If you research general discussion about how Spectre worked, it appears
it was dependent on data being brought into cache or not from the path
not taken. Timing how long it took to access the data indirectly a
second time could reveal something about the data value.
On 2022-04-07 12:30 p.m., Ed Jaffe wrote:
On 4/7/2022 9:16 AM, Paul Gilmartin wrote:
On Apr 7, 2022, at 09:57:35, Ed Jaffe wrote:
z/Architecture does *not* require an alternative path around
TBEGINC/TEND.
How, then, does z/Architecture defend against such as Spectre?
Does it balance paths so all exhibit the worst-case timing?
Speculative execution is constantly being done for all instruction
paths, not just those inside TBEGINC/TEND.
How IBM Z defends against spectre has never been disclosed.
Gary Weinhold
Senior Application Architect
DATAKINETICS | Data Performance & Optimization
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