Bug Summary

File:obj-scan-build/../xen/grant.c
Location:line 132, column 6
Description:Branch condition evaluates to a garbage value

Annotated Source Code

1/*
2 * Copyright (C) 2006-2009 Free Software Foundation
3 *
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 the program ; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19#include <sys/types.h>
20#include <mach/vm_param.h>
21#include <machine/spl.h>
22#include <vm/pmap.h>
23#include <vm/vm_map.h>
24#include <vm/vm_kern.h>
25#include "grant.h"
26
27#define NR_RESERVED_ENTRIES8 8
28#define NR_GRANT_PAGES4 4
29
30decl_simple_lock_data(static,lock)static struct simple_lock_data_empty lock;;
31static struct grant_entry *grants;
32static vm_map_entry_t grants_map_entry;
33static int last_grant = NR_RESERVED_ENTRIES8;
34
35static grant_ref_t free_grants = -1;
36
37static grant_ref_t grant_alloc(void) {
38 grant_ref_t grant;
39 if (free_grants != -1) {
40 grant = free_grants;
41 free_grants = grants[grant].frame;
42 } else {
43 grant = last_grant++;
44 if (grant == (NR_GRANT_PAGES4 * PAGE_SIZE(1 << 12))/sizeof(*grants))
45 panic("not enough grant entries, increase NR_GRANT_PAGES");
46 }
47 return grant;
48}
49
50static void grant_free(grant_ref_t grant) {
51 grants[grant].frame = free_grants;
52 free_grants = grant;
53}
54
55static grant_ref_t grant_set(domid_t domid, unsigned long mfn, uint16_t flags) {
56 spl_t spl = splhigh();
57 simple_lock(&lock);
58
59 grant_ref_t grant = grant_alloc();
60 grants[grant].domid = domid;
61 grants[grant].frame = mfn;
62 wmb()__asm__ __volatile__("lock; addl $0,0(%esp)");
63 grants[grant].flags = flags;
64
65 simple_unlock(&lock)((void)(&lock));
66 splx(spl);
67 return grant;
68}
69
70grant_ref_t hyp_grant_give(domid_t domid, unsigned long frame, int readonly) {
71 return grant_set(domid, pfn_to_mfn(frame)(mfn_list[frame]),
72 GTF_permit_access(1U<<0) | (readonly ? GTF_readonly(1U<<(2)) : 0));
73}
74
75grant_ref_t hyp_grant_accept_transfer(domid_t domid, unsigned long frame) {
76 return grant_set(domid, frame, GTF_accept_transfer(2U<<0));
77}
78
79unsigned long hyp_grant_finish_transfer(grant_ref_t grant) {
80 unsigned long frame;
81 spl_t spl = splhigh();
82 simple_lock(&lock);
83
84 if (!(grants[grant].flags & GTF_transfer_committed(1U<<(2))))
85 panic("grant transfer %x not committed\n", grant);
86 while (!(grants[grant].flags & GTF_transfer_completed(1U<<(3))))
87 machine_relax();
88 rmb()__asm__ __volatile__("lock; addl $0,0(%esp)");
89 frame = grants[grant].frame;
90 grant_free(grant);
91
92 simple_unlock(&lock)((void)(&lock));
93 splx(spl);
94 return frame;
95}
96
97void hyp_grant_takeback(grant_ref_t grant) {
98 spl_t spl = splhigh();
99 simple_lock(&lock);
100
101 if (grants[grant].flags & (GTF_reading(1U<<(3))|GTF_writing(1U<<(4))))
102 panic("grant %d still in use (%lx)\n", grant, grants[grant].flags);
103
104 /* Note: this is not safe, a cmpxchg is needed, see grant_table.h */
105 grants[grant].flags = 0;
106 wmb()__asm__ __volatile__("lock; addl $0,0(%esp)");
107
108 grant_free(grant);
109
110 simple_unlock(&lock)((void)(&lock));
111 splx(spl);
112}
113
114void *hyp_grant_address(grant_ref_t grant) {
115 return &grants[grant];
116}
117
118void hyp_grant_init(void) {
119 struct gnttab_setup_table setup;
120 unsigned long frame[NR_GRANT_PAGES4];
121 long ret;
122 int i;
123 vm_offset_t addr;
124
125 setup.dom = DOMID_SELF(0x7FF0U);
126 setup.nr_frames = NR_GRANT_PAGES4;
127 setup.frame_list = (void*) kvtolin(frame)((vm_offset_t)(frame) - 0xC0000000UL + ((0xc0000000UL)));
128
129 ret = hyp_grant_table_op(GNTTABOP_setup_table2, kvtolin(&setup)((vm_offset_t)(&setup) - 0xC0000000UL + ((0xc0000000UL))), 1);
130 if (ret)
1
Assuming 'ret' is 0
→
2
←
Taking false branch
→
131 panic("setup grant table error %d", ret);
132 if (setup.status)
3
←
Branch condition evaluates to a garbage value
133 panic("setup grant table: %d\n", setup.status);
134
135 simple_lock_init(&lock);
136 vm_map_find_entry(kernel_map, &addr, NR_GRANT_PAGES4 * PAGE_SIZE(1 << 12),
137 (vm_offset_t) 0, kernel_object, &grants_map_entry);
138 grants = (void*) addr;
139
140 for (i = 0; i < NR_GRANT_PAGES4; i++)
141 pmap_map_mfn((void *)grants + i * PAGE_SIZE(1 << 12), frame[i]);
142}