cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

main.c (4390B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* -*- linux-c -*- ------------------------------------------------------- *
      3 *
      4 *   Copyright (C) 1991, 1992 Linus Torvalds
      5 *   Copyright 2007 rPath, Inc. - All Rights Reserved
      6 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
      7 *
      8 * ----------------------------------------------------------------------- */
      9
     10/*
     11 * Main module for the real-mode kernel code
     12 */
     13#include <linux/build_bug.h>
     14
     15#include "boot.h"
     16#include "string.h"
     17
     18struct boot_params boot_params __attribute__((aligned(16)));
     19
     20struct port_io_ops pio_ops;
     21
     22char *HEAP = _end;
     23char *heap_end = _end;		/* Default end of heap = no heap */
     24
     25/*
     26 * Copy the header into the boot parameter block.  Since this
     27 * screws up the old-style command line protocol, adjust by
     28 * filling in the new-style command line pointer instead.
     29 */
     30
     31static void copy_boot_params(void)
     32{
     33	struct old_cmdline {
     34		u16 cl_magic;
     35		u16 cl_offset;
     36	};
     37	const struct old_cmdline * const oldcmd =
     38		absolute_pointer(OLD_CL_ADDRESS);
     39
     40	BUILD_BUG_ON(sizeof(boot_params) != 4096);
     41	memcpy(&boot_params.hdr, &hdr, sizeof(hdr));
     42
     43	if (!boot_params.hdr.cmd_line_ptr &&
     44	    oldcmd->cl_magic == OLD_CL_MAGIC) {
     45		/* Old-style command line protocol. */
     46		u16 cmdline_seg;
     47
     48		/* Figure out if the command line falls in the region
     49		   of memory that an old kernel would have copied up
     50		   to 0x90000... */
     51		if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
     52			cmdline_seg = ds();
     53		else
     54			cmdline_seg = 0x9000;
     55
     56		boot_params.hdr.cmd_line_ptr =
     57			(cmdline_seg << 4) + oldcmd->cl_offset;
     58	}
     59}
     60
     61/*
     62 * Query the keyboard lock status as given by the BIOS, and
     63 * set the keyboard repeat rate to maximum.  Unclear why the latter
     64 * is done here; this might be possible to kill off as stale code.
     65 */
     66static void keyboard_init(void)
     67{
     68	struct biosregs ireg, oreg;
     69	initregs(&ireg);
     70
     71	ireg.ah = 0x02;		/* Get keyboard status */
     72	intcall(0x16, &ireg, &oreg);
     73	boot_params.kbd_status = oreg.al;
     74
     75	ireg.ax = 0x0305;	/* Set keyboard repeat rate */
     76	intcall(0x16, &ireg, NULL);
     77}
     78
     79/*
     80 * Get Intel SpeedStep (IST) information.
     81 */
     82static void query_ist(void)
     83{
     84	struct biosregs ireg, oreg;
     85
     86	/* Some older BIOSes apparently crash on this call, so filter
     87	   it from machines too old to have SpeedStep at all. */
     88	if (cpu.level < 6)
     89		return;
     90
     91	initregs(&ireg);
     92	ireg.ax  = 0xe980;	 /* IST Support */
     93	ireg.edx = 0x47534943;	 /* Request value */
     94	intcall(0x15, &ireg, &oreg);
     95
     96	boot_params.ist_info.signature  = oreg.eax;
     97	boot_params.ist_info.command    = oreg.ebx;
     98	boot_params.ist_info.event      = oreg.ecx;
     99	boot_params.ist_info.perf_level = oreg.edx;
    100}
    101
    102/*
    103 * Tell the BIOS what CPU mode we intend to run in.
    104 */
    105static void set_bios_mode(void)
    106{
    107#ifdef CONFIG_X86_64
    108	struct biosregs ireg;
    109
    110	initregs(&ireg);
    111	ireg.ax = 0xec00;
    112	ireg.bx = 2;
    113	intcall(0x15, &ireg, NULL);
    114#endif
    115}
    116
    117static void init_heap(void)
    118{
    119	char *stack_end;
    120
    121	if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
    122		asm("leal %P1(%%esp),%0"
    123		    : "=r" (stack_end) : "i" (-STACK_SIZE));
    124
    125		heap_end = (char *)
    126			((size_t)boot_params.hdr.heap_end_ptr + 0x200);
    127		if (heap_end > stack_end)
    128			heap_end = stack_end;
    129	} else {
    130		/* Boot protocol 2.00 only, no heap available */
    131		puts("WARNING: Ancient bootloader, some functionality "
    132		     "may be limited!\n");
    133	}
    134}
    135
    136void main(void)
    137{
    138	init_default_io_ops();
    139
    140	/* First, copy the boot header into the "zeropage" */
    141	copy_boot_params();
    142
    143	/* Initialize the early-boot console */
    144	console_init();
    145	if (cmdline_find_option_bool("debug"))
    146		puts("early console in setup code\n");
    147
    148	/* End of heap check */
    149	init_heap();
    150
    151	/* Make sure we have all the proper CPU support */
    152	if (validate_cpu()) {
    153		puts("Unable to boot - please use a kernel appropriate "
    154		     "for your CPU.\n");
    155		die();
    156	}
    157
    158	/* Tell the BIOS what CPU mode we intend to run in. */
    159	set_bios_mode();
    160
    161	/* Detect memory layout */
    162	detect_memory();
    163
    164	/* Set keyboard repeat rate (why?) and query the lock flags */
    165	keyboard_init();
    166
    167	/* Query Intel SpeedStep (IST) information */
    168	query_ist();
    169
    170	/* Query APM information */
    171#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
    172	query_apm_bios();
    173#endif
    174
    175	/* Query EDD information */
    176#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
    177	query_edd();
    178#endif
    179
    180	/* Set the video mode */
    181	set_video();
    182
    183	/* Do the last things and invoke protected mode */
    184	go_to_protected_mode();
    185}