Commit dc1d0553 authored by ndesaulniers@google.com's avatar ndesaulniers@google.com Committed by Josh Poimboeuf
Browse files

start_kernel: Omit prevent_tail_call_optimization() for newer toolchains 



prevent_tail_call_optimization() was added in
commit a9a3ed1e ("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: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230412-no_stackp-v2-2-116f9fe4bbe7@google.com


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 514ca14e

init/main.c

+6 −0
Original line number Diff line number Diff line
@@ -1088,7 +1088,13 @@ 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. */