On 12/05/2017 04:53 PM, Daniel Borkmann wrote: > On 12/04/2017 10:56 AM, Hendrik Brueckner wrote: >> Perf tool bpf selftests revealed a broken uapi for s390 and arm64. >> With the BPF_PROG_TYPE_PERF_EVENT program type the bpf_perf_event >> structure exports the pt_regs structure for all architectures. >> >> This fails for s390 and arm64 because pt_regs are not part of the >> user api and kept in-kernel only. To mitigate the broken uapi, >> introduce a wrapper that exports pt_regs in an asm-generic way. >> For arm64, export the exising user_pt_regs structure. For s390, >> introduce a user_pt_regs structure that exports the beginning of >> pt_regs. >> >> Note that user_pt_regs must export from the beginning of pt_regs >> as BPF_PROG_TYPE_PERF_EVENT program type is not the only type for >> running BPF programs. >> >> Some more background: >> For the bpf_perf_event, there is a uapi definition that is >> passed to the BPF program. For other "probe" points like >> trace points, kprobes, and uprobes, there is no uapi and the >> BPF program is always passed pt_regs (which is OK as the BPF >> program runs in the kernel context). The perf tool can attach >> BPF programs to all of these "probe" points and, optionally, >> can create a BPF prologue to access particular arguments >> (passed as registers). For this, it uses DWARF/CFI >> information to obtain the register and calls a perf-arch >> backend function, regs_query_register_offset(). This function >> returns the index into (user_)pt_regs for a particular >> register. Then, perf creates a BPF prologue that accesses >> this register based on the passed stucture from the "probe" >> point. >> >> Part of this series, are also updates to the testing and bpf selftest >> to deal with asm-specifics. To complete the bpf support in perf, the >> the regs_query_register_offset function is added for s390 to support >> BPF prologue creation. >> >> Changelog v1 -> v2: >> - Correct kbuild test bot issues by including >> asm-generic/bpf_perf_event.h for archictectures that do not have >> their own asm version. >> - Added patch to clean-up whitespace and coding style issues in s390 >> asm/ptrace.h (#4/6) as suggested by Alexei. >> >> >> Hendrik Brueckner (6): >> bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type >> s390/bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program >> type >> arm64/bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program >> type >> s390/uapi: correct whitespace & coding style in asm/ptrace.h >> selftests/bpf: sync kernel headers and introduce arch support in >> Makefile >> perf s390: add regs_query_register_offset() > > Series looks good to me, thanks for working on this Hendrik! If nobody > hollers, I would take the fixes via bpf tree later tonight. Done, applied to bpf, thanks Hendrik! -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
