From: ndesaulniers@google•com
To: "Borislav Petkov (AMD)" <bp@alien8•de>
Cc: llvm@lists•linux.dev, Peter Zijlstra <peterz@infradead•org>,
x86@kernel•org, Nick Desaulniers <ndesaulniers@google•com>,
linux-kernel@vger•kernel.org,
Nathan Chancellor <nathan@kernel•org>,
Nicholas Piggin <npiggin@gmail•com>, Tom Rix <trix@redhat•com>,
Miguel Ojeda <ojeda@kernel•org>,
linuxppc-dev@lists•ozlabs.org,
Josh Poimboeuf <jpoimboe@kernel•org>
Subject: [PATCH 2/2] start_kernel: omit prevent_tail_call_optimization for newer toolchains
Date: Mon, 17 Apr 2023 14:54:08 -0700 [thread overview]
Message-ID: <20230412-no_stackp-v1-2-86d2034a4d06@google.com> (raw)
In-Reply-To: <20230412-no_stackp-v1-0-86d2034a4d06@google.com>
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 <nathan@kernel•org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead•org>
Signed-off-by: Nick Desaulniers <ndesaulniers@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
next prev parent reply other threads:[~2023-04-17 21:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-17 21:54 [PATCH 0/2] start_kernel: omit stack canary ndesaulniers
2023-04-17 21:54 ` [PATCH 1/2] start_kernel: add no_stack_protector fn attr ndesaulniers
2023-04-17 21:54 ` ndesaulniers [this message]
-- strict thread matches above, loose matches on Subject: below --
2023-04-12 18:32 [PATCH 0/2] start_kernel: omit stack canary ndesaulniers
2023-04-12 18:32 ` [PATCH 2/2] start_kernel: omit prevent_tail_call_optimization for newer toolchains ndesaulniers
2023-04-12 22:04 ` Nathan Chancellor
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