[tip: locking/urgent] static_call: Fix static_call_text_reserved() vs __init

tip-bot2 for Peter Zijlstra
2021-07-05T09:05:22Z

The following commit has been merged into the locking/urgent branch of tip:

Commit-ID: 2bee6d16e4379326b1eea454e68c98b17456769e
Gitweb: https://git.kernel.org/tip/2bee6d16e4379326b1eea454e68c98b17456769e
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Mon, 28 Jun 2021 13:24:11 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Mon, 05 Jul 2021 10:46:33 +02:00

static_call: Fix static_call_text_reserved() vs __init

It turns out that static_call_text_reserved() was reporting __init
text as being reserved past the time when the __init text was freed
and re-used.

This is mostly harmless and will at worst result in refusing a kprobe.

Fixes: 6333e8f73b83 ("static_call: Avoid kprobes on inline static_call()s")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210628113045.106211657@infradead.org
---
kernel/static_call.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/kernel/static_call.c b/kernel/static_call.c
index 723fcc9..43ba0b1 100644
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -292,13 +292,15 @@ static int addr_conflict(struct static_call_site *site, void *start, void *end)

static int __static_call_text_reserved(struct static_call_site *iter_start,
struct static_call_site *iter_stop,
- void *start, void *end)
+ void *start, void *end, bool init)
{
struct static_call_site *iter = iter_start;

while (iter < iter_stop) {
- if (addr_conflict(iter, start, end))
- return 1;
+ if (init || !static_call_is_init(iter)) {
+ if (addr_conflict(iter, start, end))
+ return 1;
+ }
iter++;
}

@@ -324,7 +326,7 @@ static int __static_call_mod_text_reserved(void *start, void *end)

ret = __static_call_text_reserved(mod->static_call_sites,
mod->static_call_sites + mod->num_static_call_sites,
- start, end);
+ start, end, mod->state == MODULE_STATE_COMING);

module_put(mod);

@@ -459,8 +461,9 @@ static inline int __static_call_mod_text_reserved(void *start, void *end)

int static_call_text_reserved(void *start, void *end)
{
+ bool init = system_state < SYSTEM_RUNNING;
int ret = __static_call_text_reserved(__start_static_call_sites,
- __stop_static_call_sites, start, end);
+ __stop_static_call_sites, start, end, init);

if (ret)
return ret;