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649f1fb344
bad/missing unwind information, which could result in libunwind dereferencing bad pointers. This mechanism is based on msync(2) system call and significantly reduces the chances of a bad pointer dereference in libunwind. The original idea was to turn this mechanism on only when necessary i.e. libunwind didn't find proper unwind information for a IP. There are a couple of problems in the current implementation. * The flag is global and is modified without locking * The flag isn't reset when starting a new unwind The attached patch makes ->validate a per-thread setting by moving it into struct cursor from unw_local_addr_space and resets it to false when starting a new unwind. As a result, cursor->as_arg points to the cursor itself instead of the ucontext (for the local case). This was found to reduce the number of msync() system calls from an application using libunwind significantly. Signed-off-by: Paul Pluzhnikov <ppluzhnikov@google.com> Signed-off-by: Arun Sharma <arun.sharma@google.com>
58 lines
1.8 KiB
C
58 lines
1.8 KiB
C
/* libunwind - a platform-independent unwind library
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Copyright (c) 2003 Hewlett-Packard Development Company, L.P.
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Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
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Modified for x86_64 by Max Asbock <masbock@us.ibm.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 "init.h"
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#include "unwind_i.h"
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PROTECTED int
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unw_init_remote (unw_cursor_t *cursor, unw_addr_space_t as, void *as_arg)
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{
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#ifdef UNW_LOCAL_ONLY
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return -UNW_EINVAL;
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#else /* !UNW_LOCAL_ONLY */
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struct cursor *c = (struct cursor *) cursor;
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if (tdep_needs_initialization)
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tdep_init ();
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Debug (1, "(cursor=%p)\n", c);
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c->dwarf.as = as;
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if (as == unw_local_addr_space)
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{
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c->dwarf.as_arg = c;
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c->uc = as_arg;
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}
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else
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{
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c->dwarf.as_arg = as_arg;
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c->uc = 0;
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}
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return common_init (c);
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#endif /* !UNW_LOCAL_ONLY */
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}
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