Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH RFC] ARM: option for loading modules into vmalloc area | Date | Wed, 19 Nov 2014 14:40:49 +0100 |
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On Tuesday 18 November 2014 21:13:56 Konstantin Khlebnikov wrote: > On 2014-11-18 20:34, Russell King - ARM Linux wrote: > > On Tue, Nov 18, 2014 at 08:21:46PM +0400, Konstantin Khlebnikov wrote: > >> Usually modules are loaded into small area prior to the kernel > >> text because they are linked with the kernel using short calls. > >> Compile-time instrumentation like GCOV or KASAN bloats code a lot, > >> and as a result huge modules no longer fit into reserved area. > >> > >> This patch adds option CONFIG_MODULES_USE_VMALLOC which lifts > >> limitation on amount of loaded modules. It links modules using > >> long-calls (option -mlong-calls) and loads them into vmalloc area. > >> > >> In few places exported symbols are called from inline assembly. > >> This patch adds macro for such call sites: __asmbl and __asmbl_clobber. > >> Call turns into single 'bl' or sequence 'movw; movt; blx' depending on > >> context and state of config option. > >> > >> Unfortunately this option isn't compatible with CONFIG_FUNCTION_TRACER. > >> Compiler emits short calls to profiling function despite of -mlong-calls. > >> This is a bug in GCC, but ftrace anyway needs an update to handle this. > > It also isn't compatible with the older architectures which don't have > > "blx". > > Ok, I'll add "depends on CPU_V6 || CPU_V7" I don't think that it is > necessary for older cpus.
Why not just use a different branch instruction for the older CPUs?
Arnd
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