gcc/ada/sigtramp-vxworks.c

   1 /****************************************************************************
   2  *                                                                          *
   3  *                         GNAT COMPILER COMPONENTS                         *
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   5  *                             S I G T R A M P                              *
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   7  *                         Asm Implementation File                          *
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   9  *         Copyright (C) 2011-2019, Free Software Foundation, Inc.          *
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  26  *                                                                          *
  27  * GNAT was originally developed  by the GNAT team at  New York University. *
  28  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  29  *                                                                          *
  30  ****************************************************************************/
  31
  32 /**************************************************
  33  * VxWorks version of the __gnat_sigtramp service *
  34  **************************************************/
  35
  36 #include "sigtramp.h"
  37 /* See sigtramp.h for a general explanation of functionality.  */
  38
  39 #include <vxWorks.h>
  40 #include <arch/../regs.h>
  41 #ifndef __RTP__
  42 #if defined(__i386__)
  43 #include <version.h>
  44 #endif
  45 #include <sigLib.h>
  46 #else
  47 #include <signal.h>
  48 #include <regs.h>
  49
  50 typedef struct mcontext
  51   {
  52     REG_SET     regs;
  53   } mcontext_t;
  54
  55 typedef struct ucontext
  56   {
  57     mcontext_t          uc_mcontext;    /* register set */
  58     struct ucontext *   uc_link;        /* not used */
  59     sigset_t            uc_sigmask;     /* set of signals blocked */
  60     stack_t             uc_stack;       /* stack of context signaled */
  61   } ucontext_t;
  62 #endif
  63
  64 /* ----------------------
  65    -- General comments --
  66    ----------------------
  67
  68    Stubs are generated from toplevel asms and .cfi directives, much simpler
  69    to use and check for correctness than manual encodings of CFI byte
  70    sequences.  The general idea is to establish CFA as sigcontext->sc_pregs
  71    (for DKM) and mcontext (for RTP) and state where to find the registers as
  72    offsets from there.
  73
  74    As of today, we support a stub providing CFI info for common
  75    registers (GPRs, LR, ...). We might need variants with support for floating
  76    point or altivec registers as well at some point.
  77
  78    Checking which variant should apply and getting at sc_pregs / mcontext
  79    is simpler to express in C (we can't use offsetof in toplevel asms and
  80    hardcoding constants is not workable with the flurry of VxWorks variants),
  81    so this is the choice for our toplevel interface.
  82
  83    Note that the registers we "restore" here are those to which we have
  84    direct access through the system sigcontext structure, which includes
  85    only a partial set of the non-volatiles ABI-wise.  */
  86
  87 /* -------------------------------------------
  88    -- Prototypes for our internal asm stubs --
  89    -------------------------------------------
  90
  91    Eventhough our symbols will remain local, the prototype claims "extern"
  92    and not "static" to prevent compiler complaints about a symbol used but
  93    never defined.  */
  94
  95 #define TRAMP_COMMON __gnat_sigtramp_common
  96
  97 /* sigtramp stub providing CFI info for common registers.  */
  98
  99 extern void
 100 TRAMP_COMMON (int signo, void *siginfo, void *sigcontext,
 101               __sigtramphandler_t * handler, REG_SET * sc_pregs);
 102
 103 /* -------------------------------------
 104    -- Common interface implementation --
 105    -------------------------------------
 106
 107    We enforce optimization to minimize the overhead of the extra layer.  */
 108
 109 #if defined(__vxworks) && (defined (__i386__) || defined (__x86_64__)) && !defined (VTHREADS)
 110 static int __gnat_is_vxsim = 0;
 111
 112 void __gnat_set_is_vxsim(int val) {
 113   __gnat_is_vxsim = val;
 114 }
 115 #endif
 116
 117 void __gnat_sigtramp (int signo, void *si, void *sc,
 118                       __sigtramphandler_t * handler)
 119      __attribute__((optimize(2)));
 120
 121 void __gnat_sigtramp (int signo, void *si, void *sc,
 122                       __sigtramphandler_t * handler)
 123 {
 124   REG_SET *pregs;
 125
 126   /* VXSIM uses a different signal context structure than the regular x86
 127      targets:
 128      * on x86-vx6: two 32-bit values are added at the end of the REG_SET, plus
 129        an explicit padding of 0xc8 characters (200 characters). The sigcontext
 130        containing a complete REG_SET just before the field 'sc_pregs', this
 131        adds a 208 bytes offset to get the value of 'sc_pregs'.
 132      * on x86-vx7: the same offset is used on vx7: 3 32-bit values are present
 133        at the end of the reg set, but the padding is then of 0xc4 characters.
 134      * on x86_64-vx7: two 64-bit values are added at the beginning of the
 135        REG_SET. This adds a 16 bytes offset to get the value of 'sc_pregs',
 136        and another 16 bytes offset within the pregs structure to retrieve the
 137        registers list.
 138
 139      * See header file regsSimlinux.h.
 140   */
 141
 142   /* Retrieve the registers to restore : */
 143 #ifndef __RTP__
 144 #ifdef __HANDLE_VXSIM_SC
 145 #if defined(__i386__)
 146   /* move sctx 208 bytes further, so that the vxsim's sc_pregs field coincide
 147      with the expected x86 one */
 148   struct sigcontext * sctx =
 149     (struct sigcontext *) (sc + (__gnat_is_vxsim ?
 150                                  (_WRS_VXWORKS_MAJOR == 7 ? 204 : 208)
 151                                  : 0));
 152 #elif defined(__x86_64__)
 153   /* move sctx 16 bytes further, so that the vxsim's sc_pregs field coincide
 154      with the expected x86_64 one */
 155   struct sigcontext * sctx =
 156     (struct sigcontext *) (sc + (__gnat_is_vxsim ? 16 : 0));
 157 #endif /* __i386__ || __x86_64__ */
 158 #else  /* __HANDLE_VXSIM_SC__ */
 159   struct sigcontext * sctx = (struct sigcontext *) sc;
 160 #endif
 161
 162   pregs = sctx->sc_pregs;
 163
 164 #else /* !defined(__RTP__) */
 165
 166   mcontext_t *mcontext = &((ucontext_t *) sc)->uc_mcontext;
 167   /* No specific offset in this case for vxsim */
 168   pregs = &(mcontext->regs);
 169
 170 #endif /* !defined(__RTP__) */
 171
 172 #if defined (__HANDLE_VXSIM_SC) && defined (__x86_64__)
 173   /* Ignore the first two values, that are not registers in case of
 174      vxsim */
 175   pregs = (REG_SET *) ((void *)pregs + (__gnat_is_vxsim ? 16 : 0));
 176 #endif
 177
 178   /* And now call the real signal trampoline with the list of registers */
 179   __gnat_sigtramp_common (signo, si, sc, handler, pregs);
 180 }
 181
 182 /* Include the target specific bits.  */
 183 #include "sigtramp-vxworks-target.inc"
 184
 185 /* sigtramp stub for common registers.  */
 186
 187 asm (SIGTRAMP_START(TRAMP_COMMON));
 188 asm (CFI_DEF_CFA);
 189 asm (CFI_COMMON_REGS);
 190 asm (SIGTRAMP_BODY);
 191 asm (SIGTRAMP_END(TRAMP_COMMON));