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Re: Fix unwinding for Thumb-2 libraries
- From: Richard Henderson <rth at twiddle dot net>
- To: libc-ports at sourceware dot org
- Date: Mon, 05 Apr 2010 08:53:12 -0700
- Subject: Re: Fix unwinding for Thumb-2 libraries
- References: <20100405141134.GA17018@caradoc.them.org>
> We can't use push/pop inside the asm because that breaks
> + unwinding (i.e. thread cancellation) for this frame. We can't
> + locally save and restore r7, because we do not know if this
> + function uses r7 or if it is our caller's r7; if it is our caller's,
> + then unwinding will fail higher up the stack. So we move the
> + syscall out of line and provide its own unwind information. */
If you've got cfi directives, you *can* manipulate the unwind
info inside the asm within the current frame.
r~