59ee987ea4
Our tracehook logic for syscall entry/exit raises a SIGTRAP back to the tracer following a ptrace request such as PTRACE_SYSCALL. As part of this procedure, we clobber the reported value of one of the tracee's general purpose registers (x7 for native tasks, r12 for compat) to indicate whether the stop occurred on syscall entry or exit. This is a slightly unfortunate ABI, as it prevents the tracer from accessing the real register value and is at odds with other similar stops such as seccomp traps. Since we're stuck with this ABI, expand the comment in our tracehook logic to acknowledge the issue and describe the behaviour in more detail. Cc: Mark Rutland <mark.rutland@arm.com> Cc: Luis Machado <luis.machado@linaro.org> Reported-by: Keno Fischer <keno@juliacomputing.com> Signed-off-by: Will Deacon <will@kernel.org>
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.