On 11/10, Andrii Nakryiko wrote: > This patch set moves a big chunk of verifier log related code from gigantic > verifier.c file into more focused kernel/bpf/log.c. This is not essential to > the rest of functionality in this patch set, so I can undo it, but it felt > like it's good to start chipping away from 20K+ verifier.c whenever we can. > > The main purpose of the patch set, though, is in improving verifier log > further. > > Patches #3-#4 start printing out register state even if that register is > spilled into stack slot. Previously we'd get only spilled register type, but > no additional information, like SCALAR_VALUE's ranges. Super limiting during > debugging. For cases of register spills smaller than 8 bytes, we also print > out STACK_MISC/STACK_ZERO/STACK_INVALID markers. This, among other things, > will make it easier to write tests for these mixed spill/misc cases. > > Patch #5 prints map name for PTR_TO_MAP_VALUE/PTR_TO_MAP_KEY/CONST_PTR_TO_MAP > registers. In big production BPF programs, it's important to map assembly to > actual map, and it's often non-trivial. Having map name helps. [..] > Patch #6 just removes visual noise in form of ubiquitous imm=0 and off=0. They > are default values, omit them. If you end up with another respin for some reason: s/verifierl/verifier/ s/furthre/futher/ (in the commit description) > Patch #7 is probably the most controversial, but it reworks how verifier log > prints numbers. For small valued integers we use decimals, but for large ones > we switch to hexadecimal. From personal experience this is a much more useful > convention. We can tune what consitutes "small value", for now it's 16-bit > range. Not sure why not always print in hex, but no strong preference here. > Patch #8 prints frame number for PTR_TO_CTX registers, if that frame is > different from the "current" one. This removes ambiguity and confusion, > especially in complicated cases with multiple subprogs passing around > pointers. > > Andrii Nakryiko (8): > bpf: move verbose_linfo() into kernel/bpf/log.c > bpf: move verifier state printing code to kernel/bpf/log.c > bpf: extract register state printing > bpf: print spilled register state in stack slot > bpf: emit map name in register state if applicable and available > bpf: omit default off=0 and imm=0 in register state log > bpf: smarter verifier log number printing logic > bpf: emit frameno for PTR_TO_STACK regs if it differs from current one Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
