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Lu" Date: Fri, 16 Feb 2024 03:53:56 -0800 Message-ID: Subject: Re: [PATCH v7 1/2] x86-64: Save APX registers in ld.so trampoline To: Florian Weimer Cc: Noah Goldstein , libc-alpha@sourceware.org, adhemerval.zanella@linaro.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-3014.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Fri, Feb 16, 2024 at 3:51=E2=80=AFAM Florian Weimer = wrote: > > * Noah Goldstein: > > >> +/* Save SSE, AVX, AVX512, mask, bound and APX registers. Bound and A= PX > >> + registers are mutually exclusive. */ > >> +# define STATE_SAVE_MASK \ > >> + ((1 << X86_XSTATE_SSE_ID) \ > >> + | (1 << X86_XSTATE_AVX_ID) \ > >> + | (1 << X86_XSTATE_BNDREGS_ID) \ > >> + | (1 << X86_XSTATE_K_ID) \ > >> + | (1 << X86_XSTATE_ZMM_H_ID) \ > >> + | (1 << X86_XSTATE_ZMM_ID) \ > >> + | (1 << X86_XSTATE_APX_F_ID)) > > > Need tile here? > > We can't save the AMX state because it's too big and will overflow > existing stacks. This change is immediately active on systems with AMX, > even for old applications which do not know about AMX at all. > > Another problem is that AMX is enabled by a syscall. When ld.so checks the xsave mask, AMX state may not be active at the time. --=20 H.J.