On Thu, Jun 22, 2023 at 10:47:08AM +0200, Puranjay Mohan wrote: > On Thu, Jun 22, 2023 at 10:23 AM Mark Rutland <mark.rutland@xxxxxxx> wrote: > > On Wed, Jun 21, 2023 at 10:57:20PM +0200, Puranjay Mohan wrote: > > > When I move the call to bpf_flush_icache() after > > > bpf_jit_binary_pack_finalize() (this does the copy to ro_header), the > > > boot issue is fixed. Would this change be enough to make this work or I > > > would need to do more with the data cache as well to catch other edge > > > cases? > > > > AFAICT, bpf_flush_icache() calls flush_icache_range(). Despite its name, > > flush_icache_range() has d-cache maintenance, i-cache maintenance, and context > > synchronization (i.e. it does everything necessary). > > > > As long as you call that with the VAs the code will be executed from, that > > should be sufficient, and you don't need to do any other work. > > Thanks for explaining this. > After reading your explanation, I feel this should work. > > bpf_jit_binary_pack_finalize() will copy the instructions from > rw_header to ro_header. > After the copy, calling bpf_flush_icache(ro_header, ctx.ro_image + > ctx.idx); will invalidate the caches > for the VAs in the ro_header, this is where the code will be executed from. > > I will send the v4 patchset with this change. Sure -- I'll be happy to review that. Mark.
