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87 lines
2.4 KiB
87 lines
2.4 KiB
6 years ago
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/* Code from https://github.com/gwsystems/silverfish/blob/master/runtime/memory/64bit_nix.c */
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#include <runtime.h>
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#include <sandbox.h>
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#ifdef USE_MEM_VM
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#include <sys/mman.h>
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#define MAX_LINEAR_MEM ((1LL << 32) + WASM_PAGE_SIZE)
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void
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alloc_linear_memory(void)
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{
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struct sandbox *curr = sandbox_current();
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// Map 4gb + PAGE_SIZE of memory that will fault when accessed
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// We allocate the extra page so that reads off the end will also fail
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sandbox_lmbase = mmap(NULL, MAX_LINEAR_MEM, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (sandbox_lmbase == MAP_FAILED) {
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perror("Mapping of initial unusable region failed");
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exit(1);
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}
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void *map_result = mmap(sandbox_lmbase, WASM_PAGE_SIZE * WASM_START_PAGES, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
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if (map_result == MAP_FAILED) {
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perror("Mapping of initial memory failed");
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exit(1);
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}
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sandbox_lmbound = WASM_PAGE_SIZE * WASM_START_PAGES;
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curr->linear_start = sandbox_lmbase;
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curr->linear_size = sandbox_lmbound;
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}
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void
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free_linear_memory(void *base, u32 bound, u32 max)
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{
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struct sandbox *curr = sandbox_current();
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assert(base && bound);
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// cannot free currently executing sandbox's memory
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assert(base != curr->linear_start || base != sandbox_lmbase);
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int ret = munmap(base, MAX_LINEAR_MEM);
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if (ret) perror("munmap");
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}
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void
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expand_memory(void)
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{
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struct sandbox *curr = sandbox_current();
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// max_pages = 0 => no limit: FIXME
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assert(sandbox_lmbound / WASM_PAGE_SIZE < WASM_MAX_PAGES);
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// Remap the relevant wasm page to readable
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char *mem_as_chars = sandbox_lmbase;
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char *page_address = &mem_as_chars[sandbox_lmbound];
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void *map_result = mmap(page_address, WASM_PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
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if (map_result == MAP_FAILED) {
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perror("Mapping of new memory failed");
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exit(1);
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}
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// TODO: check curr->linear_max_size
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sandbox_lmbound += WASM_PAGE_SIZE;
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curr->linear_size = sandbox_lmbound;
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}
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INLINE char *
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get_memory_ptr_for_runtime(u32 offset, u32 bounds_check)
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{
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// Due to how we setup memory for x86, the virtual memory mechanism will catch the error, if bounds < WASM_PAGE_SIZE
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assert(bounds_check < WASM_PAGE_SIZE ||
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(sandbox_lmbound > bounds_check &&
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offset <= sandbox_lmbound - bounds_check));
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char *mem_as_chars = (char *)sandbox_lmbase;
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char *address = &mem_as_chars[offset];
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return address;
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}
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#else
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#error "Incorrect runtime memory module!"
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#endif
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