Messages in this thread | | | Date | Fri, 23 May 2008 00:22:06 +0200 | From | Mikael Pettersson <> | Subject | Re: [RFC] x86: xsave/xrstor support, ucontext_t extensions |
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H. Peter Anvin writes: > > But user can potentially change the _fpstate pointer in sigcontext struct. > > If so, they get what they bargained for... I am not even sure the kernel > will successfully clean up the stack frame if they do that.
Why would that be a problem? The stack is defined by the user's SP, which is in the integer state part of the sigframe. We do a sigreturn(), reload SP/PC/etc, and off we go. Where fpstate pointed to doesn't matter, as long as it was NULL or a valid fpstate image.
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