Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1116
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probe — Probe Access
(
) probe.r
Format:
qp
(
) probe.w
qp
(
) probe.r
qp
(
) probe.w
qp
(
) probe.r.fault
qp
(
) probe.w.fault
qp
(
) probe.rw.fault
qp
This instruction determines whether read or write access, with a specified privilege
Description:
level, to a given virtual address is permitted. In the regular_form, GR
specified access is allowed and to 0 otherwise. In the fault_form, if the specified access
is allowed this instruction does nothing; if the specified access is not allowed, a fault is
taken.
When PSR.dt is 1, the DTLB and the VHPT are queried for present translations to
determine if access to the virtual address specified by GR
register indexed by GR
either GR
The read or write form specifies whether the instruction checks for read or write access,
or both.
When PSR.dt is 0, a regular_form probe uses its address operand as a virtual address
to query the DTLB only, because the VHPT walker is disabled. If the probed address is
found in the DTLB, the regular_form probe returns the appropriate value, if not an
Alternate Data TLB fault is raised if psr.ic is 1 or a Data Nested TLB fault is raised if
psr.ic is 0 or in-flight.
When PSR.dt is 0, a fault_form probe treats its address operand as a physical address,
and takes no TLB related faults.
A regular_form probe to an unimplemented virtual address returns 0. A fault_form
probe to an unimplemented virtual address (when PSR.dt is 1) or unimplemented
physical address (when PSR.dt is 0) takes an Unimplemented Data Address fault.
If this instruction faults, then it will set the non-access bit in the ISR and set the ISR
read or write bits depending on the completer. The faults generated by the different
forms of the probe instruction are shown in
Volume 3: Instruction Reference
=
,
r
r
r
1
3
2
=
,
r
r
r
1
3
2
=
,
r
r
imm
1
3
2
=
,
r
r
imm
1
3
2
,
r
imm
3
2
,
r
imm
3
2
,
r
imm
3
2
bits {63:61}, is permitted at the privilege level given by
r
3
bits{1:0} or
. If PSR.pk is 1, protection key checks are also performed.
r
imm
2
2
regular_form, read_form, register_form
regular_form, write_form, register_form
regular_form, read_form, immediate_form
regular_form, write_form, immediate_form
fault_form, read_form, immediate_form
fault_form, write_form, immediate_form
fault_form, read_write_form, immediate_form
bits {60:0} and the region
r
3
Table 2-47
below:
probe
M38
M38
M39
M39
M40
M40
M40
is set to 1 if the
r
1
3:217
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