From dc1d05536f44cee16e46e86316e6718b2c0d8872 Mon Sep 17 00:00:00 2001 From: "ndesaulniers@google.com" Date: Mon, 17 Apr 2023 15:00:06 -0700 Subject: [PATCH] start_kernel: Omit prevent_tail_call_optimization() for newer toolchains 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 Acked-by: Peter Zijlstra (Intel) Signed-off-by: Nick Desaulniers Link: https://lore.kernel.org/r/20230412-no_stackp-v2-2-116f9fe4bbe7@google.com Signed-off-by: Josh Poimboeuf --- init/main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/init/main.c b/init/main.c index c445c1f..c0b6499 100644 --- a/init/main.c +++ b/init/main.c @@ -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. */ -- 2.7.4