John Rose

The pattern in the Loom (a blanket statement) http://cr.openjdk.java.net/~jrose/pres/201907-LoomBlanket/loom-blanket.html … #jvmls

# hopscotch vs. nopscotch F: ... if (need_fancy_ret()) { inc rsp[0], (A-N); ret } ... call F N: jmp 1f A: call do_fancy_ret # normal ret point 1: mov rsp[-8],rax call F N: .bytes 0x0F,0x1F,0x84 A: call do_fancy_ret # normal ret point mov rsp[-8],rax

// type vars simulating Einstein labels interface EinInt { //(inline record type?) String label(); int value(); } interface EinTensor2<I extends EinInt, J extends EinInt> { I firstDim(); J lastDim(); <K extends EinInt> EinTensor2<I,K> mulBy(EinTensor2<J,K> that); }

Yesterday's talk from Vladimir and me, posted in the usual places for the record: http://cr.openjdk.java.net/~vlivanov/talks/2019_JVMLS_Vector_Numerics.pdf … http://cr.openjdk.java.net/~jrose/pres/201907-Vectors.pdf …

It seems to me that the #NotreDame fire is one of those lucid moments, often tragic, when most of us (Catholics like me, or of different or no faith) connect, in common, with a deep longing for the transcendent. Even wounded, Notre Dame does the work set for her by her builders.

The wise man learns from his own mistakes. Any sod can learn from others' mistakes.

Suppose an “alignment class” is a set A(n,x) of all virtual addresses of the form a*n+x, where n=2^i and 0<=x<n. If x=0 they are n-byte-aligned addresses. Compactly encode A(n,x) as k=n+x. Decode n=2^floor(lg k) and x=k-n. So k=1016 describes 8b header + aligned 512b payload.

Java 11 script option config: cat <<\. >jscr; chmod +x jscr; ./jscr x y #! /bin/sh //bin/sh -c :;exec java -DS="$0" -ea --source 11 "$0" "$@" interface C { static void main(String[] av) { System.out.println("calling "+System.getProperty("S")+" on "+java.util.List.of(av)); } } .

Case studies in living without long term memory: 1. The Lost Mariner https://sites.google.com/site/neurobiologyreadings/OliverSacks_ManMistookWifeForHat/02-the-lost-mariner … 2. Any IRC channel.

Scott Meyers on "The Keyhole Problem" http://www.aristeia.com/TKP/  ...this is an anti-pattern to avoid when designing code review engines. Referential integrity and automation are wonderful, but they also need APIs and backends so your robots can talk to their robots.

Ok, it's already in there: The same blue label states control the w/h inputs in the way I want. Where is all this stuff documented? Where's the Missing Manual?

Tweets are sometimes difficult to unpack; I expect this one is, since it sketches a technical approach to disabling bad speculations with little cost to good ones. Here's a guide for those who want to read more than 280 characters. http://rosehome.org/work/zorb.html  @intel @IntelSecurity

Ghost medicine heals bad speculative loads. ℞ Take one zorb, via base or index register. Mix fresh in a clean cmov after each branch. # define MIX(zorb,p) zorb+=LD(CMOV(p?&ZERO:BADPTR)); # define HEAL(x,zorb) x+=zorb; int zorb=0; if (i<n){ MIX(zorb,i<n); HEAL(a,zorb); r=a[i]; }

Happy π day. Since one good half-turn deserves another, I'm also looking forward to τ day. (Only 106 shopping days left!)

Unwanted spectres? Try ghost poison! Safe for pets. # define ghost_poison(b, a) \ a = cmov(b ? a : random()) if (i < a_len) { ghost_poison(i < a_len, a); return a[i]; } if (q=http://obj.is _string()) { ghost_poison(q, obj); return ((string)obj).char_at(1); }

On the tenth day of Christmas, some white hats gave to me: 10 clouds a-booting, 9 PRs dancing, 8 pulls requesting, 7 maps remapping, 6 bounds a-clipping, 5 retpolines! 4 side channels, 3 hacked rets, 2 gadgets found, and a branch burning spectrall-y!

Nerdy Spectre metaphors: Victim's job is to play secret tune on a piano (whose keys are cache lines); attacker in the next room has tuning forks sensitive to some notes. Attacker and victim are parallel brane-universes which interact only via weak or exotic forces (D$, BT$).