kernel-ark/Documentation/arm64
Kristina Martsenko f0e421b1bf arm64: documentation: document tagged pointer stack constraints
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: d50240a5f6 ("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>
2017-05-09 17:43:18 +01:00
..
acpi_object_usage.txt ARM64: ACPI: Update documentation for latest specification version 2016-06-21 16:26:09 +01:00
arm-acpi.txt ARM64: ACPI: Update documentation for latest specification version 2016-06-21 16:26:09 +01:00
booting.txt arm64: add the initrd region to the linear mapping explicitly 2016-04-14 16:20:45 +01:00
cpu-feature-registers.txt arm64: v8.3: Support for weaker release consistency 2017-03-20 16:30:22 +00:00
legacy_instructions.txt arm64: Emulate SETEND for AArch32 tasks 2015-01-23 17:11:44 +00:00
memory.txt Documentation/arm64/memory.txt: fix typo 2014-10-20 17:55:38 +01:00
silicon-errata.txt arm64: cpu_errata: Add capability to advertise Cortex-A73 erratum 858921 2017-04-07 11:22:08 +01:00
tagged-pointers.txt arm64: documentation: document tagged pointer stack constraints 2017-05-09 17:43:18 +01:00