mono/utils/mono-signal-handler.h

   1 /*
   2  * mono-signal-handler.h: Handle signal handler differences across platforms
   3  *
   4  * Copyright (C) 2013 Xamarin Inc
   5  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   6  */
   7
   8 #ifndef __MONO_SIGNAL_HANDLER_H__
   9 #define __MONO_SIGNAL_HANDLER_H__
  10
  11 #include "config.h"
  12
  13 /*
  14  * When a signal is delivered to a thread on a Krait Android device
  15  * that's in the middle of skipping over an "IT" block, such as this
  16  * one:
  17  *
  18  * 0x40184ef0 <dlfree+1308>:    ldr     r1, [r3, #0]
  19  * 0x40184ef2 <dlfree+1310>:    add.w   r5, r12, r2, lsl #3
  20  * 0x40184ef6 <dlfree+1314>:    lsls.w  r2, r0, r2
  21  * 0x40184efa <dlfree+1318>:    tst     r2, r1
  22  * ### this is the IT instruction
  23  * 0x40184efc <dlfree+1320>:    itt     eq
  24  * 0x40184efe <dlfree+1322>:    orreq   r2, r1
  25  * ### signal arrives here
  26  * 0x40184f00 <dlfree+1324>:    streq   r2, [r3, #0]
  27  * 0x40184f02 <dlfree+1326>:    beq.n   0x40184f1a <dlfree+1350>
  28  * 0x40184f04 <dlfree+1328>:    ldr     r2, [r5, #8]
  29  * 0x40184f06 <dlfree+1330>:    ldr     r3, [r3, #16]
  30  *
  31  * then the first few (at most four, one would assume) instructions of
  32  * the signal handler (!) might be skipped.  They happen to be the
  33  * push of the frame pointer and return address, so once the signal
  34  * handler has done its work, it returns into a SIGSEGV.
  35  */
  36
  37 #if defined (TARGET_ARM) && defined (HAVE_ARMV7) && defined (TARGET_ANDROID)
  38 #define KRAIT_IT_BUG_WORKAROUND 1
  39 #endif
  40
  41 #ifdef KRAIT_IT_BUG_WORKAROUND
  42 #define MONO_SIGNAL_HANDLER_FUNC(access, name, arglist)         \
  43         static void __krait_ ## name arglist;   \
  44         __attribute__ ((__naked__)) access void                         \
  45         name arglist                                                    \
  46         {                                                               \
  47                 asm volatile (                                          \
  48                               "mov r0, r0\n\t"                          \
  49                               "mov r0, r0\n\t"                          \
  50                               "mov r0, r0\n\t"                          \
  51                               "mov r0, r0\n\t"                          \
  52                                   "b __krait_" # name                   \
  53                                   "\n\t");                                              \
  54         }       \
  55         static __attribute__ ((__used__)) void __krait_ ## name arglist
  56 #endif
  57
  58 /* Don't use this */
  59 #ifndef MONO_SIGNAL_HANDLER_FUNC
  60 #define MONO_SIGNAL_HANDLER_FUNC(access, name, arglist) access void name arglist
  61 #endif
  62
  63 /*
  64  * Macros to work around signal handler differences on various platforms.
  65  *
  66  * To declare a signal handler function:
  67  * void MONO_SIG_HANDLER_SIGNATURE (handler_func)
  68  * To define a signal handler function:
  69  * MONO_SIG_HANDLER_FUNC(access, name)
  70  * To call another signal handler function:
  71  * handler_func (MONO_SIG_HANDLER_PARAMS);
  72  * To obtain the signal number:
  73  * int signo = MONO_SIG_HANDLER_GET_SIGNO ();
  74  * To obtain the signal context:
  75  * MONO_SIG_HANDLER_GET_CONTEXT ().
  76  * This will define a variable name 'ctx'.
  77  */
  78
  79 #ifdef HOST_WIN32
  80 #define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, EXCEPTION_POINTERS *_info, void *context)
  81 #define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, EXCEPTION_POINTERS *_info, void *context))
  82 #define MONO_SIG_HANDLER_PARAMS _dummy, _info, context
  83 #define MONO_SIG_HANDLER_GET_SIGNO() (_dummy)
  84 #define MONO_SIG_HANDLER_GET_INFO() (_info)
  85 #define MONO_SIG_HANDLER_INFO_TYPE EXCEPTION_POINTERS
  86 /* seh_vectored_exception_handler () passes in a CONTEXT* */
  87 #define MONO_SIG_HANDLER_GET_CONTEXT \
  88     void *ctx = context;
  89 #else
  90 /* sigaction */
  91 #define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, siginfo_t *_info, void *context)
  92 #define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, siginfo_t *_info, void *context))
  93 #define MONO_SIG_HANDLER_PARAMS _dummy, _info, context
  94 #define MONO_SIG_HANDLER_GET_SIGNO() (_dummy)
  95 #define MONO_SIG_HANDLER_GET_INFO() (_info)
  96 #define MONO_SIG_HANDLER_INFO_TYPE siginfo_t
  97 #define MONO_SIG_HANDLER_GET_CONTEXT \
  98     void *ctx = context;
  99 #endif
 100
 101 #endif