From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/perf/tests/mem.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 tools/perf/tests/mem.c (limited to 'tools/perf/tests/mem.c') diff --git a/tools/perf/tests/mem.c b/tools/perf/tests/mem.c new file mode 100644 index 000000000..cb3d749e1 --- /dev/null +++ b/tools/perf/tests/mem.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "util/map_symbol.h" +#include "util/mem-events.h" +#include "util/mem-info.h" +#include "util/symbol.h" +#include "linux/perf_event.h" +#include "util/debug.h" +#include "tests.h" +#include + +static int check(union perf_mem_data_src data_src, + const char *string) +{ + char out[100]; + char failure[100]; + struct mem_info *mi = mem_info__new(); + int n; + + TEST_ASSERT_VAL("Memory allocation failed", mi); + *mem_info__data_src(mi) = data_src; + n = perf_mem__snp_scnprintf(out, sizeof out, mi); + n += perf_mem__lvl_scnprintf(out + n, sizeof out - n, mi); + mem_info__put(mi); + scnprintf(failure, sizeof failure, "unexpected %s", out); + TEST_ASSERT_VAL(failure, !strcmp(string, out)); + return 0; +} + +static int test__mem(struct test_suite *text __maybe_unused, int subtest __maybe_unused) +{ + int ret = 0; + union perf_mem_data_src src; + + memset(&src, 0, sizeof(src)); + + src.mem_lvl = PERF_MEM_LVL_HIT; + src.mem_lvl_num = 4; + + ret |= check(src, "N/AL4 hit"); + + src.mem_remote = 1; + + ret |= check(src, "N/ARemote L4 hit"); + + src.mem_lvl = PERF_MEM_LVL_MISS; + src.mem_lvl_num = PERF_MEM_LVLNUM_PMEM; + src.mem_remote = 0; + + ret |= check(src, "N/APMEM miss"); + + src.mem_remote = 1; + + ret |= check(src, "N/ARemote PMEM miss"); + + src.mem_snoopx = PERF_MEM_SNOOPX_FWD; + src.mem_lvl_num = PERF_MEM_LVLNUM_RAM; + + ret |= check(src , "FwdRemote RAM miss"); + + return ret; +} + +DEFINE_SUITE("Test data source output", mem); -- cgit v1.3.1