Messages in this thread | | | Date | Mon, 12 Jan 2015 12:22:10 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: introduce push/pop macros which generate CFI_REL_OFFSET and CFI_RESTORE |
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On 01/12/2015 12:14 PM, Andy Lutomirski wrote: > On Mon, Jan 12, 2015 at 12:11 PM, Borislav Petkov <bp@alien8.de> wrote: >> On Mon, Jan 12, 2015 at 11:46:53AM -0800, Andy Lutomirski wrote: >>> Dumb example: >>> >>> pushq_cfi $__KERNEL_DS /* ss */ >>> >>> This doesn't save anything that the unwinder would care about. >> >> And? The unwinder or whatever looks at that info simply ignores stuff it >> is not interested in, no? > > But CFI_REL_OFFSET $__KERNEL_DS, 0 probably isn't even well-formed and > won't build. >
I think this is relatively easy to deal with at the expense of a large .ifeq statement in the macro.
-hpa
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