diff options
| author | Sami Tolvanen <samitolvanen@google.com> | 2020-04-27 09:00:09 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-15 16:35:49 +0100 |
| commit | 5bbaf9d1fcb9be696ee9a61636ab6803556c70f2 (patch) | |
| tree | 6654b089420824522d0f304575400dceffc70707 | |
| parent | 628d06a48f57c36abdc2a024930212e654a501b7 (diff) | |
scs: Add support for stack usage debugging
Implements CONFIG_DEBUG_STACK_USAGE for shadow stacks. When enabled,
also prints out the highest shadow stack usage per process.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Will Deacon <will@kernel.org>
[will: rewrote most of scs_check_usage()]
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | kernel/scs.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/kernel/scs.c b/kernel/scs.c index 6d2f983ac54e..9389c28f0853 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -63,10 +63,37 @@ int scs_prepare(struct task_struct *tsk, int node) task_scs(tsk) = s; task_scs_offset(tsk) = 0; scs_account(tsk, 1); - return 0; } +static void scs_check_usage(struct task_struct *tsk) +{ + static unsigned long highest; + + unsigned long *p, prev, curr = highest, used = 0; + + if (!IS_ENABLED(CONFIG_DEBUG_STACK_USAGE)) + return; + + for (p = task_scs(tsk); p < __scs_magic(tsk); ++p) { + if (!READ_ONCE_NOCHECK(*p)) + break; + used++; + } + + while (used > curr) { + prev = cmpxchg_relaxed(&highest, curr, used); + + if (prev == curr) { + pr_info("%s (%d): highest shadow stack usage: %lu bytes\n", + tsk->comm, task_pid_nr(tsk), used); + break; + } + + curr = prev; + } +} + void scs_release(struct task_struct *tsk) { void *s = task_scs(tsk); @@ -75,6 +102,7 @@ void scs_release(struct task_struct *tsk) return; WARN(scs_corrupted(tsk), "corrupted shadow stack detected when freeing task\n"); + scs_check_usage(tsk); scs_account(tsk, -1); scs_free(s); } |