Peter Zijlstra 1e4d3001f5 x86/entry: Harden return-to-user
Make the CONFIG_DEBUG_ENTRY=y check that validates CS is a user segment
unconditional and move it nearer to IRET.

  PRE:
       140,026,608      cycles:k                                                      ( +-  0.01% )
       236,696,176      instructions:k            #    1.69  insn per cycle           ( +-  0.00% )

  POST:
       139,957,681      cycles:k                                                      ( +-  0.01% )
       236,681,819      instructions:k            #    1.69  insn per cycle           ( +-  0.00% )

(this is with --repeat 100 and the run-to-run variance is bigger than
the difference shown)

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231120143626.753200755@infradead.org
2023-11-21 13:57:31 +01:00
2023-11-21 13:57:31 +01:00
2023-11-15 15:30:09 -08:00
…
…
2023-11-19 15:02:14 -08:00
…

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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