173e65f6bc
When return from exception, we need to distinguish if it's system call return or for other type exceptions for setting sample flags. Due to the exception return packet doesn't contain exception number, so we cannot decide sample flags based on exception number. On the other hand, the exception return packet is followed by an instruction range packet; this range packet deliveries the start address after exception handling, we can check if it is a SVC instruction just before the start address. If there has one SVC instruction is found ahead the return address, this means it's an exception return for system call; otherwise it is an normal return for other exceptions. This patch is to set sample flags for exception return packet, firstly it simply set sample flags as PERF_IP_FLAG_INTERRUPT for all exception returns since at this point it doesn't know what's exactly the exception type. We will defer to decide if it's an exception return for system call when the next instruction range packet comes, it checks if there has one SVC instruction prior to the start address and if so we will change sample flags to PERF_IP_FLAG_SYSCALLRET for system call return. Signed-off-by: Leo Yan <leo.yan@linaro.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Leach <mike.leach@linaro.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Robert Walker <robert.walker@arm.com> Cc: Suzuki K Poulouse <suzuki.poulose@arm.com> Cc: coresight ml <coresight@lists.linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20190129122842.32041-9-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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.