// Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. #include "config.h" #include "go-assert.h" #include #include #include #include #include #include #include #include #include #include #include #include #ifdef HAVE_SYS_MMAN_H #include #endif #include "interface.h" #include "go-alloc.h" #define _STRINGIFY2_(x) #x #define _STRINGIFY_(x) _STRINGIFY2_(x) #define GOSYM_PREFIX _STRINGIFY_(__USER_LABEL_PREFIX__) /* This file supports C files copied from the 6g runtime library. This is a version of the 6g runtime.h rewritten for gccgo's version of the code. */ typedef signed int int8 __attribute__ ((mode (QI))); typedef unsigned int uint8 __attribute__ ((mode (QI))); typedef signed int int16 __attribute__ ((mode (HI))); typedef unsigned int uint16 __attribute__ ((mode (HI))); typedef signed int int32 __attribute__ ((mode (SI))); typedef unsigned int uint32 __attribute__ ((mode (SI))); typedef signed int int64 __attribute__ ((mode (DI))); typedef unsigned int uint64 __attribute__ ((mode (DI))); typedef float float32 __attribute__ ((mode (SF))); typedef double float64 __attribute__ ((mode (DF))); typedef signed int intptr __attribute__ ((mode (pointer))); typedef unsigned int uintptr __attribute__ ((mode (pointer))); typedef intptr intgo; // Go's int typedef uintptr uintgo; // Go's uint typedef uintptr uintreg; /* Defined types. */ typedef uint8 bool; typedef uint8 byte; typedef struct Func Func; typedef struct G G; typedef struct Lock Lock; typedef struct M M; typedef struct P P; typedef struct Note Note; typedef struct String String; typedef struct FuncVal FuncVal; typedef struct SigTab SigTab; typedef struct MCache MCache; typedef struct FixAlloc FixAlloc; typedef struct Hchan Hchan; typedef struct Timers Timers; typedef struct Timer Timer; typedef struct GCStats GCStats; typedef struct LFNode LFNode; typedef struct ParFor ParFor; typedef struct ParForThread ParForThread; typedef struct CgoMal CgoMal; typedef struct PollDesc PollDesc; typedef struct DebugVars DebugVars; typedef struct __go_open_array Slice; typedef struct __go_interface Iface; typedef struct __go_empty_interface Eface; typedef struct __go_type_descriptor Type; typedef struct __go_defer_stack Defer; typedef struct __go_panic_stack Panic; typedef struct __go_ptr_type PtrType; typedef struct __go_func_type FuncType; typedef struct __go_interface_type InterfaceType; typedef struct __go_map_type MapType; typedef struct __go_channel_type ChanType; typedef struct Traceback Traceback; typedef struct Location Location; /* * Per-CPU declaration. */ extern M* runtime_m(void); extern G* runtime_g(void); extern M runtime_m0; extern G runtime_g0; /* * defined constants */ enum { // G status // // If you add to this list, add to the list // of "okay during garbage collection" status // in mgc0.c too. Gidle, Grunnable, Grunning, Gsyscall, Gwaiting, Gmoribund_unused, // currently unused, but hardcoded in gdb scripts Gdead, }; enum { // P status Pidle, Prunning, Psyscall, Pgcstop, Pdead, }; enum { true = 1, false = 0, }; enum { PtrSize = sizeof(void*), }; enum { // Per-M stack segment cache size. StackCacheSize = 32, // Global <-> per-M stack segment cache transfer batch size. StackCacheBatch = 16, }; /* * structures */ struct Lock { // Futex-based impl treats it as uint32 key, // while sema-based impl as M* waitm. // Used to be a union, but unions break precise GC. uintptr key; }; struct Note { // Futex-based impl treats it as uint32 key, // while sema-based impl as M* waitm. // Used to be a union, but unions break precise GC. uintptr key; }; struct String { const byte* str; intgo len; }; struct FuncVal { void (*fn)(void); // variable-size, fn-specific data here }; struct GCStats { // the struct must consist of only uint64's, // because it is casted to uint64[]. uint64 nhandoff; uint64 nhandoffcnt; uint64 nprocyield; uint64 nosyield; uint64 nsleep; }; // A location in the program, used for backtraces. struct Location { uintptr pc; String filename; String function; intgo lineno; }; struct G { Defer* defer; Panic* panic; void* exception; // current exception being thrown bool is_foreign; // whether current exception from other language void *gcstack; // if status==Gsyscall, gcstack = stackbase to use during gc size_t gcstack_size; void* gcnext_segment; void* gcnext_sp; void* gcinitial_sp; ucontext_t gcregs; byte* entry; // initial function void* param; // passed parameter on wakeup bool fromgogo; // reached from gogo int16 status; uint32 selgen; // valid sudog pointer int64 goid; int64 waitsince; // approx time when the G become blocked const char* waitreason; // if status==Gwaiting G* schedlink; bool ispanic; bool issystem; // do not output in stack dump bool isbackground; // ignore in deadlock detector bool paniconfault; // panic (instead of crash) on unexpected fault address M* m; // for debuggers, but offset not hard-coded M* lockedm; int32 sig; int32 writenbuf; byte* writebuf; uintptr sigcode0; uintptr sigcode1; // uintptr sigpc; uintptr gopc; // pc of go statement that created this goroutine int32 ncgo; CgoMal* cgomal; Traceback* traceback; ucontext_t context; void* stack_context[10]; }; struct M { G* g0; // goroutine with scheduling stack G* gsignal; // signal-handling G byte* gsignalstack; size_t gsignalstacksize; void (*mstartfn)(void); G* curg; // current running goroutine G* caughtsig; // goroutine running during fatal signal P* p; // attached P for executing Go code (nil if not executing Go code) P* nextp; int32 id; int32 mallocing; int32 throwing; int32 gcing; int32 locks; int32 softfloat; int32 dying; int32 profilehz; int32 helpgc; bool spinning; // M is out of work and is actively looking for work bool blocked; // M is blocked on a Note uint32 fastrand; uint64 ncgocall; // number of cgo calls in total int32 ncgo; // number of cgo calls currently in progress CgoMal* cgomal; Note park; M* alllink; // on allm M* schedlink; MCache *mcache; G* lockedg; Location createstack[32]; // Stack that created this thread. uint32 locked; // tracking for LockOSThread M* nextwaitm; // next M waiting for lock uintptr waitsema; // semaphore for parking on locks uint32 waitsemacount; uint32 waitsemalock; GCStats gcstats; bool needextram; bool dropextram; // for gccgo: drop after call is done. uint8 traceback; bool (*waitunlockf)(G*, void*); void* waitlock; uintptr end[]; }; struct P { Lock; int32 id; uint32 status; // one of Pidle/Prunning/... P* link; uint32 schedtick; // incremented on every scheduler call uint32 syscalltick; // incremented on every system call M* m; // back-link to associated M (nil if idle) MCache* mcache; Defer* deferpool; // pool of available Defer structs (see panic.c) // Cache of goroutine ids, amortizes accesses to runtime_sched.goidgen. uint64 goidcache; uint64 goidcacheend; // Queue of runnable goroutines. uint32 runqhead; uint32 runqtail; G* runq[256]; // Available G's (status == Gdead) G* gfree; int32 gfreecnt; byte pad[64]; }; // The m->locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread. // The low bit (LockExternal) is a boolean reporting whether any LockOSThread call is active. // External locks are not recursive; a second lock is silently ignored. // The upper bits of m->lockedcount record the nesting depth of calls to lockOSThread // (counting up by LockInternal), popped by unlockOSThread (counting down by LockInternal). // Internal locks can be recursive. For instance, a lock for cgo can occur while the main // goroutine is holding the lock during the initialization phase. enum { LockExternal = 1, LockInternal = 2, }; struct SigTab { int32 sig; int32 flags; void* fwdsig; }; enum { SigNotify = 1<<0, // let signal.Notify have signal, even if from kernel SigKill = 1<<1, // if signal.Notify doesn't take it, exit quietly SigThrow = 1<<2, // if signal.Notify doesn't take it, exit loudly SigPanic = 1<<3, // if the signal is from the kernel, panic SigDefault = 1<<4, // if the signal isn't explicitly requested, don't monitor it SigHandling = 1<<5, // our signal handler is registered SigGoExit = 1<<6, // cause all runtime procs to exit (only used on Plan 9). }; // Layout of in-memory per-function information prepared by linker // See http://golang.org/s/go12symtab. // Keep in sync with linker and with ../../libmach/sym.c // and with package debug/gosym. struct Func { String name; uintptr entry; // entry pc }; #ifdef GOOS_nacl enum { NaCl = 1, }; #else enum { NaCl = 0, }; #endif #ifdef GOOS_windows enum { Windows = 1 }; #else enum { Windows = 0 }; #endif #ifdef GOOS_solaris enum { Solaris = 1 }; #else enum { Solaris = 0 }; #endif struct Timers { Lock; G *timerproc; bool sleeping; bool rescheduling; Note waitnote; Timer **t; int32 len; int32 cap; }; // Package time knows the layout of this structure. // If this struct changes, adjust ../time/sleep.go:/runtimeTimer. // For GOOS=nacl, package syscall knows the layout of this structure. // If this struct changes, adjust ../syscall/net_nacl.go:/runtimeTimer. struct Timer { intgo i; // heap index // Timer wakes up at when, and then at when+period, ... (period > 0 only) // each time calling f(now, arg) in the timer goroutine, so f must be // a well-behaved function and not block. int64 when; int64 period; FuncVal *fv; Eface arg; uintptr seq; }; // Lock-free stack node. struct LFNode { LFNode *next; uintptr pushcnt; }; // Parallel for descriptor. struct ParFor { const FuncVal *body; // executed for each element uint32 done; // number of idle threads uint32 nthr; // total number of threads uint32 nthrmax; // maximum number of threads uint32 thrseq; // thread id sequencer uint32 cnt; // iteration space [0, cnt) bool wait; // if true, wait while all threads finish processing, // otherwise parfor may return while other threads are still working ParForThread *thr; // array of thread descriptors // stats uint64 nsteal; uint64 nstealcnt; uint64 nprocyield; uint64 nosyield; uint64 nsleep; }; // Track memory allocated by code not written in Go during a cgo call, // so that the garbage collector can see them. struct CgoMal { CgoMal *next; void *alloc; }; // Holds variables parsed from GODEBUG env var. struct DebugVars { int32 allocfreetrace; int32 cgocheck; int32 efence; int32 gccheckmark; int32 gcpacertrace; int32 gcshrinkstackoff; int32 gcstackbarrieroff; int32 gcstackbarrierall; int32 gcstoptheworld; int32 gctrace; int32 gcdead; int32 invalidptr; int32 sbrk; int32 scavenge; int32 scheddetail; int32 schedtrace; int32 wbshadow; }; extern bool runtime_precisestack; extern bool runtime_copystack; /* * defined macros * you need super-gopher-guru privilege * to add this list. */ #define nelem(x) (sizeof(x)/sizeof((x)[0])) #define nil ((void*)0) #define USED(v) ((void) v) #define ROUND(x, n) (((x)+(n)-1)&~(uintptr)((n)-1)) /* all-caps to mark as macro: it evaluates n twice */ byte* runtime_startup_random_data; uint32 runtime_startup_random_data_len; void runtime_get_random_data(byte**, int32*); enum { // hashinit wants this many random bytes HashRandomBytes = 32 }; void runtime_hashinit(void); void runtime_traceback(void); void runtime_tracebackothers(G*); enum { // The maximum number of frames we print for a traceback TracebackMaxFrames = 100, }; /* * external data */ extern uintptr runtime_zerobase; extern G** runtime_allg; extern uintptr runtime_allglen; extern G* runtime_lastg; extern M* runtime_allm; extern P** runtime_allp; extern int32 runtime_gomaxprocs; extern uint32 runtime_needextram; extern uint32 runtime_panicking; extern int8* runtime_goos; extern int32 runtime_ncpu; extern void (*runtime_sysargs)(int32, uint8**); extern uint32 runtime_Hchansize; extern DebugVars runtime_debug; extern uintptr runtime_maxstacksize; extern bool runtime_isstarted; extern bool runtime_isarchive; /* * common functions and data */ #define runtime_strcmp(s1, s2) __builtin_strcmp((s1), (s2)) #define runtime_strncmp(s1, s2, n) __builtin_strncmp((s1), (s2), (n)) #define runtime_strstr(s1, s2) __builtin_strstr((s1), (s2)) intgo runtime_findnull(const byte*); intgo runtime_findnullw(const uint16*); void runtime_dump(byte*, int32); void runtime_gogo(G*); struct __go_func_type; void runtime_args(int32, byte**); void runtime_osinit(); void runtime_goargs(void); void runtime_goenvs(void); void runtime_goenvs_unix(void); void runtime_throw(const char*) __attribute__ ((noreturn)); void runtime_panicstring(const char*) __attribute__ ((noreturn)); bool runtime_canpanic(G*); void runtime_prints(const char*); void runtime_printf(const char*, ...); int32 runtime_snprintf(byte*, int32, const char*, ...); #define runtime_mcmp(a, b, s) __builtin_memcmp((a), (b), (s)) #define runtime_memmove(a, b, s) __builtin_memmove((a), (b), (s)) void* runtime_mal(uintptr); String runtime_gostring(const byte*); String runtime_gostringnocopy(const byte*); void runtime_schedinit(void); void runtime_initsig(void); void runtime_sigenable(uint32 sig); void runtime_sigdisable(uint32 sig); void runtime_sigignore(uint32 sig); int32 runtime_gotraceback(bool *crash); void runtime_goroutineheader(G*); void runtime_printtrace(Location*, int32, bool); #define runtime_open(p, f, m) open((p), (f), (m)) #define runtime_read(d, v, n) read((d), (v), (n)) #define runtime_write(d, v, n) write((d), (v), (n)) #define runtime_close(d) close(d) void runtime_ready(G*); String runtime_getenv(const char*); int32 runtime_atoi(const byte*, intgo); void* runtime_mstart(void*); G* runtime_malg(int32, byte**, size_t*); void runtime_mpreinit(M*); void runtime_minit(void); void runtime_unminit(void); void runtime_needm(void); void runtime_dropm(void); void runtime_signalstack(byte*, int32); MCache* runtime_allocmcache(void); void runtime_freemcache(MCache*); void runtime_mallocinit(void); void runtime_mprofinit(void); #define runtime_malloc(s) __go_alloc(s) #define runtime_free(p) __go_free(p) #define runtime_getcallersp(p) __builtin_frame_address(1) int32 runtime_mcount(void); int32 runtime_gcount(void); void runtime_mcall(void(*)(G*)); uint32 runtime_fastrand1(void); int32 runtime_timediv(int64, int32, int32*); int32 runtime_round2(int32 x); // round x up to a power of 2. // atomic operations #define runtime_cas(pval, old, new) __sync_bool_compare_and_swap (pval, old, new) #define runtime_cas64(pval, old, new) __sync_bool_compare_and_swap (pval, old, new) #define runtime_casp(pval, old, new) __sync_bool_compare_and_swap (pval, old, new) // Don't confuse with XADD x86 instruction, // this one is actually 'addx', that is, add-and-fetch. #define runtime_xadd(p, v) __sync_add_and_fetch (p, v) #define runtime_xadd64(p, v) __sync_add_and_fetch (p, v) #define runtime_xchg(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST) #define runtime_xchg64(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST) #define runtime_xchgp(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST) #define runtime_atomicload(p) __atomic_load_n (p, __ATOMIC_SEQ_CST) #define runtime_atomicstore(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST) #define runtime_atomicstore64(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST) #define runtime_atomicload64(p) __atomic_load_n (p, __ATOMIC_SEQ_CST) #define runtime_atomicloadp(p) __atomic_load_n (p, __ATOMIC_SEQ_CST) #define runtime_atomicstorep(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST) void runtime_setmg(M*, G*); void runtime_newextram(void); #define runtime_exit(s) exit(s) #define runtime_breakpoint() __builtin_trap() void runtime_gosched(void); void runtime_gosched0(G*); void runtime_schedtrace(bool); void runtime_park(bool(*)(G*, void*), void*, const char*); void runtime_parkunlock(Lock*, const char*); void runtime_tsleep(int64, const char*); M* runtime_newm(void); void runtime_goexit(void); void runtime_entersyscall(void) __asm__ (GOSYM_PREFIX "syscall.Entersyscall"); void runtime_entersyscallblock(void); void runtime_exitsyscall(void) __asm__ (GOSYM_PREFIX "syscall.Exitsyscall"); G* __go_go(void (*pfn)(void*), void*); void siginit(void); bool __go_sigsend(int32 sig); int32 runtime_callers(int32, Location*, int32, bool keep_callers); int64 runtime_nanotime(void); // monotonic time int64 runtime_unixnanotime(void); // real time, can skip void runtime_dopanic(int32) __attribute__ ((noreturn)); void runtime_startpanic(void); void runtime_freezetheworld(void); void runtime_unwindstack(G*, byte*); void runtime_sigprof(); void runtime_resetcpuprofiler(int32); void runtime_setcpuprofilerate(void(*)(uintptr*, int32), int32); void runtime_usleep(uint32); int64 runtime_cputicks(void); int64 runtime_tickspersecond(void); void runtime_blockevent(int64, int32); extern int64 runtime_blockprofilerate; void runtime_addtimer(Timer*); bool runtime_deltimer(Timer*); G* runtime_netpoll(bool); void runtime_netpollinit(void); int32 runtime_netpollopen(uintptr, PollDesc*); int32 runtime_netpollclose(uintptr); void runtime_netpollready(G**, PollDesc*, int32); uintptr runtime_netpollfd(PollDesc*); void runtime_netpollarm(PollDesc*, int32); void** runtime_netpolluser(PollDesc*); bool runtime_netpollclosing(PollDesc*); void runtime_netpolllock(PollDesc*); void runtime_netpollunlock(PollDesc*); void runtime_crash(void); void runtime_parsedebugvars(void); void _rt0_go(void); void* runtime_funcdata(Func*, int32); int32 runtime_setmaxthreads(int32); G* runtime_timejump(void); void runtime_iterate_finq(void (*callback)(FuncVal*, void*, const FuncType*, const PtrType*)); void runtime_stoptheworld(void); void runtime_starttheworld(void); extern uint32 runtime_worldsema; /* * mutual exclusion locks. in the uncontended case, * as fast as spin locks (just a few user-level instructions), * but on the contention path they sleep in the kernel. * a zeroed Lock is unlocked (no need to initialize each lock). */ void runtime_lock(Lock*); void runtime_unlock(Lock*); /* * sleep and wakeup on one-time events. * before any calls to notesleep or notewakeup, * must call noteclear to initialize the Note. * then, exactly one thread can call notesleep * and exactly one thread can call notewakeup (once). * once notewakeup has been called, the notesleep * will return. future notesleep will return immediately. * subsequent noteclear must be called only after * previous notesleep has returned, e.g. it's disallowed * to call noteclear straight after notewakeup. * * notetsleep is like notesleep but wakes up after * a given number of nanoseconds even if the event * has not yet happened. if a goroutine uses notetsleep to * wake up early, it must wait to call noteclear until it * can be sure that no other goroutine is calling * notewakeup. * * notesleep/notetsleep are generally called on g0, * notetsleepg is similar to notetsleep but is called on user g. */ void runtime_noteclear(Note*); void runtime_notesleep(Note*); void runtime_notewakeup(Note*); bool runtime_notetsleep(Note*, int64); // false - timeout bool runtime_notetsleepg(Note*, int64); // false - timeout /* * low-level synchronization for implementing the above */ uintptr runtime_semacreate(void); int32 runtime_semasleep(int64); void runtime_semawakeup(M*); // or void runtime_futexsleep(uint32*, uint32, int64); void runtime_futexwakeup(uint32*, uint32); /* * Lock-free stack. * Initialize uint64 head to 0, compare with 0 to test for emptiness. * The stack does not keep pointers to nodes, * so they can be garbage collected if there are no other pointers to nodes. */ void runtime_lfstackpush(uint64 *head, LFNode *node) __asm__ (GOSYM_PREFIX "runtime.lfstackpush"); LFNode* runtime_lfstackpop(uint64 *head); /* * Parallel for over [0, n). * body() is executed for each iteration. * nthr - total number of worker threads. * if wait=true, threads return from parfor() when all work is done; * otherwise, threads can return while other threads are still finishing processing. */ ParFor* runtime_parforalloc(uint32 nthrmax); void runtime_parforsetup(ParFor *desc, uint32 nthr, uint32 n, bool wait, const FuncVal *body); void runtime_parfordo(ParFor *desc); void runtime_parforiters(ParFor*, uintptr, uintptr*, uintptr*); /* * low level C-called */ #define runtime_mmap mmap #define runtime_munmap munmap #define runtime_madvise madvise #define runtime_memclr(buf, size) __builtin_memset((buf), 0, (size)) #define runtime_getcallerpc(p) __builtin_return_address(0) #ifdef __rtems__ void __wrap_rtems_task_variable_add(void **); #endif /* * Names generated by gccgo. */ #define runtime_printbool __go_print_bool #define runtime_printfloat __go_print_double #define runtime_printint __go_print_int64 #define runtime_printiface __go_print_interface #define runtime_printeface __go_print_empty_interface #define runtime_printstring __go_print_string #define runtime_printpointer __go_print_pointer #define runtime_printuint __go_print_uint64 #define runtime_printslice __go_print_slice #define runtime_printcomplex __go_print_complex /* * runtime go-called */ void runtime_printbool(_Bool); void runtime_printbyte(int8); void runtime_printfloat(double); void runtime_printint(int64); void runtime_printiface(Iface); void runtime_printeface(Eface); void runtime_printstring(String); void runtime_printpc(void*); void runtime_printpointer(void*); void runtime_printuint(uint64); void runtime_printhex(uint64); void runtime_printslice(Slice); void runtime_printcomplex(complex double); void reflect_call(const struct __go_func_type *, FuncVal *, _Bool, _Bool, void **, void **) __asm__ (GOSYM_PREFIX "reflect.call"); #define runtime_panic __go_panic /* * runtime c-called (but written in Go) */ void runtime_printany(Eface) __asm__ (GOSYM_PREFIX "runtime.Printany"); void runtime_newTypeAssertionError(const String*, const String*, const String*, const String*, Eface*) __asm__ (GOSYM_PREFIX "runtime.NewTypeAssertionError"); void runtime_newErrorCString(const char*, Eface*) __asm__ (GOSYM_PREFIX "runtime.NewErrorCString"); /* * wrapped for go users */ void runtime_semacquire(uint32 volatile *, bool); void runtime_semrelease(uint32 volatile *); int32 runtime_gomaxprocsfunc(int32 n); void runtime_procyield(uint32); void runtime_osyield(void); void runtime_lockOSThread(void); void runtime_unlockOSThread(void); bool runtime_lockedOSThread(void); bool runtime_showframe(String, bool); void runtime_printcreatedby(G*); uintptr runtime_memlimit(void); #define ISNAN(f) __builtin_isnan(f) enum { UseSpanType = 1, }; #define runtime_setitimer setitimer void runtime_check(void); // A list of global variables that the garbage collector must scan. struct root_list { struct root_list *next; struct root { void *decl; size_t size; } roots[]; }; void __go_register_gc_roots(struct root_list*); // Size of stack space allocated using Go's allocator. // This will be 0 when using split stacks, as in that case // the stacks are allocated by the splitstack library. extern uintptr runtime_stacks_sys; struct backtrace_state; extern struct backtrace_state *__go_get_backtrace_state(void); extern _Bool __go_file_line(uintptr, String*, String*, intgo *); extern byte* runtime_progname(); extern void runtime_main(void*); extern uint32 runtime_in_callers; int32 getproccount(void); #define PREFETCH(p) __builtin_prefetch(p) bool runtime_gcwaiting(void); void runtime_badsignal(int); Defer* runtime_newdefer(void); void runtime_freedefer(Defer*); struct time_now_ret { int64_t sec; int32_t nsec; }; struct time_now_ret now() __asm__ (GOSYM_PREFIX "time.now") __attribute__ ((no_split_stack)); extern void _cgo_wait_runtime_init_done (void); extern void _cgo_notify_runtime_init_done (void); extern _Bool runtime_iscgo; extern _Bool runtime_cgoHasExtraM; extern Hchan *runtime_main_init_done; extern uintptr __go_end __attribute__ ((weak));