mono/utils/mach-support-arm.c

   1 /*
   2  * mach-support-arm.c: mach support for ARM
   3  *
   4  * Authors:
   5  *   Geoff Norton (gnorton@novell.com)
   6  *   Rodrigo Kumpera (kumpera@gmail.com)
   7  *
   8  * (C) 2010 Novell, Inc.
   9  * (C) 2011 Xamarin, Inc.
  10  */
  11
  12 #include <config.h>
  13
  14 #if defined(__MACH__)
  15 #include <stdint.h>
  16 #include <glib.h>
  17 #include <pthread.h>
  18 #include "utils/mono-sigcontext.h"
  19 #include "utils/mono-compiler.h"
  20 #include "mach-support.h"
  21
  22 /* _mcontext.h now defines __darwin_mcontext32, not __darwin_mcontext, starting with Xcode 5.1 */
  23 #ifdef _STRUCT_MCONTEXT32
  24        #define __darwin_mcontext       __darwin_mcontext32
  25 #endif
  26
  27 /* Known offsets used for TLS storage*/
  28
  29
  30 static const int known_tls_offsets[] = {
  31         0x48, /*Found on iOS 6 */
  32         0xA4,
  33         0xA8,
  34 };
  35
  36 #define TLS_PROBE_COUNT (sizeof (known_tls_offsets) / sizeof (int))
  37
  38 /* This is 2 slots less than the known low */
  39 #define TLS_PROBE_LOW_WATERMARK 0x40
  40 /* This is 24 slots above the know high, which is the same diff as the knowns high-low*/
  41 #define TLS_PROBE_HIGH_WATERMARK 0x108
  42
  43 static int tls_vector_offset;
  44
  45 void *
  46 mono_mach_arch_get_ip (thread_state_t state)
  47 {
  48         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  49
  50         return (void *) arch_state->__pc;
  51 }
  52
  53 void *
  54 mono_mach_arch_get_sp (thread_state_t state)
  55 {
  56         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  57
  58         return (void *) arch_state->__sp;
  59 }
  60
  61 int
  62 mono_mach_arch_get_mcontext_size ()
  63 {
  64         return sizeof (struct __darwin_mcontext);
  65 }
  66
  67 void
  68 mono_mach_arch_thread_state_to_mcontext (thread_state_t state, void *context)
  69 {
  70         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  71         struct __darwin_mcontext *ctx = (struct __darwin_mcontext *) context;
  72
  73         ctx->__ss = *arch_state;
  74 }
  75
  76 void
  77 mono_mach_arch_mcontext_to_thread_state (void *context, thread_state_t state)
  78 {
  79         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  80         struct __darwin_mcontext *ctx = (struct __darwin_mcontext *) context;
  81
  82         *arch_state = ctx->__ss;
  83 }
  84
  85 int
  86 mono_mach_arch_get_thread_state_size ()
  87 {
  88         return sizeof (arm_thread_state_t);
  89 }
  90
  91 kern_return_t
  92 mono_mach_arch_get_thread_state (thread_port_t thread, thread_state_t state, mach_msg_type_number_t *count)
  93 {
  94         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  95         kern_return_t ret;
  96
  97         *count = ARM_THREAD_STATE_COUNT;
  98
  99         ret = thread_get_state (thread, ARM_THREAD_STATE, (thread_state_t) arch_state, count);
 100
 101         return ret;
 102 }
 103
 104 kern_return_t
 105 mono_mach_arch_set_thread_state (thread_port_t thread, thread_state_t state, mach_msg_type_number_t count)
 106 {
 107         return thread_set_state (thread, ARM_THREAD_STATE_COUNT, state, count);
 108 }
 109
 110 void *
 111 mono_mach_get_tls_address_from_thread (pthread_t thread, pthread_key_t key)
 112 {
 113         /* Mach stores TLS values in a hidden array inside the pthread_t structure
 114          * They are keyed off a giant array from a known offset into the pointer. This value
 115          * is baked into their pthread_getspecific implementation
 116          */
 117         intptr_t *p = (intptr_t *) thread;
 118         intptr_t **tsd = (intptr_t **) ((char*)p + tls_vector_offset);
 119
 120         return (void *) &tsd [key];
 121 }
 122
 123 void *
 124 mono_mach_arch_get_tls_value_from_thread (pthread_t thread, guint32 key)
 125 {
 126         return *(void**)mono_mach_get_tls_address_from_thread (thread, key);
 127 }
 128
 129 void
 130 mono_mach_init (pthread_key_t key)
 131 {
 132         int i;
 133         void *old_value = pthread_getspecific (key);
 134         void *canary = (void*)0xDEADBEEFu;
 135
 136         pthread_key_create (&key, NULL);
 137         g_assert (old_value != canary);
 138
 139         pthread_setspecific (key, canary);
 140
 141         /*First we probe for cats*/
 142         for (i = 0; i < TLS_PROBE_COUNT; ++i) {
 143                 tls_vector_offset = known_tls_offsets [i];
 144                 if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary)
 145                         goto ok;
 146         }
 147
 148         /*Fallback to scanning a large range of offsets*/
 149         for (i = TLS_PROBE_LOW_WATERMARK; i <= TLS_PROBE_HIGH_WATERMARK; i += 4) {
 150                 tls_vector_offset = i;
 151                 if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary) {
 152                         g_warning ("Found new TLS offset at %d", i);
 153                         goto ok;
 154                 }
 155         }
 156
 157         g_error ("could not discover the mach TLS offset");
 158 ok:
 159         pthread_setspecific (key, old_value);
 160 }
 161
 162 #endif