On Sat, Apr 28, 2018 at 10:28:06PM -0700, Yonghong Song wrote: > Currently, stackmap and bpf_get_stackid helper are provided > for bpf program to get the stack trace. This approach has > a limitation though. If two stack traces have the same hash, > only one will get stored in the stackmap table regardless of > whether BPF_F_REUSE_STACKID is specified or not, > so some stack traces may be missing from user perspective. > > This patch implements a new helper, bpf_get_stack, will > send stack traces directly to bpf program. The bpf program > is able to see all stack traces, and then can do in-kernel > processing or send stack traces to user space through > shared map or bpf_perf_event_output. > > Patches #1 and #2 implemented the core kernel support. > Patch #3 removes two never-hit branches in verifier. > Patches #4 and #5 are two verifier improves to make > bpf programming easier. Patch #6 synced the new helper > to tools headers. Patch #7 moved perf_event polling code > and ksym lookup code from samples/bpf to > tools/testing/selftests/bpf. Patch #8 added a verifier > test in tools/bpf for new verifier change. > Patches #9 and #10 added tests for raw tracepoint prog > and tracepoint prog respectively. > > Changelogs: > v8 -> v9: > . make function perf_event_mmap (in trace_helpers.c) extern > to decouple perf_event_mmap and perf_event_poller. > . add jit enabled handling for kernel stack verification > in Patch #9. Since we did not have a good way to > verify jit enabled kernel stack, just return true if > the kernel stack is not empty. > . In path #9, using raw_syscalls/sys_enter instead of > sched/sched_switch, removed calling cmd > "task 1 dd if=/dev/zero of=/dev/null" which is left > with dangling process after the program exited. > > v7 -> v8: > . rebase on top of latest bpf-next > . simplify BPF_ARSH dst_reg->smin_val/smax_value tracking > . rewrite the description of bpf_get_stack() in uapi bpf.h > based on new format. > v6 -> v7: > . do perf callchain buffer allocation inside the > verifier. so if the prog->has_callchain_buf is set, > it is guaranteed that the buffer has been allocated. > . change condition "trace_nr <= skip" to "trace_nr < skip" > so that for zero size buffer, return 0 instead of -EFAULT > v5 -> v6: > . after refining return register smax_value and umax_value > for helpers bpf_get_stack and bpf_probe_read_str, > bounds and var_off of the return register are further refined. > . added missing commit message for tools header sync commit. > . removed one unnecessary empty line. > v4 -> v5: > . relied on dst_reg->var_off to refine umin_val/umax_val > in verifier handling BPF_ARSH value range tracking, > suggested by Edward. > v3 -> v4: > . fixed a bug when meta ptr is set to NULL in check_func_arg. > . introduced tnum_arshift and added detailed comments for > the underlying implementation > . avoided using VLA in tools/bpf test_progs. > v2 -> v3: > . used meta to track helper memory size argument > . implemented range checking for ARSH in verifier > . moved perf event polling and ksym related functions > from samples/bpf to tools/bpf > . added test to compare build id's between bpf_get_stackid > and bpf_get_stack > v1 -> v2: > . fixed compilation error when CONFIG_PERF_EVENTS is not enabled
Applied, Thanks Yonghong.
