text: /**
   * \file
   * mach support for x86
   *
   * Authors:
   *   Geoff Norton (gnorton@novell.com)
   *
   * (C) 2010 Novell, Inc.
   */
  
  #include <config.h>
  
  #if defined(__MACH__)
  #include <stdint.h>
  #include <glib.h>
  #include <pthread.h>
  #include "utils/mono-sigcontext.h"
  #include "mach-support.h"
  
  // For reg numbers
  #include <mono/arch/amd64/amd64-codegen.h>
  
  /* Known offsets used for TLS storage*/
  
  /* All OSX versions up to 10.8 */
  #define TLS_VECTOR_OFFSET_CATS 0x48
  #define TLS_VECTOR_OFFSET_10_9 0xb0
  #define TLS_VECTOR_OFFSET_10_11 0x100
  
  
  /* This is 2 slots less than the known low */
  #define TLS_PROBE_LOW_WATERMARK 0x40
  /* This is 28 slots above the know high, which is more than the known high-low*/
  #define TLS_PROBE_HIGH_WATERMARK 0x120
  
  
  static int tls_vector_offset;
  
  void *
  mono_mach_arch_get_ip (thread_state_t state)
  {
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  
  	return (void *) arch_state->__eip;
  }
  
  void *
  mono_mach_arch_get_sp (thread_state_t state)
  {
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  
  	return (void *) arch_state->__esp;
  }
  
  int
  mono_mach_arch_get_mcontext_size ()
  {
  	return sizeof (struct __darwin_mcontext32);
  }
  
  void
  mono_mach_arch_thread_states_to_mcontext (thread_state_t state, thread_state_t fpstate, void *context)
  {
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  	x86_float_state32_t *arch_fpstate = (x86_float_state32_t *) fpstate;
  	struct __darwin_mcontext32 *ctx = (struct __darwin_mcontext32 *) context;
  	ctx->__ss = *arch_state;
  	ctx->__fs = *arch_fpstate;
  }
  
  void
  mono_mach_arch_mcontext_to_thread_states (void *context, thread_state_t state, thread_state_t fpstate)
  {
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  	x86_float_state32_t *arch_fpstate = (x86_float_state32_t *) fpstate;
  	struct __darwin_mcontext32 *ctx = (struct __darwin_mcontext32 *) context;
  	*arch_state = ctx->__ss;
  	*arch_fpstate = ctx->__fs;
  }
  
  void
  mono_mach_arch_thread_states_to_mono_context (thread_state_t state, thread_state_t fpstate, MonoContext *context)
  {
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  	x86_float_state32_t *arch_fpstate = (x86_float_state32_t *) state;
  	context->eax = arch_state->__eax;
  	context->ebx = arch_state->__ebx;
  	context->ecx = arch_state->__ecx;
  	context->edx = arch_state->__edx;
  	context->ebp = arch_state->__ebp;
  	context->esp = arch_state->__esp;
  	context->esi = arch_state->__edi;
  	context->edi = arch_state->__esi;
  	context->eip = arch_state->__eip;
  	context->fregs [X86_XMM0] = arch_fpstate->__fpu_xmm0;
  	context->fregs [X86_XMM1] = arch_fpstate->__fpu_xmm1;
  	context->fregs [X86_XMM2] = arch_fpstate->__fpu_xmm2;
  	context->fregs [X86_XMM3] = arch_fpstate->__fpu_xmm3;
  	context->fregs [X86_XMM4] = arch_fpstate->__fpu_xmm4;
  	context->fregs [X86_XMM5] = arch_fpstate->__fpu_xmm5;
  	context->fregs [X86_XMM6] = arch_fpstate->__fpu_xmm6;
  	context->fregs [X86_XMM7] = arch_fpstate->__fpu_xmm7;
  }
  
  int
  mono_mach_arch_get_thread_state_size ()
  {
  	return sizeof (x86_thread_state32_t);
  }
  
  int
  mono_mach_arch_get_thread_fpstate_size ()
  {
  	return sizeof (x86_float_state32_t);
  }
  
  kern_return_t
  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)
  {
  #if defined(HOST_WATCHOS)
  	g_error ("thread_get_state() is not supported by this platform");
  #else
  	x86_thread_state32_t *arch_state = (x86_thread_state32_t *) state;
  	x86_float_state32_t *arch_fpstate = (x86_float_state32_t *) fpstate;
  	kern_return_t ret;
  
  	*count = x86_THREAD_STATE32_COUNT;
  	*fpcount = x86_FLOAT_STATE32_COUNT;
  
  	ret = thread_get_state (thread, x86_THREAD_STATE32, (thread_state_t)arch_state, count);
  	if (ret != KERN_SUCCESS)
  		return ret;
  
  	ret = thread_get_state (thread, x86_FLOAT_STATE32, (thread_state_t)arch_fpstate, fpcount);
  	return ret;
  #endif
  }
  
  kern_return_t
  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)
  {
  #if defined(HOST_WATCHOS)
  	g_error ("thread_set_state() is not supported by this platform");
  #else
  	kern_return_t ret;
  	ret = thread_set_state (thread, x86_THREAD_STATE32, state, count);
  	if (ret != KERN_SUCCESS)
  		return ret;
  	ret = thread_set_state (thread, x86_FLOAT_STATE32, fpstate, fpcount);
  	return ret;
  #endif	
  }
  
  void *
  mono_mach_get_tls_address_from_thread (pthread_t thread, pthread_key_t key)
  {
  	/* OSX stores TLS values in a hidden array inside the pthread_t structure
  	 * They are keyed off a giant array from a known offset into the pointer.  This value
  	 * is baked into their pthread_getspecific implementation
  	 */
  	intptr_t *p = (intptr_t *) thread;
  	intptr_t **tsd = (intptr_t **) ((char*)p + tls_vector_offset);
  	g_assert (tls_vector_offset != -1);
  
  	return (void *) &tsd [key];	
  }
  
  void *
  mono_mach_arch_get_tls_value_from_thread (pthread_t thread, guint32 key)
  {
  	return *(void**)mono_mach_get_tls_address_from_thread (thread, key);
  }
  
  void
  mono_mach_init (pthread_key_t key)
  {
  	int i;
  	void *old_value = pthread_getspecific (key);
  	void *canary = (void*)0xDEADBEEFu;
  
  	pthread_key_create (&key, NULL);
  	g_assert (old_value != canary);
  
  	pthread_setspecific (key, canary);
  
  	/*First we probe for cats*/
  	tls_vector_offset = TLS_VECTOR_OFFSET_CATS;
  	if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary)
  		goto ok;
  
  	tls_vector_offset = TLS_VECTOR_OFFSET_10_9;
  	if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary)
  		goto ok;
  
  	tls_vector_offset = TLS_VECTOR_OFFSET_10_11;
  	if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary)
  		goto ok;
  
  	/*Fallback to scanning a large range of offsets*/
  	for (i = TLS_PROBE_LOW_WATERMARK; i <= TLS_PROBE_HIGH_WATERMARK; i += 4) {
  		tls_vector_offset = i;
  		if (mono_mach_arch_get_tls_value_from_thread (pthread_self (), key) == canary) {
  			g_warning ("Found new TLS offset at %d", i);
  			goto ok;
  		}
  	}
  
  	tls_vector_offset = -1;
  	g_warning ("could not discover the mach TLS offset");
  ok:
  	pthread_setspecific (key, old_value);
  }
  
  #endif
  