> -----Original Message-----
> From: Ard Biesheuvel <a...@kernel.org>
> Sent: Wednesday, September 7, 2022 10:16 AM
> To: Jeff Brasen <jbra...@nvidia.com>
> Cc: devel@edk2.groups.io; ardb+tianoc...@kernel.org;
> abner.ch...@amd.com; g...@danielschaefer.me; quic_llind...@quicinc.com
> Subject: Re: [PATCH v2] EmbeddedPkg/PrePiMemoryAllocationLib: Check for
> space on offset allocation
>
> External email: Use caution opening links or attachments
>
>
> On Wed, 7 Sept 2022 at 17:46, Jeff Brasen <jbra...@nvidia.com> wrote:
> >
> > Update check for enough space to occur prior to alignment offset
> > modification. This prevents a case where EfiFreeMemoryTop could be
> > less than EfiFreeMemoryBottom
> >
> > Signed-off-by: Jeff Brasen <jbra...@nvidia.com>
>
> Thanks for the respin. I have caught up in the mean time.
>
>
> > ---
> > .../MemoryAllocationLib.c | 53 +++++++++++--------
> > 1 file changed, 30 insertions(+), 23 deletions(-)
> >
> > diff --git
> >
> a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> >
> b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> > index 2cc2a71121..9208826565 100644
> > ---
> >
> a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> > +++
> b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib
> > +++ .c
> > @@ -27,37 +27,44 @@ InternalAllocatePages (
> >
> > Hob.Raw = GetHobList ();
> >
> > - // Check to see if on 4k boundary
> > Offset = Hob.HandoffInformationTable->EfiFreeMemoryTop & 0xFFF;
> > + //
> > + // Verify that there is sufficient memory to satisfy the allocation
> > + and padding prior to updating anything // if
> > + ((Hob.HandoffInformationTable->EfiFreeMemoryTop - ((Pages *
> EFI_PAGE_SIZE) + sizeof (EFI_HOB_MEMORY_ALLOCATION)) - Offset) <
> Hob.HandoffInformationTable->EfiFreeMemoryBottom) {
> > + if (Offset != 0) {
> > + DEBUG ((DEBUG_ERROR, "Offset applied without enough
> space\r\n"));
> > + } else {
> > + DEBUG ((DEBUG_ERROR, "Out of memory\r\n"));
> > + }
> > +
> > + ASSERT (FALSE);
> > + return 0;
> > + }
> > +
> > + // Check to see if on 4k boundary
> > if (Offset != 0) {
> > // If not aligned, make the allocation aligned.
> > Hob.HandoffInformationTable->EfiFreeMemoryTop -= Offset;
> > }
> >
>
> I understand how you are trying to stick with the original code as much as
> possible, but this is all extremely clunky, and I'd prefer we just clean it
> up, if
> you don't mind.
>
> Would something like the below work for you as well?
Yup this looks good to me and cleaner as well.
>
>
>
> diff --git
> a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> index 2cc2a7112197..547117dc13d6 100644
> ---
> a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> +++
> b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c
> @@ -23,41 +23,36 @@ InternalAllocatePages (
> )
> {
> EFI_PEI_HOB_POINTERS Hob;
> - EFI_PHYSICAL_ADDRESS Offset;
> + EFI_PHYSICAL_ADDRESS NewTop;
>
> Hob.Raw = GetHobList ();
>
> - // Check to see if on 4k boundary
> - Offset = Hob.HandoffInformationTable->EfiFreeMemoryTop & 0xFFF;
> - if (Offset != 0) {
> - // If not aligned, make the allocation aligned.
> - Hob.HandoffInformationTable->EfiFreeMemoryTop -= Offset;
> - }
> + NewTop = Hob.HandoffInformationTable->EfiFreeMemoryTop &
> ~(EFI_PHYSICAL_ADDRESS)EFI_PAGE_MASK;
> + NewTop -= Pages * EFI_PAGE_SIZE;
>
> //
> // Verify that there is sufficient memory to satisfy the allocation
> //
> - if (Hob.HandoffInformationTable->EfiFreeMemoryTop - ((Pages *
> EFI_PAGE_SIZE) + sizeof (EFI_HOB_MEMORY_ALLOCATION)) <
> Hob.HandoffInformationTable->EfiFreeMemoryBottom) {
> - return 0;
> - } else {
> - //
> - // Update the PHIT to reflect the memory usage
> - //
> - Hob.HandoffInformationTable->EfiFreeMemoryTop -= Pages *
> EFI_PAGE_SIZE;
> -
> - // This routine used to create a memory allocation HOB a la PEI,
> but that's not
> - // necessary for us.
> -
> - //
> - // Create a memory allocation HOB.
> - //
> - BuildMemoryAllocationHob (
> - Hob.HandoffInformationTable->EfiFreeMemoryTop,
> - Pages * EFI_PAGE_SIZE,
> - MemoryType
> - );
> - return (VOID *)(UINTN)Hob.HandoffInformationTable-
> >EfiFreeMemoryTop;
> + if (NewTop < (Hob.HandoffInformationTable->EfiFreeMemoryBottom +
> sizeof (EFI_HOB_MEMORY_ALLOCATION)))
> + {
> + return NULL;
> }
> +
> + //
> + // Update the PHIT to reflect the memory usage //
> + Hob.HandoffInformationTable->EfiFreeMemoryTop = NewTop;
> +
> + //
> + // Create a memory allocation HOB.
> + //
> + BuildMemoryAllocationHob (
> + Hob.HandoffInformationTable->EfiFreeMemoryTop,
> + Pages * EFI_PAGE_SIZE,
> + MemoryType
> + );
> +
> + return (VOID *)(UINTN)Hob.HandoffInformationTable-
> >EfiFreeMemoryTop;
> }
>
> /**
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