On Wed, Oct 25, 2023 at 10:30:52PM +0100, Andrew Cooper wrote: > On 25/10/2023 10:28 pm, Josh Poimboeuf wrote: > > On Wed, Oct 25, 2023 at 10:10:41PM +0100, Andrew Cooper wrote: > >> On 25/10/2023 9:52 pm, Pawan Gupta wrote: > >>> diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S > >>> index bfb7bcb362bc..f8ba0c0b6e60 100644 > >>> --- a/arch/x86/entry/entry.S > >>> +++ b/arch/x86/entry/entry.S > >>> @@ -20,3 +23,16 @@ SYM_FUNC_END(entry_ibpb) > >>> EXPORT_SYMBOL_GPL(entry_ibpb); > >>> > >>> .popsection > >>> + > >>> +.pushsection .entry.text, "ax" > >>> + > >>> +.align L1_CACHE_BYTES, 0xcc > >>> +SYM_CODE_START_NOALIGN(mds_verw_sel) > >>> + UNWIND_HINT_UNDEFINED > >>> + ANNOTATE_NOENDBR > >>> + .word __KERNEL_DS > >> You need another .align here. Otherwise subsequent code will still > >> start in this cacheline and defeat the purpose of trying to keep it > >> separate. > >> > >>> +SYM_CODE_END(mds_verw_sel); > >> Thinking about it, should this really be CODE and not a data entry? > >> > >> It lives in .entry.text but it really is data and objtool shouldn't be > >> writing ORC data for it at all. > >> > >> (Not to mention that if it's marked as STT_OBJECT, objdump -d will do > >> the sensible thing and not even try to disassemble it). > >> > >> ~Andrew > >> > >> P.S. Please CC on the full series. Far less effort than fishing the > >> rest off lore. > > +1 to putting it in .rodata or so. > > It's necessarily in .entry.text so it doesn't explode with KPTI active. Ah, right. In general tooling doesn't take too kindly to putting data in a text section. But it might be ok. -- Josh
