diff --git a/src/arm/ffi.c b/src/arm/ffi.c index 7da69c18..4b8e6ded 100644 --- a/src/arm/ffi.c +++ b/src/arm/ffi.c @@ -273,6 +273,220 @@ ffi_prep_incoming_args_SYSV(char *stack, void **rvalue, /* How to make a trampoline. */ +#if FFI_EXEC_TRAMPOLINE_TABLE + +#include +#include +#include +#include + +extern void *ffi_closure_trampoline_table_page; + +typedef struct ffi_trampoline_table ffi_trampoline_table; +typedef struct ffi_trampoline_table_entry ffi_trampoline_table_entry; + +struct ffi_trampoline_table { + /* contigious writable and executable pages */ + vm_address_t config_page; + vm_address_t trampoline_page; + + /* free list tracking */ + uint16_t free_count; + ffi_trampoline_table_entry *free_list; + ffi_trampoline_table_entry *free_list_pool; + + ffi_trampoline_table *prev; + ffi_trampoline_table *next; +}; + +struct ffi_trampoline_table_entry { + void *(*trampoline)(); + ffi_trampoline_table_entry *next; +}; + +/* Override the standard architecture trampoline size */ +// XXX TODO - Fix +#undef FFI_TRAMPOLINE_SIZE +#define FFI_TRAMPOLINE_SIZE 12 + +/* The trampoline configuration is placed at 4080 bytes prior to the trampoline's entry point */ +#define FFI_TRAMPOLINE_CODELOC_CONFIG(codeloc) ((void **) (((uint8_t *) codeloc) - 4080)); + +/* The first 16 bytes of the config page are unused, as they are unaddressable from the trampoline page. */ +#define FFI_TRAMPOLINE_CONFIG_PAGE_OFFSET 16 + +/* Total number of trampolines that fit in one trampoline table */ +#define FFI_TRAMPOLINE_COUNT ((PAGE_SIZE - FFI_TRAMPOLINE_CONFIG_PAGE_OFFSET) / FFI_TRAMPOLINE_SIZE) + +static pthread_mutex_t ffi_trampoline_lock = PTHREAD_MUTEX_INITIALIZER; +static ffi_trampoline_table *ffi_trampoline_tables = NULL; + +static ffi_trampoline_table * +ffi_trampoline_table_alloc () +{ + ffi_trampoline_table *table = NULL; + + /* Loop until we can allocate two contigious pages */ + while (table == NULL) { + vm_address_t config_page = 0x0; + kern_return_t kt; + + /* Try to allocate two pages */ + kt = vm_allocate (mach_task_self (), &config_page, PAGE_SIZE*2, VM_FLAGS_ANYWHERE); + if (kt != KERN_SUCCESS) { + fprintf(stderr, "vm_allocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); + break; + } + + /* Now drop the second half of the allocation to make room for the trampoline table */ + vm_address_t trampoline_page = config_page+PAGE_SIZE; + kt = vm_deallocate (mach_task_self (), trampoline_page, PAGE_SIZE); + if (kt != KERN_SUCCESS) { + fprintf(stderr, "vm_deallocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); + break; + } + + /* Remap the trampoline table to directly follow the config page */ + vm_prot_t cur_prot; + vm_prot_t max_prot; + + kt = vm_remap (mach_task_self (), &trampoline_page, PAGE_SIZE, 0x0, FALSE, mach_task_self (), (vm_address_t) &ffi_closure_trampoline_table_page, FALSE, &cur_prot, &max_prot, VM_INHERIT_SHARE); + + /* If we lost access to the destination trampoline page, drop our config allocation mapping and retry */ + if (kt != KERN_SUCCESS) { + /* Log unexpected failures */ + if (kt != KERN_NO_SPACE) { + fprintf(stderr, "vm_remap() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); + } + + vm_deallocate (mach_task_self (), config_page, PAGE_SIZE); + continue; + } + + /* We have valid trampoline and config pages */ + table = calloc (1, sizeof(ffi_trampoline_table)); + table->free_count = FFI_TRAMPOLINE_COUNT; + table->config_page = config_page; + table->trampoline_page = trampoline_page; + + /* Create and initialize the free list */ + table->free_list_pool = calloc(FFI_TRAMPOLINE_COUNT, sizeof(ffi_trampoline_table_entry)); + + uint16_t i; + for (i = 0; i < table->free_count; i++) { + ffi_trampoline_table_entry *entry = &table->free_list_pool[i]; + entry->trampoline = (void *) (table->trampoline_page + (i * FFI_TRAMPOLINE_SIZE)); + + if (i < table->free_count - 1) + entry->next = &table->free_list_pool[i+1]; + } + + table->free_list = table->free_list_pool; + } + + return table; +} + +void * +ffi_closure_alloc (size_t size, void **code) +{ + /* Create the closure */ + ffi_closure *closure = malloc(size); + if (closure == NULL) + return NULL; + + pthread_mutex_lock(&ffi_trampoline_lock); + + /* Check for an active trampoline table with available entries. */ + ffi_trampoline_table *table = ffi_trampoline_tables; + if (table == NULL || table->free_list == NULL) { + table = ffi_trampoline_table_alloc (); + if (table == NULL) { + free(closure); + return NULL; + } + + /* Insert the new table at the top of the list */ + table->next = ffi_trampoline_tables; + if (table->next != NULL) + table->next->prev = table; + + ffi_trampoline_tables = table; + } + + /* Claim the free entry */ + ffi_trampoline_table_entry *entry = ffi_trampoline_tables->free_list; + ffi_trampoline_tables->free_list = entry->next; + ffi_trampoline_tables->free_count--; + entry->next = NULL; + + pthread_mutex_unlock(&ffi_trampoline_lock); + + /* Initialize the return values */ + *code = entry->trampoline; + closure->trampoline_table = table; + closure->trampoline_table_entry = entry; + + return closure; +} + +void +ffi_closure_free (void *ptr) +{ + ffi_closure *closure = ptr; + + pthread_mutex_lock(&ffi_trampoline_lock); + + /* Fetch the table and entry references */ + ffi_trampoline_table *table = closure->trampoline_table; + ffi_trampoline_table_entry *entry = closure->trampoline_table_entry; + + /* Return the entry to the free list */ + entry->next = table->free_list; + table->free_list = entry; + table->free_count++; + + /* If all trampolines within this table are free, and at least one other table exists, deallocate + * the table */ + if (table->free_count == FFI_TRAMPOLINE_COUNT && ffi_trampoline_tables != table) { + /* Remove from the list */ + if (table->prev != NULL) + table->prev->next = table->next; + + if (table->next != NULL) + table->next->prev = table->prev; + + /* Deallocate pages */ + kern_return_t kt; + kt = vm_deallocate (mach_task_self (), table->config_page, PAGE_SIZE); + if (kt != KERN_SUCCESS) + fprintf(stderr, "vm_deallocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); + + kt = vm_deallocate (mach_task_self (), table->trampoline_page, PAGE_SIZE); + if (kt != KERN_SUCCESS) + fprintf(stderr, "vm_deallocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); + + /* Deallocate free list */ + free (table->free_list_pool); + free (table); + } else if (ffi_trampoline_tables != table) { + /* Otherwise, bump this table to the top of the list */ + table->prev = NULL; + table->next = ffi_trampoline_tables; + if (ffi_trampoline_tables != NULL) + ffi_trampoline_tables->prev = table; + + ffi_trampoline_tables = table; + } + + pthread_mutex_unlock (&ffi_trampoline_lock); + + /* Free the closure */ + free (closure); +} + +#else + #define FFI_INIT_TRAMPOLINE(TRAMP,FUN,CTX) \ ({ unsigned char *__tramp = (unsigned char*)(TRAMP); \ unsigned int __fun = (unsigned int)(FUN); \ @@ -285,6 +499,7 @@ ffi_prep_incoming_args_SYSV(char *stack, void **rvalue, __clear_cache((&__tramp[0]), (&__tramp[19])); \ }) +#endif /* the cif must already be prep'ed */ @@ -298,8 +513,7 @@ ffi_prep_closure_loc (ffi_closure* closure, FFI_ASSERT (cif->abi == FFI_SYSV); #if FFI_EXEC_TRAMPOLINE_TABLE - // XXX - hardcoded offset - void **config = (void **) (((uint8_t *) codeloc) - 4080); + void **config = FFI_TRAMPOLINE_CODELOC_CONFIG(codeloc); config[0] = closure; config[1] = ffi_closure_SYSV; #else diff --git a/src/arm/trampoline.S b/src/arm/trampoline.S index 9f5891ed..83be0dc7 100644 --- a/src/arm/trampoline.S +++ b/src/arm/trampoline.S @@ -3,8 +3,8 @@ .text .align 12 -.globl _ffi_closure_trampoline_table -_ffi_closure_trampoline_table: +.globl _ffi_closure_trampoline_table_page +_ffi_closure_trampoline_table_page: // trampoline // Save to stack diff --git a/src/closures.c b/src/closures.c index c2141966..ac878df0 100644 --- a/src/closures.c +++ b/src/closures.c @@ -65,85 +65,7 @@ # if FFI_EXEC_TRAMPOLINE_TABLE -// XXX - non-thread-safe, non-portable implementation, intended for initial testing -#include -#include -#include - -extern void *ffi_closure_trampoline_table; - -static void *tramp_table = NULL; -static void **config_table = NULL; -static int tramp_table_free = 0; - -void * -ffi_closure_alloc (size_t size, void **code) -{ - if (!code) - return NULL; - - /* Allocate our config page and remap the trampoline table */ - while (tramp_table == NULL) { - vm_address_t config_page = 0x0; - kern_return_t kt; - - /* Try to allocate two pages */ - kt = vm_allocate(mach_task_self(), &config_page, PAGE_SIZE*2, VM_FLAGS_ANYWHERE); - if (kt != KERN_SUCCESS) { - fprintf(stderr, "vm_allocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); - break; - } - - /* Now drop the second half of the allocation to make room for the trampoline table */ - kt = vm_deallocate(mach_task_self(), config_page+PAGE_SIZE, PAGE_SIZE); - if (kt != KERN_SUCCESS) { - fprintf(stderr, "vm_deallocate() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); - break; - } - - /* Remap the trampoline table to directly follow the config page */ - vm_address_t table_page = config_page+PAGE_SIZE; - vm_prot_t cur_prot; - vm_prot_t max_prot; - - kt = vm_remap(mach_task_self(), &table_page, PAGE_SIZE, 0x0, FALSE, mach_task_self(), (vm_address_t) &ffi_closure_trampoline_table, FALSE, &cur_prot, &max_prot, VM_INHERIT_SHARE); - - /* If we lost access to the destination trampoline page, drop our config allocation mapping and retry */ - if (kt != KERN_SUCCESS) { - /* Log unexpected failures */ - if (kt != KERN_NO_SPACE) { - fprintf(stderr, "vm_remap() failure: %d at %s:%d\n", kt, __FILE__, __LINE__); - } - - vm_deallocate(mach_task_self(), config_page, PAGE_SIZE); - continue; - } - - tramp_table = (void *) table_page; - config_table = (void **) config_page; - config_table += 4; // XXX - there's a 16 byte offset into the config page on ARM - - fprintf(stderr, "[DEBUG] Allocated config page at %p, trampoline page at %p, configs start at %p\n", (void *) config_page, (void *) table_page, config_table); - } - - /* Check for permanent allocation failure */ - if (tramp_table == NULL) - return *code = NULL; - - *code = tramp_table + (3 * tramp_table_free); - tramp_table_free++; - - void *closure = malloc(size); - - return closure; -} - -void -ffi_closure_free (void *ptr) -{ - // TODO - //free (ptr); -} +// Per-target implementation; It's unclear what can reasonable be shared between two OS/architecture implementations. # elif FFI_MMAP_EXEC_WRIT /* !FFI_EXEC_TRAMPOLINE_TABLE */