Struct x86_64::structures::gdt::DescriptorFlags [−][src]
pub struct DescriptorFlags { /* fields omitted */ }
Expand description
Flags for a GDT descriptor. Not all flags are valid for all descriptor types.
Implementations
Set by the processor if this segment has been accessed. Only cleared by software. Setting this bit in software prevents GDT writes on first use.
For 32-bit data segments, sets the segment as writable. For 32-bit code segments, sets the segment as readable. In 64-bit mode, ignored for all segments.
For code segments, sets the segment as “conforming”, influencing the privilege checks that occur on control transfers. For 32-bit data segments, sets the segment as “expand down”. In 64-bit mode, ignored for data segments.
This flag must be set for code segments and unset for data segments.
This flag must be set for user segments (in contrast to system segments).
The DPL for this descriptor is Ring 3. In 64-bit mode, ignored for data segments.
Must be set for any segment, causes a segment not present exception if not set.
Use 32-bit (as opposed to 16-bit) operands. If LONG_MODE
is set,
this must be unset. In 64-bit mode, ignored for data segments.
Limit field is scaled by 4096 bytes. In 64-bit mode, ignored for all segments.
Bits 0..=15
of the limit field (ignored in 64-bit mode)
Bits 16..=19
of the limit field (ignored in 64-bit mode)
Bits 0..=23
of the base field (ignored in 64-bit mode, except for fs and gs)
Bits 24..=31
of the base field (ignored in 64-bit mode, except for fs and gs)
Convert from underlying bit representation, unless that representation contains bits that do not correspond to a flag.
Convert from underlying bit representation, dropping any bits that do not correspond to flags.
Convert from underlying bit representation, preserving all bits (even those not corresponding to a defined flag).
Safety
The caller of the bitflags!
macro can chose to allow or
disallow extra bits for their bitflags type.
The caller of from_bits_unchecked()
has to ensure that
all bits correspond to a defined flag or that extra bits
are valid for this bitflags type.
Returns true
if there are flags common to both self
and other
.
Returns true
if all of the flags in other
are contained within self
.
Inserts or removes the specified flags depending on the passed value.
Returns the intersection between the flags in self
and
other
.
Specifically, the returned set contains only the flags which are
present in both self
and other
.
This is equivalent to using the &
operator (e.g.
ops::BitAnd
), as in flags & other
.
Returns the union of between the flags in self
and other
.
Specifically, the returned set contains all flags which are
present in either self
or other
, including any which are
present in both (see Self::symmetric_difference
if that
is undesirable).
This is equivalent to using the |
operator (e.g.
ops::BitOr
), as in flags | other
.
Returns the difference between the flags in self
and other
.
Specifically, the returned set contains all flags present in
self
, except for the ones present in other
.
It is also conceptually equivalent to the “bit-clear” operation:
flags & !other
(and this syntax is also supported).
This is equivalent to using the -
operator (e.g.
ops::Sub
), as in flags - other
.
Returns the symmetric difference between the flags
in self
and other
.
Specifically, the returned set contains the flags present which
are present in self
or other
, but that are not present in
both. Equivalently, it contains the flags present in exactly
one of the sets self
and other
.
This is equivalent to using the ^
operator (e.g.
ops::BitXor
), as in flags ^ other
.
Returns the complement of this set of flags.
Specifically, the returned set contains all the flags which are
not set in self
, but which are allowed for this type.
Alternatively, it can be thought of as the set difference
between Self::all()
and self
(e.g. Self::all() - self
)
This is equivalent to using the !
operator (e.g.
ops::Not
), as in !flags
.
The following constants define default values for common GDT entries. They
are all “flat” segments, meaning they can access the entire address space.
These values all set WRITABLE
and
ACCESSED
. They also match the values loaded
by the syscall
/sysret
and sysenter
/sysexit
instructions.
In short, these values disable segmentation, permission checks, and access tracking at the GDT level. Kernels using these values should use paging to implement this functionality.
A kernel data segment (64-bit or flat 32-bit)
A flat 32-bit kernel code segment
A 64-bit kernel code segment
A flat 32-bit user code segment
A 64-bit user code segment
Trait Implementations
Disables all flags disabled in the set.
Returns the union of the two sets of flags.
type Output = Self
type Output = Self
The resulting type after applying the |
operator.
Adds the set of flags.
Toggles the set of flags.
Extends a collection with the contents of an iterator. Read more
extend_one
)Extends a collection with exactly one element.
extend_one
)Reserves capacity in a collection for the given number of additional elements. Read more
Creates a value from an iterator. Read more
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
This method tests for !=
.
This method returns an ordering between self
and other
values if one exists. Read more
This method tests less than (for self
and other
) and is used by the <
operator. Read more
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
Disables all flags enabled in the set.