summaryrefslogtreecommitdiff
path: root/Documentation/arm64/tagged-pointers.txt
AgeCommit message (Collapse)Author
2013-09-20arm64: documentation: tighten up tagged pointer documentationWill Deacon
Commit d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0") added support for tagged pointers in userspace, but the corresponding update to Documentation/ contained some imprecise statements. This patch fixes up some minor ambiguities in the text, hopefully making it more clear about exactly what the kernel expects from user virtual addresses. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-09-03arm64: mm: permit use of tagged pointers at EL0Will Deacon
TCR.TBI0 can be used to cause hardware address translation to ignore the top byte of userspace virtual addresses. Whilst not especially useful in standard C programs, this can be used by JITs to `tag' pointers with various pieces of metadata. This patch enables this bit for AArch64 Linux, and adds a new file to Documentation/arm64/ which describes some potential caveats when using tagged virtual addresses. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>