1                 : /*
       2                 :  * Copyright 2010 The Native Client Authors. All rights reserved.
       3                 :  * Use of this source code is governed by a BSD-style license that can
       4                 :  * be found in the LICENSE file.
       5                 :  */
       6                 : 
       7                 : #include <signal.h>
       8                 : #if !NACL_ANDROID
       9                 : #include <sys/ucontext.h>
      10                 : #endif
      11                 : 
      12                 : #include "native_client/src/trusted/service_runtime/linux/android_compat.h"
      13                 : #include "native_client/src/trusted/service_runtime/nacl_signal.h"
      14                 : 
      15                 : /*
      16                 :  * Definition of the POSIX ucontext_t for Linux can be found in:
      17                 :  * /usr/include/sys/ucontext.h
      18                 :  */
      19                 : 
      20                 : /*
      21                 :  * Fill a signal context structure from the raw platform dependent
      22                 :  * signal information.
      23                 :  */
      24          140375 : void NaClSignalContextFromHandler(struct NaClSignalContext *sig_ctx,
      25                 :                                   const void *raw_ctx) {
      26          140375 :   const ucontext_t *uctx = (const ucontext_t *) raw_ctx;
      27          140375 :   const mcontext_t *mctx = &uctx->uc_mcontext;
      28                 : 
      29          140375 :   sig_ctx->prog_ctr = mctx->gregs[REG_EIP];
      30          140375 :   sig_ctx->stack_ptr = mctx->gregs[REG_ESP];
      31                 : 
      32          140375 :   sig_ctx->eax = mctx->gregs[REG_EAX];
      33          140375 :   sig_ctx->ebx = mctx->gregs[REG_EBX];
      34          140375 :   sig_ctx->ecx = mctx->gregs[REG_ECX];
      35          140375 :   sig_ctx->edx = mctx->gregs[REG_EDX];
      36          140375 :   sig_ctx->esi = mctx->gregs[REG_ESI];
      37          140375 :   sig_ctx->edi = mctx->gregs[REG_EDI];
      38          140375 :   sig_ctx->ebp = mctx->gregs[REG_EBP];
      39          140375 :   sig_ctx->flags = mctx->gregs[REG_EFL];
      40                 :    /*
      41                 :     * We need to drop the top 16 bits with the casts below.  In some
      42                 :     * situations, Linux does not assign to the top 2 bytes of the
      43                 :     * REG_CS array entry when writing %cs to the stack (and similarly
      44                 :     * for the other segment registers).  Therefore we need to drop the
      45                 :     * undefined top 2 bytes.
      46                 :     *
      47                 :     * This happens in 32-bit processes running on the 64-bit kernel
      48                 :     * from Ubuntu Hardy, but not on 32-bit kernels.  The kernel
      49                 :     * version in Ubuntu Lucid also does not have this problem.
      50                 :     *
      51                 :     * See http://code.google.com/p/nativeclient/issues/detail?id=1486
      52                 :     */
      53          140375 :   sig_ctx->cs = (uint16_t) mctx->gregs[REG_CS];
      54          140375 :   sig_ctx->ss = (uint16_t) mctx->gregs[REG_SS];
      55          140375 :   sig_ctx->ds = (uint16_t) mctx->gregs[REG_DS];
      56          140375 :   sig_ctx->es = (uint16_t) mctx->gregs[REG_ES];
      57          140375 :   sig_ctx->fs = (uint16_t) mctx->gregs[REG_FS];
      58          140375 :   sig_ctx->gs = (uint16_t) mctx->gregs[REG_GS];
      59          140375 : }
      60                 : 
      61                 : 
      62                 : /*
      63                 :  * Update the raw platform dependent signal information from the
      64                 :  * signal context structure.
      65                 :  */
      66          125943 : void NaClSignalContextToHandler(void *raw_ctx,
      67                 :                                 const struct NaClSignalContext *sig_ctx) {
      68          125943 :   ucontext_t *uctx = (ucontext_t *) raw_ctx;
      69          125943 :   mcontext_t *mctx = &uctx->uc_mcontext;
      70                 : 
      71          125943 :   mctx->gregs[REG_EIP] = sig_ctx->prog_ctr;
      72          125943 :   mctx->gregs[REG_ESP] = sig_ctx->stack_ptr;
      73                 : 
      74          125943 :   mctx->gregs[REG_EAX] = sig_ctx->eax;
      75          125943 :   mctx->gregs[REG_EBX] = sig_ctx->ebx;
      76          125943 :   mctx->gregs[REG_ECX] = sig_ctx->ecx;
      77          125943 :   mctx->gregs[REG_EDX] = sig_ctx->edx;
      78          125943 :   mctx->gregs[REG_ESI] = sig_ctx->esi;
      79          125943 :   mctx->gregs[REG_EDI] = sig_ctx->edi;
      80          125943 :   mctx->gregs[REG_EBP] = sig_ctx->ebp;
      81          125943 :   mctx->gregs[REG_EFL] = sig_ctx->flags;
      82          125943 :   mctx->gregs[REG_CS] = sig_ctx->cs;
      83          125943 :   mctx->gregs[REG_SS] = sig_ctx->ss;
      84          125943 :   mctx->gregs[REG_DS] = sig_ctx->ds;
      85          125943 :   mctx->gregs[REG_ES] = sig_ctx->es;
      86          125943 :   mctx->gregs[REG_FS] = sig_ctx->fs;
      87          125943 :   mctx->gregs[REG_GS] = sig_ctx->gs;
      88          125943 : }
      89                 : 
      90                 : 
      91                 :