Marvin: How about directly use PCD checker with IsNodeInList()? ASSERT (IsNodeInList (FirstEntry, SecondEntry)); ==> ASSERT (FeaturePcdGet (PcdVerifyNodeInList) && IsNodeInList (FirstEntry, SecondEntry))|| InternalBaseLibIsListValid (FirstEntry));
Thanks Liming >-----Original Message----- >From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of >Marvin H?user >Sent: Friday, July 28, 2017 12:20 AM >To: edk2-devel@lists.01.org >Cc: Kinney, Michael D <michael.d.kin...@intel.com>; Gao, Liming ><liming....@intel.com> >Subject: Re: [edk2] [PATCH 1/2] MdePkg/BaseLib: Add IsNodeInList() function. > >Hi Liming, > >Comments are inline. Thanks for your response! > >Regards, >Marvin. > >> -----Original Message----- >> From: Gao, Liming [mailto:liming....@intel.com] >> Sent: Thursday, July 27, 2017 5:32 PM >> To: marvin.haeu...@outlook.com; edk2-devel@lists.01.org >> Cc: Kinney, Michael D <michael.d.kin...@intel.com> >> Subject: RE: [PATCH 1/2] MdePkg/BaseLib: Add IsNodeInList() function. >> >> Marvin: >> Once this API is exposed as the public library API, what code will you >update >> to consume this API? > >The code which gave me the idea for this patch is this: >https://github.com/tianocore/edk2-platforms/blob/devel- >MinPlatform/Silicon/Intel/KabylakeSiliconPkg/Pch/PchSmiDispatcher/Smm/Io >Trap.c#L508 >ForwardLink is obviously checked against EFI_BAD_POINTER to verify whether >the entry is still valid. Though, after being freed, the value stored in this >location may just be overwritten. >The code linked currently doesn't seem to do anything as ForwardLink is never >set to EFI_BAD_POINTER, though it can be updated with IsNodeInList() to >function (regardless of the entry being freed). >It seems to me that this is a leftover from the EDK era as EDK's >RemoveEntryList() does set the Links to EFI_BAD_POINTER. > >> >> And, for the patch, I have two comments. >> 1) Original logic uses PcdVerifyNodeInList to turn on the verification of >> NodeInList. New logic always turns on it. Because this check takes much >> overhead, this PCD is FALSE as the default value in MdePkg.dec. >> 2) In IsListEmpty(), ASSERT() is missing for InternalBaseLibIsListValid >> (ListHead). > >Sorry for these oversights. Would you prefer an internal, static function or a >macro to do the PCD check and following the ASSERTin v2? > >> >> Thanks >> Liming >> > -----Original Message----- >> > From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of >> > Marvin H?user >> > Sent: Tuesday, July 25, 2017 12:53 AM >> > To: edk2-devel@lists.01.org >> > Cc: Kinney, Michael D <michael.d.kin...@intel.com> >> > Subject: Re: [edk2] [PATCH 1/2] MdePkg/BaseLib: Add IsNodeInList() >> function. >> > >> > Hey Mike, >> > >> > In contrast to setting 'BackLink' and 'ForwardLink' to dummy values >> > such as EFI_BAD_POINTER, verifying that a node is part of a known list >> > is a safe way to determine whether a link is still valid without >> > needing to keep the memory allocated. If the Node, which had its links >> > set to dummys, is freed, the dummy values may be overwriten and the >> > check would pass despite the node being invalid. This can, for example, be >> used in OpenKabylake's PchSmiDispatcher, which does the described check >> against EFI_BAD_POINTER (though if I remember correctly, the value is >> actually never explicitely set). The issue is that some function may pass a >> handle that was unregistered to the function. IsNodeInList() can be used to >> determine whether it was previously removed. >> > >> > Thanks for your response! >> > >> > Regards, >> > Marvin. >> > >> > > -----Original Message----- >> > > From: Kinney, Michael D [mailto:michael.d.kin...@intel.com] >> > > Sent: Monday, July 24, 2017 6:31 PM >> > > To: Marvin Häuser <marvin.haeu...@outlook.com>; edk2- >> > > de...@lists.01.org; Kinney, Michael D <michael.d.kin...@intel.com> >> > > Cc: Gao, Liming <liming....@intel.com> >> > > Subject: RE: [PATCH 1/2] MdePkg/BaseLib: Add IsNodeInList() function. >> > > >> > > Hi Marvin, >> > > >> > > Can you provide a few more details on why you would like to see tis >> > > internal function promoted to a library class API? >> > > >> > > Thanks, >> > > >> > > Mike >> > > >> > > > -----Original Message----- >> > > > From: Marvin Häuser [mailto:marvin.haeu...@outlook.com] >> > > > Sent: Sunday, July 23, 2017 3:11 AM >> > > > To: edk2-devel@lists.01.org >> > > > Cc: Kinney, Michael D <michael.d.kin...@intel.com>; Gao, Liming >> > > > <liming....@intel.com> >> > > > Subject: [PATCH 1/2] MdePkg/BaseLib: Add IsNodeInList() function. >> > > > >> > > > This patch adds IsNodeInList() to BaseLib, which verifies the >> > > > given Node is part of the doubly-linked List provided. >> > > > >> > > > Contributed-under: TianoCore Contribution Agreement 1.1 >> > > > Signed-off-by: Marvin Haeuser <marvin.haeu...@outlook.com> >> > > > --- >> > > > MdePkg/Library/BaseLib/LinkedList.c | 70 >> > > > +++++++++++++++++++- >> > > > MdePkg/Include/Library/BaseLib.h | 25 +++++++ >> > > > MdePkg/Library/BaseLib/BaseLibInternals.h | 28 -------- >> > > > 3 files changed, 94 insertions(+), 29 deletions(-) >> > > > >> > > > diff --git a/MdePkg/Library/BaseLib/LinkedList.c >> > > > b/MdePkg/Library/BaseLib/LinkedList.c >> > > > index ba373f4b7be3..b364ae41c647 100644 >> > > > --- a/MdePkg/Library/BaseLib/LinkedList.c >> > > > +++ b/MdePkg/Library/BaseLib/LinkedList.c >> > > > @@ -1,7 +1,7 @@ >> > > > /** @file >> > > > Linked List Library Functions. >> > > > >> > > > - Copyright (c) 2006 - 2013, Intel Corporation. All rights >> > > > reserved.<BR> >> > > > + Copyright (c) 2006 - 2017, Intel Corporation. All rights >> > > > reserved.<BR> >> > > > This program and the accompanying materials >> > > > are licensed and made available under the terms and conditions >> > > > of the BSD License >> > > > which accompanies this distribution. The full text of the >> > > > license may be found at @@ -113,6 +113,74 @@ >> > > > InternalBaseLibIsNodeInList ( } >> > > > >> > > > /** >> > > > + Checks whether Node is part of a doubly-linked list. >> > > > + >> > > > + If List is NULL, then ASSERT(). >> > > > + If List->ForwardLink is NULL, then ASSERT(). >> > > > + If List->BackLink is NULL, then ASSERT(). >> > > > + If Node is NULL, then ASSERT(); If PcdMaximumLinkedListLength >> > > > + is not zero, and List contains >> > > > more than >> > > > + PcdMaximumLinkedListLength nodes, then ASSERT(). >> > > > + >> > > > + @param List A pointer to a node in a linked list. >> > > > + @param Node A pointer to the node to locate. >> > > > + >> > > > + @retval TRUE Node is in List. >> > > > + @retval FALSE Node isn't in List, or List is invalid. >> > > > + >> > > > +**/ >> > > > +BOOLEAN >> > > > +EFIAPI >> > > > +IsNodeInList ( >> > > > + IN CONST LIST_ENTRY *List, >> > > > + IN CONST LIST_ENTRY *Node >> > > > + ) >> > > > +{ >> > > > + UINTN Count; >> > > > + CONST LIST_ENTRY *Ptr; >> > > > + >> > > > + // >> > > > + // Test the validity of List and Node // ASSERT (List != >> > > > + NULL); ASSERT (List->ForwardLink != NULL); ASSERT >> > > > + (List->BackLink != NULL); ASSERT (Node != NULL); >> > > > + >> > > > + // >> > > > + // ASSERT List not too long >> > > > + // >> > > > + ASSERT (InternalBaseLibIsNodeInList (ListHead, Entry, FALSE)); >> > > > + >> > > > + Count = 0; >> > > > + Ptr = List; >> > > > + >> > > > + // >> > > > + // Check to see if Node is a member of List. >> > > > + // Exit early if the number of nodes in List >= >> > > > PcdMaximumLinkedListLength >> > > > + // >> > > > + do { >> > > > + Ptr = Ptr->ForwardLink; >> > > > + if (PcdGet32 (PcdMaximumLinkedListLength) > 0) { >> > > > + Count++; >> > > > + >> > > > + // >> > > > + // Return if the linked list is too long >> > > > + // >> > > > + if (Count == PcdGet32 (PcdMaximumLinkedListLength)) { >> > > > + return (BOOLEAN)(Ptr == Node); >> > > > + } >> > > > + } >> > > > + >> > > > + if (Ptr == Node) { >> > > > + return TRUE; >> > > > + } >> > > > + } while (Ptr != List); >> > > > + >> > > > + return FALSE; >> > > > +} >> > > > + >> > > > +/** >> > > > Initializes the head node of a doubly-linked list, and returns >> > > > the pointer to >> > > > the head node of the doubly-linked list. >> > > > >> > > > diff --git a/MdePkg/Include/Library/BaseLib.h >> > > > b/MdePkg/Include/Library/BaseLib.h >> > > > index 791849b80406..4f3f4fd51f3f 100644 >> > > > --- a/MdePkg/Include/Library/BaseLib.h >> > > > +++ b/MdePkg/Include/Library/BaseLib.h >> > > > @@ -2869,6 +2869,31 @@ PathCleanUpDirectories( >> > > > >> > > > >> > > > /** >> > > > + Checks whether Node is part of a doubly-linked list. >> > > > + >> > > > + If List is NULL, then ASSERT(). >> > > > + If List->ForwardLink is NULL, then ASSERT(). >> > > > + If List->BackLink is NULL, then ASSERT(). >> > > > + If Node is NULL, then ASSERT(); If PcdMaximumLinkedListLength >> > > > + is not zero, and List contains >> > > > more than >> > > > + PcdMaximumLinkedListLength nodes, then ASSERT(). >> > > > + >> > > > + @param List A pointer to a node in a linked list. >> > > > + @param Node A pointer to the node to locate. >> > > > + >> > > > + @retval TRUE Node is in List. >> > > > + @retval FALSE Node isn't in List, or List is invalid. >> > > > + >> > > > +**/ >> > > > +BOOLEAN >> > > > +EFIAPI >> > > > +IsNodeInList ( >> > > > + IN CONST LIST_ENTRY *List, >> > > > + IN CONST LIST_ENTRY *Node >> > > > + ); >> > > > + >> > > > + >> > > > +/** >> > > > Initializes the head node of a doubly linked list, and returns >> > > > the pointer to >> > > > the head node of the doubly linked list. >> > > > >> > > > diff --git a/MdePkg/Library/BaseLib/BaseLibInternals.h >> > > > b/MdePkg/Library/BaseLib/BaseLibInternals.h >> > > > index ea387ce37d27..9dca97a0dcc9 100644 >> > > > --- a/MdePkg/Library/BaseLib/BaseLibInternals.h >> > > > +++ b/MdePkg/Library/BaseLib/BaseLibInternals.h >> > > > @@ -340,34 +340,6 @@ InternalSwitchStack ( >> > > > >> > > > >> > > > /** >> > > > - Worker function that locates the Node in the List. >> > > > - >> > > > - By searching the List, finds the location of the Node in List. >> > > > At the same time, >> > > > - verifies the validity of this list. >> > > > - >> > > > - If List is NULL, then ASSERT(). >> > > > - If List->ForwardLink is NULL, then ASSERT(). >> > > > - If List->backLink is NULL, then ASSERT(). >> > > > - If Node is NULL, then ASSERT(); >> > > > - If PcdMaximumLinkedListLength is not zero, and prior to >> > > > insertion the number >> > > > - of nodes in ListHead, including the ListHead node, is greater >> > > > than or >> > > > - equal to PcdMaximumLinkedListLength, then ASSERT(). >> > > > - >> > > > - @param List A pointer to a node in a linked list. >> > > > - @param Node A pointer to one nod. >> > > > - >> > > > - @retval TRUE Node is in List. >> > > > - @retval FALSE Node isn't in List, or List is invalid. >> > > > - >> > > > -**/ >> > > > -BOOLEAN >> > > > -EFIAPI >> > > > -IsNodeInList ( >> > > > - IN CONST LIST_ENTRY *List, >> > > > - IN CONST LIST_ENTRY *Node >> > > > - ); >> > > > - >> > > > -/** >> > > > Worker function that returns a bit field from Operand. >> > > > >> > > > Returns the bitfield specified by the StartBit and the EndBit >> > > > from Operand. >> > > > -- >> > > > 2.12.2.windows.2 >> > >> > _______________________________________________ >> > edk2-devel mailing list >> > edk2-devel@lists.01.org >> > https://lists.01.org/mailman/listinfo/edk2-devel >_______________________________________________ >edk2-devel mailing list >edk2-devel@lists.01.org >https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
