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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,289 @@ | ||
| #define DEFAULT_CHANNEL instr | ||
| #include "debug.h" | ||
| #include "asbestos/asbestos.h" | ||
| #include "asbestos/gen.h" | ||
| #include "asbestos/frame.h" | ||
| #include "emu/cpu.h" | ||
| #include "emu/memory.h" | ||
| #include "emu/interrupt.h" | ||
| #include "util/list.h" | ||
|
|
||
| extern int current_pid(void); | ||
|
|
||
| static void fiber_block_disconnect(struct asbestos *asbestos, struct fiber_block *block); | ||
| static void fiber_block_free(struct asbestos *asbestos, struct fiber_block *block); | ||
| static void fiber_free_jetsam(struct asbestos *asbestos); | ||
| static void fiber_resize_hash(struct asbestos *asbestos, size_t new_size); | ||
|
|
||
| struct asbestos *asbestos_new(struct mmu *mmu) { | ||
| struct asbestos *asbestos = calloc(1, sizeof(struct asbestos)); | ||
| asbestos->mmu = mmu; | ||
| fiber_resize_hash(asbestos, FIBER_INITIAL_HASH_SIZE); | ||
| asbestos->page_hash = calloc(FIBER_PAGE_HASH_SIZE, sizeof(*asbestos->page_hash)); | ||
| list_init(&asbestos->jetsam); | ||
| lock_init(&asbestos->lock); | ||
| wrlock_init(&asbestos->jetsam_lock); | ||
| return asbestos; | ||
| } | ||
|
|
||
| void asbestos_free(struct asbestos *asbestos) { | ||
| for (size_t i = 0; i < asbestos->hash_size; i++) { | ||
| struct fiber_block *block, *tmp; | ||
| if (list_null(&asbestos->hash[i])) | ||
| continue; | ||
| list_for_each_entry_safe(&asbestos->hash[i], block, tmp, chain) { | ||
| fiber_block_free(asbestos, block); | ||
| } | ||
| } | ||
| fiber_free_jetsam(asbestos); | ||
| free(asbestos->page_hash); | ||
| free(asbestos->hash); | ||
| free(asbestos); | ||
| } | ||
|
|
||
| static inline struct list *blocks_list(struct asbestos *asbestos, page_t page, int i) { | ||
| // TODO is this a good hash function? | ||
| return &asbestos->page_hash[page % FIBER_PAGE_HASH_SIZE].blocks[i]; | ||
| } | ||
|
|
||
| void asbestos_invalidate_range(struct asbestos *absestos, page_t start, page_t end) { | ||
| lock(&absestos->lock); | ||
| struct fiber_block *block, *tmp; | ||
| for (page_t page = start; page < end; page++) { | ||
| for (int i = 0; i <= 1; i++) { | ||
| struct list *blocks = blocks_list(absestos, page, i); | ||
| if (list_null(blocks)) | ||
| continue; | ||
| list_for_each_entry_safe(blocks, block, tmp, page[i]) { | ||
| fiber_block_disconnect(absestos, block); | ||
| block->is_jetsam = true; | ||
| list_add(&absestos->jetsam, &block->jetsam); | ||
| } | ||
| } | ||
| } | ||
| unlock(&absestos->lock); | ||
| } | ||
|
|
||
| void asbestos_invalidate_page(struct asbestos *asbestos, page_t page) { | ||
| asbestos_invalidate_range(asbestos, page, page + 1); | ||
| } | ||
| void asbestos_invalidate_all(struct asbestos *asbestos) { | ||
| asbestos_invalidate_range(asbestos, 0, MEM_PAGES); | ||
| } | ||
|
|
||
| static void fiber_resize_hash(struct asbestos *asbestos, size_t new_size) { | ||
| TRACE_(verbose, "%d resizing hash to %lu, using %lu bytes for gadgets\n", current_pid(), new_size, asbestos->mem_used); | ||
| struct list *new_hash = calloc(new_size, sizeof(struct list)); | ||
| for (size_t i = 0; i < asbestos->hash_size; i++) { | ||
| if (list_null(&asbestos->hash[i])) | ||
| continue; | ||
| struct fiber_block *block, *tmp; | ||
| list_for_each_entry_safe(&asbestos->hash[i], block, tmp, chain) { | ||
| list_remove(&block->chain); | ||
| list_init_add(&new_hash[block->addr % new_size], &block->chain); | ||
| } | ||
| } | ||
| free(asbestos->hash); | ||
| asbestos->hash = new_hash; | ||
| asbestos->hash_size = new_size; | ||
| } | ||
|
|
||
| static void fiber_insert(struct asbestos *asbestos, struct fiber_block *block) { | ||
| asbestos->mem_used += block->used; | ||
| asbestos->num_blocks++; | ||
| // target an average hash chain length of 1-2 | ||
| if (asbestos->num_blocks >= asbestos->hash_size * 2) | ||
| fiber_resize_hash(asbestos, asbestos->hash_size * 2); | ||
|
|
||
| list_init_add(&asbestos->hash[block->addr % asbestos->hash_size], &block->chain); | ||
| list_init_add(blocks_list(asbestos, PAGE(block->addr), 0), &block->page[0]); | ||
| if (PAGE(block->addr) != PAGE(block->end_addr)) | ||
| list_init_add(blocks_list(asbestos, PAGE(block->end_addr), 1), &block->page[1]); | ||
| } | ||
|
|
||
| static struct fiber_block *fiber_lookup(struct asbestos *asbestos, addr_t addr) { | ||
| struct list *bucket = &asbestos->hash[addr % asbestos->hash_size]; | ||
| if (list_null(bucket)) | ||
| return NULL; | ||
| struct fiber_block *block; | ||
| list_for_each_entry(bucket, block, chain) { | ||
| if (block->addr == addr) | ||
| return block; | ||
| } | ||
| return NULL; | ||
| } | ||
|
|
||
| static struct fiber_block *fiber_block_compile(addr_t ip, struct tlb *tlb) { | ||
| struct gen_state state; | ||
| TRACE("%d %08x --- compiling:\n", current_pid(), ip); | ||
| gen_start(ip, &state); | ||
| while (true) { | ||
| if (!gen_step(&state, tlb)) | ||
| break; | ||
| // no block should span more than 2 pages | ||
| // guarantee this by limiting total block size to 1 page | ||
| // guarantee that by stopping as soon as there's less space left than | ||
| // the maximum length of an x86 instruction | ||
| // TODO refuse to decode instructions longer than 15 bytes | ||
| if (state.ip - ip >= PAGE_SIZE - 15) { | ||
| gen_exit(&state); | ||
| break; | ||
| } | ||
| } | ||
| gen_end(&state); | ||
| assert(state.ip - ip <= PAGE_SIZE); | ||
| state.block->used = state.capacity; | ||
| return state.block; | ||
| } | ||
|
|
||
| // Remove all pointers to the block. It can't be freed yet because another | ||
| // thread may be executing it. | ||
| static void fiber_block_disconnect(struct asbestos *asbestos, struct fiber_block *block) { | ||
| if (asbestos != NULL) { | ||
| asbestos->mem_used -= block->used; | ||
| asbestos->num_blocks--; | ||
| } | ||
| list_remove(&block->chain); | ||
| for (int i = 0; i <= 1; i++) { | ||
| list_remove(&block->page[i]); | ||
| list_remove_safe(&block->jumps_from_links[i]); | ||
|
|
||
| struct fiber_block *prev_block, *tmp; | ||
| list_for_each_entry_safe(&block->jumps_from[i], prev_block, tmp, jumps_from_links[i]) { | ||
| if (prev_block->jump_ip[i] != NULL) | ||
| *prev_block->jump_ip[i] = prev_block->old_jump_ip[i]; | ||
| list_remove(&prev_block->jumps_from_links[i]); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| static void fiber_block_free(struct asbestos *asbestos, struct fiber_block *block) { | ||
| fiber_block_disconnect(asbestos, block); | ||
| free(block); | ||
| } | ||
|
|
||
| static void fiber_free_jetsam(struct asbestos *asbestos) { | ||
| struct fiber_block *block, *tmp; | ||
| list_for_each_entry_safe(&asbestos->jetsam, block, tmp, jetsam) { | ||
| list_remove(&block->jetsam); | ||
| free(block); | ||
| } | ||
| } | ||
|
|
||
| int fiber_enter(struct fiber_block *block, struct fiber_frame *frame, struct tlb *tlb); | ||
|
|
||
| static inline size_t fiber_cache_hash(addr_t ip) { | ||
| return (ip ^ (ip >> 12)) % FIBER_CACHE_SIZE; | ||
| } | ||
|
|
||
| static int cpu_step_to_interrupt(struct cpu_state *cpu, struct tlb *tlb) { | ||
| struct asbestos *asbestos = cpu->mmu->asbestos; | ||
| read_wrlock(&asbestos->jetsam_lock); | ||
|
|
||
| struct fiber_block **cache = calloc(FIBER_CACHE_SIZE, sizeof(*cache)); | ||
| struct fiber_frame *frame = malloc(sizeof(struct fiber_frame)); | ||
| memset(frame, 0, sizeof(*frame)); | ||
| frame->cpu = *cpu; | ||
| assert(asbestos->mmu == cpu->mmu); | ||
|
|
||
| int interrupt = INT_NONE; | ||
| while (interrupt == INT_NONE) { | ||
| addr_t ip = frame->cpu.eip; | ||
| size_t cache_index = fiber_cache_hash(ip); | ||
| struct fiber_block *block = cache[cache_index]; | ||
| if (block == NULL || block->addr != ip) { | ||
| lock(&asbestos->lock); | ||
| block = fiber_lookup(asbestos, ip); | ||
| if (block == NULL) { | ||
| block = fiber_block_compile(ip, tlb); | ||
| fiber_insert(asbestos, block); | ||
| } else { | ||
| TRACE("%d %08x --- missed cache\n", current_pid(), ip); | ||
| } | ||
| cache[cache_index] = block; | ||
| unlock(&asbestos->lock); | ||
| } | ||
| struct fiber_block *last_block = frame->last_block; | ||
| if (last_block != NULL && | ||
| (last_block->jump_ip[0] != NULL || | ||
| last_block->jump_ip[1] != NULL)) { | ||
| lock(&asbestos->lock); | ||
| // can't mint new pointers to a block that has been marked jetsam | ||
| // and is thus assumed to have no pointers left | ||
| if (!last_block->is_jetsam && !block->is_jetsam) { | ||
| for (int i = 0; i <= 1; i++) { | ||
| if (last_block->jump_ip[i] != NULL && | ||
| (*last_block->jump_ip[i] & 0xffffffff) == block->addr) { | ||
| *last_block->jump_ip[i] = (unsigned long) block->code; | ||
| list_add(&block->jumps_from[i], &last_block->jumps_from_links[i]); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| unlock(&asbestos->lock); | ||
| } | ||
| frame->last_block = block; | ||
|
|
||
| // block may be jetsam, but that's ok, because it can't be freed until | ||
| // every thread on this asbestos is not executing anything | ||
|
|
||
| TRACE("%d %08x --- cycle %ld\n", current_pid(), ip, frame->cpu.cycle); | ||
|
|
||
| interrupt = fiber_enter(block, frame, tlb); | ||
| if (interrupt == INT_NONE && __atomic_exchange_n(cpu->poked_ptr, false, __ATOMIC_SEQ_CST)) | ||
| interrupt = INT_TIMER; | ||
| if (interrupt == INT_NONE && ++frame->cpu.cycle % (1 << 10) == 0) | ||
| interrupt = INT_TIMER; | ||
| *cpu = frame->cpu; | ||
| } | ||
|
|
||
| free(frame); | ||
| free(cache); | ||
| read_wrunlock(&asbestos->jetsam_lock); | ||
| return interrupt; | ||
| } | ||
|
|
||
| static int cpu_single_step(struct cpu_state *cpu, struct tlb *tlb) { | ||
| struct gen_state state; | ||
| gen_start(cpu->eip, &state); | ||
| gen_step(&state, tlb); | ||
| gen_exit(&state); | ||
| gen_end(&state); | ||
|
|
||
| struct fiber_block *block = state.block; | ||
| struct fiber_frame frame = {.cpu = *cpu}; | ||
| int interrupt = fiber_enter(block, &frame, tlb); | ||
| *cpu = frame.cpu; | ||
| fiber_block_free(NULL, block); | ||
| if (interrupt == INT_NONE) | ||
| interrupt = INT_DEBUG; | ||
| return interrupt; | ||
| } | ||
|
|
||
| int cpu_run_to_interrupt(struct cpu_state *cpu, struct tlb *tlb) { | ||
| if (cpu->poked_ptr == NULL) | ||
| cpu->poked_ptr = &cpu->_poked; | ||
| tlb_refresh(tlb, cpu->mmu); | ||
| int interrupt = (cpu->tf ? cpu_single_step : cpu_step_to_interrupt)(cpu, tlb); | ||
| cpu->trapno = interrupt; | ||
|
|
||
| struct asbestos *asbestos = cpu->mmu->asbestos; | ||
| lock(&asbestos->lock); | ||
| if (!list_empty(&asbestos->jetsam)) { | ||
| // write-lock the jetsam_lock to wait until other asbestos threads get | ||
| // to this point, so they will all clear out their block pointers | ||
| // TODO: use RCU for better performance | ||
| unlock(&asbestos->lock); | ||
| write_wrlock(&asbestos->jetsam_lock); | ||
| lock(&asbestos->lock); | ||
| fiber_free_jetsam(asbestos); | ||
| write_wrunlock(&asbestos->jetsam_lock); | ||
| } | ||
| unlock(&asbestos->lock); | ||
|
|
||
| return interrupt; | ||
| } | ||
|
|
||
| void cpu_poke(struct cpu_state *cpu) { | ||
| __atomic_store_n(cpu->poked_ptr, true, __ATOMIC_SEQ_CST); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,15 @@ | ||
| #include <stdatomic.h> | ||
| #include "emu/cpu.h" | ||
|
|
||
| // keep in sync with asm | ||
| #define FIBER_RETURN_CACHE_SIZE 4096 | ||
| #define FIBER_RETURN_CACHE_HASH(x) ((x) & 0xFFF0) >> 4) | ||
|
|
||
| struct fiber_frame { | ||
| struct cpu_state cpu; | ||
| void *bp; | ||
| addr_t value_addr; | ||
| uint64_t value[2]; // buffer for crosspage crap | ||
| struct fiber_block *last_block; | ||
| long ret_cache[FIBER_RETURN_CACHE_SIZE]; // a map of ip to pointer-to-call-gadget-arguments | ||
| }; |
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