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- /* Callout/callback interface for Etherboot
- *
- * This file provides the mechanisms for making calls from Etherboot
- * to external programs and vice-versa.
- *
- * Initial version by Michael Brown <mbrown@fensystems.co.uk>, January 2004.
- */
-
- #include "etherboot.h"
- #include "callbacks.h"
- #include "realmode.h"
- #include <stdarg.h>
-
- /* Maximum amount of stack data that prefix may request to be passed
- * to its exit routine
- */
- #define MAX_PREFIX_STACK_DATA 16
-
- /* Prefix exit routine is defined in prefix object */
- extern void prefix_exit ( void );
- extern void prefix_exit_end ( void );
-
- /*****************************************************************************
- *
- * IN_CALL INTERFACE
- *
- *****************************************************************************
- */
-
- /* in_call(): entry point for calls in to Etherboot from external code.
- *
- * Parameters: some set up by assembly code _in_call(), others as
- * passed from external code.
- */
- uint32_t i386_in_call ( va_list ap, i386_pm_in_call_data_t pm_data,
- uint32_t opcode ) {
- uint32_t ret;
- i386_rm_in_call_data_t rm_data;
- in_call_data_t in_call_data = { &pm_data, NULL };
- struct {
- int data[MAX_PREFIX_STACK_DATA/4];
- } in_stack;
-
- /* Fill out rm_data if we were called from real mode */
- if ( opcode & EB_CALL_FROM_REAL_MODE ) {
- in_call_data.rm = &rm_data;
- rm_data = va_arg ( ap, typeof(rm_data) );
- /* Null return address indicates to use the special
- * prefix exit mechanism, and that there are
- * parameters on the stack that the prefix wants
- * handed to its exit routine.
- */
- if ( rm_data.ret_addr.offset == 0 ) {
- int n = va_arg ( ap, int ) / 4;
- int i;
- for ( i = 0; i < n; i++ ) {
- in_stack.data[i] = va_arg ( ap, int );
- }
- }
- }
-
- /* Hand off to main in_call() routine */
- ret = in_call ( &in_call_data, opcode, ap );
-
- /* If real-mode return address is null, it means that we
- * should exit via the prefix's exit path, which is part of
- * our image. (This arrangement is necessary since the prefix
- * code itself may have been vapourised by the time we want to
- * return.)
- */
- if ( ( opcode & EB_CALL_FROM_REAL_MODE ) &&
- ( rm_data.ret_addr.offset == 0 ) ) {
- real_call ( prefix_exit, &in_stack, NULL );
- /* Should never return */
- }
-
- return ret;
- }
-
- #ifdef CODE16
-
- /* install_rm_callback_interface(): install real-mode callback
- * interface at specified address.
- *
- * Real-mode code may then call to this address (or lcall to this
- * address plus RM_IN_CALL_FAR) in order to make an in_call() to
- * Etherboot.
- *
- * Returns the size of the installed code, or 0 if the code could not
- * be installed.
- */
- int install_rm_callback_interface ( void *address, size_t available ) {
- if ( available &&
- ( available < rm_callback_interface_size ) ) return 0;
-
- /* Inform RM code where to find Etherboot */
- rm_etherboot_location = virt_to_phys(_text);
-
- /* Install callback interface */
- memcpy ( address, &rm_callback_interface,
- rm_callback_interface_size );
-
- return rm_callback_interface_size;
- }
-
- #endif /* CODE16 */
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