tjh.dev
+4
-4
arch/x86/entry/entry_64_compat.S
+4
-4
arch/x86/entry/entry_64_compat.S
···
84
84
pushq %rdx /* pt_regs->dx */
85
85
pushq %rcx /* pt_regs->cx */
86
86
pushq $-ENOSYS /* pt_regs->ax */
87
-
pushq $0 /* pt_regs->r8 = 0 */
87
+
pushq %r8 /* pt_regs->r8 */
88
88
xorl %r8d, %r8d /* nospec r8 */
89
-
pushq $0 /* pt_regs->r9 = 0 */
89
+
pushq %r9 /* pt_regs->r9 */
90
90
xorl %r9d, %r9d /* nospec r9 */
91
-
pushq $0 /* pt_regs->r10 = 0 */
91
+
pushq %r10 /* pt_regs->r10 */
92
92
xorl %r10d, %r10d /* nospec r10 */
93
-
pushq $0 /* pt_regs->r11 = 0 */
93
+
pushq %r11 /* pt_regs->r11 */
94
94
xorl %r11d, %r11d /* nospec r11 */
95
95
pushq %rbx /* pt_regs->rbx */
96
96
xorl %ebx, %ebx /* nospec rbx */
+21
-14
tools/testing/selftests/x86/test_syscall_vdso.c
+21
-14
tools/testing/selftests/x86/test_syscall_vdso.c
···
100
100
" shl $32, %r8\n"
101
101
" orq $0x7f7f7f7f, %r8\n"
102
102
" movq %r8, %r9\n"
103
-
" movq %r8, %r10\n"
104
-
" movq %r8, %r11\n"
105
-
" movq %r8, %r12\n"
106
-
" movq %r8, %r13\n"
107
-
" movq %r8, %r14\n"
108
-
" movq %r8, %r15\n"
103
+
" incq %r9\n"
104
+
" movq %r9, %r10\n"
105
+
" incq %r10\n"
106
+
" movq %r10, %r11\n"
107
+
" incq %r11\n"
108
+
" movq %r11, %r12\n"
109
+
" incq %r12\n"
110
+
" movq %r12, %r13\n"
111
+
" incq %r13\n"
112
+
" movq %r13, %r14\n"
113
+
" incq %r14\n"
114
+
" movq %r14, %r15\n"
115
+
" incq %r15\n"
109
116
" ret\n"
110
117
" .code32\n"
111
118
" .popsection\n"
···
135
128
int err = 0;
136
129
int num = 8;
137
130
uint64_t *r64 = ®s64.r8;
131
+
uint64_t expected = 0x7f7f7f7f7f7f7f7fULL;
138
132
139
133
if (!kernel_is_64bit)
140
134
return 0;
141
135
142
136
do {
143
-
if (*r64 == 0x7f7f7f7f7f7f7f7fULL)
137
+
if (*r64 == expected++)
144
138
continue; /* register did not change */
145
139
if (syscall_addr != (long)&int80) {
146
140
/*
···
155
147
continue;
156
148
}
157
149
} else {
158
-
/* INT80 syscall entrypoint can be used by
150
+
/*
151
+
* INT80 syscall entrypoint can be used by
159
152
* 64-bit programs too, unlike SYSCALL/SYSENTER.
160
153
* Therefore it must preserve R12+
161
154
* (they are callee-saved registers in 64-bit C ABI).
162
155
*
163
-
* This was probably historically not intended,
164
-
* but R8..11 are clobbered (cleared to 0).
165
-
* IOW: they are the only registers which aren't
166
-
* preserved across INT80 syscall.
156
+
* Starting in Linux 4.17 (and any kernel that
157
+
* backports the change), R8..11 are preserved.
158
+
* Historically (and probably unintentionally), they
159
+
* were clobbered or zeroed.
167
160
*/
168
-
if (*r64 == 0 && num <= 11)
169
-
continue;
170
161
}
171
162
printf("[FAIL]\tR%d has changed:%016llx\n", num, *r64);
172
163
err++;