Re: [PATCH] MIPS: lib: Mark intrinsics notrace

From	Ralf Baechle <ralf@linux-mips.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] MIPS: lib: Mark intrinsics notrace
Date	2016-05-29 23:10 +0200
Message-ID	<rEg89-331-5@gated-at.bofh.it> (permalink)
References	<rCDVf-89T-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, May 25, 2016 at 11:06:35AM +0100, Harvey Hunt wrote:

> On certain MIPS32 devices, the ftrace tracer "function_graph" uses
> __lshrdi3() during the capturing of trace data. ftrace then attempts to
> trace __lshrdi3() which leads to infinite recursion and a stack overflow.
> Fix this by marking __lshrdi3() as notrace. Mark the other compiler
> intrinsics as notrace in case the compiler decides to use them in the
> ftrace path.

Makes perfect sense - but I'm wondering how you triggered it.  Was this
a build with the GCC option -Os that is CONFIG_CC_OPTIMIZE_FOR_SIZE?
Usually people build with CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE that is -O2
which results in intrinsics being inlined.

  Ralf

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[PATCH] MIPS: lib: Mark intrinsics notrace Harvey Hunt <harvey.hunt@imgtec.com> - 2016-05-25 12:10 +0200
  Re: [PATCH] MIPS: lib: Mark intrinsics notrace Ralf Baechle <ralf@linux-mips.org> - 2016-05-29 23:10 +0200

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