On 3/30/21 4:40 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. > > Changelog: > v8: > * Add warn suppress parameter to arm_gen_branch_link() > v7: > * rebased > v6: > * rebased > v5: > * BUILD_BUG_ON() ensures fixed_plts[] always fits one PLT block > * use "for" loop instead of "while" > * scripts/recordmcount is filtering reloc types > v4: > * Fixed build without CONFIG_FUNCTION_TRACER > * Reorganized pre-allocated PLTs handling in get_module_plt(), > now compiler eliminates the whole FTRACE-related handling code > if ARRAY_SIZE(fixed_plts) == 0 > v3: > * Only extend struct dyn_arch_ftrace when ARM_MODULE_PLTS is enabled > v2: > * As suggested by Steven Rostedt, refrain from tree-wide API modification, > save module pointer in struct dyn_arch_ftrace instead (PowerPC way) > > Alexander Sverdlin (3): > ARM: PLT: Move struct plt_entries definition to header > ARM: Add warn suppress parameter to arm_gen_branch_link() > ARM: ftrace: Add MODULE_PLTS support
Tested-by: Florian Fainelli <f.faine...@gmail.com> Thanks a lot! -- Florian