On Mon, Feb 15, 2021 at 7:32 PM Ard Biesheuvel <a...@kernel.org> wrote: > > (+ Linus) > > On Wed, 3 Feb 2021 at 19:24, Florian Fainelli <f.faine...@gmail.com> wrote: > > > > On 1/27/21 3:09 AM, Alexander A Sverdlin wrote: > > > From: Alexander Sverdlin <alexander.sverd...@nokia.com> > > > > > > FTRACE's function tracer currently doesn't always work on ARM with > > > MODULE_PLT option enabled. If the module is loaded too far, FTRACE's > > > code modifier cannot cope with introduced veneers and turns the > > > function tracer off globally. > > > > > > ARM64 already has a solution for the problem, refer to the following > > > patches: > > > > > > arm64: ftrace: emit ftrace-mod.o contents through code > > > arm64: module-plts: factor out PLT generation code for ftrace > > > arm64: ftrace: fix !CONFIG_ARM64_MODULE_PLTS kernels > > > arm64: ftrace: fix building without CONFIG_MODULES > > > arm64: ftrace: add support for far branches to dynamic ftrace > > > arm64: ftrace: don't validate branch via PLT in ftrace_make_nop() > > > > > > But the presented ARM variant has just a half of the footprint in terms of > > > the changed LoCs. It also retains the code validation-before-modification > > > instead of switching it off. > > > > Ard, Russell should this be sent to the patch tracker? > > Apologies for the delay. Unfortunately, I don't have time to review this. > > Linus?
I can look at them, I just need some starting strip because I honestly almost never use tracing, so I need to figure out how to provoke the error before the patches and then how to test that it is gone after. Any suggestions on a quick use case that illustrates how the problem manifest and how to test it is gone? The errors in patch 2, what do I need to configure in to get them? Does it manifest at modprobe? Yours, Linus Walleij
