154 lines
No EOL
3.9 KiB
C
154 lines
No EOL
3.9 KiB
C
#include <stdint.h>
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#include "panic.h"
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#include "pmap.h"
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#define PAGEMAP_START (0x00040000)
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#define PAGEMAP_END (0x00060000)
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#define PAGE_USED(n) ((*(uint8_t *)(PAGEMAP_START + (n >> 3)) >> (n & 7)) & 1)
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#define CLEAR_PAGE(n) *(uint8_t *)(PAGEMAP_START + (n >> 3)) &= ~(1 << (n & 7))
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#define SET_PAGE(n) *(uint8_t *)(PAGEMAP_START + (n >> 3)) |= 1 << (n & 7)
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#define KBSS_START (0x04000000)
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#define USER_START (0x08000000)
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extern const void _kernel_bss_end;
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uint32_t kernel_pages_left;
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uint32_t user_pages_left;
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uint32_t max_kernel_pages;
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uint32_t max_user_pages;
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enum {
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BMET_FREE = 1
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};
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enum {
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BMEF_NON_VOLATILE = 0x02
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};
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struct bios_mmap_entry {
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uint64_t base;
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uint64_t length;
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uint32_t type;
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uint32_t flags;
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};
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void init_pagemap() {
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for (uint32_t *i = (uint32_t *)(PAGEMAP_START + (KBSS_START >> 15)); i < (uint32_t *)PAGEMAP_END; ++i)
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*i = 0xffffffff;
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const struct bios_mmap_entry *mmap_p = (const struct bios_mmap_entry *)0x00010000;
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const struct bios_mmap_entry *mmap_e = (const struct bios_mmap_entry *)(0x00010000 + *(uint16_t *)0x00004006);
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for (; mmap_p < mmap_e; ++mmap_p) {
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if (mmap_p->type != BMET_FREE)
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continue;
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if (mmap_p->base > 0xffffffff)
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continue;
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uint32_t base_page = ((mmap_p->base - 1) >> 12) + 1;
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uint64_t end = mmap_p->base + mmap_p->length;
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if (end > 0xffffffff)
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end = 0x100000000;
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uint32_t end_page = end >> 12;
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for (uint32_t i = base_page; i < end_page; ++i)
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CLEAR_PAGE(i);
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}
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uint32_t kernel_pages = (((uint32_t)&_kernel_bss_end - 1) >> 12) + 1;
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for (uint32_t i = 0; i < kernel_pages; ++i)
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SET_PAGE(i);
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kernel_pages_left = 0;
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for (uint32_t i = KBSS_START >> 12; i < USER_START >> 12; ++i)
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if (!PAGE_USED(i))
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++kernel_pages_left;
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max_kernel_pages = kernel_pages_left;
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user_pages_left = 0;
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for (uint32_t i = USER_START >> 12; i < 1048576; ++i)
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if (!PAGE_USED(i))
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++user_pages_left;
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max_user_pages = user_pages_left;
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}
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//very inneficient algorithm, just returns first hole big enough.
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//a smarter algorithm might pick the smallest one available,
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//and go by bytes (or dwords) instead of bits where possible.
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void *allocate_kernel_pages(uint32_t n) {
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//logsz("trace: allocate_kernel_pages(");
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//char nbuf[11];
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//u32_dec(n, nbuf);
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//logsz(nbuf);
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//logsz(") = 0x");
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uint32_t run = 0;
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for (uint32_t page = KBSS_START >> 12; page < USER_START >> 12; ++page) {
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if (PAGE_USED(page))
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run = 0;
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else if (++run == n) {
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uint32_t start = page - run + 1;
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for (uint32_t i = start; i <= page; ++i)
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SET_PAGE(i);
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kernel_pages_left -= n;
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//u32_hex(start << 12, nbuf);
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//logsz(nbuf);
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//logch('\n');
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return (void *)(start << 12);
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}
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}
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return 0;
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}
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//very inneficient algorithm, just returns first hole big enough.
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//a smarter algorithm might pick the smallest one available,
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//and go by bytes (or dwords) instead of bits where possible.
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void *allocate_user_pages(uint32_t n) {
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//logsz("trace: allocate_user_pages(");
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//char nbuf[11];
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//u32_dec(n, nbuf);
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//logsz(nbuf);
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//logsz(") = 0x");
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uint32_t run = 0;
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for (uint32_t page = USER_START >> 12; page < 1048576; ++page) {
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if (PAGE_USED(page))
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run = 0;
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else if (++run == n) {
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uint32_t start = page - run + 1;
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for (uint32_t i = start; i <= page; ++i)
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SET_PAGE(i);
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user_pages_left -= n;
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//u32_hex(start << 12, nbuf);
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//logsz(nbuf);
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//logch('\n');
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return (void *)(start << 12);
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}
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}
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return 0;
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}
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//in the future, change this to go by bytes or dwords instead of bits.
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void free_pages(const void *ptr, uint32_t n) {
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//logsz("trace: free_pages(0x");
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//char nbuf[11];
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//u32_hex(ptr, nbuf);
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//logsz(nbuf);
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//logsz(", ");
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//u32_dec(n, nbuf);
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//logsz(nbuf);
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//logsz(")\n");
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uint32_t page = (uint32_t)ptr >> 12;
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for (uint32_t i = page; i < page + n; ++i)
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CLEAR_PAGE(i);
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if ((uint32_t)ptr >= USER_START)
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user_pages_left += n;
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else
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kernel_pages_left += n;
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} |