jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
target/i386: fix fxam handling of invalid encodings
The fxam implementation does not check for invalid encodings, instead
treating them like NaN or normal numbers depending on the exponent.
Fix it to check that the high bit of the significand is set before
treating an encoding as NaN or normal, thus resulting in correct
handling (all of C0, C2 and C3 cleared) for invalid encodings.
Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005132349311.11687@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
authored by
Joseph Myers
and committed by
Paolo Bonzini
34b9cc07
80b4008c
+145
-2
+2
-2
target/i386/fpu_helper.c
+2
-2
target/i386/fpu_helper.c
···
1099
1099
if (expdif == MAXEXPD) {
1100
1100
if (MANTD(temp) == 0x8000000000000000ULL) {
1101
1101
env->fpus |= 0x500; /* Infinity */
1102
-
} else {
1102
+
} else if (MANTD(temp) & 0x8000000000000000ULL) {
1103
1103
env->fpus |= 0x100; /* NaN */
1104
1104
}
1105
1105
} else if (expdif == 0) {
···
1108
1108
} else {
1109
1109
env->fpus |= 0x4400; /* Denormal */
1110
1110
}
1111
-
} else {
1111
+
} else if (MANTD(temp) & 0x8000000000000000ULL) {
1112
1112
env->fpus |= 0x400;
1113
1113
}
1114
1114
}
+143
tests/tcg/i386/test-i386-fxam.c
+143
tests/tcg/i386/test-i386-fxam.c
···
1
+
/* Test fxam instruction. */
2
+
3
+
#include <stdint.h>
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+
#include <stdio.h>
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+
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union u {
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struct { uint64_t sig; uint16_t sign_exp; } s;
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long double ld;
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};
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+
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volatile union u ld_pseudo_m16382 = { .s = { UINT64_C(1) << 63, 0 } };
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volatile union u ld_pseudo_nm16382 = { .s = { UINT64_C(1) << 63, 0x8000 } };
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volatile union u ld_invalid_1 = { .s = { 1, 1234 } };
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+
volatile union u ld_invalid_2 = { .s = { 0, 1234 } };
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+
volatile union u ld_invalid_3 = { .s = { 0, 0x7fff } };
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+
volatile union u ld_invalid_4 = { .s = { (UINT64_C(1) << 63) - 1, 0x7fff } };
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volatile union u ld_invalid_n1 = { .s = { 1, 0x8123 } };
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+
volatile union u ld_invalid_n2 = { .s = { 0, 0x8123 } };
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volatile union u ld_invalid_n3 = { .s = { 0, 0xffff } };
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volatile union u ld_invalid_n4 = { .s = { (UINT64_C(1) << 63) - 1, 0xffff } };
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+
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#define C0 (1 << 8)
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#define C1 (1 << 9)
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#define C2 (1 << 10)
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#define C3 (1 << 14)
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#define FLAGS (C0 | C1 | C2 | C3)
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+
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int main(void)
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{
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short sw;
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int ret = 0;
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__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (0.0L));
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+
if ((sw & FLAGS) != C3) {
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printf("FAIL: +0\n");
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ret = 1;
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+
}
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__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-0.0L));
38
+
if ((sw & FLAGS) != (C3 | C1)) {
39
+
printf("FAIL: -0\n");
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+
ret = 1;
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+
}
42
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (1.0L));
43
+
if ((sw & FLAGS) != C2) {
44
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printf("FAIL: +normal\n");
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ret = 1;
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+
}
47
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__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-1.0L));
48
+
if ((sw & FLAGS) != (C2 | C1)) {
49
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printf("FAIL: -normal\n");
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+
ret = 1;
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+
}
52
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (__builtin_infl()));
53
+
if ((sw & FLAGS) != (C2 | C0)) {
54
+
printf("FAIL: +inf\n");
55
+
ret = 1;
56
+
}
57
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-__builtin_infl()));
58
+
if ((sw & FLAGS) != (C2 | C1 | C0)) {
59
+
printf("FAIL: -inf\n");
60
+
ret = 1;
61
+
}
62
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (__builtin_nanl("")));
63
+
if ((sw & FLAGS) != C0) {
64
+
printf("FAIL: +nan\n");
65
+
ret = 1;
66
+
}
67
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-__builtin_nanl("")));
68
+
if ((sw & FLAGS) != (C1 | C0)) {
69
+
printf("FAIL: -nan\n");
70
+
ret = 1;
71
+
}
72
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__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (__builtin_nansl("")));
73
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if ((sw & FLAGS) != C0) {
74
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printf("FAIL: +snan\n");
75
+
ret = 1;
76
+
}
77
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__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-__builtin_nansl("")));
78
+
if ((sw & FLAGS) != (C1 | C0)) {
79
+
printf("FAIL: -snan\n");
80
+
ret = 1;
81
+
}
82
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (0x1p-16445L));
83
+
if ((sw & FLAGS) != (C3 | C2)) {
84
+
printf("FAIL: +denormal\n");
85
+
ret = 1;
86
+
}
87
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (-0x1p-16445L));
88
+
if ((sw & FLAGS) != (C3 | C2 | C1)) {
89
+
printf("FAIL: -denormal\n");
90
+
ret = 1;
91
+
}
92
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_pseudo_m16382.ld));
93
+
if ((sw & FLAGS) != (C3 | C2)) {
94
+
printf("FAIL: +pseudo-denormal\n");
95
+
ret = 1;
96
+
}
97
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_pseudo_nm16382.ld));
98
+
if ((sw & FLAGS) != (C3 | C2 | C1)) {
99
+
printf("FAIL: -pseudo-denormal\n");
100
+
ret = 1;
101
+
}
102
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_1.ld));
103
+
if ((sw & FLAGS) != 0) {
104
+
printf("FAIL: +invalid 1\n");
105
+
ret = 1;
106
+
}
107
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_n1.ld));
108
+
if ((sw & FLAGS) != C1) {
109
+
printf("FAIL: -invalid 1\n");
110
+
ret = 1;
111
+
}
112
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_2.ld));
113
+
if ((sw & FLAGS) != 0) {
114
+
printf("FAIL: +invalid 2\n");
115
+
ret = 1;
116
+
}
117
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_n2.ld));
118
+
if ((sw & FLAGS) != C1) {
119
+
printf("FAIL: -invalid 2\n");
120
+
ret = 1;
121
+
}
122
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_3.ld));
123
+
if ((sw & FLAGS) != 0) {
124
+
printf("FAIL: +invalid 3\n");
125
+
ret = 1;
126
+
}
127
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_n3.ld));
128
+
if ((sw & FLAGS) != C1) {
129
+
printf("FAIL: -invalid 3\n");
130
+
ret = 1;
131
+
}
132
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_4.ld));
133
+
if ((sw & FLAGS) != 0) {
134
+
printf("FAIL: +invalid 4\n");
135
+
ret = 1;
136
+
}
137
+
__asm__ volatile ("fxam\nfnstsw" : "=a" (sw) : "t" (ld_invalid_n4.ld));
138
+
if ((sw & FLAGS) != C1) {
139
+
printf("FAIL: -invalid 4\n");
140
+
ret = 1;
141
+
}
142
+
return ret;
143
+
}