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8c42819b61
Since the upper regs don't exist for ia32 code, preserving them doesn't hurt and it simplifies the code. This doesn't add any attack surface that would not already be available through INT80. Notably: - 32bit SYSENTER: didn't clear si, dx, cx. - 32bit SYSCALL, INT80: *do* clear si since the C functions don't take a second argument. - 64bit: didn't clear si since the C functions take a second argument; except the error_entry path might have only one argument, so clearing si was missing here. 32b SYSENTER should be clearing all those 3 registers, nothing uses them and selftests pass. Unconditionally clear rsi since it simplifies code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220506121631.293889636@infradead.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.