mirror of
https://github.com/grub4dos/ntloader.git
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106 lines
2.8 KiB
C
106 lines
2.8 KiB
C
/*
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* Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* @file
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*
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* Memory map
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*
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*/
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#include <stddef.h>
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#include <stdio.h>
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#include <string.h>
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#include <ntboot.h>
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#include <memmap.h>
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/** Buffer for INT 15,e820 calls */
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static struct e820_entry e820_buf __attribute__ ((section (".bss16")));
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/** Continuation value for next INT 15,e820 call */
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static uint32_t e820_ebx;
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/**
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* Get system memory map entry
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*
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* @v prev Previous system memory map entry, or NULL at start
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* @v next Next system memory map entry, or NULL at end
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*/
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struct e820_entry *memmap_next (struct e820_entry *prev)
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{
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struct bootapp_callback_params params;
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/* Reset buffer and continuation value if restarting */
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if (! prev)
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{
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memset (&e820_buf, 0, sizeof (e820_buf));
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e820_ebx = 0;
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}
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else if (e820_ebx == 0)
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{
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/* Reach the end */
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return NULL;
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}
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/* Read system memory map */
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memset (¶ms, 0, sizeof (params));
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do
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{
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/* Call INT 15,e820 */
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params.vector.interrupt = 0x15;
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params.eax = 0xe820;
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params.ebx = e820_ebx;
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params.ecx = sizeof (e820_buf);
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params.edx = E820_SMAP;
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params.es = BASE_SEG;
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params.edi = (((void *) &e820_buf) -
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((void *) BASE_ADDRESS));
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call_interrupt (¶ms);
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/* Record continuation value */
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e820_ebx = params.ebx;
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/* Check result */
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if (params.eflags & CF)
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{
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DBG ("INT 15,e820 failed: error %02x\n", params.ah);
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break;
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}
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if (params.eax != E820_SMAP)
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{
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DBG ("INT 15,e820 invalid SMAP signature %08x\n",
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params.eax);
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break;
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}
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DBG2 ("INT 15,e820 region [%llx,%llx) type %d\n",
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e820_buf.start, (e820_buf.start + e820_buf.len),
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e820_buf.type);
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/* Skip non-RAM regions */
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if (e820_buf.type != E820_TYPE_RAM)
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continue;
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if (params.ecx > offsetof (typeof (e820_buf), attrs))
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{
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if (! (e820_buf.attrs & E820_ATTR_ENABLED))
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continue;
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if (e820_buf.attrs & E820_ATTR_NONVOLATILE)
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continue;
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}
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/* Return this region */
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return &e820_buf;
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}
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while (e820_ebx != 0);
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return NULL;
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}
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