github.com/xushiwei/go@v0.0.0-20130601165731-2b9d83f45bc9/src/pkg/runtime/cgo/gcc_netbsd_arm.c (about)

     1  // Copyright 2013 The Go Authors.  All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include <sys/types.h>
     6  #include <pthread.h>
     7  #include <signal.h>
     8  #include <string.h>
     9  #include "libcgo.h"
    10  
    11  static void *threadentry(void*);
    12  
    13  // We have to resort to TLS variable to save g(R10) and
    14  // m(R9). One reason is that external code might trigger
    15  // SIGSEGV, and our runtime.sigtramp don't even know we
    16  // are in external code, and will continue to use R10/R9,
    17  // this might as well result in another SIGSEGV.
    18  // Note: all three functions will clobber R0, and the last
    19  // two can be called from 5c ABI code.
    20  void __aeabi_read_tp(void) __attribute__((naked));
    21  void x_cgo_save_gm(void) __attribute__((naked));
    22  void x_cgo_load_gm(void) __attribute__((naked));
    23  
    24  void
    25  __aeabi_read_tp(void)
    26  {
    27  	// this function is only allowed to clobber r0
    28  	__asm__ __volatile__ (
    29  		"mrc p15, 0, r0, c13, c0, 3\n\t"
    30  		"cmp r0, #0\n\t"
    31  		"movne pc, lr\n\t"
    32  		"push {r1,r2,r3,r12}\n\t"
    33  		"svc 0x00a0013c\n\t" // _lwp_getprivate
    34  		"pop {r1,r2,r3,r12}\n\t"
    35  		"mov pc, lr\n\t"
    36  	);
    37  }
    38  
    39  // g (R10) at 8(TP), m (R9) at 12(TP)
    40  void
    41  x_cgo_load_gm(void)
    42  {
    43  	__asm__ __volatile__ (
    44  		"push {lr}\n\t"
    45  		"bl __aeabi_read_tp\n\t"
    46  		"ldr r10, [r0, #8]\n\t"
    47  		"ldr r9, [r0, #12]\n\t"
    48  		"pop {pc}\n\t"
    49  	);
    50  }
    51  
    52  void
    53  x_cgo_save_gm(void)
    54  {
    55  	__asm__ __volatile__ (
    56  		"push {lr}\n\t"
    57  		"bl __aeabi_read_tp\n\t"
    58  		"str r10, [r0, #8]\n\t"
    59  		"str r9, [r0, #12]\n\t"
    60  		"pop {pc}\n\t"
    61  	);
    62  }
    63  
    64  void
    65  x_cgo_init(G *g)
    66  {
    67  	pthread_attr_t attr;
    68  	size_t size;
    69  	x_cgo_save_gm(); // save g and m for the initial thread
    70  
    71  	pthread_attr_init(&attr);
    72  	pthread_attr_getstacksize(&attr, &size);
    73  	g->stackguard = (uintptr)&attr - size + 4096;
    74  	pthread_attr_destroy(&attr);
    75  }
    76  
    77  
    78  void
    79  _cgo_sys_thread_start(ThreadStart *ts)
    80  {
    81  	pthread_attr_t attr;
    82  	sigset_t ign, oset;
    83  	pthread_t p;
    84  	size_t size;
    85  	int err;
    86  
    87  	sigfillset(&ign);
    88  	sigprocmask(SIG_SETMASK, &ign, &oset);
    89  
    90  	pthread_attr_init(&attr);
    91  	pthread_attr_getstacksize(&attr, &size);
    92  	ts->g->stackguard = size;
    93  	err = pthread_create(&p, &attr, threadentry, ts);
    94  
    95  	sigprocmask(SIG_SETMASK, &oset, nil);
    96  
    97  	if (err != 0) {
    98  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
    99  		abort();
   100  	}
   101  }
   102  
   103  extern void crosscall_arm2(void (*fn)(void), void *g, void *m);
   104  static void*
   105  threadentry(void *v)
   106  {
   107  	ThreadStart ts;
   108  
   109  	ts = *(ThreadStart*)v;
   110  	free(v);
   111  
   112  	ts.g->stackbase = (uintptr)&ts;
   113  
   114  	/*
   115  	 * _cgo_sys_thread_start set stackguard to stack size;
   116  	 * change to actual guard pointer.
   117  	 */
   118  	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096 * 2;
   119  
   120  	crosscall_arm2(ts.fn, (void *)ts.g, (void *)ts.m);
   121  	return nil;
   122  }