fix msim to load non page aligned segments
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parent
9ae3442c85
commit
5befb8b4e6
GPG key ID:
744AB800E383AE52
2 changed files with 88 additions and 69 deletions
156
msim/load.c
156
msim/load.c
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@ -9,6 +9,9 @@
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#include "sim.h"
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#define SEC_ALIGN 0x1000
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#define PAGE_SIZE 4096
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#define BITFILED_LEN (UINT32_MAX / PAGE_SIZE / 8)
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struct load_state {
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FILE *file;
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@ -106,95 +109,112 @@ static int load_phdr(struct load_state *state)
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return M_SUCCESS;
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}
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static int load_segment(struct simulator *sim,
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struct load_state *state, Elf32_Phdr *hdr)
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static void set_page(uint8_t *bitfield, uint32_t addr)
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{
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uint32_t off = B32(hdr->p_offset);
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uint32_t len = B32(hdr->p_filesz);
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uint32_t is_text = B32(hdr->p_flags) & PF_X;
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int idx = (addr / PAGE_SIZE) / 8;
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int off = (addr / PAGE_SIZE) % 8;
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bitfield[idx] |= 1 << off;
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}
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static int get_page(const uint8_t *const bitfield, uint32_t addr)
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{
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int idx = (addr / PAGE_SIZE) / 8;
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int off = (addr / PAGE_SIZE) % 8;
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return ((bitfield[idx] >> off) & 1);
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}
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static int load_segment(struct simulator *sim, struct load_state *state,
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Elf32_Phdr *hdr, uint8_t* bitfield)
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{
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uint32_t addr = B32(hdr->p_vaddr),
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off = B32(hdr->p_offset),
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len = B32(hdr->p_filesz),
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flags = B32(hdr->p_flags);
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bool exec = flags & PF_X;
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// ignore if empty
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if (len < 1)
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return M_SUCCESS;
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// make sure segment is acutally inside
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// the file
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if (BOUND_CHK(state->file_sz, len, off)) {
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ERROR("segment location invalid");
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return M_ERROR;
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}
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uintptr_t addr = 0;
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uint32_t add = 0;
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if (len % SEC_ALIGN) {
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add = SEC_ALIGN - (len % SEC_ALIGN);
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len += add;
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}
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if (is_text) {
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addr = sim->text_max;
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sim->text_max += len;
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} else {
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addr = sim->data_max;
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sim->data_max += len;
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}
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bool read = B32(hdr->p_flags) & PF_R;
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bool write = B32(hdr->p_flags) & PF_W;
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uint32_t prot = 0;
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if (read)
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prot |= PROT_READ;
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if (write)
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prot |= PROT_WRITE;
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void *res = mmap((void*)addr, len, prot, MAP_PRIVATE | MAP_FIXED,
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state->fd, off);
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if ((uintptr_t)res != addr) {
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PERROR("failed to map executable");
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// make sure the vitural address is also
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// valid
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if (BOUND_CHK(UINT32_MAX, len, addr)) {
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ERROR("segment vitural addr invalid");
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return M_ERROR;
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}
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// update text seg bounds
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if (exec) {
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if (addr < sim->text_min)
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sim->text_min = addr;
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if (addr + len > sim->text_max)
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sim->text_max = addr + len;
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}
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// align the mapping ptr to
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// the page size
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uintptr_t ptr = (addr / PAGE_SIZE) * PAGE_SIZE;
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// map each page that the segment
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// requires
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for (; ptr < addr + len; ptr += PAGE_SIZE) {
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// dont remap if address is
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// already mapped
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if (get_page(bitfield, ptr))
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continue;
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// set page as mapped
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set_page(bitfield, ptr);
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void *res = mmap(
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(void *) ptr, PAGE_SIZE,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1, 0);
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if ((uintptr_t) res != ptr) {
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PERROR("failed to map executable");
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return M_ERROR;
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}
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}
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// load the segment into the mapped memory
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fseek(state->file, off, SEEK_SET);
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fread((void *) (uintptr_t) addr, 1, len, state->file);
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return M_SUCCESS;
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}
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static int load_memory(struct simulator *sim, struct load_state *state)
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{
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uint32_t base = 0;
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// map each page in a 32bit address space to a single bit
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// in the bitfield
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uint8_t *bitfield = malloc(BITFILED_LEN);
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if (bitfield == NULL) {
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PERROR("cannot alloc");
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return M_ERROR;
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}
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memset(bitfield, 0, BITFILED_LEN);
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for (uint32_t i = 0; i < state->phdr_len; i++) {
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Elf32_Phdr *hdr = NULL;
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uint32_t min = UINT32_MAX;
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Elf32_Phdr *hdr = &state->phdr[i];
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if (B32(state->phdr[i].p_filesz) < 1)
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continue;
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// we need to load segments in order
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for (uint32_t j = 0; j < state->phdr_len; j++) {
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Elf32_Phdr *temp = &state->phdr[j];
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uint32_t off = B32(temp->p_offset);
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uint32_t len = B32(temp->p_filesz);
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if (len < 1)
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continue;
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if (off <= base)
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continue;
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if (off >= min)
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continue;
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min = off;
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hdr = temp;
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}
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base = min;
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if (hdr == NULL) {
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ERROR("invalid elf phdr");
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return M_ERROR;
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}
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if (load_segment(sim, state, hdr))
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if (load_segment(sim, state, hdr, bitfield))
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return M_ERROR;
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}
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free(bitfield);
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return M_SUCCESS;
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}
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@ -34,7 +34,6 @@ struct simulator_args {
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struct simulator {
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struct simulator_args *args;
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/// the registers
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uint32_t reg[32];
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