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Differential D31916

amd64 acpi_wakeup: map 1:1 whole low 4G for initial page table
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Authored by kib on Sep 11 2021, 6:42 PM.
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grahamperrin

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markj
Commits
rGdb2ba218d9fe: amd64 acpi_wakeup: map 1:1 whole low 4G for the trampoline page table
rGceca8ac1ce47: x86 acpi_install_wakeup_handler(): style
rGe99255c8a6ca: amd64: do not touch low memory in acpi_wakeup_ap() if booted by UEFI
Summary

This is required since kernel text might be physically located anywhere below 4G.

Also avoid touching unowned low memory when booted from UEFI.

PR: 258432

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rG FreeBSD src repository
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Event Timeline

kib requested review of this revision.Sep 11 2021, 6:42 PM
kib created this revision.
grahamperrin added a subscriber: grahamperrin.Sep 12 2021, 12:54 AM
kib updated this revision to Diff 94994.Sep 12 2021, 4:17 PM

Do not forget to install KVA mappings into the trampoline page table.

kib edited the summary of this revision. (Show Details)Sep 12 2021, 5:53 PM
kib added a reviewer: markj.
markj accepted this revision.Sep 13 2021, 12:41 PM
markj added inline comments.
sys/x86/acpica/acpi_wakeup.c
507

Why do we set PG_U here?

This revision is now accepted and ready to land.Sep 13 2021, 12:41 PM
kib added inline comments.Sep 13 2021, 4:55 PM
sys/x86/acpica/acpi_wakeup.c
507

I do not think there is a reason now. It might be there was some reason before, if e.g. vm86 mode was used on the wakeup path [Or any other trampoline from real mode to final protection mode, we are consistent to set PG_U on all trampoline ptes, I believe] So it probably was moved from i386 to amd64 and live there since.

I have another change to the acpi_wakeup.c in pipe, after that I might look into coalescing code that creates page table for low 4G 1:1.

Closed by commit rGe99255c8a6ca: amd64: do not touch low memory in acpi_wakeup_ap() if booted by UEFI (authored by kib). · Explain WhySep 13 2021, 4:56 PM
This revision was automatically updated to reflect the committed changes.
kib added a commit: rGe99255c8a6ca: amd64: do not touch low memory in acpi_wakeup_ap() if booted by UEFI.
kib added a commit: rGceca8ac1ce47: x86 acpi_install_wakeup_handler(): style.
kib added a commit: rGdb2ba218d9fe: amd64 acpi_wakeup: map 1:1 whole low 4G for the trampoline page table.

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sys/
x86/
acpica/
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sys/x86/acpica/acpi_wakeup.c

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