mono/utils/mach-support-arm.c

   1 /**
   2  * \file
   3  * mach support for ARM
   4  *
   5  * Authors:
   6  *   Geoff Norton (gnorton@novell.com)
   7  *   Rodrigo Kumpera (kumpera@gmail.com)
   8  *
   9  * (C) 2010 Novell, Inc.
  10  * (C) 2011 Xamarin, Inc.
  11  */
  12
  13 #include <config.h>
  14
  15 #if defined(__MACH__)
  16 #include <stdint.h>
  17 #include <glib.h>
  18 #include <pthread.h>
  19 #include "utils/mono-sigcontext.h"
  20 #include "utils/mono-compiler.h"
  21 #include "mach-support.h"
  22
  23 /* _mcontext.h now defines __darwin_mcontext32, not __darwin_mcontext, starting with Xcode 5.1 */
  24 #ifdef _STRUCT_MCONTEXT32
  25        #define __darwin_mcontext       __darwin_mcontext32
  26 #endif
  27
  28 /* Known offsets used for TLS storage*/
  29
  30
  31 static const int known_tls_offsets[] = {
  32         0x48, /*Found on iOS 6 */
  33         0xA4,
  34         0xA8,
  35 };
  36
  37 #define TLS_PROBE_COUNT (sizeof (known_tls_offsets) / sizeof (int))
  38
  39 /* This is 2 slots less than the known low */
  40 #define TLS_PROBE_LOW_WATERMARK 0x40
  41 /* This is 24 slots above the know high, which is the same diff as the knowns high-low*/
  42 #define TLS_PROBE_HIGH_WATERMARK 0x108
  43
  44 static int tls_vector_offset;
  45
  46 void *
  47 mono_mach_arch_get_ip (thread_state_t state)
  48 {
  49         /* Can't use unified_thread_state on !ARM64 since this has to compile on armv6 too */
  50         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  51
  52         return (void *) arch_state->__pc;
  53 }
  54
  55 void *
  56 mono_mach_arch_get_sp (thread_state_t state)
  57 {
  58         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  59
  60         return (void *) arch_state->__sp;
  61 }
  62
  63 int
  64 mono_mach_arch_get_mcontext_size ()
  65 {
  66         return sizeof (struct __darwin_mcontext);
  67 }
  68
  69 void
  70 mono_mach_arch_thread_states_to_mcontext (thread_state_t state, thread_state_t fpstate, void *context)
  71 {
  72         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  73         struct __darwin_mcontext *ctx = (struct __darwin_mcontext *) context;
  74
  75         ctx->__ss = *arch_state;
  76 }
  77
  78 void
  79 mono_mach_arch_mcontext_to_thread_states (void *context, thread_state_t state, thread_state_t fpstate)
  80 {
  81         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  82         struct __darwin_mcontext *ctx = (struct __darwin_mcontext *) context;
  83
  84         *arch_state = ctx->__ss;
  85 }
  86
  87 void
  88 mono_mach_arch_thread_states_to_mono_context (thread_state_t state, thread_state_t fpstate, MonoContext *context)
  89 {
  90         int i;
  91         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
  92         for (i = 0; i < 13; ++i)
  93                 context->regs [i] = arch_state->__r [i];
  94         context->regs [ARMREG_R13] = arch_state->__sp;
  95         context->regs [ARMREG_R14] = arch_state->__lr;
  96         context->regs [ARMREG_R15] = arch_state->__pc;
  97         context->pc = arch_state->__pc;
  98         context->cpsr = arch_state->__cpsr;
  99 }
 100
 101 int
 102 mono_mach_arch_get_thread_state_size ()
 103 {
 104         return sizeof (arm_thread_state_t);
 105 }
 106
 107 int
 108 mono_mach_arch_get_thread_fpstate_size ()
 109 {
 110         return sizeof (arm_neon_state_t);
 111 }
 112
 113 kern_return_t
 114 mono_mach_arch_get_thread_states (thread_port_t thread, thread_state_t state, mach_msg_type_number_t *count, thread_state_t fpstate, mach_msg_type_number_t *fpcount)
 115 {
 116 #if defined(HOST_WATCHOS)
 117         g_error ("thread_get_state() is not supported by this platform");
 118 #else
 119         arm_thread_state_t *arch_state = (arm_thread_state_t *) state;
 120         kern_return_t ret;
 121
 122         *count = ARM_THREAD_STATE_COUNT;
 123
 124         ret = thread_get_state (thread, ARM_THREAD_STATE, (thread_state_t) arch_state, count);
 125         return ret;
 126 #endif
 127 }
 128
 129 kern_return_t
 130 mono_mach_arch_set_thread_states (thread_port_t thread, thread_state_t state, mach_msg_type_number_t count, thread_state_t fpstate, mach_msg_type_number_t fpcount)
 131 {
 132 #if defined(HOST_WATCHOS)
 133         g_error ("thread_set_state() is not supported by this platform");
 134 #else
 135         return thread_set_state (thread, ARM_THREAD_STATE, state, count);
 136 #endif
 137 }
 138
 139 void *
 140 mono_mach_get_tls_address_from_thread (pthread_t thread, pthread_key_t key)
 141 {
 142         /* Mach stores TLS values in a hidden array inside the pthread_t structure
 143          * They are keyed off a giant array from a known offset into the pointer. This value
 144          * is baked into their pthread_getspecific implementation
 145          */
 146         intptr_t *p = (intptr_t *) thread;
 147         intptr_t **tsd = (intptr_t **) ((char*)p + tls_vector_offset);
 148         g_assert (tls_vector_offset != -1);
 149
 150         return (void *) &tsd [key];
 151 }
 152
 153 void *
 154 mono_mach_arch_get_tls_value_from_thread (pthread_t thread, guint32 key)
 155 {
 156         return *(void**)mono_mach_get_tls_address_from_thread (thread, key);
 157 }
 158
 159 void
 160 mono_mach_init (pthread_key_t key)
 161 {
 162         int i;
 163         void *old_value = pthread_getspecific (key);
 164         void *canary = (void*)0xDEADBEEFu;
 165
 166         pthread_key_create (&key, NULL);
 167         g_assert (old_value != canary);
 168
 169         pthread_setspecific (key, canary);
 170
 171         /*First we probe for cats*/
 172         for (i = 0; i < TLS_PROBE_COUNT; ++i) {
 173                 tls_vector_offset = known_tls_offsets [i];
 174                 if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary)
 175                         goto ok;
 176         }
 177
 178         /*Fallback to scanning a large range of offsets*/
 179         for (i = TLS_PROBE_LOW_WATERMARK; i <= TLS_PROBE_HIGH_WATERMARK; i += 4) {
 180                 tls_vector_offset = i;
 181                 if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary) {
 182                         g_warning ("Found new TLS offset at %d", i);
 183                         goto ok;
 184                 }
 185         }
 186
 187         tls_vector_offset = -1;
 188         g_warning ("could not discover the mach TLS offset");
 189 ok:
 190         pthread_setspecific (key, old_value);
 191 }
 192
 193 #endif