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      1 /* libunwind - a platform-independent unwind library
      2    Copyright (C) 2010, 2011 by FERMI NATIONAL ACCELERATOR LABORATORY
      3 
      4 This file is part of libunwind.
      5 
      6 Permission is hereby granted, free of charge, to any person obtaining
      7 a copy of this software and associated documentation files (the
      8 "Software"), to deal in the Software without restriction, including
      9 without limitation the rights to use, copy, modify, merge, publish,
     10 distribute, sublicense, and/or sell copies of the Software, and to
     11 permit persons to whom the Software is furnished to do so, subject to
     12 the following conditions:
     13 
     14 The above copyright notice and this permission notice shall be
     15 included in all copies or substantial portions of the Software.
     16 
     17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     18 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     19 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     20 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
     21 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
     22 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     23 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
     24 
     25 #include "unwind_i.h"
     26 #include "ucontext_i.h"
     27 
     28 HIDDEN void
     29 tdep_stash_frame (struct dwarf_cursor *d, struct dwarf_reg_state *rs)
     30 {
     31   struct cursor *c = (struct cursor *) dwarf_to_cursor (d);
     32   unw_tdep_frame_t *f = &c->frame_info;
     33 
     34   Debug (4, "ip=0x%lx cfa=0x%lx type %d cfa [where=%d val=%ld] cfaoff=%ld"
     35 	 " ra=0x%lx rbp [where=%d val=%ld @0x%lx] rsp [where=%d val=%ld @0x%lx]\n",
     36 	 d->ip, d->cfa, f->frame_type,
     37 	 rs->reg[DWARF_CFA_REG_COLUMN].where,
     38 	 rs->reg[DWARF_CFA_REG_COLUMN].val,
     39 	 rs->reg[DWARF_CFA_OFF_COLUMN].val,
     40 	 DWARF_GET_LOC(d->loc[d->ret_addr_column]),
     41 	 rs->reg[RBP].where, rs->reg[RBP].val, DWARF_GET_LOC(d->loc[RBP]),
     42 	 rs->reg[RSP].where, rs->reg[RSP].val, DWARF_GET_LOC(d->loc[RSP]));
     43 
     44   /* A standard frame is defined as:
     45       - CFA is register-relative offset off RBP or RSP;
     46       - Return address is saved at CFA-8;
     47       - RBP is unsaved or saved at CFA+offset, offset != -1;
     48       - RSP is unsaved or saved at CFA+offset, offset != -1.  */
     49   if (f->frame_type == UNW_X86_64_FRAME_OTHER
     50       && (rs->reg[DWARF_CFA_REG_COLUMN].where == DWARF_WHERE_REG)
     51       && (rs->reg[DWARF_CFA_REG_COLUMN].val == RBP
     52 	  || rs->reg[DWARF_CFA_REG_COLUMN].val == RSP)
     53       && labs(rs->reg[DWARF_CFA_OFF_COLUMN].val) < (1 << 29)
     54       && DWARF_GET_LOC(d->loc[d->ret_addr_column]) == d->cfa-8
     55       && (rs->reg[RBP].where == DWARF_WHERE_UNDEF
     56 	  || rs->reg[RBP].where == DWARF_WHERE_SAME
     57 	  || (rs->reg[RBP].where == DWARF_WHERE_CFAREL
     58 	      && labs(rs->reg[RBP].val) < (1 << 14)
     59 	      && rs->reg[RBP].val+1 != 0))
     60       && (rs->reg[RSP].where == DWARF_WHERE_UNDEF
     61 	  || rs->reg[RSP].where == DWARF_WHERE_SAME
     62 	  || (rs->reg[RSP].where == DWARF_WHERE_CFAREL
     63 	      && labs(rs->reg[RSP].val) < (1 << 14)
     64 	      && rs->reg[RSP].val+1 != 0)))
     65   {
     66     /* Save information for a standard frame. */
     67     f->frame_type = UNW_X86_64_FRAME_STANDARD;
     68     f->cfa_reg_rsp = (rs->reg[DWARF_CFA_REG_COLUMN].val == RSP);
     69     f->cfa_reg_offset = rs->reg[DWARF_CFA_OFF_COLUMN].val;
     70     if (rs->reg[RBP].where == DWARF_WHERE_CFAREL)
     71       f->rbp_cfa_offset = rs->reg[RBP].val;
     72     if (rs->reg[RSP].where == DWARF_WHERE_CFAREL)
     73       f->rsp_cfa_offset = rs->reg[RSP].val;
     74     Debug (4, " standard frame\n");
     75   }
     76 
     77   /* Signal frame was detected via augmentation in tdep_fetch_frame()  */
     78   else if (f->frame_type == UNW_X86_64_FRAME_SIGRETURN)
     79   {
     80     /* Later we are going to fish out {RBP,RSP,RIP} from sigcontext via
     81        their ucontext_t offsets.  Confirm DWARF info agrees with the
     82        offsets we expect.  */
     83 
     84 #ifndef NDEBUG
     85     const unw_word_t uc = c->sigcontext_addr;
     86 
     87     assert (DWARF_GET_LOC(d->loc[RIP]) - uc == UC_MCONTEXT_GREGS_RIP);
     88     assert (DWARF_GET_LOC(d->loc[RBP]) - uc == UC_MCONTEXT_GREGS_RBP);
     89     assert (DWARF_GET_LOC(d->loc[RSP]) - uc == UC_MCONTEXT_GREGS_RSP);
     90 #endif
     91 
     92     Debug (4, " sigreturn frame\n");
     93   }
     94 
     95   /* PLT and guessed RBP-walked frames are handled in unw_step(). */
     96   else
     97     /* ANDROID support update. */
     98     {
     99       Debug (4, " unusual frame\n");
    100     }
    101     /* End of ANDROID update. */
    102 }
    103