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unwinding through signal frame on ARM
- From: Peng Yuan <yingbo dot com at gmail dot com>
- To: gcc <gcc at gcc dot gnu dot org>
- Cc: Paul Brook <paul at codesourcery dot com>
- Date: Wed, 12 Mar 2014 23:33:17 +0800
- Subject: unwinding through signal frame on ARM
- Authentication-results: sourceware.org; auth=none
Hi,
I'm using backtrace() to obtain call context by sending signals. But
program segfaults if the first instruction of a function receives
signal for backtrace.
ARM unwinding in libgcc uses "return_address -= 2" to get the caller
address. It is OK for normal function call with "bl xxx". But it
cannot handle signal frame case because "return_address -= 2" may go
to the preceding function.
See get_eit_entry() in libgcc/unwind-arm-common.inc.
Both GDB and libunwind take signal frame as a special case on ARM
unwinding. Does libgcc also need to fix the case?
--
Regards,
Peng