prevent_tail_call_optimization was added in
commit a9a3ed1eff36 ("x86: Fix early boot crash on gcc-10, third try")
to work around stack canaries getting inserted into functions that would
initialize the stack canary in the first place.
Now that we have no_stack_protector function attribute (gcc-11+,
clang-7+) and use it on start_kernel, remove the call to
prevent_tail_call_optimization such that we may one day remove it
outright.
Reviewed-by: Nathan Chancellor <nat...@kernel.org>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
---
init/main.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/init/main.c b/init/main.c
index 1265c8d11052..c6eef497c8c9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1152,7 +1152,13 @@ void start_kernel(void)
/* Do the rest non-__init'ed, we're now alive */
arch_call_rest_init();
+ /*
+ * Avoid stack canaries in callers of boot_init_stack_canary for gcc-10
+ * and older.
+ */
+#if !__has_attribute(__no_stack_protector__)
prevent_tail_call_optimization();
+#endif
}
/* Call all constructor functions linked into the kernel. */
--
2.40.0.634.g4ca3ef3211-goog
