1cf6022bd9
Quoth the man page:
```
If the tracee was restarted by PTRACE_SYSCALL or PTRACE_SYSEMU, the
tracee enters syscall-enter-stop just prior to entering any system
call (which will not be executed if the restart was using
PTRACE_SYSEMU, regardless of any change made to registers at this
point or how the tracee is restarted after this stop).
```
The parenthetical comment is currently true on x86 and powerpc,
but not currently true on arm64. arm64 re-checks the _TIF_SYSCALL_EMU
flag after the syscall entry ptrace stop. However, at this point,
it reflects which method was used to re-start the syscall
at the entry stop, rather than the method that was used to reach it.
Fix that by recording the original flag before performing the ptrace
stop, bringing the behavior in line with documentation and x86/powerpc.
Fixes: f086f67485c5 ("arm64: ptrace: add support for syscall emulation")
Cc: <stable@vger.kernel.org> # 5.3.x-
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Bin Lu <Bin.Lu@arm.com>
[catalin.marinas@arm.com: moved 'flags' bit masking]
[catalin.marinas@arm.com: changed 'flags' type to unsigned long]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.