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84d4150668
Greetings,
We use libunwind just for stack traces (I suspect many others do as well).
The use pattern is:
GetStackTrace(void** result, int max_depth)
{
...
unw_getcontext(&uc);
unw_init_local(&cursor, &uc);
while (n < max_depth) {
if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
break;
}
result[n++] = ip;
if (unw_step(&cursor) <= 0) {
break;
}
}
Given this usage, it is quite convenient for us to block signals (or
prevent signal handlers from re-entering libunwind by other means) at the
"top level", which makes most of the sigprocmask calls performed by
libunwind itself unneccessary.
The second patch in this series adds a configure option which removes most
of the sigprocmask calls.
Attached patch is a preliminary for it -- consolidating all of the
"sigprocmask; mutex_lock;" sequences into lock_acquire and "mutex_unlock;
sigprocmask;" sequences into lock_release.
Thanks,
--
Paul Pluzhnikov
commit 402d15b123d54a7669db7cf17a76dd315094e472
Author: Paul Pluzhnikov <ppluzhnikov@google.com>
Date: Mon Sep 21 10:18:28 2009 -0700
Replace "sigprocmask + mutext_lock" with a single lock_acquire.
Likewise, replace "mutext_unlock + sigprocmask" with lock_release.
65 lines
2 KiB
C
65 lines
2 KiB
C
/* libunwind - a platform-independent unwind library
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Copyright (C) 2008 CodeSourcery
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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 "dwarf_i.h"
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HIDDEN pthread_mutex_t mips_lock = PTHREAD_MUTEX_INITIALIZER;
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HIDDEN int tdep_needs_initialization = 1;
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/* FIXME: I'm pretty sure we don't need this at all for MIPS, but "generic"
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code (include/dwarf_i.h) seems to expect it to be here at present. */
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HIDDEN uint8_t dwarf_to_unw_regnum_map[] =
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{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31
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};
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HIDDEN void
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tdep_init (void)
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{
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intrmask_t saved_mask;
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sigfillset (&unwi_full_mask);
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lock_acquire (&mips_lock, saved_mask);
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{
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if (!tdep_needs_initialization)
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/* another thread else beat us to it... */
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goto out;
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mi_init ();
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dwarf_init ();
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#ifndef UNW_REMOTE_ONLY
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mips_local_addr_space_init ();
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#endif
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tdep_needs_initialization = 0; /* signal that we're initialized... */
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}
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out:
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lock_release (&mips_lock, saved_mask);
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}
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