On Thu, Feb 18, 2021 at 05:59:40PM +0100, Peter Zijlstra wrote: > By using int3 as a speculation fence instead of lfence, we can shrink > the longest alternative to just 15 bytes: > > 0: e8 05 00 00 00 callq a <.altinstr_replacement+0xa> > 5: f3 90 pause > 7: cc int3 > 8: eb fb jmp 5 <.altinstr_replacement+0x5> > a: 48 89 04 24 mov %rax,(%rsp) > e: c3 retq > > This means we can change the alignment from 32 to 16 bytes and get 4 > retpolines per cacheline, $I win.
You mean I$ :) In any case, for both: Reviewed-by: Borislav Petkov <[email protected]> and it looks real nice here, the size: readelf -s vmlinux | grep __x86_indirect 78966: ffffffff81c023e0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 81653: ffffffff81c02390 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 82338: ffffffff81c02430 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 82955: ffffffff81c02380 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 85057: ffffffff81c023f0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 89996: ffffffff81c023a0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 91094: ffffffff81c02400 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 91278: ffffffff81c023b0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 92015: ffffffff81c02360 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 92722: ffffffff81c023c0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 97062: ffffffff81c02410 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 98687: ffffffff81c023d0 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 99076: ffffffff81c02350 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 99500: ffffffff81c02370 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] 100579: ffffffff81c02420 15 FUNC GLOBAL DEFAULT 1 __x86_indirect_t[...] -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
