Author: tychon
Date: Fri Jun 26 18:00:29 2015
New Revision: 284877
URL: https://svnweb.freebsd.org/changeset/base/284877
Log:
verify_gla() needs to account for non-zero segment base addresses.
Reviewed by: neel
Modified:
head/sys/amd64/vmm/vmm_instruction_emul.c
Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c Fri Jun 26 17:13:23 2015
(r284876)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c Fri Jun 26 18:00:29 2015
(r284877)
@@ -2321,10 +2321,13 @@ decode_moffset(struct vie *vie)
* page table fault matches with our instruction decoding.
*/
static int
-verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
+verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie,
+ enum vm_cpu_mode cpu_mode)
{
int error;
- uint64_t base, idx, gla2;
+ uint64_t base, segbase, idx, gla2;
+ enum vm_reg_name seg;
+ struct seg_desc desc;
/* Skip 'gla' verification */
if (gla == VIE_INVALID_GLA)
@@ -2357,14 +2360,48 @@ verify_gla(struct vm *vm, int cpuid, uin
}
}
- /* XXX assuming that the base address of the segment is 0 */
- gla2 = base + vie->scale * idx + vie->displacement;
+ /*
+ * From "Specifying a Segment Selector", Intel SDM, Vol 1
+ *
+ * In 64-bit mode, segmentation is generally (but not
+ * completely) disabled. The exceptions are the FS and GS
+ * segments.
+ *
+ * In legacy IA-32 mode, when the ESP or EBP register is used
+ * as the base, the SS segment is the default segment. For
+ * other data references, except when relative to stack or
+ * string destination the DS segment is the default. These
+ * can be overridden to allow other segments to be accessed.
+ */
+ if (vie->segment_override)
+ seg = vie->segment_register;
+ else if (vie->base_register == VM_REG_GUEST_RSP ||
+ vie->base_register == VM_REG_GUEST_RBP)
+ seg = VM_REG_GUEST_SS;
+ else
+ seg = VM_REG_GUEST_DS;
+ if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS &&
+ seg != VM_REG_GUEST_GS) {
+ segbase = 0;
+ } else {
+ error = vm_get_seg_desc(vm, cpuid, seg, &desc);
+ if (error) {
+ printf("verify_gla: error %d getting segment"
+ " descriptor %d", error,
+ vie->segment_register);
+ return (-1);
+ }
+ segbase = desc.base;
+ }
+
+ gla2 = segbase + base + vie->scale * idx + vie->displacement;
gla2 &= size2mask[vie->addrsize];
if (gla != gla2) {
- printf("verify_gla mismatch: "
+ printf("verify_gla mismatch: segbase(0x%0lx)"
"base(0x%0lx), scale(%d), index(0x%0lx), "
"disp(0x%0lx), gla(0x%0lx), gla2(0x%0lx)\n",
- base, vie->scale, idx, vie->displacement, gla, gla2);
+ segbase, base, vie->scale, idx, vie->displacement,
+ gla, gla2);
return (-1);
}
@@ -2398,7 +2435,7 @@ vmm_decode_instruction(struct vm *vm, in
return (-1);
if ((vie->op.op_flags & VIE_OP_F_NO_GLA_VERIFICATION) == 0) {
- if (verify_gla(vm, cpuid, gla, vie))
+ if (verify_gla(vm, cpuid, gla, vie, cpu_mode))
return (-1);
}
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