Xin Li (Intel) 2a03531c00 selftests/x86: Add a test to detect infinite SIGTRAP handler loop
commit f287822688eeb44ae1cf6ac45701d965efc33218 upstream.

When FRED is enabled, if the Trap Flag (TF) is set without an external
debugger attached, it can lead to an infinite loop in the SIGTRAP
handler.  To avoid this, the software event flag in the augmented SS
must be cleared, ensuring that no single-step trap remains pending when
ERETU completes.

This test checks for that specific scenario—verifying whether the kernel
correctly prevents an infinite SIGTRAP loop in this edge case when FRED
is enabled.

The test should _always_ pass with IDT event delivery, thus no need to
disable the test even when FRED is not enabled.

Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250609084054.2083189-3-xin%40zytor.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-27 11:08:59 +01:00
2022-09-28 09:02:20 +02:00
2025-06-19 15:28:47 +02:00

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.
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