diff options
Diffstat (limited to 'yjit_asm.c')
| -rw-r--r-- | yjit_asm.c | 48 |
1 files changed, 45 insertions, 3 deletions
diff --git a/yjit_asm.c b/yjit_asm.c index 2ae50295a9..d093b2edde 100644 --- a/yjit_asm.c +++ b/yjit_asm.c @@ -163,7 +163,7 @@ static uint8_t *alloc_exec_mem(uint32_t mem_size) mem_block = (uint8_t*)mmap( (void*)req_addr, mem_size, - PROT_READ | PROT_WRITE | PROT_EXEC, + PROT_READ | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE, -1, 0 @@ -184,7 +184,7 @@ static uint8_t *alloc_exec_mem(uint32_t mem_size) mem_block = (uint8_t*)mmap( (void*)alloc_exec_mem, mem_size, - PROT_READ | PROT_WRITE | PROT_EXEC, + PROT_READ | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 @@ -197,7 +197,7 @@ static uint8_t *alloc_exec_mem(uint32_t mem_size) mem_block = (uint8_t*)mmap( NULL, mem_size, - PROT_READ | PROT_WRITE | PROT_EXEC, + PROT_READ | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 @@ -210,9 +210,17 @@ static uint8_t *alloc_exec_mem(uint32_t mem_size) exit(-1); } + codeblock_t block; + block.current_aligned_write_pos = ALIGNED_WRITE_POSITION_NONE; + block.mem_block = mem_block; + block.mem_size = mem_size; + + codeblock_t * cb = █ // Fill the executable memory with INT3 (0xCC) so that // executing uninitialized memory will fault + cb_mark_all_writeable(cb); memset(mem_block, 0xCC, mem_size); + cb_mark_all_executable(cb); return mem_block; #else @@ -230,6 +238,7 @@ void cb_init(codeblock_t *cb, uint8_t *mem_block, uint32_t mem_size) cb->write_pos = 0; cb->num_labels = 0; cb->num_refs = 0; + cb->current_aligned_write_pos = ALIGNED_WRITE_POSITION_NONE; } // Align the current write position to a multiple of bytes @@ -277,6 +286,7 @@ void cb_write_byte(codeblock_t *cb, uint8_t byte) { assert (cb->mem_block); assert (cb->write_pos + 1 <= cb->mem_size); + cb_mark_position_writeable(cb, cb->write_pos); cb->mem_block[cb->write_pos++] = byte; } @@ -1771,3 +1781,35 @@ void cb_write_lock_prefix(codeblock_t *cb) { cb_write_byte(cb, 0xF0); } + +void cb_mark_all_writeable(codeblock_t * cb) +{ + if (mprotect(cb->mem_block, cb->mem_size, PROT_READ | PROT_WRITE)) { + fprintf(stderr, "Couldn't make JIT page (%p) writeable, errno: %s", (void *)cb->mem_block, strerror(errno)); + abort(); + } +} + +void cb_mark_position_writeable(codeblock_t * cb, uint32_t write_pos) +{ + uint32_t pagesize = (uint32_t)sysconf(_SC_PAGESIZE); + uint32_t aligned_position = (write_pos / pagesize) * pagesize; + + if (cb->current_aligned_write_pos != aligned_position) { + cb->current_aligned_write_pos = aligned_position; + if (mprotect(cb->mem_block + aligned_position, pagesize, PROT_READ | PROT_WRITE)) { + fprintf(stderr, "Couldn't make JIT page (%p) writeable, errno: %s", (void *)(cb->mem_block + aligned_position), strerror(errno)); + abort(); + } + } +} + +void cb_mark_all_executable(codeblock_t * cb) +{ + cb->current_aligned_write_pos = ALIGNED_WRITE_POSITION_NONE; + if (mprotect(cb->mem_block, cb->mem_size, PROT_READ | PROT_EXEC)) { + fprintf(stderr, "Couldn't make JIT page (%p) executable, errno: %s", (void *)cb->mem_block, strerror(errno)); + abort(); + } +} + |