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i386: global descriptor table manipulation functions

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This commit is contained in:
Jan Dolezal
2014-11-20 15:00:30 +01:00
committed by Gedare Bloom
parent b2db1f5c76
commit 74d2d94041
2 changed files with 207 additions and 40 deletions
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91
c/src/lib/libcpu/i386/cpu.h
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@@ -28,7 +28,7 @@
*/
#include <rtems/score/interrupts.h>
#include <stdint.h>
#include <rtems/score/basedefs.h>
/*
* Segment Access Routines
@@ -256,7 +256,7 @@ typedef struct {
unsigned int operation_size : 1;
unsigned int granularity : 1;
unsigned int base_address_31_24 : 8;
}segment_descriptors;
} RTEMS_COMPILER_PACKED_ATTRIBUTE segment_descriptors;
/*
* C callable function enabling to get easilly usable info from
@@ -271,11 +271,94 @@ extern void i386_get_info_from_GDTR (segment_descriptors** table,
extern void i386_set_GDTR (segment_descriptors*,
uint16_t limit);
/**
* C callable function:
* Puts global descriptor @sd to the global descriptor table on index
* @segment_selector_index
*
* @retval 0 FAILED out of GDT range or index is 0, which is not valid
* index in GDT
* 1 SUCCESS
*/
extern uint32_t i386_raw_gdt_entry (uint16_t segment_selector_index,
segment_descriptors* sd);
/**
* C callable function
* fills @sd with provided @base in appropriate fields of @sd
*
* @param base 32-bit address to be set as descriptor's base
* @param sd descriptor being filled with @base
*/
extern void i386_fill_segment_desc_base (uint32_t base,
segment_descriptors* sd);
/**
* C callable function
* fills @sd with provided @limit in appropriate fields of @sd
* also influences granularity bit
*
* @param limit 32-bit value representing number of limit bytes
* @param sd descriptor being filled with @limit
*/
extern void i386_fill_segment_desc_limit (uint32_t limit,
segment_descriptors* sd);
/*
* C callable function enabling to set up one raw interrupt handler
*/
extern int i386_set_gdt_entry (unsigned short segment_selector, unsigned base,
unsigned limit);
extern uint32_t i386_set_gdt_entry (uint16_t segment_selector,
uint32_t base,
uint32_t limit);
/**
* C callable function returns next empty descriptor in GDT.
*
* @retval 0 FAILED GDT is full
* <1;65535> segment_selector number as index to GDT
*/
extern uint16_t i386_next_empty_gdt_entry (void);
/**
* Copies GDT entry at index @segment_selector to structure
* pointed to by @struct_to_fill
*
* @param segment_selector index to GDT table for specifying descriptor to copy
* @retval 0 FAILED segment_selector out of GDT range
* <1;65535> retrieved segment_selector
*/
extern uint16_t i386_cpy_gdt_entry (uint16_t segment_selector,
segment_descriptors* struct_to_fill);
/**
* Returns pointer to GDT table at index given by @segment_selector
*
* @param segment_selector index to GDT table for specifying descriptor to get
* @retval NULL FAILED segment_selector out of GDT range
* pointer to GDT table at @segment_selector
*/
extern segment_descriptors* i386_get_gdt_entry (uint16_t sgmnt_selector);
/**
* Extracts base address from GDT entry pointed to by @gdt_entry
*
* @param gdt_entry pointer to entry from which base should be retrieved
* @retval base address from GDT entry
*/
RTEMS_INLINE_ROUTINE void* i386_base_gdt_entry (segment_descriptors* gdt_entry)
{
return (void*)(gdt_entry->base_address_15_0 |
(gdt_entry->base_address_23_16<<16) |
(gdt_entry->base_address_31_24<<24));
}
/**
* Extracts limit in bytes from GDT entry pointed to by @gdt_entry
*
* @param gdt_entry pointer to entry from which limit should be retrieved
* @retval limit value in bytes from GDT entry
*/
extern uint32_t i386_limit_gdt_entry (segment_descriptors* gdt_entry);
/*
* See page 11.18 Figure 11-12.