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      1 /*	$NetBSD: prekern.c,v 1.14 2021/05/04 21:09:16 khorben Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2017-2020 The NetBSD Foundation, Inc. All rights reserved.
      5  *
      6  * This code is derived from software contributed to The NetBSD Foundation
      7  * by Maxime Villard.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     20  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     21  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     22  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     28  * POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include "prekern.h"
     32 
     33 #include <machine/reg.h>
     34 #include <machine/specialreg.h>
     35 #include <machine/frame.h>
     36 
     37 #define _KERNEL
     38 #include <machine/bootinfo.h>
     39 #undef _KERNEL
     40 
     41 #include <machine/tss.h>
     42 #include <machine/segments.h>
     43 
     44 int boothowto;
     45 struct bootinfo bootinfo;
     46 
     47 extern paddr_t kernpa_start, kernpa_end;
     48 
     49 static uint8_t idtstore[PAGE_SIZE] __aligned(PAGE_SIZE);
     50 
     51 #define IDTVEC(name) __CONCAT(X, name)
     52 typedef void (vector)(void);
     53 extern vector *x86_exceptions[];
     54 
     55 void fatal(char *msg)
     56 {
     57 	print("\n");
     58 	print_ext(RED_ON_BLACK, "********** FATAL ***********\n");
     59 	print_ext(RED_ON_BLACK, msg);
     60 	print("\n");
     61 	print_ext(RED_ON_BLACK, "****************************\n");
     62 
     63 	while (1);
     64 }
     65 
     66 /* -------------------------------------------------------------------------- */
     67 
     68 struct smallframe {
     69 	uint64_t sf_trapno;
     70 	uint64_t sf_err;
     71 	uint64_t sf_rip;
     72 	uint64_t sf_cs;
     73 	uint64_t sf_rflags;
     74 	uint64_t sf_rsp;
     75 	uint64_t sf_ss;
     76 };
     77 
     78 void trap(struct smallframe *);
     79 
     80 static char *trap_type[] = {
     81 	"privileged instruction fault",		/*  0 T_PRIVINFLT */
     82 	"breakpoint trap",			/*  1 T_BPTFLT */
     83 	"arithmetic trap",			/*  2 T_ARITHTRAP */
     84 	"asynchronous system trap",		/*  3 T_ASTFLT */
     85 	"protection fault",			/*  4 T_PROTFLT */
     86 	"trace trap",				/*  5 T_TRCTRAP */
     87 	"page fault",				/*  6 T_PAGEFLT */
     88 	"alignment fault",			/*  7 T_ALIGNFLT */
     89 	"integer divide fault",			/*  8 T_DIVIDE */
     90 	"non-maskable interrupt",		/*  9 T_NMI */
     91 	"overflow trap",			/* 10 T_OFLOW */
     92 	"bounds check fault",			/* 11 T_BOUND */
     93 	"FPU not available fault",		/* 12 T_DNA */
     94 	"double fault",				/* 13 T_DOUBLEFLT */
     95 	"FPU operand fetch fault",		/* 14 T_FPOPFLT */
     96 	"invalid TSS fault",			/* 15 T_TSSFLT */
     97 	"segment not present fault",		/* 16 T_SEGNPFLT */
     98 	"stack fault",				/* 17 T_STKFLT */
     99 	"machine check fault",			/* 18 T_MCA */
    100 	"SSE FP exception",			/* 19 T_XMM */
    101 	"reserved trap",			/* 20 T_RESERVED */
    102 };
    103 static int trap_types = __arraycount(trap_type);
    104 
    105 /*
    106  * Trap handler.
    107  */
    108 void
    109 trap(struct smallframe *sf)
    110 {
    111 	uint64_t trapno = sf->sf_trapno;
    112 	char *buf;
    113 
    114 	if (trapno < trap_types) {
    115 		buf = trap_type[trapno];
    116 	} else {
    117 		buf = "unknown trap";
    118 	}
    119 
    120 	print("\n");
    121 	print_ext(RED_ON_BLACK, "****** FAULT OCCURRED ******\n");
    122 	print_ext(RED_ON_BLACK, buf);
    123 	print("\n");
    124 	print_ext(RED_ON_BLACK, "****************************\n");
    125 
    126 	while (1);
    127 }
    128 
    129 /* -------------------------------------------------------------------------- */
    130 
    131 static void
    132 setregion(struct region_descriptor *rd, void *base, uint16_t limit)
    133 {
    134 	rd->rd_limit = limit;
    135 	rd->rd_base = (uint64_t)base;
    136 }
    137 
    138 static void
    139 setgate(struct gate_descriptor *gd, void *func, int ist, int type, int dpl,
    140     int sel)
    141 {
    142 	gd->gd_looffset = (uint64_t)func & 0xffff;
    143 	gd->gd_selector = sel;
    144 	gd->gd_ist = ist;
    145 	gd->gd_type = type;
    146 	gd->gd_dpl = dpl;
    147 	gd->gd_p = 1;
    148 	gd->gd_hioffset = (uint64_t)func >> 16;
    149 	gd->gd_zero = 0;
    150 	gd->gd_xx1 = 0;
    151 	gd->gd_xx2 = 0;
    152 	gd->gd_xx3 = 0;
    153 }
    154 
    155 static void
    156 init_idt(void)
    157 {
    158 	struct region_descriptor region;
    159 	struct gate_descriptor *idt;
    160 	size_t i;
    161 
    162 	idt = (struct gate_descriptor *)&idtstore;
    163 	for (i = 0; i < NCPUIDT; i++) {
    164 		setgate(&idt[i], x86_exceptions[i], 0, SDT_SYS386IGT,
    165 		    SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
    166 	}
    167 
    168 	setregion(&region, &idtstore, PAGE_SIZE - 1);
    169 	lidt(&region);
    170 }
    171 
    172 /* -------------------------------------------------------------------------- */
    173 
    174 #define PREKERN_API_VERSION	2
    175 
    176 struct prekern_args {
    177 	int version;
    178 	int boothowto;
    179 	void *bootinfo;
    180 	void *bootspace;
    181 	int esym;
    182 	int biosextmem;
    183 	int biosbasemem;
    184 	int cpuid_level;
    185 	uint32_t nox_flag;
    186 	uint64_t PDPpaddr;
    187 	vaddr_t atdevbase;
    188 	vaddr_t lwp0uarea;
    189 	paddr_t first_avail;
    190 };
    191 
    192 struct prekern_args pkargs;
    193 
    194 static void
    195 init_prekern_args(void)
    196 {
    197 	extern struct bootspace bootspace;
    198 	extern int esym;
    199 	extern int biosextmem;
    200 	extern int biosbasemem;
    201 	extern int cpuid_level;
    202 	extern uint32_t nox_flag;
    203 	extern uint64_t PDPpaddr;
    204 	extern vaddr_t iom_base;
    205 	extern paddr_t stkpa;
    206 	extern paddr_t pa_avail;
    207 
    208 	memset(&pkargs, 0, sizeof(pkargs));
    209 	pkargs.version = PREKERN_API_VERSION;
    210 	pkargs.boothowto = boothowto;
    211 	pkargs.bootinfo = (void *)&bootinfo;
    212 	pkargs.bootspace = &bootspace;
    213 	pkargs.esym = esym;
    214 	pkargs.biosextmem = biosextmem;
    215 	pkargs.biosbasemem = biosbasemem;
    216 	pkargs.cpuid_level = cpuid_level;
    217 	pkargs.nox_flag = nox_flag;
    218 	pkargs.PDPpaddr = PDPpaddr;
    219 	pkargs.atdevbase = iom_base;
    220 	pkargs.lwp0uarea = bootspace.boot.va + (stkpa - bootspace.boot.pa);
    221 	pkargs.first_avail = pa_avail;
    222 
    223 	extern vaddr_t stkva;
    224 	stkva = pkargs.lwp0uarea + (USPACE - FRAMESIZE);
    225 }
    226 
    227 void
    228 exec_kernel(vaddr_t ent)
    229 {
    230 	int (*jumpfunc)(struct prekern_args *);
    231 	int ret;
    232 
    233 	/*
    234 	 * Normally, the function does not return. If it does, it means the
    235 	 * kernel had trouble processing the arguments, and we panic here. The
    236 	 * return value is here for debug.
    237 	 */
    238 	jumpfunc = (void *)ent;
    239 	ret = (*jumpfunc)(&pkargs);
    240 
    241 	if (ret == -1) {
    242 		fatal("kernel returned: wrong API version");
    243 	} else {
    244 		fatal("kernel returned: unknown value");
    245 	}
    246 }
    247 
    248 /*
    249  * Main entry point of the Prekern.
    250  */
    251 void
    252 init_prekern(paddr_t pa_start)
    253 {
    254 	vaddr_t ent;
    255 
    256 	init_cons();
    257 	print_banner();
    258 
    259 	if (kernpa_start == 0 || kernpa_end == 0) {
    260 		fatal("init_prekern: unable to locate the kernel");
    261 	}
    262 	if (kernpa_start != (1UL << 21)) {
    263 		fatal("init_prekern: invalid kernpa_start");
    264 	}
    265 	if (kernpa_start % PAGE_SIZE != 0) {
    266 		fatal("init_prekern: kernpa_start not aligned");
    267 	}
    268 	if (kernpa_end % PAGE_SIZE != 0) {
    269 		fatal("init_prekern: kernpa_end not aligned");
    270 	}
    271 	if (kernpa_end <= kernpa_start) {
    272 		fatal("init_prekern: kernpa_end >= kernpa_start");
    273 	}
    274 
    275 	/*
    276 	 * Our physical space starts after the end of the kernel.
    277 	 */
    278 	if (pa_start < kernpa_end) {
    279 		fatal("init_prekern: physical space inside kernel");
    280 	}
    281 	mm_init(pa_start);
    282 
    283 	/*
    284 	 * Init the IDT. We mostly don't care about this, it's just here
    285 	 * to properly handle traps.
    286 	 */
    287 	init_idt();
    288 
    289 	print_state(STATE_NORMAL, "Prekern loaded");
    290 
    291 	/*
    292 	 * Init the PRNG.
    293 	 */
    294 	prng_init();
    295 
    296 	/*
    297 	 * Relocate the kernel.
    298 	 */
    299 	mm_map_kernel();
    300 	elf_build_info();
    301 	ent = elf_kernel_reloc();
    302 	mm_bootspace_mprotect();
    303 
    304 	/*
    305 	 * Build the arguments.
    306 	 */
    307 	init_prekern_args();
    308 
    309 	/*
    310 	 * Finally, jump into the kernel.
    311 	 */
    312 	print_state(STATE_NORMAL, "Jumping into the kernel");
    313 	jump_kernel(ent);
    314 
    315 	fatal("init_prekern: unreachable!");
    316 }
    317