1fbcd1dd1Schristos /*
2fbcd1dd1Schristos * Copyright (c) 2010 The FreeBSD Foundation
3fbcd1dd1Schristos * All rights reserved.
4fbcd1dd1Schristos *
5fbcd1dd1Schristos * This software was developed by Rui Paulo under sponsorship from the
6fbcd1dd1Schristos * FreeBSD Foundation.
7fbcd1dd1Schristos *
8fbcd1dd1Schristos * Redistribution and use in source and binary forms, with or without
9fbcd1dd1Schristos * modification, are permitted provided that the following conditions
10fbcd1dd1Schristos * are met:
11fbcd1dd1Schristos * 1. Redistributions of source code must retain the above copyright
12fbcd1dd1Schristos * notice, this list of conditions and the following disclaimer.
13fbcd1dd1Schristos * 2. Redistributions in binary form must reproduce the above copyright
14fbcd1dd1Schristos * notice, this list of conditions and the following disclaimer in the
15fbcd1dd1Schristos * documentation and/or other materials provided with the distribution.
16fbcd1dd1Schristos *
17fbcd1dd1Schristos * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18fbcd1dd1Schristos * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19fbcd1dd1Schristos * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20fbcd1dd1Schristos * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21fbcd1dd1Schristos * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22fbcd1dd1Schristos * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23fbcd1dd1Schristos * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24fbcd1dd1Schristos * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25fbcd1dd1Schristos * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26fbcd1dd1Schristos * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27fbcd1dd1Schristos * SUCH DAMAGE.
28fbcd1dd1Schristos */
29fbcd1dd1Schristos
30fbcd1dd1Schristos #include <sys/cdefs.h>
3152ebe1c2Schristos #ifdef __FBSDID
32fbcd1dd1Schristos __FBSDID("$FreeBSD: head/lib/libproc/proc_bkpt.c 287106 2015-08-24 12:17:15Z andrew $");
3352ebe1c2Schristos #else
34*da66a31aSchristos __RCSID("$NetBSD: proc_bkpt.c,v 1.6 2018/07/20 20:50:34 christos Exp $");
3552ebe1c2Schristos #endif
36fbcd1dd1Schristos
37fbcd1dd1Schristos #include <sys/types.h>
38fbcd1dd1Schristos #include <sys/ptrace.h>
39fbcd1dd1Schristos #include <sys/wait.h>
40fbcd1dd1Schristos
41fbcd1dd1Schristos #include <assert.h>
429a58287bSchristos #include <string.h>
43fbcd1dd1Schristos #include <err.h>
44fbcd1dd1Schristos #include <errno.h>
4552ebe1c2Schristos #include <inttypes.h>
46fbcd1dd1Schristos #include <signal.h>
47fbcd1dd1Schristos #include <stdio.h>
48fbcd1dd1Schristos #include "_libproc.h"
49fbcd1dd1Schristos
509a58287bSchristos #ifndef PTRACE_BREAKPOINT
51fbcd1dd1Schristos #error "Add support for your architecture"
52fbcd1dd1Schristos #endif
53fbcd1dd1Schristos
54fbcd1dd1Schristos static int
proc_stop(struct proc_handle * phdl)55fbcd1dd1Schristos proc_stop(struct proc_handle *phdl)
56fbcd1dd1Schristos {
57fbcd1dd1Schristos int status;
58fbcd1dd1Schristos
59fbcd1dd1Schristos if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
60fbcd1dd1Schristos DPRINTF("kill %d", proc_getpid(phdl));
61fbcd1dd1Schristos return (-1);
62fbcd1dd1Schristos } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
63fbcd1dd1Schristos DPRINTF("waitpid %d", proc_getpid(phdl));
64fbcd1dd1Schristos return (-1);
65fbcd1dd1Schristos } else if (!WIFSTOPPED(status)) {
66fbcd1dd1Schristos DPRINTFX("waitpid: unexpected status 0x%x", status);
67fbcd1dd1Schristos return (-1);
68fbcd1dd1Schristos }
69fbcd1dd1Schristos
70fbcd1dd1Schristos return (0);
71fbcd1dd1Schristos }
72fbcd1dd1Schristos
73fbcd1dd1Schristos int
proc_bkptset(struct proc_handle * phdl,uintptr_t address,proc_breakpoint_t * saved)74fbcd1dd1Schristos proc_bkptset(struct proc_handle *phdl, uintptr_t address,
759a58287bSchristos proc_breakpoint_t *saved)
76fbcd1dd1Schristos {
77fbcd1dd1Schristos struct ptrace_io_desc piod;
78fbcd1dd1Schristos unsigned long paddr, caddr;
79fbcd1dd1Schristos int ret = 0, stopped;
809a58287bSchristos proc_breakpoint_t copy;
81fbcd1dd1Schristos
82fbcd1dd1Schristos if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
83fbcd1dd1Schristos phdl->status == PS_IDLE) {
84fbcd1dd1Schristos errno = ENOENT;
85fbcd1dd1Schristos return (-1);
86fbcd1dd1Schristos }
87fbcd1dd1Schristos
88fe6dc027Srin DPRINTFX("adding breakpoint at 0x%" PRIxPTR, address);
89fbcd1dd1Schristos
90fbcd1dd1Schristos stopped = 0;
91fbcd1dd1Schristos if (phdl->status != PS_STOP) {
92fbcd1dd1Schristos if (proc_stop(phdl) != 0)
93fbcd1dd1Schristos return (-1);
94fbcd1dd1Schristos stopped = 1;
95fbcd1dd1Schristos }
96fbcd1dd1Schristos
97fbcd1dd1Schristos /*
98fbcd1dd1Schristos * Read the original instruction.
99fbcd1dd1Schristos */
100fbcd1dd1Schristos caddr = address;
101fbcd1dd1Schristos paddr = 0;
102fbcd1dd1Schristos piod.piod_op = PIOD_READ_I;
103fbcd1dd1Schristos piod.piod_offs = (void *)caddr;
1049a58287bSchristos piod.piod_addr = (void *)saved->data;
1059a58287bSchristos piod.piod_len = sizeof(saved->data);
10658ec3b3bSchristos if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
107fbcd1dd1Schristos DPRINTF("ERROR: couldn't read instruction at address 0x%"
108fe6dc027Srin PRIxPTR, address);
109fbcd1dd1Schristos ret = -1;
110fbcd1dd1Schristos goto done;
111fbcd1dd1Schristos }
112fbcd1dd1Schristos /*
113fbcd1dd1Schristos * Write a breakpoint instruction to that address.
114fbcd1dd1Schristos */
115fbcd1dd1Schristos caddr = address;
116fbcd1dd1Schristos piod.piod_op = PIOD_WRITE_I;
117fbcd1dd1Schristos piod.piod_offs = (void *)caddr;
1189a58287bSchristos piod.piod_addr = (void *)PTRACE_BREAKPOINT;
1199a58287bSchristos piod.piod_len = sizeof(PTRACE_BREAKPOINT);
12058ec3b3bSchristos if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
121fbcd1dd1Schristos DPRINTF("ERROR: couldn't write instruction at address 0x%"
122fe6dc027Srin PRIxPTR, address);
123fbcd1dd1Schristos ret = -1;
124fbcd1dd1Schristos goto done;
125fbcd1dd1Schristos }
126fbcd1dd1Schristos
127fbcd1dd1Schristos done:
128fbcd1dd1Schristos if (stopped)
129fbcd1dd1Schristos /* Restart the process if we had to stop it. */
130fbcd1dd1Schristos proc_continue(phdl);
131fbcd1dd1Schristos
132fbcd1dd1Schristos return (ret);
133fbcd1dd1Schristos }
134fbcd1dd1Schristos
135fbcd1dd1Schristos int
proc_bkptdel(struct proc_handle * phdl,uintptr_t address,proc_breakpoint_t * saved)136fbcd1dd1Schristos proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
1379a58287bSchristos proc_breakpoint_t *saved)
138fbcd1dd1Schristos {
139fbcd1dd1Schristos struct ptrace_io_desc piod;
140fbcd1dd1Schristos unsigned long paddr, caddr;
141fbcd1dd1Schristos int ret = 0, stopped;
142fbcd1dd1Schristos
143fbcd1dd1Schristos if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
144fbcd1dd1Schristos phdl->status == PS_IDLE) {
145fbcd1dd1Schristos errno = ENOENT;
146fbcd1dd1Schristos return (-1);
147fbcd1dd1Schristos }
148fbcd1dd1Schristos
149fe6dc027Srin DPRINTFX("removing breakpoint at 0x%" PRIxPTR, address);
150fbcd1dd1Schristos
151fbcd1dd1Schristos stopped = 0;
152fbcd1dd1Schristos if (phdl->status != PS_STOP) {
153fbcd1dd1Schristos if (proc_stop(phdl) != 0)
154fbcd1dd1Schristos return (-1);
155fbcd1dd1Schristos stopped = 1;
156fbcd1dd1Schristos }
157fbcd1dd1Schristos
158fbcd1dd1Schristos /*
159fbcd1dd1Schristos * Overwrite the breakpoint instruction that we setup previously.
160fbcd1dd1Schristos */
161fbcd1dd1Schristos caddr = address;
162fbcd1dd1Schristos piod.piod_op = PIOD_WRITE_I;
163fbcd1dd1Schristos piod.piod_offs = (void *)caddr;
1649a58287bSchristos piod.piod_addr = (void *)saved->data;
1659a58287bSchristos piod.piod_len = sizeof(saved->data);
16658ec3b3bSchristos if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
167fbcd1dd1Schristos DPRINTF("ERROR: couldn't write instruction at address 0x%"
168fe6dc027Srin PRIxPTR, address);
169fbcd1dd1Schristos ret = -1;
170fbcd1dd1Schristos }
171fbcd1dd1Schristos
172fbcd1dd1Schristos if (stopped)
173fbcd1dd1Schristos /* Restart the process if we had to stop it. */
174fbcd1dd1Schristos proc_continue(phdl);
175fbcd1dd1Schristos
176fbcd1dd1Schristos return (ret);
177fbcd1dd1Schristos }
178fbcd1dd1Schristos
179fbcd1dd1Schristos /*
180fbcd1dd1Schristos * Decrement pc so that we delete the breakpoint at the correct
1819a58287bSchristos * address, i.e. at the breakpoint instruction address.
182fbcd1dd1Schristos *
183fbcd1dd1Schristos * This is only needed on some architectures where the pc value
184fbcd1dd1Schristos * when reading registers points at the instruction after the
185fbcd1dd1Schristos * breakpoint, e.g. x86.
186fbcd1dd1Schristos */
187fbcd1dd1Schristos void
proc_bkptregadj(unsigned long * pc)188fbcd1dd1Schristos proc_bkptregadj(unsigned long *pc)
189fbcd1dd1Schristos {
190fbcd1dd1Schristos
191fbcd1dd1Schristos (void)pc;
1929a58287bSchristos #ifdef PTRACE_BREAKPOINT_ADJ
1939a58287bSchristos *pc = *pc - PTRACE_BREAKPOINT_ADJ;
194fbcd1dd1Schristos #endif
195fbcd1dd1Schristos }
196fbcd1dd1Schristos
197fbcd1dd1Schristos /*
198fbcd1dd1Schristos * Step over the breakpoint.
199fbcd1dd1Schristos */
200fbcd1dd1Schristos int
proc_bkptexec(struct proc_handle * phdl,proc_breakpoint_t * saved)2019a58287bSchristos proc_bkptexec(struct proc_handle *phdl, proc_breakpoint_t *saved)
202fbcd1dd1Schristos {
203fbcd1dd1Schristos unsigned long pc;
2049a58287bSchristos proc_breakpoint_t samesaved;
205fbcd1dd1Schristos int status;
206fbcd1dd1Schristos
207fbcd1dd1Schristos if (proc_regget(phdl, REG_PC, &pc) < 0) {
208fbcd1dd1Schristos DPRINTFX("ERROR: couldn't get PC register");
209fbcd1dd1Schristos return (-1);
210fbcd1dd1Schristos }
211fbcd1dd1Schristos proc_bkptregadj(&pc);
212fbcd1dd1Schristos if (proc_bkptdel(phdl, pc, saved) < 0) {
213fbcd1dd1Schristos DPRINTFX("ERROR: couldn't delete breakpoint");
214fbcd1dd1Schristos return (-1);
215fbcd1dd1Schristos }
216fbcd1dd1Schristos /*
217fbcd1dd1Schristos * Go back in time and step over the new instruction just
218fbcd1dd1Schristos * set up by proc_bkptdel().
219fbcd1dd1Schristos */
220fbcd1dd1Schristos proc_regset(phdl, REG_PC, pc);
221*da66a31aSchristos #ifdef PT_STEP
22258ec3b3bSchristos if (ptrace(PT_STEP, proc_getpid(phdl), (void *)(intptr_t)1, 0) < 0) {
223fbcd1dd1Schristos DPRINTFX("ERROR: ptrace step failed");
224fbcd1dd1Schristos return (-1);
225fbcd1dd1Schristos }
226*da66a31aSchristos #endif
227fbcd1dd1Schristos proc_wstatus(phdl);
228fbcd1dd1Schristos status = proc_getwstat(phdl);
229fbcd1dd1Schristos if (!WIFSTOPPED(status)) {
230fbcd1dd1Schristos DPRINTFX("ERROR: don't know why process stopped");
231fbcd1dd1Schristos return (-1);
232fbcd1dd1Schristos }
233fbcd1dd1Schristos /*
234fbcd1dd1Schristos * Restore the breakpoint. The saved instruction should be
235fbcd1dd1Schristos * the same as the one that we were passed in.
236fbcd1dd1Schristos */
237fbcd1dd1Schristos if (proc_bkptset(phdl, pc, &samesaved) < 0) {
238fbcd1dd1Schristos DPRINTFX("ERROR: couldn't restore breakpoint");
239fbcd1dd1Schristos return (-1);
240fbcd1dd1Schristos }
2419a58287bSchristos
2429a58287bSchristos assert(memcmp(saved, &samesaved, sizeof(samesaved)) == 0);
243fbcd1dd1Schristos
244fbcd1dd1Schristos return (0);
245fbcd1dd1Schristos }
246