From: "H.J. Lu" <hjl.tools@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Noah Goldstein <goldstein.w.n@gmail.com>,
libc-alpha@sourceware.org, adhemerval.zanella@linaro.org
Subject: Re: [PATCH v7 1/2] x86-64: Save APX registers in ld.so trampoline
Date: Fri, 16 Feb 2024 03:53:56 -0800 [thread overview]
Message-ID: <CAMe9rOoz-gPuhiOdVjVGoaQoCUmzAK1SsVXy522Ek28Dupy97g@mail.gmail.com> (raw)
In-Reply-To: <87ttm8630c.fsf@oldenburg.str.redhat.com>
On Fri, Feb 16, 2024 at 3:51 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Noah Goldstein:
>
> >> +/* Save SSE, AVX, AVX512, mask, bound and APX registers. Bound and APX
> >> + 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.
--
H.J.
next prev parent reply other threads:[~2024-02-16 11:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-16 0:21 [PATCH v7 0/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers H.J. Lu
2024-02-16 0:21 ` [PATCH v7 1/2] x86-64: Save APX registers in ld.so trampoline H.J. Lu
2024-02-16 7:39 ` Noah Goldstein
2024-02-16 11:51 ` Florian Weimer
2024-02-16 11:53 ` H.J. Lu [this message]
2024-02-16 0:21 ` [PATCH v7 2/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers H.J. Lu
2024-02-16 8:04 ` Noah Goldstein
2024-02-16 12:15 ` H.J. Lu
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