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Assume the following ftrace code sequence that was patched in earlier by ftrace_make_call(): PAGE A: ffc: addr of ftrace_caller() PAGE B: 000: 0x6fc10080 /* stw,ma r1,40(sp) */ 004: 0x48213fd1 /* ldw -18(r1),r1 */ 008: 0xe820c002 /* bv,n r0(r1) */ 00c: 0xe83f1fdf /* b,l,n .-c,r1 */ When a Code sequences that is to be patched spans a page break, we might have already cleared the part on the PAGE A. If an interrupt is coming in during the remap of the fixed mapping to PAGE B, it might execute the patched function with only parts of the FTRACE code cleared. To prevent this, clear the jump to our mini trampoline first, and clear the remaining parts after this. This might also happen when patch_text() patches a function that it calls during remap. Signed-off-by: Sven Schnelle <svens@stackframe.org> Cc: <stable@vger.kernel.org> # 5.2+ Signed-off-by: Helge Deller <deller@gmx.de>
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.