97 lines
4.1 KiB
C
97 lines
4.1 KiB
C
#include <print.h>
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#include <types.h>
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#include <mm.h>
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#define SCTLR 15,0,1,0,0
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#define TTBR0 15,0,2,0,0
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#define TTBR1 15,0,2,0,1
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#define TTBCR 15,0,2,0,2
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#define _cp_read(var, cp, opc1, CRn, CRm, opc2) asm("mrc p" #cp ", " #opc1 ", %0, c" #CRn ", c" #CRm ", " #opc2 ";" : "=r"(var) : )
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#define _cp_write(var, cp, opc1, CRn, CRm, opc2) asm("mcr p" #cp ", " #opc1 ", %0, c" #CRn ", c" #CRm ", " #opc2 ";" : : "r"(var) )
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#define cp_read(var, ...) _cp_read(var, __VA_ARGS__)
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#define cp_write(var, ...) _cp_write(var, __VA_ARGS__)
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#define TT_BASE_SIZE (1<<14) /* 16k */
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#define TT_SECTION_SIZE (1<<20) /* 1mb */
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uint32 *kernel_start_phys, *kernel_start_virt, *kernel_end_phys, *kernel_end_virt;
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void print_mapping(void *addr) {
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extern uint32 tt_base_virtual;
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print("%x: %x\n", addr, *(uint32 *)(tt_base_virtual + (((uint32)addr)>>18)));
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}
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void mmu_reinit() {
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extern uint32 tt_base_virtual, tt_base_physical, start;
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uint32 curr_addr;
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uint32 *curr_tt_entry;
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int virt_phys_offset;
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virt_phys_offset = tt_base_virtual - tt_base_physical;
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kernel_start_virt = &start;
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kernel_start_phys = kernel_start_virt - virt_phys_offset/4;
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kernel_end_virt = (uint32 *)(tt_base_virtual + TT_BASE_SIZE);
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kernel_end_phys = (uint32 *)(tt_base_physical + TT_BASE_SIZE);
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//get the current translation table base address
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curr_tt_entry = (uint32 *)tt_base_virtual;
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//do first loop iteration outside the loop, because we have to check against wrapping back around to know we're done
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*curr_tt_entry = 0xc02; /* 0xc02 means read/write at any priviledge level, and that it's a section w/o PXN bit set */
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curr_tt_entry++;
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//create identity mapping for entire address space using sections.
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//BUT, if we've relocated the kernel from where it is in physical
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//memory, make sure we keep those mappings correct, and we'll actually
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//swap the twp mappings so all of memory is addressable.
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for (curr_addr = 0x00100000; curr_addr != 0; curr_addr += 0x00100000) {
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if ((uint32 *)curr_addr >= kernel_start_phys && (uint32 *)curr_addr < kernel_end_phys) {
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*curr_tt_entry = (curr_addr + virt_phys_offset) | 0xc02;
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} else if ((uint32 *)curr_addr >= kernel_start_virt && (uint32 *)curr_addr < kernel_end_virt) {
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*curr_tt_entry = (curr_addr - virt_phys_offset) | 0xc02;
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} else {
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*curr_tt_entry = curr_addr | 0xc02;
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}
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curr_tt_entry++;
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}
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}
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int mmu_region_contains(void *lower_a, void *upper_a, void *lower_b, void *upper_b) {
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return lower_b >= lower_a && upper_b <= upper_a;
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}
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#define section_round_down(ptr) (((uint32)ptr) & ~(TT_SECTION_SIZE-1))
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#define section_round_up(ptr) (((((uint32)ptr) & ~1) + (TT_SECTION_SIZE-1) ) & ~(TT_SECTION_SIZE-1))
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/* Called one per physical memory region by bootup code. This function is
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* responsible for only adding (via mm_add_free_region()) those parts of the
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* memory region which are still available (i.e. aren't in the kernel and
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* haven't been remapped anywhere else. */
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void declare_memory_region(void *lower, void *upper) {
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void *k_section_start_phys = (void *)section_round_down(kernel_start_phys);
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void *k_section_end_phys = (void *)(section_round_up(kernel_end_phys) - 1);
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void *k_section_start_virt = (void *)section_round_down(kernel_start_virt);
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void *k_section_end_virt = (void *)(section_round_up(kernel_end_virt) - 1);
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if (upper - lower < 1) {
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print("Warning: declare_memory_region() called with lower=%x, upper=%x. Ignoring.\n", lower, upper);
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return;
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}
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//TODO It's possible (though highly unlikely) that the kernel (virtual)
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//is split across two different memory regions. We should probably
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//handle this.
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if (mmu_region_contains(lower, upper, k_section_start_phys, k_section_end_phys)) {
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//Don't map any of the physical kernel's memory
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declare_memory_region(lower, (void *) ((char *)k_section_start_phys - 1));
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declare_memory_region((void *) ((char *)k_section_end_phys + 1), upper);
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mm_add_free_region(kernel_end_virt, k_section_end_virt);
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} else if (mmu_region_contains(lower, upper, k_section_start_virt, k_section_end_virt)) {
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declare_memory_region(lower, (void *) ((char *)k_section_start_virt - 1));
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declare_memory_region((void *) ((char *)k_section_end_virt + 1), upper);
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} else {
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mm_add_free_region(lower, upper);
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}
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}
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