[PATCH] arm64: doc: Add brk/mmap/mremap() to the Tagged Address ABI Exceptions

* [PATCH] arm64: doc: Add brk/mmap/mremap() to the Tagged Address ABI Exceptions
@ 2021-04-23 17:51 Catalin Marinas
  2021-04-30 17:56 ` Catalin Marinas
  0 siblings, 1 reply; 2+ messages in thread
From: Catalin Marinas @ 2021-04-23 17:51 UTC (permalink / raw)
  To: linux-arm-kernel; +Cc: Peter Maydell, Will Deacon, Vincenzo Frascino

Prior to commit dcde237319e6 ("mm: Avoid creating virtual address
aliases in brk()/mmap()/mremap()"), the kernel allowed tagged addresses
to be passed to the brk/mmap/mremap() syscalls. This relaxation was
tightened in 5.6 (backported to stable 5.4) but the
tagged-address-abi.rst document was only partially updated.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: dcde237319e6 ("mm: Avoid creating virtual address aliases in brk()/mmap()/mremap()")
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 Documentation/arm64/tagged-address-abi.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/arm64/tagged-address-abi.rst b/Documentation/arm64/tagged-address-abi.rst
index cbc4d4500241..459e6b66ff68 100644
--- a/Documentation/arm64/tagged-address-abi.rst
+++ b/Documentation/arm64/tagged-address-abi.rst
@@ -113,6 +113,12 @@ ABI relaxation:
 
 - ``shmat()`` and ``shmdt()``.
 
+- ``brk()`` (since kernel v5.6).
+
+- ``mmap()`` (since kernel v5.6).
+
+- ``mremap()``, the ``new_address`` argument (since kernel v5.6).
+
 Any attempt to use non-zero tagged pointers may result in an error code
 being returned, a (fatal) signal being raised, or other modes of
 failure.

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