From: ndesaulniers@google.com To: "Borislav Petkov (AMD)" <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org>, Josh Poimboeuf <jpoimboe@kernel.org>, x86@kernel.org, Michael Ellerman <mpe@ellerman.id.au>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@csgroup.eu>, Miguel Ojeda <ojeda@kernel.org>, Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Nick Desaulniers <ndesaulniers@google.com> Subject: [PATCH 2/2] start_kernel: omit prevent_tail_call_optimization for newer toolchains Date: Wed, 12 Apr 2023 11:32:13 -0700 [thread overview] Message-ID: <20230412-no_stackp-v1-2-46a69b507a4b@google.com> (raw) In-Reply-To: <20230412-no_stackp-v1-0-46a69b507a4b@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. Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- init/main.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/init/main.c b/init/main.c index 213baf7b8cb1..c8503d02dfa6 100644 --- a/init/main.c +++ b/init/main.c @@ -1152,7 +1152,12 @@ 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. */ -- 2.40.0.577.gac1e443424-goog
WARNING: multiple messages have this Message-ID (diff)
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: Wed, 12 Apr 2023 11:32:13 -0700 [thread overview] Message-ID: <20230412-no_stackp-v1-2-46a69b507a4b@google.com> (raw) In-Reply-To: <20230412-no_stackp-v1-0-46a69b507a4b@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. Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- init/main.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/init/main.c b/init/main.c index 213baf7b8cb1..c8503d02dfa6 100644 --- a/init/main.c +++ b/init/main.c @@ -1152,7 +1152,12 @@ 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. */ -- 2.40.0.577.gac1e443424-goog
next prev parent reply other threads:[~2023-04-12 18:32 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-04-12 18:32 [PATCH 0/2] start_kernel: omit stack canary ndesaulniers 2023-04-12 18:32 ` ndesaulniers 2023-04-12 18:32 ` [PATCH 1/2] start_kernel: add no_stack_protector fn attr ndesaulniers 2023-04-12 18:32 ` ndesaulniers 2023-04-12 20:22 ` Miguel Ojeda 2023-04-12 20:22 ` Miguel Ojeda 2023-04-12 22:03 ` Nathan Chancellor 2023-04-12 22:03 ` Nathan Chancellor 2023-04-14 0:09 ` Michael Ellerman 2023-04-14 0:09 ` Michael Ellerman 2023-04-12 18:32 ` ndesaulniers [this message] 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 2023-04-12 22:04 ` Nathan Chancellor 2023-04-13 7:51 ` [PATCH 0/2] start_kernel: omit stack canary Peter Zijlstra 2023-04-13 7:51 ` Peter Zijlstra 2023-04-17 21:54 ndesaulniers 2023-04-17 21:54 ` [PATCH 2/2] start_kernel: omit prevent_tail_call_optimization for newer toolchains ndesaulniers 2023-04-17 21:54 ` ndesaulniers
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