Messages in this thread | | | Subject | Re: [PATCH] MIPS: lib: Mark intrinsics notrace | From | Harvey Hunt <> | Date | Tue, 31 May 2016 13:18:28 +0100 |
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Hi Ralf,
On 29/05/16 22:03, Ralf Baechle wrote: > 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.
This is triggered by building with CONFIG_CC_OPTIMIZE_FOR_SIZE. This explains why I only saw it on certain MIPS32 devices - Malta's defconfigs don't have CONFIG_CC_OPTIMIZE_FOR_SIZE enabled, but the pistachio and Ci20 defconfigs do.
> > Ralf >
Thanks,
Harvey
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