0x31) == 0x20) ||
786 ((insn[1] & 0x31) == 0x21)) {
787 /*
788 * jmp near and far, absolute indirect
789 * ip is correct. And this is boostable
790 */
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100791 p->ainsn.boostable = 1;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100792 goto no_change;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 default:
795 break;
796 }
797
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100798 if (p->ainsn.boostable == 0) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100799 if ((regs->ip > copy_ip) &&
800 (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100801 /*
802 * These instructions can be executed directly if it
803 * jumps back to correct address.
804 */
805 set_jmp_op((void *)regs->ip,
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100806 (void *)orig_ip + (regs->ip - copy_ip));
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100807 p->ainsn.boostable = 1;
808 } else {
809 p->ainsn.boostable = -1;
810 }
811 }
812
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100813 regs->ip += orig_ip - copy_ip;
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100814
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100815no_change:
Roland McGrath1ecc7982008-01-30 13:30:54 +0100816 restore_btf();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817}
818
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100819/*
820 * Interrupts are disabled on entry as trap1 is an interrupt gate and they
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200821 * remain disabled throughout this function.
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100822 */
823static int __kprobes post_kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800825 struct kprobe *cur = kprobe_running();
826 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
827
828 if (!cur)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 return 0;
830
Yakov Lerneracb5b8a2008-03-16 03:21:21 -0500831 resume_execution(cur, regs, kcb);
832 regs->flags |= kcb->kprobe_saved_flags;
Yakov Lerneracb5b8a2008-03-16 03:21:21 -0500833
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800834 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
835 kcb->kprobe_status = KPROBE_HIT_SSDONE;
836 cur->post_handler(cur, regs, 0);
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700837 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100839 /* Restore back the original saved kprobes variables and continue. */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800840 if (kcb->kprobe_status == KPROBE_REENTER) {
841 restore_previous_kprobe(kcb);
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700842 goto out;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700843 }
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800844 reset_current_kprobe();
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700845out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 preempt_enable_no_resched();
847
848 /*
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100849 * if somebody else is singlestepping across a probe point, flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 * will have TF set, in which case, continue the remaining processing
851 * of do_debug, as if this is not a probe hit.
852 */
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100853 if (regs->flags & X86_EFLAGS_TF)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 return 0;
855
856 return 1;
857}
858
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700859int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800861 struct kprobe *cur = kprobe_running();
862 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
863
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100864 switch (kcb->kprobe_status) {
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800865 case KPROBE_HIT_SS:
866 case KPROBE_REENTER:
867 /*
868 * We are here because the instruction being single
869 * stepped caused a page fault. We reset the current
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100870 * kprobe and the ip points back to the probe address
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800871 * and allow the page fault handler to continue as a
872 * normal page fault.
873 */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100874 regs->ip = (unsigned long)cur->addr;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100875 regs->flags |= kcb->kprobe_old_flags;
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800876 if (kcb->kprobe_status == KPROBE_REENTER)
877 restore_previous_kprobe(kcb);
878 else
879 reset_current_kprobe();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 preempt_enable_no_resched();
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800881 break;
882 case KPROBE_HIT_ACTIVE:
883 case KPROBE_HIT_SSDONE:
884 /*
885 * We increment the nmissed count for accounting,
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100886 * we can also use npre/npostfault count for accounting
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800887 * these specific fault cases.
888 */
889 kprobes_inc_nmissed_count(cur);
890
891 /*
892 * We come here because instructions in the pre/post
893 * handler caused the page_fault, this could happen
894 * if handler tries to access user space by
895 * copy_from_user(), get_user() etc. Let the
896 * user-specified handler try to fix it first.
897 */
898 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
899 return 1;
900
901 /*
902 * In case the user-specified fault handler returned
903 * zero, try to fix up.
904 */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100905 if (fixup_exception(regs))
906 return 1;
Harvey Harrison6d485832008-01-30 13:31:41 +0100907
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800908 /*
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100909 * fixup routine could not handle it,
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800910 * Let do_page_fault() fix it.
911 */
912 break;
913 default:
914 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 }
916 return 0;
917}
918
919/*
920 * Wrapper routine for handling exceptions.
921 */
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700922int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
923 unsigned long val, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924{
Jan Engelhardtade1af72008-01-30 13:33:23 +0100925 struct die_args *args = data;
Ananth N Mavinakayanahalli66ff2d062005-11-07 01:00:07 -0800926 int ret = NOTIFY_DONE;
927
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100928 if (args->regs && user_mode_vm(args->regs))
bibo,mao2326c772006-03-26 01:38:21 -0800929 return ret;
930
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 switch (val) {
932 case DIE_INT3:
933 if (kprobe_handler(args->regs))
Ananth N Mavinakayanahalli66ff2d062005-11-07 01:00:07 -0800934 ret = NOTIFY_STOP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935 break;
936 case DIE_DEBUG:
K.Prasad62edab92009-06-01 23:47:06 +0530937 if (post_kprobe_handler(args->regs)) {
938 /*
939 * Reset the BS bit in dr6 (pointed by args->err) to
940 * denote completion of processing
941 */
942 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
Ananth N Mavinakayanahalli66ff2d062005-11-07 01:00:07 -0800943 ret = NOTIFY_STOP;
K.Prasad62edab92009-06-01 23:47:06 +0530944 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 break;
946 case DIE_GPF:
Quentin Barnesb506a9d2008-01-30 13:32:32 +0100947 /*
948 * To be potentially processing a kprobe fault and to
949 * trust the result from kprobe_running(), we have
950 * be non-preemptible.
951 */
952 if (!preemptible() && kprobe_running() &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 kprobe_fault_handler(args->regs, args->trapnr))
Ananth N Mavinakayanahalli66ff2d062005-11-07 01:00:07 -0800954 ret = NOTIFY_STOP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955 break;
956 default:
957 break;
958 }
Ananth N Mavinakayanahalli66ff2d062005-11-07 01:00:07 -0800959 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960}
961
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700962int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963{
964 struct jprobe *jp = container_of(p, struct jprobe, kp);
965 unsigned long addr;
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800966 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800968 kcb->jprobe_saved_regs = *regs;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100969 kcb->jprobe_saved_sp = stack_addr(regs);
970 addr = (unsigned long)(kcb->jprobe_saved_sp);
971
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 /*
973 * As Linus pointed out, gcc assumes that the callee
974 * owns the argument space and could overwrite it, e.g.
975 * tailcall optimization. So, to be absolutely safe
976 * we also save and restore enough stack bytes to cover
977 * the argument area.
978 */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800979 memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100980 MIN_STACK_SIZE(addr));
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100981 regs->flags &= ~X86_EFLAGS_IF;
Peter Zijlstra58dfe882007-10-11 22:25:25 +0200982 trace_hardirqs_off();
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100983 regs->ip = (unsigned long)(jp->entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 return 1;
985}
986
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700987void __kprobes jprobe_return(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800989 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
990
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100991 asm volatile (
992#ifdef CONFIG_X86_64
993 " xchg %%rbx,%%rsp \n"
994#else
995 " xchgl %%ebx,%%esp \n"
996#endif
997 " int3 \n"
998 " .globl jprobe_return_end\n"
999 " jprobe_return_end: \n"
1000 " nop \n"::"b"
1001 (kcb->jprobe_saved_sp):"memory");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002}
1003
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -07001004int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001006 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
H. Peter Anvin65ea5b02008-01-30 13:30:56 +01001007 u8 *addr = (u8 *) (regs->ip - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008 struct jprobe *jp = container_of(p, struct jprobe, kp);
1009
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001010 if ((addr > (u8 *) jprobe_return) &&
1011 (addr < (u8 *) jprobe_return_end)) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001012 if (stack_addr(regs) != kcb->jprobe_saved_sp) {
Masami Hiramatsu29b6cd72007-12-18 18:05:58 +01001013 struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001014 printk(KERN_ERR
1015 "current sp %p does not match saved sp %p\n",
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001016 stack_addr(regs), kcb->jprobe_saved_sp);
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001017 printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 show_registers(saved_regs);
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001019 printk(KERN_ERR "Current registers\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 show_registers(regs);
1021 BUG();
1022 }
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001023 *regs = kcb->jprobe_saved_regs;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001024 memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
1025 kcb->jprobes_stack,
1026 MIN_STACK_SIZE(kcb->jprobe_saved_sp));
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -08001027 preempt_enable_no_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 return 1;
1029 }
1030 return 0;
1031}
Rusty Lynchba8af122005-06-27 15:17:10 -07001032
Rusty Lynch67729262005-07-05 18:54:50 -07001033int __init arch_init_kprobes(void)
Rusty Lynchba8af122005-06-27 15:17:10 -07001034{
Masami Hiramatsuda07ab02008-01-30 13:31:21 +01001035 return 0;
Rusty Lynchba8af122005-06-27 15:17:10 -07001036}
Ananth N Mavinakayanahallibf8f6e5b2007-05-08 00:34:16 -07001037
1038int __kprobes arch_trampoline_kprobe(struct kprobe *p)
1039{
Ananth N Mavinakayanahallibf8f6e5b2007-05-08 00:34:16 -07001040 return 0;
1041}