jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
tests/tcg: target/s390x: Test MVC
Let's add a test that especially verifies that no data will be touched
in case we cross page boundaries and one page access triggers a fault.
Before the fault-safe handling fixes, the test failes with:
TEST mvc on s390x
data modified during a fault
make[2]: *** [../Makefile.target:116: run-mvc] Error 1
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
+110
+1
tests/tcg/s390x/Makefile.target
+1
tests/tcg/s390x/Makefile.target
+109
tests/tcg/s390x/mvc.c
+109
tests/tcg/s390x/mvc.c
···
1
+
#include <stdint.h>
2
+
#include <stdlib.h>
3
+
#include <stdio.h>
4
+
#include <string.h>
5
+
#include <sys/mman.h>
6
+
#include <signal.h>
7
+
#include <setjmp.h>
8
+
9
+
jmp_buf jmp_env;
10
+
11
+
static void handle_sigsegv(int sig)
12
+
{
13
+
siglongjmp(jmp_env, 1);
14
+
}
15
+
16
+
#define ALLOC_SIZE (2 * 4096)
17
+
18
+
static inline void mvc_256(const char *dst, const char *src)
19
+
{
20
+
asm volatile (
21
+
" mvc 0(256,%[dst]),0(%[src])\n"
22
+
:
23
+
: [dst] "d" (dst),
24
+
[src] "d" (src)
25
+
: "memory");
26
+
}
27
+
28
+
int main(void)
29
+
{
30
+
char *src, *dst;
31
+
int i;
32
+
33
+
/* register the SIGSEGV handler */
34
+
if (signal(SIGSEGV, handle_sigsegv) == SIG_ERR) {
35
+
fprintf(stderr, "SIGSEGV not registered\n");
36
+
return 1;
37
+
}
38
+
39
+
/* prepare the buffers - two consecutive pages */
40
+
src = valloc(ALLOC_SIZE);
41
+
dst = valloc(ALLOC_SIZE);
42
+
memset(src, 0xff, ALLOC_SIZE);
43
+
memset(dst, 0x0, ALLOC_SIZE);
44
+
45
+
/* protect the second pages */
46
+
if (mprotect(src + 4096, 4096, PROT_NONE) ||
47
+
mprotect(dst + 4096, 4096, PROT_NONE)) {
48
+
fprintf(stderr, "mprotect failed\n");
49
+
return 1;
50
+
}
51
+
52
+
/* fault on second destination page */
53
+
if (sigsetjmp(jmp_env, 1) == 0) {
54
+
mvc_256(dst + 4096 - 128, src);
55
+
fprintf(stderr, "fault not triggered\n");
56
+
return 1;
57
+
}
58
+
59
+
/* fault on second source page */
60
+
if (sigsetjmp(jmp_env, 1) == 0) {
61
+
mvc_256(dst, src + 4096 - 128);
62
+
fprintf(stderr, "fault not triggered\n");
63
+
return 1;
64
+
}
65
+
66
+
/* fault on second source and second destination page */
67
+
if (sigsetjmp(jmp_env, 1) == 0) {
68
+
mvc_256(dst + 4096 - 128, src + 4096 - 128);
69
+
fprintf(stderr, "fault not triggered\n");
70
+
return 1;
71
+
}
72
+
73
+
/* restore permissions */
74
+
if (mprotect(src + 4096, 4096, PROT_READ | PROT_WRITE) ||
75
+
mprotect(dst + 4096, 4096, PROT_READ | PROT_WRITE)) {
76
+
fprintf(stderr, "mprotect failed\n");
77
+
return 1;
78
+
}
79
+
80
+
/* no data must be touched during the faults */
81
+
for (i = 0; i < ALLOC_SIZE; i++) {
82
+
if (src[i] != 0xff || dst[i]) {
83
+
fprintf(stderr, "data modified during a fault\n");
84
+
return 1;
85
+
}
86
+
}
87
+
88
+
/* test if MVC works now correctly accross page boundaries */
89
+
mvc_256(dst + 4096 - 128, src + 4096 - 128);
90
+
for (i = 0; i < ALLOC_SIZE; i++) {
91
+
if (src[i] != 0xff) {
92
+
fprintf(stderr, "src modified\n");
93
+
return 1;
94
+
}
95
+
if (i < 4096 - 128 || i >= 4096 + 128) {
96
+
if (dst[i]) {
97
+
fprintf(stderr, "wrong dst modified\n");
98
+
return 1;
99
+
}
100
+
} else {
101
+
if (dst[i] != 0xff) {
102
+
fprintf(stderr, "wrong data moved\n");
103
+
return 1;
104
+
}
105
+
}
106
+
}
107
+
108
+
return 0;
109
+
}