1 /*
2  * Copyright (c) 2013-2019, Intel Corporation
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  *  * Redistributions of source code must retain the above copyright notice,
8  *    this list of conditions and the following disclaimer.
9  *  * Redistributions in binary form must reproduce the above copyright notice,
10  *    this list of conditions and the following disclaimer in the documentation
11  *    and/or other materials provided with the distribution.
12  *  * Neither the name of Intel Corporation nor the names of its contributors
13  *    may be used to endorse or promote products derived from this software
14  *    without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26  * POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #ifndef PT_RETSTACK_H
30 #define PT_RETSTACK_H
31 
32 #include <stdint.h>
33 
34 
35 /* The size of the call/return stack in number of entries. */
36 enum {
37 	pt_retstack_size	= 64
38 };
39 
40 /* A stack of return addresses used for return compression. */
41 struct pt_retstack {
42 	/* The stack of return addresses.
43 	 *
44 	 * We use one additional entry in order to distinguish a full from
45 	 * an empty stack.
46 	 */
47 	uint64_t stack[pt_retstack_size + 1];
48 
49 	/* The top of the stack. */
50 	uint8_t top;
51 
52 	/* The bottom of the stack. */
53 	uint8_t bottom;
54 };
55 
56 /* Initialize (or reset) a call/return stack. */
57 extern void pt_retstack_init(struct pt_retstack *);
58 
59 /* Test a call/return stack for emptiness.
60  *
61  * Returns zero if @retstack contains at least one element.
62  * Returns a positive integer if @retstack is empty.
63  * Returns -pte_invalid if @retstack is NULL.
64  */
65 extern int pt_retstack_is_empty(const struct pt_retstack *retstack);
66 
67 /* Pop and return the topmost IP.
68  *
69  * If @ip is not NULL, provides the topmost return address on success.
70  * If @retstack is not empty, pops the topmost return address on success.
71  *
72  * Returns zero on success.
73  * Returns -pte_invalid if @retstack is NULL.
74  * Returns -pte_noip if @retstack is empty.
75  */
76 extern int pt_retstack_pop(struct pt_retstack *retstack, uint64_t *ip);
77 
78 /* Push a return address onto the stack.
79  *
80  * Pushes @ip onto @retstack.
81  * If @retstack is full, drops the oldest return address.
82  *
83  * Returns zero on success.
84  */
85 extern int pt_retstack_push(struct pt_retstack *retstack, uint64_t ip);
86 
87 #endif /* PT_RETSTACK_H */
88