On Sun, Aug 27, 2023 at 10:48:44AM +0800, Yafang Shao wrote:
On Sat, Aug 26, 2023 at 10:46 PM Rong Tao rtoax@foxmail.com wrote:
From: Rong Tao rongtao@cestc.cn
Static ksyms often have problems because the number of symbols exceeds the MAX_SYMS limit. Like changing the MAX_SYMS from 300000 to 400000 in commit e76a014334a6("selftests/bpf: Bump and validate MAX_SYMS") solves the problem somewhat, but it's not the perfect way.
This commit uses dynamic memory allocation, which completely solves the problem caused by the limitation of the number of kallsyms.
Acked-by: Stanislav Fomichev sdf@google.com Signed-off-by: Rong Tao rongtao@cestc.cn
v8: Resolves inter-thread contention for ksyms global variables. v7: https://lore.kernel.org/lkml/tencent_BD6E19C00BF565CD5C36A9A0BD828CFA210A@qq... Fix __must_check macro. v6: https://lore.kernel.org/lkml/tencent_4A09A36F883A06EA428A593497642AF8AF08@qq... Apply libbpf_ensure_mem() v5: https://lore.kernel.org/lkml/tencent_0E9E1A1C0981678D5E7EA9E4BDBA8EE2200A@qq... Release the allocated memory once the load_kallsyms_refresh() upon error given it's dynamically allocated. v4: https://lore.kernel.org/lkml/tencent_59C74613113F0C728524B2A82FE5540A5E09@qq... Make sure most cases we don't need the realloc() path to begin with, and check strdup() return value. v3: https://lore.kernel.org/lkml/tencent_50B4B2622FE7546A5FF9464310650C008509@qq... Do not use structs and judge ksyms__add_symbol function return value. v2: https://lore.kernel.org/lkml/tencent_B655EE5E5D463110D70CD2846AB3262EED09@qq... Do the usual len/capacity scheme here to amortize the cost of realloc, and don't free symbols. v1: https://lore.kernel.org/lkml/tencent_AB461510B10CD484E0B2F62E3754165F2909@qq...
samples/bpf/Makefile | 4 + samples/bpf/offwaketime_user.c | 7 +- samples/bpf/sampleip_user.c | 9 +- samples/bpf/spintest_user.c | 7 +- samples/bpf/task_fd_query_user.c | 13 +- samples/bpf/trace_event_user.c | 7 +- .../selftests/bpf/prog_tests/bpf_cookie.c | 7 +- .../selftests/bpf/prog_tests/fill_link_info.c | 9 +- .../bpf/prog_tests/get_stack_raw_tp.c | 10 +- .../bpf/prog_tests/kprobe_multi_test.c | 13 +- .../prog_tests/kprobe_multi_testmod_test.c | 13 +- tools/testing/selftests/bpf/trace_helpers.c | 116 ++++++++++++------ tools/testing/selftests/bpf/trace_helpers.h | 10 +- 13 files changed, 154 insertions(+), 71 deletions(-)
I think we'd better split it into two patches: one for samples/bpf/ and another for tools/testing/selftests/bpf.
BTW, why can't we just load it once for all ? IOW, load the kallsyms before we start each individual test, and free it after all tests finish.
there are bpf_testmod tests that unload module so we need fresh symbols after that
jirka