gcc/ada/sigtramp-vxworks.c

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