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Re: [Patch] MIPS: Fix unwinding through signal frames.
- From: Richard Sandiford <rsandifo at nildram dot co dot uk>
- To: David Daney <ddaney at avtrex dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 14 Nov 2007 20:28:13 +0000
- Subject: Re: [Patch] MIPS: Fix unwinding through signal frames.
- References: <473B4DA7.1060204@avtrex.com>
David Daney <ddaney@avtrex.com> writes:
> Certain MIPS processors have an errata workaround that changes the stack
> layout for signal handlers. The current MD_FALLBACK_FRAME_STATE_FOR for
> mips/Linux assumes that the signal context is at a constant offset from
> the signal trampoline. When the workaround is in effect, the signal
> context is not in the expected location, so unwinding fails.
>
> I discovered this problem while running the testsuite on an SGI O2
> system. All the other mips systems I test with don't have the
> workaround so were not effected by the bug.
>
> The patch changes the calculation of the signal context so that it uses
> the CFA of the unwind context to find the signal context. This has the
> advantage of working on system either with or without the workaround.
>
> Tested on mipsel-linux (without workaround) and spot checked on
> mips64-linux n32 ABI (with workaround) with full mips64-linux test in
> progress.
>
> OK to commit?
Yup. Thanks for working on this.
> + u_int32_t ass[4];
Can you put "/* Argument save space for o32. */" next to this,
as I fear the name isn't self-descriptive...
Richard