1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/init.h>
3 #include <linux/seq_file.h>
4 #include <linux/fs.h>
5 #include <linux/mm.h>
6 #include <linux/proc_fs.h>
7 #include <linux/slab.h>
8 #include <xen/interface/platform.h>
9 #include <asm/xen/hypercall.h>
10 #include <xen/xen-ops.h>
11 #include "xenfs.h"
12 
13 
14 #define XEN_KSYM_NAME_LEN 127 /* Hypervisor may have different name length */
15 
16 struct xensyms {
17 	struct xen_platform_op op;
18 	char *name;
19 	uint32_t namelen;
20 };
21 
22 /* Grab next output page from the hypervisor */
xensyms_next_sym(struct xensyms * xs)23 static int xensyms_next_sym(struct xensyms *xs)
24 {
25 	int ret;
26 	struct xenpf_symdata *symdata = &xs->op.u.symdata;
27 	uint64_t symnum;
28 
29 	memset(xs->name, 0, xs->namelen);
30 	symdata->namelen = xs->namelen;
31 
32 	symnum = symdata->symnum;
33 
34 	ret = HYPERVISOR_platform_op(&xs->op);
35 	if (ret < 0)
36 		return ret;
37 
38 	/*
39 	 * If hypervisor's symbol didn't fit into the buffer then allocate
40 	 * a larger buffer and try again.
41 	 */
42 	if (unlikely(symdata->namelen > xs->namelen)) {
43 		kfree(xs->name);
44 
45 		xs->namelen = symdata->namelen;
46 		xs->name = kzalloc(xs->namelen, GFP_KERNEL);
47 		if (!xs->name)
48 			return -ENOMEM;
49 
50 		set_xen_guest_handle(symdata->name, xs->name);
51 		symdata->symnum--; /* Rewind */
52 
53 		ret = HYPERVISOR_platform_op(&xs->op);
54 		if (ret < 0)
55 			return ret;
56 	}
57 
58 	if (symdata->symnum == symnum)
59 		/* End of symbols */
60 		return 1;
61 
62 	return 0;
63 }
64 
xensyms_start(struct seq_file * m,loff_t * pos)65 static void *xensyms_start(struct seq_file *m, loff_t *pos)
66 {
67 	struct xensyms *xs = (struct xensyms *)m->private;
68 
69 	xs->op.u.symdata.symnum = *pos;
70 
71 	if (xensyms_next_sym(xs))
72 		return NULL;
73 
74 	return m->private;
75 }
76 
xensyms_next(struct seq_file * m,void * p,loff_t * pos)77 static void *xensyms_next(struct seq_file *m, void *p, loff_t *pos)
78 {
79 	struct xensyms *xs = (struct xensyms *)m->private;
80 
81 	xs->op.u.symdata.symnum = ++(*pos);
82 
83 	if (xensyms_next_sym(xs))
84 		return NULL;
85 
86 	return p;
87 }
88 
xensyms_show(struct seq_file * m,void * p)89 static int xensyms_show(struct seq_file *m, void *p)
90 {
91 	struct xensyms *xs = (struct xensyms *)m->private;
92 	struct xenpf_symdata *symdata = &xs->op.u.symdata;
93 
94 	seq_printf(m, "%016llx %c %s\n", symdata->address,
95 		   symdata->type, xs->name);
96 
97 	return 0;
98 }
99 
xensyms_stop(struct seq_file * m,void * p)100 static void xensyms_stop(struct seq_file *m, void *p)
101 {
102 }
103 
104 static const struct seq_operations xensyms_seq_ops = {
105 	.start = xensyms_start,
106 	.next = xensyms_next,
107 	.show = xensyms_show,
108 	.stop = xensyms_stop,
109 };
110 
xensyms_open(struct inode * inode,struct file * file)111 static int xensyms_open(struct inode *inode, struct file *file)
112 {
113 	struct seq_file *m;
114 	struct xensyms *xs;
115 	int ret;
116 
117 	ret = seq_open_private(file, &xensyms_seq_ops,
118 			       sizeof(struct xensyms));
119 	if (ret)
120 		return ret;
121 
122 	m = file->private_data;
123 	xs = (struct xensyms *)m->private;
124 
125 	xs->namelen = XEN_KSYM_NAME_LEN + 1;
126 	xs->name = kzalloc(xs->namelen, GFP_KERNEL);
127 	if (!xs->name) {
128 		seq_release_private(inode, file);
129 		return -ENOMEM;
130 	}
131 	set_xen_guest_handle(xs->op.u.symdata.name, xs->name);
132 	xs->op.cmd = XENPF_get_symbol;
133 	xs->op.u.symdata.namelen = xs->namelen;
134 
135 	return 0;
136 }
137 
xensyms_release(struct inode * inode,struct file * file)138 static int xensyms_release(struct inode *inode, struct file *file)
139 {
140 	struct seq_file *m = file->private_data;
141 	struct xensyms *xs = (struct xensyms *)m->private;
142 
143 	kfree(xs->name);
144 	return seq_release_private(inode, file);
145 }
146 
147 const struct file_operations xensyms_ops = {
148 	.open = xensyms_open,
149 	.read = seq_read,
150 	.llseek = seq_lseek,
151 	.release = xensyms_release
152 };
153