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(-)i386_get_ldt.2 (-18 / +32 lines)
Lines 52-97 Link Here
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The
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The
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.Fn i386_get_ldt
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.Fn i386_get_ldt
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system call
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system call
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will return the list of i386 descriptors that the process has in its
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will copy the list of i386 descriptors that the process has in its
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LDT.
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LDT. It does so starting from the LDT entry index
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.Fa start_sel
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into an arrary pointed to by
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.Fa descs ,
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which must be
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.Fa num_sel
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elements wide.
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.Pp
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The
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The
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.Fn i386_set_ldt
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.Fn i386_set_ldt
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system call
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system call
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will set a list of i386 descriptors for the current process in its
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will set a list of i386 descriptors for the current process in its
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LDT.
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LDT, starting from the LDT entry index
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Both routines accept a starting selector number
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.Fa start_sel .
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.Fa start_sel ,
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It copies
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an array of memory that
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.Fa num_descs
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will contain the descriptors to be set or returned
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descriptors in the array pointed to by
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.Fa descs ,
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.Fa descs
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and the number of entries to set or return
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into the LDT.
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.Fa num_sels .
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.Pp
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.Pp
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The argument
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The argument
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.Fa descs
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.Fa descs
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can be either segment_descriptor or gate_descriptor and are defined in
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can be either segment_descriptor or gate_descriptor and are defined in
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.Aq Pa i386/segments.h .
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.Aq Pa i386/segments.h .
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These structures are defined by the architecture
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These structures are defined by the architecture
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as disjoint bit-fields, so care must be taken in constructing them.
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as disjoint bit-fields, so you must take care in constructing them.
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.Sh RETURN VALUES
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.Sh RETURN VALUES
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Upon successful completion,
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If successful,
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.Fn i386_get_ldt
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.Fn i386_get_ldt
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returns the number of descriptors currently in the LDT.
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returns the number of descriptors currently in the LDT.
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The
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.Fn i386_set_ldt
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.Fn i386_set_ldt
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system call
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returns the index first selector that it set on success.  If an error
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returns the first selector set.
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occurred, the procedures return a value of -1 and set the global
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Otherwise, a value of -1 is returned and the global
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variable
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variable
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.Va errno
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.Va errno
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is set to indicate the error.
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to indicate the error.
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.Sh EXAMPLES
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To set the
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.Va "my_ldt_index"
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th slot of the process's LDT to the value of
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.Va my_ldt_entry ,
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use something like this:
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.Bd -literal -offset indent
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if (i386_set_ldt(my_ldt_index, &my_ldt_entry, 1) < 0) {
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	perror("i386_set_ldt");
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}
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.Sh ERRORS
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.Sh ERRORS
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The
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The
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.Fn i386_get_ldt
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.Fn i386_get_ldt
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and
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and
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.Fn i386_set_ldt
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.Fn i386_set_ldt
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system calls
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system calls
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will fail if:
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will fail with:
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.Bl -tag -width Er
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.Bl -tag -width Er
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.It Bq Er EINVAL
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.It Bq Er EINVAL
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An inappropriate value was used for
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An inappropriate value was used for

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