linux-dev/Documentation/arm64/tagged-pointers.txt, branch masterLinux kernel development work - see feature brancheshttps://git.zx2c4.com/linux-dev/atom/Documentation/arm64/tagged-pointers.txt?h=master2019-06-14T20:20:27Zdocs: arm64: convert docs to ReST and rename to .rst2019-06-14T20:20:27ZMauro Carvalho Chehabmchehab+samsung@kernel.org2019-06-12T17:52:38Zurn:sha1:b693d0b372afb39432e1c49ad7b3454855bc6bed
The documentation is in a format that is very close to ReST format.
The conversion is actually:
- add blank lines in order to identify paragraphs;
- fixing tables markups;
- adding some lists markups;
- marking literal blocks;
- adjust some title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
arm64: documentation: document tagged pointer stack constraints2017-05-09T16:43:18ZKristina Martsenkokristina.martsenko@arm.com2017-05-03T15:37:48Zurn:sha1:f0e421b1bf7af97f026e1bb8bfe4c5a7a8c08f42
Some kernel features don't currently work if a task puts a non-zero
address tag in its stack pointer, frame pointer, or frame record entries
(FP, LR).
For example, with a tagged stack pointer, the kernel can't deliver
signals to the process, and the task is killed instead. As another
example, with a tagged frame pointer or frame records, perf fails to
generate call graphs or resolve symbols.
For now, just document these limitations, instead of finding and fixing
everything that doesn't work, as it's not known if anyone needs to use
tags in these places anyway.
In addition, as requested by Dave Martin, generalize the limitations
into a general kernel address tag policy, and refactor
tagged-pointers.txt to include it.
Fixes: d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0")
Cc: <stable@vger.kernel.org> # 3.12.x-
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: documentation: tighten up tagged pointer documentation2013-09-20T08:56:06ZWill Deaconwill.deacon@arm.com2013-09-17T10:46:23Zurn:sha1:374ed9d18e658704235b84a60589888ca52ab0fe
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>
arm64: mm: permit use of tagged pointers at EL02013-09-03T09:18:02ZWill Deaconwill.deacon@arm.com2013-06-12T15:28:04Zurn:sha1:d50240a5f6ceaf690a77b0fccb17be51cfa151c2
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>