| Message ID | 1461140380-19345-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | Accepted |
| Commit | d1ec2b2f78b752b9dfc06843f994cbfad134ea63 |
| Headers | show |
On Wed, Apr 20, 2016 at 10:19:40AM +0200, Ard Biesheuvel wrote: > When we split a block entry into a table entry, the UXN/PXN/XN permission > attributes are inherited both by the new table entry and by the new block > entries at the next level down. Unlike the NS bit, which only affects the > next level of lookup, the XN table bits supersede the permissions of the > final translation, and setting the permissions at multiple levels is not > only redundant, it also prevents us from lifting XN restrictions on a > subregion of the original block entry by simply clearing the appropriate > bits at the lowest level. > > So drop the code that sets the UXN/PXN/XN bits on the table entries. > > Reported-by: "Oliyil Kunnil, Vishal" <vishalo@qti.qualcomm.com> > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> > --- > ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c > index 48ca8271849c..cf9b7222b47b 100644 > --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c > +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c > @@ -306,13 +306,6 @@ GetBlockEntryListFromAddress ( > > // Convert the block entry attributes into Table descriptor attributes > TableAttributes = TT_TABLE_AP_NO_PERMISSION; > - if (Attributes & TT_PXN_MASK) { > - TableAttributes = TT_TABLE_PXN; > - } > - // XN maps to UXN in the EL1&0 translation regime > - if (Attributes & TT_XN_MASK) { > - TableAttributes = TT_TABLE_XN; > - } > if (Attributes & TT_NS) { > TableAttributes = TT_TABLE_NS; > } > -- > 2.5.0 > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c index 48ca8271849c..cf9b7222b47b 100644 --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c @@ -306,13 +306,6 @@ GetBlockEntryListFromAddress ( // Convert the block entry attributes into Table descriptor attributes TableAttributes = TT_TABLE_AP_NO_PERMISSION; - if (Attributes & TT_PXN_MASK) { - TableAttributes = TT_TABLE_PXN; - } - // XN maps to UXN in the EL1&0 translation regime - if (Attributes & TT_XN_MASK) { - TableAttributes = TT_TABLE_XN; - } if (Attributes & TT_NS) { TableAttributes = TT_TABLE_NS; }
When we split a block entry into a table entry, the UXN/PXN/XN permission attributes are inherited both by the new table entry and by the new block entries at the next level down. Unlike the NS bit, which only affects the next level of lookup, the XN table bits supersede the permissions of the final translation, and setting the permissions at multiple levels is not only redundant, it also prevents us from lifting XN restrictions on a subregion of the original block entry by simply clearing the appropriate bits at the lowest level. So drop the code that sets the UXN/PXN/XN bits on the table entries. Reported-by: "Oliyil Kunnil, Vishal" <vishalo@qti.qualcomm.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c | 7 ------- 1 file changed, 7 deletions(-) -- 2.5.0 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel