1 /* This changes the definition of ucontext_t */
2 #define _XOPEN_SOURCE 1
3 #include <stdio.h>
4 #include <unistd.h>
5 #include <signal.h>
6 #include <string.h>
7 #include <stdbool.h>
8 #include <valgrind.h>
9
10 #define offsetof(type, fld) ((unsigned long)&((type *)0)->fld)
11 #define stringify(x) #x
12
13 static int verbose = 0;
14
15 #define _ASSERT_OP(a, op, b) \
16 do { \
17 unsigned long long _a = (unsigned long long)(a); \
18 unsigned long long _b = (unsigned long long)(b); \
19 if (verbose) \
20 fprintf(stderr, "%s:%d: ASSERT(" stringify(a) \
21 " " stringify(op) " " stringify(b) ")\n", \
22 __FILE__, __LINE__); \
23 if (!(_a op _b)) { \
24 fprintf(stderr, "%s:%d: FAILED ASSERT((" stringify(a) \
25 "=0x%016llx) " stringify(op) " (" stringify(b) "=0x%016llx))\n", \
26 __FILE__, __LINE__, _a, _b); \
27 _exit(1); \
28 } \
29 } while(0)
30 #define ASSERT_EQ(a, b) _ASSERT_OP(a, ==, b)
31 #define ASSERT_NE(a, b) _ASSERT_OP(a, !=, b)
32 #define ASSERT_LTE(a, b) _ASSERT_OP(a, <=, b)
33 #define ASSERT_GTE(a, b) _ASSERT_OP(a, >=, b)
34 #define ASSERT(e) \
35 do { \
36 if (verbose) \
37 fprintf(stderr, "%s:%d: ASSERT(" stringify(e) ")\n", \
38 __FILE__, __LINE__); \
39 if (!(e)) { \
40 fprintf(stderr, "%s:%d: FAILED ASSERT(" stringify(e) ")\n", \
41 __FILE__, __LINE__); \
42 _exit(1); \
43 } \
44 } while(0)
45
46
47 static bool using_int3 = false;
48 static volatile int sig_count = 0;
49 static volatile int ran_after_fault = 0;
50 static void *top_of_stack;
51 static void *bottom_of_stack;
52
this_function_halts(unsigned long long a0,unsigned long long a1,unsigned long long a2,unsigned long long a3,unsigned long long a4,unsigned long long a5)53 void this_function_halts(unsigned long long a0, unsigned long long a1,
54 unsigned long long a2, unsigned long long a3,
55 unsigned long long a4, unsigned long long a5)
56 {
57 int foo;
58 bottom_of_stack = &foo;
59
60 /* Set up registers with known values which will be tested in the signal handler */
61 __asm__ volatile("movq $0xfeed01010101cafe,%rax");
62 __asm__ volatile("movq $0xfeed02020202cafe,%rbx");
63 __asm__ volatile("movq $0xfeed03030303cafe,%r10");
64 __asm__ volatile("movq $0xfeed04040404cafe,%r11");
65 __asm__ volatile("movq $0xfeed05050505cafe,%r12");
66 __asm__ volatile("movq $0xfeed06060606cafe,%r13");
67 __asm__ volatile("movq $0xfeed07070707cafe,%r14");
68 __asm__ volatile("movq $0xfeed08080808cafe,%r15");
69 __asm__ volatile("hlt");
70 ran_after_fault++;
71 }
72
this_function_int3s(unsigned long long a0,unsigned long long a1,unsigned long long a2,unsigned long long a3,unsigned long long a4,unsigned long long a5)73 void this_function_int3s(unsigned long long a0, unsigned long long a1,
74 unsigned long long a2, unsigned long long a3,
75 unsigned long long a4, unsigned long long a5)
76 {
77 int foo;
78 bottom_of_stack = &foo;
79
80 /* Set up registers with known values which will be tested in the signal handler */
81 __asm__ volatile("movq $0xfeed01010101cafe,%rax");
82 __asm__ volatile("movq $0xfeed02020202cafe,%rbx");
83 __asm__ volatile("movq $0xfeed03030303cafe,%r10");
84 __asm__ volatile("movq $0xfeed04040404cafe,%r11");
85 __asm__ volatile("movq $0xfeed05050505cafe,%r12");
86 __asm__ volatile("movq $0xfeed06060606cafe,%r13");
87 __asm__ volatile("movq $0xfeed07070707cafe,%r14");
88 __asm__ volatile("movq $0xfeed08080808cafe,%r15");
89 __asm__ volatile("int $3");
90 ran_after_fault++;
91 }
92
93
94 static void
handle_signal(int sig,siginfo_t * si,void * vuc)95 handle_signal(int sig, siginfo_t *si, void *vuc)
96 {
97 ucontext_t *uc = (ucontext_t *)vuc;
98
99 if (verbose)
100 {
101 fprintf(stderr, "handle_signal\n");
102 fflush(stderr);
103 }
104
105 sig_count++;
106 ASSERT(sig_count == 1);
107
108 int expected_sig = (using_int3 ? SIGTRAP : SIGSEGV);
109 ASSERT_EQ(sig, expected_sig);
110 ASSERT_NE(si, NULL);
111 ASSERT_NE(uc, NULL);
112 ASSERT_NE(uc->uc_mcontext, NULL);
113
114 /* Test that the siginfo is set up right for this signal */
115 ASSERT_EQ(si->si_signo, expected_sig);
116 ASSERT_EQ(si->si_errno, 0);
117 int expected_code = (using_int3 ? 1 : 0);
118 ASSERT_EQ(si->si_code, expected_code);
119 ASSERT_EQ(si->si_pid, 0);
120 ASSERT_EQ(si->si_uid, 0);
121 ASSERT_EQ(si->si_status, 0);
122 ASSERT_EQ(si->si_addr, 0);
123 ASSERT_EQ(si->si_band, 0);
124
125 /* Test that RAX is saved to the signal ucontext */
126 ASSERT_EQ(uc->uc_mcontext->__ss.__rax, 0xfeed01010101cafe);
127
128 /* Test that the registers used to pass the 1st 6
129 * function arguments were saved in the signal ucontext */
130 ASSERT_EQ(uc->uc_mcontext->__ss.__rdi, 0xbabe01010101cedeULL);
131 ASSERT_EQ(uc->uc_mcontext->__ss.__rsi, 0xbabe02020202cedeULL);
132 ASSERT_EQ(uc->uc_mcontext->__ss.__rdx, 0xbabe03030303cedeULL);
133 ASSERT_EQ(uc->uc_mcontext->__ss.__rcx, 0xbabe04040404cedeULL);
134 ASSERT_EQ(uc->uc_mcontext->__ss.__r8, 0xbabe05050505cedeULL);
135 ASSERT_EQ(uc->uc_mcontext->__ss.__r9, 0xbabe06060606cedeULL);
136
137 /* Test that the saved RBP and RSP point into roughly the right
138 * part of the stack */
139 ASSERT_GTE(uc->uc_mcontext->__ss.__rbp, bottom_of_stack);
140 ASSERT_LTE(uc->uc_mcontext->__ss.__rbp, top_of_stack);
141 ASSERT_GTE(uc->uc_mcontext->__ss.__rsp, bottom_of_stack);
142 ASSERT_LTE(uc->uc_mcontext->__ss.__rsp, top_of_stack);
143
144 /* Test that the saved RIP points into roughly the
145 * right part of the text segment */
146 char *calling_fn = (using_int3 ? (char *)&this_function_int3s : (char *)&this_function_halts);
147 ASSERT_GTE(uc->uc_mcontext->__ss.__rip, calling_fn);
148 ASSERT_LTE(uc->uc_mcontext->__ss.__rip, calling_fn+400);
149
150 ASSERT_EQ(uc->uc_mcontext->__ss.__rbx, 0xfeed02020202cafe);
151 ASSERT_EQ(uc->uc_mcontext->__ss.__r10, 0xfeed03030303cafe);
152 ASSERT_EQ(uc->uc_mcontext->__ss.__r11, 0xfeed04040404cafe);
153 ASSERT_EQ(uc->uc_mcontext->__ss.__r12, 0xfeed05050505cafe);
154 ASSERT_EQ(uc->uc_mcontext->__ss.__r13, 0xfeed06060606cafe);
155 ASSERT_EQ(uc->uc_mcontext->__ss.__r14, 0xfeed07070707cafe);
156 ASSERT_EQ(uc->uc_mcontext->__ss.__r15, 0xfeed08080808cafe);
157 /*
158 printf(" RFLAGS 0x%016llx\n", (unsigned long long)uc->uc_mcontext->__ss.__rflags);
159 */
160
161 /*
162 * Test that the RIP is restored from the signal ucontext;
163 * this should skip past the HLT/INT instruction and
164 * allow execution to continue back out to main()
165 */
166 if (verbose)
167 {
168 fprintf(stderr, "Setting up to return past the HLT\n");
169 fflush(stderr);
170 }
171 uc->uc_mcontext->__ss.__rip += (using_int3 ? 0 : 1);
172
173 if (verbose)
174 {
175 fprintf(stderr, "Returning from signal handler\n");
176 fflush(stderr);
177 }
178 }
179
main(int argc,char ** argv)180 int main(int argc, char **argv)
181 {
182 int r;
183 struct sigaction act;
184
185 top_of_stack = (void *)&act;
186
187 if (argc > 1 && !strcmp(argv[1], "--verbose"))
188 verbose = 1;
189
190 if (verbose)
191 printf("Setting up signal handler\n");
192 memset(&act, 0, sizeof(act));
193 act.sa_sigaction = handle_signal;
194 act.sa_flags |= SA_SIGINFO;
195 if (RUNNING_ON_VALGRIND)
196 using_int3 = true;
197 r = sigaction((using_int3 ? SIGTRAP : SIGSEGV), &act, NULL);
198 ASSERT_EQ(r, 0);
199
200 if (verbose)
201 {
202 fprintf(stderr, "Calling function with a breakpoint insn in it\n");
203 fflush(stderr);
204 }
205 if (using_int3)
206 this_function_int3s(0xbabe01010101cedeULL,
207 0xbabe02020202cedeULL,
208 0xbabe03030303cedeULL,
209 0xbabe04040404cedeULL,
210 0xbabe05050505cedeULL,
211 0xbabe06060606cedeULL);
212 else
213 this_function_halts(0xbabe01010101cedeULL,
214 0xbabe02020202cedeULL,
215 0xbabe03030303cedeULL,
216 0xbabe04040404cedeULL,
217 0xbabe05050505cedeULL,
218 0xbabe06060606cedeULL);
219 ASSERT_EQ(ran_after_fault, 1);
220
221 fprintf(stderr, "PASS\n");
222 return 0;
223 }
224