mirror of
https://github.com/jart/cosmopolitan.git
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d3efa47f81
* [metal] Refactoring: separate out sys_writev_vga() and _vga_init() modules * [metal] Read VGA info from BDA before long mode entry, not after If using a pre-existing VGA text console, the VGA initialization code now retrieves the cursor position & character height from the BIOS data area while still in real mode — rather than reading from the BIOS data area only after entering long mode. (This should help make the code more correct, if Cosmopolitan were to support UEFI graphics output in the future. If the program were booted via UEFI, then the long mode IsMetal() code would still be activated, but the BIOS data area might not have been initialized in that case.) This change also means that there are now a few more fields in the `struct mman`. * [metal] VGA console can now show "screen of death" upon a crash There is now a new function _klog_vga(), which can be called by kprintf() to output system messages — e.g. information about CPU exceptions — on the VGA screen. * [metal] CPU exception handler now dumps cr2 value * [metal] Add demo of program crash reporting w/ bare metal VGA TTY * [metal] Reduce size of "screen of death" code
204 lines
11 KiB
C
204 lines
11 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╠──────────────────────────────────────────────────────────────────────────────╣
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╠──────────────────────────────────────────────────────▌▀▄─▐──▀▄─▐▄─▐▄▐▄─▐▄─▐▄─│
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│ αcτµαlly pδrταblε εxεcµταblε § no-frills virtual memory management │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "ape/relocations.h"
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#include "libc/elf/def.h"
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#include "libc/elf/struct/phdr.h"
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#include "libc/macros.internal.h"
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#include "libc/nexgen32e/uart.internal.h"
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#include "libc/runtime/e820.internal.h"
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#include "libc/runtime/metalprintf.internal.h"
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#include "libc/runtime/pc.internal.h"
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#include "libc/runtime/runtime.h"
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/**
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* Allocates new page of physical memory.
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*/
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noasan texthead uint64_t __new_page(struct mman *mm) {
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uint64_t p;
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if (mm->pdpi == mm->e820n) {
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/* TODO: reclaim free pages */
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return 0;
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}
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while (mm->pdp >= mm->e820[mm->pdpi].addr + mm->e820[mm->pdpi].size) {
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if (++mm->pdpi == mm->e820n) return 0;
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mm->pdp = mm->e820[mm->pdpi].addr;
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}
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p = mm->pdp;
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mm->pdp += 4096;
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return p;
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}
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/**
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* Returns pointer to page table entry for page at virtual address.
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* Additional page tables are allocated if needed as a side-effect.
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*/
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noasan textreal uint64_t *__get_virtual(struct mman *mm, uint64_t *t,
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int64_t vaddr, bool maketables) {
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uint64_t *e, p;
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unsigned char h;
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for (h = 39;; h -= 9) {
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e = t + ((vaddr >> h) & 511);
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if (h == 12) return e;
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if (!(*e & PAGE_V)) {
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if (!maketables) return NULL;
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if (!(p = __new_page(mm))) return NULL;
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__clear_page(BANE + p);
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*e = p | PAGE_V | PAGE_RW;
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}
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t = (uint64_t *)(BANE + (*e & PAGE_TA));
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}
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}
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/**
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* Sorts, rounds, and filters BIOS memory map.
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*/
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static noasan textreal void __normalize_e820(struct mman *mm) {
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uint64_t a, b;
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uint64_t x, y;
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unsigned i, j, n;
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for (n = i = 0; mm->e820[i].size; ++i) {
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mm->e820[n] = mm->e820[i];
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x = mm->e820[n].addr;
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y = mm->e820[n].addr + mm->e820[n].size;
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a = ROUNDUP(x, 4096);
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b = ROUNDDOWN(y, 4096);
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if (b > a && mm->e820[i].type == kMemoryUsable) {
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b -= a;
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mm->e820[n].addr = a;
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mm->e820[n].size = b;
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++n;
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}
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}
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for (i = 1; i < n; ++i) {
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for (j = i; j > 0 && mm->e820[i].addr < mm->e820[j - 1].addr; --j) {
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mm->e820[j] = mm->e820[j - 1];
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}
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mm->e820[j] = mm->e820[i];
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}
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mm->pdp = MAX(0x80000, mm->e820[0].addr);
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mm->pdpi = 0;
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mm->e820n = n;
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}
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/**
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* Identity maps an area of physical memory to its negative address.
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*/
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noasan textreal void __invert_memory_area(struct mman *mm, uint64_t *pml4t,
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uint64_t ps, uint64_t size,
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uint64_t pte_flags) {
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uint64_t pe = ps + size, p, *m;
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ps = ROUNDDOWN(ps, 4096);
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pe = ROUNDUP(pe, 4096);
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for (p = ps; p != pe; p += 4096) {
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m = __get_virtual(mm, pml4t, BANE + p, true);
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if (m && !(*m & PAGE_V)) {
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*m = p | PAGE_V | pte_flags;
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}
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}
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}
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/**
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* Identity maps all usable physical memory to its negative address.
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*/
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static noasan textreal void __invert_memory(struct mman *mm, uint64_t *pml4t) {
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uint64_t i, j, *m, p, pe;
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for (i = 0; i < mm->e820n; ++i) {
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uint64_t ps = mm->e820[i].addr, size = mm->e820[i].size;
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/* ape/ape.S has already mapped the first 2 MiB of physical memory. */
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if (ps < 0x200000 && ps + size <= 0x200000)
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continue;
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__invert_memory_area(mm, pml4t, ps, size, PAGE_RW);
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}
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}
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/**
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* Exports information about the offset of a field within a structure type,
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* so that assembly language routines can use it. This macro can be invoked
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* from inside a function whose code is known to be emitted.
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*/
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#define export_offsetof(type, member) \
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do { \
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asm volatile(".globl \"" #type "::" #member "\"\n\t" \
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".set \"" #type "::" #member "\",%c0" \
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: /* no outputs */ \
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: "i" (offsetof(type, member))); \
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} while (0)
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noasan textreal void __setup_mman(struct mman *mm, uint64_t *pml4t) {
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export_offsetof(struct mman, pc_drive_base_table);
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export_offsetof(struct mman, pc_drive_last_sector);
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export_offsetof(struct mman, pc_drive_last_head);
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export_offsetof(struct mman, e820);
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export_offsetof(struct mman, e820_end);
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export_offsetof(struct mman, bad_idt);
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export_offsetof(struct mman, pc_video_type);
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export_offsetof(struct mman, pc_video_stride);
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export_offsetof(struct mman, pc_video_width);
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export_offsetof(struct mman, pc_video_height);
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export_offsetof(struct mman, pc_video_framebuffer);
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export_offsetof(struct mman, pc_video_framebuffer_size);
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export_offsetof(struct mman, pc_video_curs_info);
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export_offsetof(struct mman, pc_video_char_height);
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__normalize_e820(mm);
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__invert_memory(mm, pml4t);
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}
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/**
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* Maps APE-defined ELF program headers into memory and clears BSS.
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*/
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noasan textreal void __map_phdrs(struct mman *mm, uint64_t *pml4t, uint64_t b) {
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struct Elf64_Phdr *p;
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uint64_t i, f, v, m, *e;
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extern char ape_phdrs[] __attribute__((__weak__));
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extern char ape_phdrs_end[] __attribute__((__weak__));
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__setup_mman(mm, pml4t);
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for (p = (struct Elf64_Phdr *)REAL(ape_phdrs), m = 0;
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p < (struct Elf64_Phdr *)REAL(ape_phdrs_end); ++p) {
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if (p->p_type == PT_LOAD || p->p_type == PT_GNU_STACK) {
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f = PAGE_V | PAGE_U;
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if (p->p_flags & PF_W) f |= PAGE_RW;
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for (i = 0; i < p->p_memsz; i += 4096) {
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if (i < p->p_filesz) {
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v = b + p->p_offset + i;
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m = MAX(m, v);
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} else {
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v = __clear_page(BANE + __new_page(mm));
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}
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*__get_virtual(mm, pml4t, p->p_vaddr + i, true) = (v & PAGE_TA) | f;
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}
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}
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}
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mm->pdp = MAX(mm->pdp, m);
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}
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