From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id 3310078003C for ; Thu, 15 Feb 2024 00:34:20 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=CMBdXO20sb9NwkLJlEuGGwDiuXvtcDDRuFDIQ8OheWk=; c=relaxed/simple; d=groups.io; h=DKIM-Filter:From:To:Cc:Subject:Date:Message-Id:MIME-Version:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Reply-To:List-Unsubscribe-Post:List-Unsubscribe:Content-Transfer-Encoding; s=20140610; t=1707957259; v=1; b=f0XOEavqg390wou6KS1raTug07L3+VewTxolwZQoWu4Mo6HijMbMCT4V3lrRFWa18OFtvnLV B+B218KAI/NExEPAaND+IXs/Rdz67D6yMlCD9MKVQpgJkUmBcjGuo6a01lI0n3sGS2NHF39kknT NFjgXTr5VmBOGWHd08496OF0= X-Received: by 127.0.0.2 with SMTP id 0mrHYY7687511xJMneShiLlX; Wed, 14 Feb 2024 16:34:19 -0800 X-Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mx.groups.io with SMTP id smtpd.web10.3486.1707957258979177110 for ; Wed, 14 Feb 2024 16:34:19 -0800 X-Received: from OSD-Desktop.redmond.corp.microsoft.com (unknown [131.107.160.171]) by linux.microsoft.com (Postfix) with ESMTPSA id 5252020B2000; Wed, 14 Feb 2024 16:34:18 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5252020B2000 From: "Oliver Smith-Denny" To: devel@edk2.groups.io Cc: Leif Lindholm , Ard Biesheuvel , Sami Mujawar , Liming Gao Subject: [edk2-devel][PATCH v1 1/1] MdeModulePkg: DxeCore: Don't Guard Large Runtime Granularity Allocations Date: Wed, 14 Feb 2024 16:34:12 -0800 Message-Id: <20240215003412.30983-1-osde@linux.microsoft.com> MIME-Version: 1.0 Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Reply-To: devel@edk2.groups.io,osde@linux.microsoft.com List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: qIdCY5qmAGSpmcAyq7T9PuZBx7686176AA= Content-Transfer-Encoding: quoted-printable X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20140610 header.b=f0XOEavq; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=linux.microsoft.com (policy=none); spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io Currently, there are multiple issues when page or pool guards are allocated for runtime and ACPI memory regions that are aligned to non-EFI_PAGE_SIZE alignments. Multiple other issues have been fixed for these same systems (notably ARM64 which has a 64k runtime page allocation granularity) recently. The heap guard system is only built to support 4k guard pages and 4k alignment. Today, the address returned to a caller of AllocatePages will not be aligned correctly to the runtime page allocation granularity, because the heap guard system does not take non-4k alignment requirements into consideration. However, even with this bug fixed, the Memory Allocation Table cannot be produced and an OS with a larger than 4k page granularity will not have aligned memory regions because the guard pages are reported as part of the same memory allocation. So what would have been, on an ARM64 system, a 64k runtime memory allocation is actually a 72k memory allocation as tracked by the Page.c code because the guard pages are tracked as part of the same allocation. This is a core function of the current heap guard architecture. This could also be fixed with rearchitecting the heap guard system to respect alignment requirements and shift the guard pages inside of the outer rounded allocation or by having guard pages be the runtime granularity. Both of these approaches have issues, in the former, the allocator of runtime memory would get an address that was not aligned with the runtime granularity (the head guard would be, but not the usuable address), which seems fraught with peril. In the latter case, an immense amount of memory is wasted to support such large guard pages, and with pool guard many systems could not support an additional 128k allocation for all runtime memory. The simpler and safer solution is to disallow page and pool guards for runtime memory allocations for systems that have a runtime granularity greater than the EFI_PAGE_SIZE (4k). The usefulness of such guards is limited, as OSes do not map guard pages today, so there is only boot time protection of these ranges, which runtime memory is typically used minimally in boot time. This also prevents other bugs from being exposed by using guards for regions that have a non-4k alignment requirement, as again, multiple have cropped up because the heap guard system was not built to support it. This patch adds both a static assert to ensure that either the runtime granularity is the EFI_PAGE_SIZE or that the PCD bits are not set to enable heap guard for runtime memory regions. It also adds a check in the page and pool allocation system to ensure that at runtime we are not allocating a runtime region and attempt to guard it (the PCDs are close t= o being removed in favor of dynamic heap guard configurations). BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3D4674 Github PR: https://github.com/tianocore/edk2/pull/5378 Cc: Leif Lindholm Cc: Ard Biesheuvel Cc: Sami Mujawar Cc: Liming Gao Signed-off-by: Oliver Smith-Denny --- MdeModulePkg/MdeModulePkg.dec | 10 ++++++++++ MdeModulePkg/Core/Dxe/Mem/HeapGuard.h | 14 ++++++++++++++ MdeModulePkg/Core/Dxe/Mem/Page.c | 11 +++++++++++ MdeModulePkg/Core/Dxe/Mem/Pool.c | 11 +++++++++++ 4 files changed, 46 insertions(+) diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.de= c index a2cd83345f5b..884734aff592 100644 --- a/MdeModulePkg/MdeModulePkg.dec +++ b/MdeModulePkg/MdeModulePkg.dec @@ -1027,6 +1027,11 @@ [PcdsFixedAtBuild] # free pages for all of them. The page allocation for the type related= to # cleared bits keeps the same as ususal. # + # The heap guard system only supports guarding EfiRuntimeServicesCode,= EfiRuntimeServicesData, + # EfiACPIReclaimMemory, and EfiACPIMemoryNVS memory types for systems = that have + # RUNTIME_PAGE_ALLOCATION_GRANULARITY =3D=3D EFI_PAGE_SIZE. This is to= preserve alignment requirements + # without extending the page guard size to very large granularities. + # # This PCD is only valid if BIT0 and/or BIT2 are set in PcdHeapGuardPr= opertyMask. # # Below is bit mask for this PCD: (Order is same as UEFI spec)
@@ -1058,6 +1063,11 @@ [PcdsFixedAtBuild] # if there's enough free memory for all of them. The pool allocation f= or the # type related to cleared bits keeps the same as ususal. # + # The heap guard system only supports guarding EfiRuntimeServicesCode,= EfiRuntimeServicesData, + # EfiACPIReclaimMemory, and EfiACPIMemoryNVS memory types for systems = that have + # RUNTIME_PAGE_ALLOCATION_GRANULARITY =3D=3D EFI_PAGE_SIZE. This is to= preserve alignment requirements + # without extending the page guard size to very large granularities. + # # This PCD is only valid if BIT1 and/or BIT3 are set in PcdHeapGuardPr= opertyMask. # # Below is bit mask for this PCD: (Order is same as UEFI spec)
diff --git a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.h b/MdeModulePkg/Core/Dx= e/Mem/HeapGuard.h index 24b4206c0e02..d4f283977b04 100644 --- a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.h +++ b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.h @@ -469,4 +469,18 @@ PromoteGuardedFreePages ( =20 extern BOOLEAN mOnGuarding; =20 +// +// the heap guard system does not support non-EFI_PAGE_SIZE alignments +// architectures that require larger RUNTIME_PAGE_ALLOCATION_GRANULARITY +// cannot have EfiRuntimeServicesCode, EfiRuntimeServicesData, EfiACPIRe= claimMemory, +// and EfiACPIMemoryNVS guarded. OSes do not map guard pages anyway, so = this is a +// minimal loss. Not guarding prevents alignment mismatches +// +STATIC_ASSERT ( + RUNTIME_PAGE_ALLOCATION_GRANULARITY =3D=3D EFI_PAGE_SIZE || + (((FixedPcdGet64 (PcdHeapGuardPageType) & 0x660) =3D=3D 0) && + ((FixedPcdGet64 (PcdHeapGuardPoolType) & 0x660) =3D=3D 0)), + "Unsupported Heap Guard configuration on system with greater than EFI_= PAGE_SIZE RUNTIME_PAGE_ALLOCATION_GRANULARITY" + ); + #endif diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem= /Page.c index 3205732ede17..ed3908b9768e 100644 --- a/MdeModulePkg/Core/Dxe/Mem/Page.c +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c @@ -1411,6 +1411,17 @@ CoreInternalAllocatePages ( Alignment =3D RUNTIME_PAGE_ALLOCATION_GRANULARITY; } =20 + // + // the heap guard system does not support non-EFI_PAGE_SIZE alignments + // architectures that require larger RUNTIME_PAGE_ALLOCATION_GRANULARI= TY + // will have the runtime and ACPI memory regions unguarded. OSes do no= t + // map guard pages anyway, so this is a minimal loss. Not guarding pre= vents + // alignment mismatches + // + if (Alignment !=3D EFI_PAGE_SIZE) { + NeedGuard =3D FALSE; + } + if (Type =3D=3D AllocateAddress) { if ((*Memory & (Alignment - 1)) !=3D 0) { return EFI_NOT_FOUND; diff --git a/MdeModulePkg/Core/Dxe/Mem/Pool.c b/MdeModulePkg/Core/Dxe/Mem= /Pool.c index 716dd045f9fd..beed5f814510 100644 --- a/MdeModulePkg/Core/Dxe/Mem/Pool.c +++ b/MdeModulePkg/Core/Dxe/Mem/Pool.c @@ -380,6 +380,17 @@ CoreAllocatePoolI ( Granularity =3D DEFAULT_PAGE_ALLOCATION_GRANULARITY; } =20 + // + // the heap guard system does not support non-EFI_PAGE_SIZE alignments + // architectures that require larger RUNTIME_PAGE_ALLOCATION_GRANULARI= TY + // will have the runtime and ACPI memory regions unguarded. OSes do no= t + // map guard pages anyway, so this is a minimal loss. Not guarding pre= vents + // alignment mismatches + // + if (Granularity !=3D EFI_PAGE_SIZE) { + NeedGuard =3D FALSE; + } + // // Adjust the size by the pool header & tail overhead // --=20 2.40.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115474): https://edk2.groups.io/g/devel/message/115474 Mute This Topic: https://groups.io/mt/104364784/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=-=-=-=-=-=-=-=-=-=-=-