From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- lib/tests/test_fprobe.c | 327 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 327 insertions(+) create mode 100644 lib/tests/test_fprobe.c (limited to 'lib/tests/test_fprobe.c') diff --git a/lib/tests/test_fprobe.c b/lib/tests/test_fprobe.c new file mode 100644 index 000000000..108c7aa33 --- /dev/null +++ b/lib/tests/test_fprobe.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * test_fprobe.c - simple sanity test for fprobe + */ + +#include +#include +#include +#include + +#define div_factor 3 + +static struct kunit *current_test; + +static u32 rand1, entry_only_val, entry_val, exit_val; +static u32 entry_only_count, entry_count, exit_count; + +/* Use indirect calls to avoid inlining the target functions */ +static u32 (*target)(u32 value); +static u32 (*target2)(u32 value); +static unsigned long target_ip; +static unsigned long target2_ip; +static int entry_return_value; + +static noinline u32 fprobe_selftest_target(u32 value) +{ + return (value / div_factor); +} + +static noinline u32 fprobe_selftest_target2(u32 value) +{ + return (value / div_factor) + 1; +} + +static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */ + if (ip != target_ip) + KUNIT_EXPECT_EQ(current_test, ip, target2_ip); + entry_val = (rand1 / div_factor); + if (fp->entry_data_size) { + KUNIT_EXPECT_NOT_NULL(current_test, data); + if (data) + *(u32 *)data = entry_val; + } else + KUNIT_EXPECT_NULL(current_test, data); + + return entry_return_value; +} + +static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + unsigned long ret = ftrace_regs_get_return_value(fregs); + + KUNIT_EXPECT_FALSE(current_test, preemptible()); + if (ip != target_ip) { + KUNIT_EXPECT_EQ(current_test, ip, target2_ip); + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1); + } else + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor)); + KUNIT_EXPECT_EQ(current_test, entry_val, (rand1 / div_factor)); + exit_val = entry_val + div_factor; + if (fp->entry_data_size) { + KUNIT_EXPECT_NOT_NULL(current_test, data); + if (data) + KUNIT_EXPECT_EQ(current_test, *(u32 *)data, entry_val); + } else + KUNIT_EXPECT_NULL(current_test, data); +} + +/* Test entry only (no rethook) */ +static void test_fprobe_entry(struct kunit *test) +{ + struct fprobe fp_entry = { + .entry_handler = fp_entry_handler, + }; + + current_test = test; + + /* Before register, unregister should be failed. */ + KUNIT_EXPECT_NE(test, 0, unregister_fprobe(&fp_entry)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp_entry, "fprobe_selftest_target*", NULL)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp_entry)); +} + +static void test_fprobe(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target*", NULL)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +static void test_fprobe_syms(struct kunit *test) +{ + static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_target2"}; + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +/* Test private entry_data */ +static void test_fprobe_data(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + .entry_data_size = sizeof(u32), + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL)); + + target(rand1); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +static void test_fprobe_skip(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL)); + + entry_return_value = 1; + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + KUNIT_EXPECT_EQ(test, 0, fp.nmissed); + entry_return_value = 0; + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +/* Handler for fprobe entry only case */ +static notrace int entry_only_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + + entry_only_count++; + entry_only_val = (rand1 / div_factor); + + return 0; +} + +static notrace int fprobe_entry_multi_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, + void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + + entry_count++; + entry_val = (rand1 / div_factor); + + return 0; +} + +static notrace void fprobe_exit_multi_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, + void *data) +{ + unsigned long ret = ftrace_regs_get_return_value(fregs); + + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor)); + + exit_count++; + exit_val = ret; +} + +static void check_fprobe_multi(struct kunit *test) +{ + entry_only_count = entry_count = exit_count = 0; + entry_only_val = entry_val = exit_val = 0; + + target(rand1); + + /* Verify all handlers were called */ + KUNIT_EXPECT_EQ(test, 1, entry_only_count); + KUNIT_EXPECT_EQ(test, 1, entry_count); + KUNIT_EXPECT_EQ(test, 1, exit_count); + + /* Verify values are correct */ + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), entry_only_val); + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), entry_val); + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), exit_val); +} + +/* Test multiple fprobes hooking the same target function */ +static void test_fprobe_multi(struct kunit *test) +{ + struct fprobe fp1 = { + .entry_handler = fprobe_entry_multi_handler, + .exit_handler = fprobe_exit_multi_handler, + }; + struct fprobe fp2 = { + .entry_handler = entry_only_handler, + }; + + current_test = test; + + /* Test Case 1: Register in order 1 -> 2 */ + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp1, "fprobe_selftest_target", NULL)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp2, "fprobe_selftest_target", NULL)); + + check_fprobe_multi(test); + + /* Unregister all */ + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp1)); + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp2)); + + /* Test Case 2: Register in order 2 -> 1 */ + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp2, "fprobe_selftest_target", NULL)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp1, "fprobe_selftest_target", NULL)); + + check_fprobe_multi(test); + + /* Unregister all */ + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp1)); + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp2)); +} + +static unsigned long get_ftrace_location(void *func) +{ + unsigned long size, addr = (unsigned long)func; + + if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size) + return 0; + + return ftrace_location_range(addr, addr + size - 1); +} + +static int fprobe_test_init(struct kunit *test) +{ + rand1 = get_random_u32_above(div_factor); + target = fprobe_selftest_target; + target2 = fprobe_selftest_target2; + target_ip = get_ftrace_location(target); + target2_ip = get_ftrace_location(target2); + + return 0; +} + +static struct kunit_case fprobe_testcases[] = { + KUNIT_CASE(test_fprobe_entry), + KUNIT_CASE(test_fprobe), + KUNIT_CASE(test_fprobe_syms), + KUNIT_CASE(test_fprobe_data), + KUNIT_CASE(test_fprobe_skip), + KUNIT_CASE(test_fprobe_multi), + {} +}; + +static struct kunit_suite fprobe_test_suite = { + .name = "fprobe_test", + .init = fprobe_test_init, + .test_cases = fprobe_testcases, +}; + +kunit_test_suites(&fprobe_test_suite); + -- cgit v1.3.1