acd644bb4a
If we use the bootloader-provided stack pointer, we might end up in a situation where the bootloader (incorrectly) pointed the stack in the middle of our heap. Catch this by simply comparing the computed heap end value to the stack pointer minus the defined stack size. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
172 lines
3.9 KiB
C
172 lines
3.9 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* arch/i386/boot/main.c
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*
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* Main module for the real-mode kernel code
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*/
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#include "boot.h"
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struct boot_params boot_params __attribute__((aligned(16)));
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char *HEAP = _end;
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char *heap_end = _end; /* Default end of heap = no heap */
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/*
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* Copy the header into the boot parameter block. Since this
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* screws up the old-style command line protocol, adjust by
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* filling in the new-style command line pointer instead.
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*/
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static void copy_boot_params(void)
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{
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struct old_cmdline {
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u16 cl_magic;
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u16 cl_offset;
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};
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const struct old_cmdline * const oldcmd =
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(const struct old_cmdline *)OLD_CL_ADDRESS;
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BUILD_BUG_ON(sizeof boot_params != 4096);
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memcpy(&boot_params.hdr, &hdr, sizeof hdr);
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if (!boot_params.hdr.cmd_line_ptr &&
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oldcmd->cl_magic == OLD_CL_MAGIC) {
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/* Old-style command line protocol. */
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u16 cmdline_seg;
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/* Figure out if the command line falls in the region
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of memory that an old kernel would have copied up
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to 0x90000... */
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if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
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cmdline_seg = ds();
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else
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cmdline_seg = 0x9000;
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boot_params.hdr.cmd_line_ptr =
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(cmdline_seg << 4) + oldcmd->cl_offset;
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}
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}
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/*
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* Set the keyboard repeat rate to maximum. Unclear why this
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* is done here; this might be possible to kill off as stale code.
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*/
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static void keyboard_set_repeat(void)
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{
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u16 ax = 0x0305;
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u16 bx = 0;
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asm volatile("int $0x16"
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: "+a" (ax), "+b" (bx)
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: : "ecx", "edx", "esi", "edi");
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}
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/*
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* Get Intel SpeedStep (IST) information.
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*/
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static void query_ist(void)
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{
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asm("int $0x15"
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: "=a" (boot_params.ist_info.signature),
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"=b" (boot_params.ist_info.command),
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"=c" (boot_params.ist_info.event),
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"=d" (boot_params.ist_info.perf_level)
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: "a" (0x0000e980), /* IST Support */
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"d" (0x47534943)); /* Request value */
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}
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/*
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* Tell the BIOS what CPU mode we intend to run in.
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*/
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static void set_bios_mode(void)
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{
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#ifdef CONFIG_X86_64
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u32 eax, ebx;
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eax = 0xec00;
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ebx = 2;
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asm volatile("int $0x15"
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: "+a" (eax), "+b" (ebx)
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: : "ecx", "edx", "esi", "edi");
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#endif
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}
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static void init_heap(void)
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{
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char *stack_end;
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if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
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asm("leal %P1(%%esp),%0"
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: "=r" (stack_end) : "i" (-STACK_SIZE));
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heap_end = (char *)
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((size_t)boot_params.hdr.heap_end_ptr + 0x200);
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if (heap_end > stack_end)
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heap_end = stack_end;
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} else {
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/* Boot protocol 2.00 only, no heap available */
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puts("WARNING: Ancient bootloader, some functionality "
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"may be limited!\n");
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}
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}
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void main(void)
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{
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/* First, copy the boot header into the "zeropage" */
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copy_boot_params();
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/* End of heap check */
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init_heap();
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/* Make sure we have all the proper CPU support */
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if (validate_cpu()) {
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puts("Unable to boot - please use a kernel appropriate "
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"for your CPU.\n");
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die();
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}
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/* Tell the BIOS what CPU mode we intend to run in. */
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set_bios_mode();
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/* Detect memory layout */
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detect_memory();
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/* Set keyboard repeat rate (why?) */
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keyboard_set_repeat();
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/* Query MCA information */
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query_mca();
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/* Voyager */
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#ifdef CONFIG_X86_VOYAGER
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query_voyager();
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#endif
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/* Query Intel SpeedStep (IST) information */
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query_ist();
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/* Query APM information */
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#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
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query_apm_bios();
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#endif
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/* Query EDD information */
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#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
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query_edd();
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#endif
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/* Set the video mode */
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set_video();
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/* Do the last things and invoke protected mode */
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go_to_protected_mode();
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}
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