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? -- Florian