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static_call: Align static_call_is_init() patching condition

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The intent is to avoid writing init code after init (because the text
might have been freed). The code is needlessly different between
jump_label and static_call and not obviously correct.

The existing code relies on the fact that the module loader clears the
init layout, such that within_module_init() always fails, while
jump_label relies on the module state which is more obvious and
matches the kernel logic.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lkml.kernel.org/r/20210318113610.636651340@infradead.org
This commit is contained in:
Peter Zijlstra 2021-03-18 11:29:56 +01:00
parent 68b1eddd42
commit 698bacefe9
1 changed files with 4 additions and 10 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

14
kernel/static_call.c
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@ -149,6 +149,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
};
for (site_mod = &first; site_mod; site_mod = site_mod->next) {
bool init = system_state < SYSTEM_RUNNING;
struct module *mod = site_mod->mod;
if (!site_mod->sites) {
@ -168,6 +169,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
if (mod) {
stop = mod->static_call_sites +
mod->num_static_call_sites;
init = mod->state == MODULE_STATE_COMING;
}
#endif
@ -175,16 +177,8 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
site < stop && static_call_key(site) == key; site++) {
void *site_addr = static_call_addr(site);
if (static_call_is_init(site)) {
/*
* Don't write to call sites which were in
* initmem and have since been freed.
*/
if (!mod && system_state >= SYSTEM_RUNNING)
continue;
if (mod && !within_module_init((unsigned long)site_addr, mod))
continue;
}
if (!init && static_call_is_init(site))
continue;
if (!kernel_text_address((unsigned long)site_addr)) {
WARN_ONCE(1, "can't patch static call site at %pS",