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127 lines
4.4 KiB
C
127 lines
4.4 KiB
C
/* libunwind - a platform-independent unwind library
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Copyright (C) 2002-2003 Hewlett-Packard Co
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Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
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This file is part of libunwind.
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the
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"Software"), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Software, and to
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permit persons to whom the Software is furnished to do so, subject to
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the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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#include "unwind_i.h"
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#include "offsets.h"
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PROTECTED int
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unw_step (unw_cursor_t *cursor)
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{
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struct cursor *c = (struct cursor *) cursor;
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int ret, i;
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Debug (2, "(cursor=%p)\n", c);
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/* Try DWARF-based unwinding... */
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ret = dwarf_step (&c->dwarf);
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if (unlikely (ret < 0))
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{
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/* DWARF failed, let's see if we can follow the frame-chain
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or skip over the signal trampoline. */
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struct dwarf_loc ebp_loc, eip_loc;
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Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);
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if (unw_is_signal_frame (cursor))
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{
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/* XXX This code is Linux-specific! */
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/* c->esp points at the arguments to the handler. Without
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SA_SIGINFO, the arguments consist of a signal number
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followed by a struct sigcontext. With SA_SIGINFO, the
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arguments consist a signal number, a siginfo *, and a
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ucontext *. */
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unw_word_t sigcontext_addr;
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unw_word_t siginfo_ptr_addr = c->dwarf.cfa + 4;
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unw_word_t sigcontext_ptr_addr = c->dwarf.cfa + 8;
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unw_word_t siginfo_ptr, sigcontext_ptr;
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struct dwarf_loc esp_loc, siginfo_ptr_loc, sigcontext_ptr_loc;
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siginfo_ptr_loc = DWARF_LOC (siginfo_ptr_addr, 0);
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sigcontext_ptr_loc = DWARF_LOC (sigcontext_ptr_addr, 0);
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ret = (dwarf_get (&c->dwarf, siginfo_ptr_loc, &siginfo_ptr)
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| dwarf_get (&c->dwarf, sigcontext_ptr_loc, &sigcontext_ptr));
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if (ret < 0)
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return 0;
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if (siginfo_ptr < c->dwarf.cfa
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|| siginfo_ptr > c->dwarf.cfa + 256
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|| sigcontext_ptr < c->dwarf.cfa
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|| sigcontext_ptr > c->dwarf.cfa + 256)
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{
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/* Not plausible for SA_SIGINFO signal */
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c->sigcontext_format = X86_SCF_LINUX_SIGFRAME;
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c->sigcontext_addr = sigcontext_addr = c->dwarf.cfa + 4;
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}
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else
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{
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/* If SA_SIGINFO were not specified, we actually read
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various segment pointers instead. We believe that at
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least fs and _fsh are always zero for linux, so it is
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not just unlikely, but impossible that we would end
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up here. */
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c->sigcontext_format = X86_SCF_LINUX_RT_SIGFRAME;
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c->sigcontext_addr = sigcontext_ptr;
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sigcontext_addr = sigcontext_ptr + LINUX_UC_MCONTEXT_OFF;
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}
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esp_loc = DWARF_LOC (sigcontext_addr + LINUX_SC_ESP_OFF, 0);
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ebp_loc = DWARF_LOC (sigcontext_addr + LINUX_SC_EBP_OFF, 0);
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eip_loc = DWARF_LOC (sigcontext_addr + LINUX_SC_EIP_OFF, 0);
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ret = dwarf_get (&c->dwarf, esp_loc, &c->dwarf.cfa);
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if (ret < 0)
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return 0;
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}
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else
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{
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ret = dwarf_get (&c->dwarf, c->dwarf.loc[EBP], &c->dwarf.cfa);
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if (ret < 0)
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return ret;
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Debug (13, "[EBP=0x%x] = 0x%xx\n", DWARF_GET_LOC (c->dwarf.loc[EBP]),
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c->dwarf.cfa);
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ebp_loc = DWARF_LOC (c->dwarf.cfa, 0);
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eip_loc = DWARF_LOC (c->dwarf.cfa + 4, 0);
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c->dwarf.cfa += 8;
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}
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/* Mark all registers unsaved, since we don't know where they
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are saved (if at all), except for the EBP and EIP. */
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for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
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c->dwarf.loc[i] = DWARF_NULL_LOC;
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c->dwarf.loc[EBP] = ebp_loc;
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c->dwarf.loc[EIP] = eip_loc;
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c->dwarf.ret_addr_column = EIP;
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if (!DWARF_IS_NULL_LOC (c->dwarf.loc[EBP]))
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{
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ret = dwarf_get (&c->dwarf, c->dwarf.loc[EIP], &c->dwarf.ip);
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if (ret < 0)
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return ret;
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}
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else
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c->dwarf.ip = 0;
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}
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return (c->dwarf.ip == 0) ? 0 : 1;
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}
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