Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
xen/PVH: Set up GS segment for stack canary
We are making calls to C code (e.g. xen_prepare_pvh()) which may use
stack canary (stored in GS segment).
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
authored by
Boris Ostrovsky
and committed by
Juergen Gross
98014068
515e6541
+25
-1
+25
-1
arch/x86/xen/xen-pvh.S
+25
-1
arch/x86/xen/xen-pvh.S
···
54
54
* charge of setting up it's own stack, GDT and IDT.
55
55
*/
56
56
57
+
#define PVH_GDT_ENTRY_CANARY 4
58
+
#define PVH_CANARY_SEL (PVH_GDT_ENTRY_CANARY * 8)
59
+
57
60
ENTRY(pvh_start_xen)
58
61
cld
59
62
···
101
98
/* 64-bit entry point. */
102
99
.code64
103
100
1:
101
+
/* Set base address in stack canary descriptor. */
102
+
mov $MSR_GS_BASE,%ecx
103
+
mov $_pa(canary), %eax
104
+
xor %edx, %edx
105
+
wrmsr
106
+
104
107
call xen_prepare_pvh
105
108
106
109
/* startup_64 expects boot_params in %rsi. */
···
115
106
jmp *%rax
116
107
117
108
#else /* CONFIG_X86_64 */
109
+
110
+
/* Set base address in stack canary descriptor. */
111
+
movl $_pa(gdt_start),%eax
112
+
movl $_pa(canary),%ecx
113
+
movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax)
114
+
shrl $16, %ecx
115
+
movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax)
116
+
movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax)
117
+
118
+
mov $PVH_CANARY_SEL,%eax
119
+
mov %eax,%gs
118
120
119
121
call mk_early_pgtbl_32
120
122
···
170
150
.quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* __KERNEL_CS */
171
151
#endif
172
152
.quad GDT_ENTRY(0xc092, 0, 0xfffff) /* __KERNEL_DS */
153
+
.quad GDT_ENTRY(0x4090, 0, 0x18) /* PVH_CANARY_SEL */
173
154
gdt_end:
174
155
175
-
.balign 4
156
+
.balign 16
157
+
canary:
158
+
.fill 48, 1, 0
159
+
176
160
early_stack:
177
161
.fill 256, 1, 0
178
162
early_stack_end: