Ian Rogers 5c34aea341 perf test: Fix DWARF unwind for optimized builds.
To ensure the stack frames are on the stack tail calls optimizations
need to be inhibited. If your compiler supports an attribute use it,
otherwise use an asm volatile barrier.

The barrier fix was suggested here:
https://lore.kernel.org/lkml/[email protected]/
Tested with an optimized clang build and by forcing the asm barrier
route with an optimized clang build.

A GCC bug tracking a proper disable_tail_calls is:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97831

Fixes: 9ae1e990f1 ("perf tools: Remove broken __no_tail_call
       attribute")

v2. is a rebase. The original fix patch generated quite a lot of
    discussion over the right place for the fix:
    https://lore.kernel.org/lkml/[email protected]/
    The patch reflects my preference of it being near the use, so that
    future code cleanups don't break this somewhat special usage.

Signed-off-by: Ian Rogers <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: [email protected]
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
2021-09-27 09:32:28 -03:00
2021-09-26 14:08:19 -07:00
…

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.
S
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