On 08/25/2011 05:57 PM, David Daney wrote: > On 08/25/2011 05:26 AM, Andrew Haley wrote: >> Throwing an exception through a segfault handler doesn't always work >> on ARM: the attached example fails on current gcc trunk. >> >> panda-9:~ $ g++ segv.cc -fnon-call-exceptions -g >> panda-9:~ $ ./a.out >> terminate called after throwing an instance of 'FoobarException*' >> Aborted >> >> The bug is that _Unwind_GetIPInfo doesn't correctly set ip_before_insn. >> Instead, it always sets it to zero; it should be set to 1 if this >> is a frame created by a signal handler: >> >> >> #define _Unwind_GetIPInfo(context, ip_before_insn) \ >> (*ip_before_insn = 0, _Unwind_GetGR (context, 15)& ~(_Unwind_Word)1) >> >> >> Fixing this on ARM is hard because signal frames aren't specially >> marked as they are on systems that use DWARF unwinder data. I have >> a patch that works on systems where the signal restorer is exactly >> >> mov r7, $SYS_rt_sigreturn >> swi 0x0 >> >> It works as a proof of concept, but it's fugly. > > For what it's worth, I did the equivalent on MIPS. > > Once you do this, it is a de facto ABI. Probably the ARM linux > maintainers should be consulted to see if they are willing to consider > the possibility of never changing it.
I think Joseph Meyers is the author of both ends of this, and I think he reads this list. Andrew.
