From: "Ard Biesheuvel" <ardb@kernel.org>
To: devel@edk2.groups.io
Cc: Ard Biesheuvel <ardb@kernel.org>,
Leif Lindholm <quic_llindhol@quicinc.com>,
Alexander Graf <agraf@csgraf.de>
Subject: [PATCH v3 06/16] ArmPkg/ArmMmuLib: Disable and re-enable MMU only when needed
Date: Mon, 26 Sep 2022 10:25:01 +0200 [thread overview]
Message-ID: <20220926082511.2110797-7-ardb@kernel.org> (raw)
In-Reply-To: <20220926082511.2110797-1-ardb@kernel.org>
When updating a page table descriptor in a way that requires break
before make, we temporarily disable the MMU to ensure that we don't
unmap the memory region that the code itself is executing from.
However, this is a condition we can check in a straight-forward manner,
and if the regions are disjoint, we don't have to bother with the MMU
controls, and we can just perform an ordinary break before make.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
ArmPkg/Include/Library/ArmMmuLib.h | 7 +-
ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 102 ++++++++++++++++----
ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S | 43 +++++++--
3 files changed, 123 insertions(+), 29 deletions(-)
diff --git a/ArmPkg/Include/Library/ArmMmuLib.h b/ArmPkg/Include/Library/ArmMmuLib.h
index 7538a8274a72..b745e2230e7e 100644
--- a/ArmPkg/Include/Library/ArmMmuLib.h
+++ b/ArmPkg/Include/Library/ArmMmuLib.h
@@ -52,9 +52,10 @@ ArmClearMemoryRegionReadOnly (
VOID
EFIAPI
ArmReplaceLiveTranslationEntry (
- IN UINT64 *Entry,
- IN UINT64 Value,
- IN UINT64 RegionStart
+ IN UINT64 *Entry,
+ IN UINT64 Value,
+ IN UINT64 RegionStart,
+ IN BOOLEAN DisableMmu
);
EFI_STATUS
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 34f1031c4de3..4d75788ed2b2 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -18,6 +18,17 @@
#include <Library/ArmMmuLib.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
+#include <Library/HobLib.h>
+
+STATIC
+VOID (
+ EFIAPI *mReplaceLiveEntryFunc
+ )(
+ IN UINT64 *Entry,
+ IN UINT64 Value,
+ IN UINT64 RegionStart,
+ IN BOOLEAN DisableMmu
+ ) = ArmReplaceLiveTranslationEntry;
STATIC
UINT64
@@ -83,14 +94,40 @@ ReplaceTableEntry (
IN UINT64 *Entry,
IN UINT64 Value,
IN UINT64 RegionStart,
+ IN UINT64 BlockMask,
IN BOOLEAN IsLiveBlockMapping
)
{
- if (!ArmMmuEnabled () || !IsLiveBlockMapping) {
+ BOOLEAN DisableMmu;
+
+ //
+ // Replacing a live block entry with a table entry (or vice versa) requires a
+ // break-before-make sequence as per the architecture. This means the mapping
+ // must be made invalid and cleaned from the TLBs first, and this is a bit of
+ // a hassle if the mapping in question covers the code that is actually doing
+ // the mapping and the unmapping, and so we only bother with this if actually
+ // necessary.
+ //
+
+ if (!IsLiveBlockMapping || !ArmMmuEnabled ()) {
+ // If the mapping is not a live block mapping, or the MMU is not on yet, we
+ // can simply overwrite the entry.
*Entry = Value;
ArmUpdateTranslationTableEntry (Entry, (VOID *)(UINTN)RegionStart);
} else {
- ArmReplaceLiveTranslationEntry (Entry, Value, RegionStart);
+ // If the mapping in question does not cover the code that updates the
+ // entry in memory, or the entry that we are intending to update, we can
+ // use an ordinary break before make. Otherwise, we will need to
+ // temporarily disable the MMU.
+ DisableMmu = FALSE;
+ if ((((RegionStart ^ (UINTN)ArmReplaceLiveTranslationEntry) & ~BlockMask) == 0) ||
+ (((RegionStart ^ (UINTN)Entry) & ~BlockMask) == 0))
+ {
+ DisableMmu = TRUE;
+ DEBUG ((DEBUG_WARN, "%a: splitting block entry with MMU disabled\n", __FUNCTION__));
+ }
+
+ ArmReplaceLiveTranslationEntry (Entry, Value, RegionStart, DisableMmu);
}
}
@@ -155,12 +192,13 @@ IsTableEntry (
STATIC
EFI_STATUS
UpdateRegionMappingRecursive (
- IN UINT64 RegionStart,
- IN UINT64 RegionEnd,
- IN UINT64 AttributeSetMask,
- IN UINT64 AttributeClearMask,
- IN UINT64 *PageTable,
- IN UINTN Level
+ IN UINT64 RegionStart,
+ IN UINT64 RegionEnd,
+ IN UINT64 AttributeSetMask,
+ IN UINT64 AttributeClearMask,
+ IN UINT64 *PageTable,
+ IN UINTN Level,
+ IN BOOLEAN TableIsLive
)
{
UINTN BlockShift;
@@ -170,6 +208,7 @@ UpdateRegionMappingRecursive (
UINT64 EntryValue;
VOID *TranslationTable;
EFI_STATUS Status;
+ BOOLEAN NextTableIsLive;
ASSERT (((RegionStart | RegionEnd) & EFI_PAGE_MASK) == 0);
@@ -198,7 +237,14 @@ UpdateRegionMappingRecursive (
// the next level. No block mappings are allowed at all at level 0,
// so in that case, we have to recurse unconditionally.
//
+ // One special case to take into account is any region that covers the page
+ // table itself: if we'd cover such a region with block mappings, we are
+ // more likely to end up in the situation later where we need to disable
+ // the MMU in order to update page table entries safely, so prefer page
+ // mappings in that particular case.
+ //
if ((Level == 0) || (((RegionStart | BlockEnd) & BlockMask) != 0) ||
+ ((Level < 3) && (((UINT64)PageTable & ~BlockMask) == RegionStart)) ||
IsTableEntry (*Entry, Level))
{
ASSERT (Level < 3);
@@ -234,7 +280,8 @@ UpdateRegionMappingRecursive (
*Entry & TT_ATTRIBUTES_MASK,
0,
TranslationTable,
- Level + 1
+ Level + 1,
+ FALSE
);
if (EFI_ERROR (Status)) {
//
@@ -246,8 +293,11 @@ UpdateRegionMappingRecursive (
return Status;
}
}
+
+ NextTableIsLive = FALSE;
} else {
TranslationTable = (VOID *)(UINTN)(*Entry & TT_ADDRESS_MASK_BLOCK_ENTRY);
+ NextTableIsLive = TableIsLive;
}
//
@@ -259,7 +309,8 @@ UpdateRegionMappingRecursive (
AttributeSetMask,
AttributeClearMask,
TranslationTable,
- Level + 1
+ Level + 1,
+ NextTableIsLive
);
if (EFI_ERROR (Status)) {
if (!IsTableEntry (*Entry, Level)) {
@@ -282,7 +333,8 @@ UpdateRegionMappingRecursive (
Entry,
EntryValue,
RegionStart,
- IsBlockEntry (*Entry, Level)
+ BlockMask,
+ TableIsLive && IsBlockEntry (*Entry, Level)
);
}
} else {
@@ -291,7 +343,7 @@ UpdateRegionMappingRecursive (
EntryValue |= (Level == 3) ? TT_TYPE_BLOCK_ENTRY_LEVEL3
: TT_TYPE_BLOCK_ENTRY;
- ReplaceTableEntry (Entry, EntryValue, RegionStart, FALSE);
+ ReplaceTableEntry (Entry, EntryValue, RegionStart, BlockMask, FALSE);
}
}
@@ -301,10 +353,11 @@ UpdateRegionMappingRecursive (
STATIC
EFI_STATUS
UpdateRegionMapping (
- IN UINT64 RegionStart,
- IN UINT64 RegionLength,
- IN UINT64 AttributeSetMask,
- IN UINT64 AttributeClearMask
+ IN UINT64 RegionStart,
+ IN UINT64 RegionLength,
+ IN UINT64 AttributeSetMask,
+ IN UINT64 AttributeClearMask,
+ IN BOOLEAN TableIsLive
)
{
UINTN T0SZ;
@@ -321,7 +374,8 @@ UpdateRegionMapping (
AttributeSetMask,
AttributeClearMask,
ArmGetTTBR0BaseAddress (),
- GetRootTableLevel (T0SZ)
+ GetRootTableLevel (T0SZ),
+ TableIsLive
);
}
@@ -336,7 +390,8 @@ FillTranslationTable (
MemoryRegion->VirtualBase,
MemoryRegion->Length,
ArmMemoryAttributeToPageAttribute (MemoryRegion->Attributes) | TT_AF,
- 0
+ 0,
+ FALSE
);
}
@@ -410,7 +465,8 @@ ArmSetMemoryAttributes (
BaseAddress,
Length,
PageAttributes,
- PageAttributeMask
+ PageAttributeMask,
+ TRUE
);
}
@@ -423,7 +479,13 @@ SetMemoryRegionAttribute (
IN UINT64 BlockEntryMask
)
{
- return UpdateRegionMapping (BaseAddress, Length, Attributes, BlockEntryMask);
+ return UpdateRegionMapping (
+ BaseAddress,
+ Length,
+ Attributes,
+ BlockEntryMask,
+ TRUE
+ );
}
EFI_STATUS
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
index 66ebca571e63..e936a5be4e11 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
@@ -12,6 +12,14 @@
.macro __replace_entry, el
+ // check whether we should disable the MMU
+ cbz x3, .L1_\@
+
+ // clean and invalidate first so that we don't clobber
+ // adjacent entries that are dirty in the caches
+ dc civac, x0
+ dsb nsh
+
// disable the MMU
mrs x8, sctlr_el\el
bic x9, x8, #CTRL_M_BIT
@@ -38,8 +46,33 @@
// re-enable the MMU
msr sctlr_el\el, x8
isb
+ b .L2_\@
+
+.L1_\@:
+ // write invalid entry
+ str xzr, [x0]
+ dsb nshst
+
+ // flush translations for the target address from the TLBs
+ lsr x2, x2, #12
+ .if \el == 1
+ tlbi vaae1, x2
+ .else
+ tlbi vae\el, x2
+ .endif
+ dsb nsh
+
+ // write updated entry
+ str x1, [x0]
+ dsb nshst
+
+.L2_\@:
.endm
+ // Align this routine to a log2 upper bound of its size, so that it is
+ // guaranteed not to cross a page or block boundary.
+ .balign 0x200
+
//VOID
//ArmReplaceLiveTranslationEntry (
// IN UINT64 *Entry,
@@ -53,12 +86,7 @@ ASM_FUNC(ArmReplaceLiveTranslationEntry)
msr daifset, #0xf
isb
- // clean and invalidate first so that we don't clobber
- // adjacent entries that are dirty in the caches
- dc civac, x0
- dsb nsh
-
- EL1_OR_EL2_OR_EL3(x3)
+ EL1_OR_EL2_OR_EL3(x5)
1:__replace_entry 1
b 4f
2:__replace_entry 2
@@ -72,3 +100,6 @@ ASM_GLOBAL ASM_PFX(ArmReplaceLiveTranslationEntrySize)
ASM_PFX(ArmReplaceLiveTranslationEntrySize):
.long . - ArmReplaceLiveTranslationEntry
+
+ // Double check that we did not overrun the assumed maximum size
+ .org ArmReplaceLiveTranslationEntry + 0x200
--
2.35.1
next prev parent reply other threads:[~2022-09-26 8:25 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-26 8:24 [PATCH v3 00/16] ArmVirtPkg/ArmVirtQemu: Performance streamlining Ard Biesheuvel
2022-09-26 8:24 ` [PATCH v3 01/16] ArmVirtPkg: remove EbcDxe from all platforms Ard Biesheuvel
2022-09-26 8:24 ` [PATCH v3 02/16] ArmVirtPkg: do not enable iSCSI driver by default Ard Biesheuvel
2022-09-26 8:24 ` [PATCH v3 03/16] ArmVirtPkg: make EFI_LOADER_DATA non-executable Ard Biesheuvel
2022-09-26 22:28 ` [edk2-devel] " Leif Lindholm
2022-11-28 15:46 ` Gerd Hoffmann
2022-12-29 18:00 ` dann frazier
2023-01-03 9:59 ` Ard Biesheuvel
2023-01-03 19:39 ` Alexander Graf
2023-01-03 22:47 ` dann frazier
2023-01-04 9:35 ` Ard Biesheuvel
2023-01-04 11:11 ` Gerd Hoffmann
2023-01-04 12:04 ` Ard Biesheuvel
2023-01-04 12:56 ` Gerd Hoffmann
2023-01-06 9:55 ` Laszlo Ersek
2023-01-06 10:06 ` Laszlo Ersek
2023-01-04 13:13 ` Alexander Graf
2023-01-05 0:09 ` Alexander Graf
2023-01-05 8:11 ` Gerd Hoffmann
2023-01-05 8:43 ` Alexander Graf
2023-01-05 9:41 ` Ard Biesheuvel
2023-01-05 11:19 ` Gerd Hoffmann
2023-01-05 11:44 ` Ard Biesheuvel
2023-01-05 15:12 ` Gerd Hoffmann
2023-01-05 19:58 ` Gerd Hoffmann
2023-01-06 2:19 ` Sean
2023-01-06 8:44 ` Gerd Hoffmann
2023-01-05 23:37 ` Alexander Graf
2022-09-26 8:24 ` [PATCH v3 04/16] ArmVirtPkg/ArmVirtQemu: wire up timeout PCD to Timeout variable Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 05/16] ArmPkg/ArmMmuLib: don't replace table entries with block entries Ard Biesheuvel
2022-09-26 22:32 ` Leif Lindholm
2022-09-26 8:25 ` Ard Biesheuvel [this message]
2022-09-26 23:28 ` [PATCH v3 06/16] ArmPkg/ArmMmuLib: Disable and re-enable MMU only when needed Leif Lindholm
2022-09-26 8:25 ` [PATCH v3 07/16] ArmPkg/ArmMmuLib: permit initial configuration with MMU enabled Ard Biesheuvel
2022-09-26 22:35 ` Leif Lindholm
2022-09-26 8:25 ` [PATCH v3 08/16] ArmPkg/ArmMmuLib: Reuse XIP MMU routines when splitting entries Ard Biesheuvel
2022-09-26 22:38 ` Leif Lindholm
2022-09-26 8:25 ` [PATCH v3 09/16] ArmPlatformPkg/PrePeiCore: permit entry with the MMU enabled Ard Biesheuvel
2022-09-26 22:39 ` [edk2-devel] " Leif Lindholm
2022-09-26 8:25 ` [PATCH v3 10/16] ArmVirtPkg/ArmVirtQemu: implement ArmPlatformLib with static ID map Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 11/16] ArmVirtPkg/ArmVirtQemu: use first 128 MiB as permanent PEI memory Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 12/16] ArmVirtPkg/ArmVirtQemu: enable initial ID map at early boot Ard Biesheuvel
2022-12-29 21:10 ` [edk2-devel] " dann frazier
2023-01-03 9:02 ` Ard Biesheuvel
2023-01-03 19:38 ` dann frazier
2022-09-26 8:25 ` [PATCH v3 13/16] ArmVirtPkg/ArmVirtQemu: Drop unused variable PEIM Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 14/16] ArmVirtPkg/ArmVirtQemu: avoid shadowing PEIMs unless necessary Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 15/16] ArmVirtPkg/QemuVirtMemInfoLib: use HOB not PCD to record the memory size Ard Biesheuvel
2022-09-26 8:25 ` [PATCH v3 16/16] ArmVirtPkg/ArmVirtQemu: omit PCD PEIM unless TPM support is enabled Ard Biesheuvel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220926082511.2110797-7-ardb@kernel.org \
--to=devel@edk2.groups.io \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox