/**
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* \file
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* Handle signal handler differences across platforms
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*
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* Copyright (C) 2013 Xamarin Inc
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* Licensed under the MIT license. See LICENSE file in the project root for full license information.
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*/
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#ifndef __MONO_SIGNAL_HANDLER_H__
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#define __MONO_SIGNAL_HANDLER_H__
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#include "config.h"
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/*
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* When a signal is delivered to a thread on a Krait Android device
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* that's in the middle of skipping over an "IT" block, such as this
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* one:
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*
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* 0x40184ef0 <dlfree+1308>: ldr r1, [r3, #0]
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* 0x40184ef2 <dlfree+1310>: add.w r5, r12, r2, lsl #3
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* 0x40184ef6 <dlfree+1314>: lsls.w r2, r0, r2
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* 0x40184efa <dlfree+1318>: tst r2, r1
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* ### this is the IT instruction
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* 0x40184efc <dlfree+1320>: itt eq
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* 0x40184efe <dlfree+1322>: orreq r2, r1
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* ### signal arrives here
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* 0x40184f00 <dlfree+1324>: streq r2, [r3, #0]
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* 0x40184f02 <dlfree+1326>: beq.n 0x40184f1a <dlfree+1350>
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* 0x40184f04 <dlfree+1328>: ldr r2, [r5, #8]
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* 0x40184f06 <dlfree+1330>: ldr r3, [r3, #16]
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*
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* then the first few (at most four, one would assume) instructions of
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* the signal handler (!) might be skipped. They happen to be the
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* push of the frame pointer and return address, so once the signal
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* handler has done its work, it returns into a SIGSEGV.
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*/
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#if defined (TARGET_ARM) && defined (HAVE_ARMV7) && defined (TARGET_ANDROID)
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#define KRAIT_IT_BUG_WORKAROUND 1
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#endif
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#ifdef KRAIT_IT_BUG_WORKAROUND
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#define MONO_SIGNAL_HANDLER_FUNC(access, name, arglist) \
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static void __krait_ ## name arglist; \
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__attribute__ ((__naked__)) access void \
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name arglist \
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{ \
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asm volatile ( \
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"mov r0, r0\n\t" \
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"mov r0, r0\n\t" \
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"mov r0, r0\n\t" \
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"mov r0, r0\n\t" \
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"b __krait_" # name \
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"\n\t"); \
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} \
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static __attribute__ ((__used__)) void __krait_ ## name arglist
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#endif
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/* Don't use this */
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#ifndef MONO_SIGNAL_HANDLER_FUNC
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#define MONO_SIGNAL_HANDLER_FUNC(access, name, arglist) access void name arglist
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#endif
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/*
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* Macros to work around signal handler differences on various platforms.
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*
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* To declare a signal handler function:
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* void MONO_SIG_HANDLER_SIGNATURE (handler_func)
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* To define a signal handler function:
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* MONO_SIG_HANDLER_FUNC(access, name)
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* To call another signal handler function:
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* handler_func (MONO_SIG_HANDLER_PARAMS);
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* To obtain the signal number:
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* int signo = MONO_SIG_HANDLER_GET_SIGNO ();
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* To obtain the signal context:
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* MONO_SIG_HANDLER_GET_CONTEXT ().
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* This will define a variable name 'ctx'.
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*/
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#ifdef HOST_WIN32
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#define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, EXCEPTION_POINTERS *_info, void *context)
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#define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, EXCEPTION_POINTERS *_info, void *context))
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#define MONO_SIG_HANDLER_PARAMS _dummy, _info, context
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#define MONO_SIG_HANDLER_GET_SIGNO() (_dummy)
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#define MONO_SIG_HANDLER_GET_INFO() (_info)
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#define MONO_SIG_HANDLER_INFO_TYPE EXCEPTION_POINTERS
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/* seh_vectored_exception_handler () passes in a CONTEXT* */
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#define MONO_SIG_HANDLER_GET_CONTEXT \
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void *ctx = context;
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#else
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/* sigaction */
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#define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, siginfo_t *_info, void *context)
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#define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, siginfo_t *_info, void *context))
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#define MONO_SIG_HANDLER_PARAMS _dummy, _info, context
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#define MONO_SIG_HANDLER_GET_SIGNO() (_dummy)
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#define MONO_SIG_HANDLER_GET_INFO() (_info)
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#define MONO_SIG_HANDLER_INFO_TYPE siginfo_t
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#define MONO_SIG_HANDLER_GET_CONTEXT \
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void *ctx = context;
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#endif
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#endif
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