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selftests/bpf: Add tests for RCU lock transfer between subprogs

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Add selftests covering the following cases:
- A static or global subprog called from within a RCU read section works
- A static subprog taking an RCU read lock which is released in caller works
- A static subprog releasing the caller's RCU read lock works

Global subprogs that leave the lock in an imbalanced state will not
work, as they are verified separately, so ensure those cases fail as
well.

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20240205055646.1112186-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kumar Kartikeya Dwivedi 2024-02-05 05:56:46 +00:00 committed by Alexei Starovoitov
parent 6fceea0fa5
commit 8be6a0147a
2 changed files with 126 additions and 0 deletions
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6
tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c
View file

@ -29,6 +29,10 @@ static void test_success(void)
bpf_program__set_autoload(skel->progs.non_sleepable_1, true);
bpf_program__set_autoload(skel->progs.non_sleepable_2, true);
bpf_program__set_autoload(skel->progs.task_trusted_non_rcuptr, true);
bpf_program__set_autoload(skel->progs.rcu_read_lock_subprog, true);
bpf_program__set_autoload(skel->progs.rcu_read_lock_global_subprog, true);
bpf_program__set_autoload(skel->progs.rcu_read_lock_subprog_lock, true);
bpf_program__set_autoload(skel->progs.rcu_read_lock_subprog_unlock, true);
err = rcu_read_lock__load(skel);
if (!ASSERT_OK(err, "skel_load"))
goto out;
@ -75,6 +79,8 @@ static const char * const inproper_region_tests[] = {
"inproper_sleepable_helper",
"inproper_sleepable_kfunc",
"nested_rcu_region",
"rcu_read_lock_global_subprog_lock",
"rcu_read_lock_global_subprog_unlock",
};
static void test_inproper_region(void)

120
tools/testing/selftests/bpf/progs/rcu_read_lock.c
View file

@ -319,3 +319,123 @@ int cross_rcu_region(void *ctx)
bpf_rcu_read_unlock();
return 0;
}
__noinline
static int static_subprog(void *ctx)
{
volatile int ret = 0;
if (bpf_get_prandom_u32())
return ret + 42;
return ret + bpf_get_prandom_u32();
}
__noinline
int global_subprog(u64 a)
{
volatile int ret = a;
return ret + static_subprog(NULL);
}
__noinline
static int static_subprog_lock(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_lock();
if (bpf_get_prandom_u32())
return ret + 42;
return ret + bpf_get_prandom_u32();
}
__noinline
int global_subprog_lock(u64 a)
{
volatile int ret = a;
return ret + static_subprog_lock(NULL);
}
__noinline
static int static_subprog_unlock(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_unlock();
if (bpf_get_prandom_u32())
return ret + 42;
return ret + bpf_get_prandom_u32();
}
__noinline
int global_subprog_unlock(u64 a)
{
volatile int ret = a;
return ret + static_subprog_unlock(NULL);
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_lock();
if (bpf_get_prandom_u32())
ret += static_subprog(ctx);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_lock();
if (bpf_get_prandom_u32())
ret += global_subprog(ret);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog_lock(void *ctx)
{
volatile int ret = 0;
ret += static_subprog_lock(ctx);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog_lock(void *ctx)
{
volatile int ret = 0;
ret += global_subprog_lock(ret);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog_unlock(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_lock();
ret += static_subprog_unlock(ctx);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog_unlock(void *ctx)
{
volatile int ret = 0;
bpf_rcu_read_lock();
ret += global_subprog_unlock(ret);
return 0;
}