Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu

From: Raymond Jennings
Date: Thu Aug 13 2015 - 18:01:28 EST




On 08/13/15 14:46, Linus Torvalds wrote:
On Thu, Aug 13, 2015 at 2:42 PM, Raymond Jennings <shentino@xxxxxxxxx> wrote:
I am curious about what's supposed to happen normally on signal delivery.

Is SS a register that's supposed to be preserved like EIP/RIP and CS when a
signal is delivered?
What exactly does "supposed" mean?
Basically, when a process/thread receives a signal, what happens to its registers?
So clearly, we're not "supposed" to save/restore it. Because reality
matters a hell of a lot more than any theoretical arguments.
So it still counts as a regression if the kernel pulls the rug out from under someone that was relying on undocumented or buggy behavior?
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