From 3d60fe1cf587a234d8df41be768d1c00db17083c Mon Sep 17 00:00:00 2001
From: Alice Ryhl <aliceryhl@google.com>
Date: Mon, 29 Jul 2024 14:22:49 +0000
Subject: [PATCH] rust: SHADOW_CALL_STACK is incompatible with Rust

commit f126745da81783fb1d082e67bf14c6795e489a88 upstream.

When using the shadow call stack sanitizer, all code must be compiled
with the -ffixed-x18 flag, but this flag is not currently being passed
to Rust. This results in crashes that are extremely difficult to debug.

To ensure that nobody else has to go through the same debugging session
that I had to, prevent configurations that enable both SHADOW_CALL_STACK
and RUST.

It is rather common for people to backport 724a75ac9542 ("arm64: rust:
Enable Rust support for AArch64"), so I recommend applying this fix all
the way back to 6.1.

Cc: stable@vger.kernel.org # 6.1 and later
Fixes: 724a75ac9542 ("arm64: rust: Enable Rust support for AArch64")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20240729-shadow-call-stack-v4-1-2a664b082ea4@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 init/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/init/Kconfig b/init/Kconfig
index 537f01eba2e6f..4cd3fc82b09e5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1924,6 +1924,7 @@ config RUST
 	depends on !MODVERSIONS
 	depends on !GCC_PLUGINS
 	depends on !RANDSTRUCT
+	depends on !SHADOW_CALL_STACK
 	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
 	help
 	  Enables Rust support in the kernel.
-- 
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