gdb/nat/x86-linux-tdesc.c

   1 /* Target description related code for GNU/Linux x86 (i386 and x86-64).
   2
   3    Copyright (C) 2024 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "nat/x86-linux-tdesc.h"
  21 #ifdef __x86_64__
  22 #include "arch/amd64.h"
  23 #include "arch/amd64-linux-tdesc.h"
  24 #endif
  25 #include "arch/i386.h"
  26 #include "arch/i386-linux-tdesc.h"
  27
  28 #include "nat/x86-linux.h"
  29 #include "nat/gdb_ptrace.h"
  30 #include "nat/x86-xstate.h"
  31 #include "gdbsupport/x86-xstate.h"
  32
  33 #ifndef __x86_64__
  34 #include <sys/procfs.h>
  35 #include "nat/i386-linux.h"
  36 #endif
  37
  38 #include <sys/uio.h>
  39 #include <elf.h>
  40
  41 #ifndef IN_PROCESS_AGENT
  42
  43 /* See nat/x86-linux-tdesc.h.  */
  44
  45 const target_desc *
  46 x86_linux_tdesc_for_tid (int tid, uint64_t *xcr0_storage,
  47                          x86_xsave_layout *xsave_layout_storage)
  48 {
  49 #ifdef __x86_64__
  50   x86_linux_arch_size arch_size = x86_linux_ptrace_get_arch_size (tid);
  51   bool is_64bit = arch_size.is_64bit ();
  52   bool is_x32 = arch_size.is_x32 ();
  53
  54   if (sizeof (void *) == 4 && is_64bit && !is_x32)
  55     {
  56 #ifdef GDBSERVER
  57       error (_("Can't debug 64-bit process with 32-bit GDBserver"));
  58 #else
  59       error (_("Can't debug 64-bit process with 32-bit GDB"));
  60 #endif
  61     }
  62
  63 #elif HAVE_PTRACE_GETFPXREGS
  64   if (have_ptrace_getfpxregs == TRIBOOL_UNKNOWN)
  65     {
  66       elf_fpxregset_t fpxregs;
  67
  68       if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
  69         {
  70           have_ptrace_getfpxregs = TRIBOOL_FALSE;
  71           have_ptrace_getregset = TRIBOOL_FALSE;
  72         }
  73       else
  74         have_ptrace_getfpxregs = TRIBOOL_TRUE;
  75     }
  76
  77   if (have_ptrace_getfpxregs == TRIBOOL_FALSE)
  78     return i386_linux_read_description (X86_XSTATE_X87_MASK);
  79 #endif
  80
  81   if (have_ptrace_getregset == TRIBOOL_UNKNOWN)
  82     {
  83       uint64_t xstateregs[(X86_XSTATE_SSE_SIZE / sizeof (uint64_t))];
  84       struct iovec iov;
  85
  86       iov.iov_base = xstateregs;
  87       iov.iov_len = sizeof (xstateregs);
  88
  89       /* Check if PTRACE_GETREGSET works.  */
  90       if (ptrace (PTRACE_GETREGSET, tid,
  91                   (unsigned int) NT_X86_XSTATE, &iov) < 0)
  92         {
  93           /* Can't fetch the xcr0 value so pick a simple default.  This
  94              default has x87 and sse bits set.  These bits are ignored for
  95              amd64 and x32 targets, but are checked for on i386.  Without
  96              these bits being set we generate a completely empty tdesc for
  97              i386 which will be rejected by GDB.  */
  98           have_ptrace_getregset = TRIBOOL_FALSE;
  99           *xcr0_storage = X86_XSTATE_SSE_MASK;
 100         }
 101       else
 102         {
 103           have_ptrace_getregset = TRIBOOL_TRUE;
 104
 105           /* Get XCR0 from XSAVE extended state.  */
 106           *xcr0_storage = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
 107                                       / sizeof (uint64_t))];
 108
 109           *xsave_layout_storage
 110             = x86_fetch_xsave_layout (*xcr0_storage, x86_xsave_length ());
 111         }
 112     }
 113
 114   /* Use cached xcr0 value.  */
 115   uint64_t xcr0_features_bits = *xcr0_storage & X86_XSTATE_ALL_MASK;
 116
 117 #ifdef __x86_64__
 118   if (is_64bit)
 119     return amd64_linux_read_description (xcr0_features_bits, is_x32);
 120   else
 121 #endif
 122     return i386_linux_read_description (xcr0_features_bits);
 123 }
 124
 125 #endif /* !IN_PROCESS_AGENT */