Boka revatsvagiri kubva kumayunivhesiti eChinese neAmerica rakaratidza kusazvibata kutsva muIntel processors inotungamira kune wechitatu-bato kuvuza kweruzivo nezve mhedzisiro yekufungidzira mashandiro, ayo anogona kushandiswa, semuenzaniso, kuronga yakavanzika yekutaurirana nzira pakati pemaitiro kana tsvaga kuvuza panguva yekurwiswa kweMeltdown.
Izvo zvakakosha zvekusagadzikana ndezvekuti shanduko yeEFLAGS processor register inoitika semugumisiro wekufungidzira kuurayiwa kwemirairo inokanganisa inotevera nguva yekuitwa kweJCC mirayiridzo (svetuka kana mamiriro akatsanangurwa asangana). Kufungidzira mashandiro haapedze uye mhedzisiro inoraswa, asi yakaraswa EFLAGS shanduko inogona kutsanangurwa nekuongorora nguva yekuuraya yeJCC mirayiridzo. Kuenzanisa mashandiro anoitwa nenzira yekufungidzira isati yachinja, kana ikabudirira, inokonzeresa kunonoka kudiki kunogona kuyerwa uye kushandiswa sechiratidzo chesarudzo yemukati.
Kusiyana nedzimwe nzira dzakafanana dzekurwiswa kweparutivi, iyo nzira nyowani haiongorore shanduko yenguva yekuwana kune cached uye isina kuvharwa data uye haidi nhanho yekudzosera iyo EFLAGS rejista kune yayo yekutanga mamiriro, izvo zvinoita kuti zviome kuona nekuvhara kurwisa. Sekuratidzira, vaongorori vakaita shanduko yeMeltdown kurwisa, vachishandisa nzira nyowani yekuwana ruzivo nezve mhedzisiro yekufungidzira kushanda. Kushanda kweiyo nzira yekuronga kubuda kweruzivo panguva yekurwiswa kweMeltdown kwakanyatso kuratidzwa pamasystem ane Intel Core i7-6700 uye i7-7700 CPU munzvimbo ine Ubuntu 22.04 uye Linux kernel 5.15. Pane system ine Intel i9-10980XE CPU, kurwiswa kwacho kwakangoitwa zvishoma.
Kusagadzikana kweMeltdown kwakavakirwa pachokwadi chekuti panguva yekufungidzira yekuitwa kwemirairo, processor inogona kuwana yakavanzika data nzvimbo uye yobva yarasa mhedzisiro nekuti iyo ropafadzo dzakasetwa dzinorambidza kupinda kwakadaro kubva mukuita kwemushandisi. Muchirongwa ichi, chivharo chekufungidzira chinopatsanurwa kubva kukodhi huru nebazi rine zvirevo, iro mumamiriro ezvinhu chaiwo rinogara richipisa, asi nekuda kwekuti chirevo chechirevo chinoshandisa kukosha kwakaverengerwa iyo processor yaasingazive panguva yekukurumidza kuuraya. iyo code, sarudzo dzese dzebazi dzinoitwa zvekufungidzira.
Muchinyakare vhezheni yeMeltdown, sezvo cache imwe chete ichishandiswa kuita zvekufungidzira mashandiro senge mirairo inowanzoitwa, zvinogoneka panguva yekufungidzira kuuraya kuseta mamaki mucache anoratidza zviri mukati mezvimedu zvega munzvimbo yakavharwa yendangariro, uyezve. sarudza mukodhi inowanzoitwa zvazvinoreva kuburikidza nekuongorora nguva yekuwana kune cached uye isina cached data. Musiyano mutsva unoshandisa shanduko murejista yeEFLAGS sechiratidzo chekuvuza. Muchiratidziro chechiteshi chekuvhara, imwe nzira yakagadzirisa data yakatumirwa kugadzira mamiriro ekushandura zviri mukati meEFLAGS register, uye imwe nzira yakaongorora shanduko munguva yekuuraya yeJCC kuraira kuti idzore zvakare data inotumirwa nekutanga maitiro.
Source: opennet.ru