From: Alice Ryhl Date: Wed, 27 May 2026 18:18:07 +0000 (+0000) Subject: rust: arm64: set uwtable llvm module flag for CONFIG_UNWIND_TABLES X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=ac35b5580ace12e5d0a0b5e61e36d2c4e1ffa29c;p=thirdparty%2Fkernel%2Flinux.git rust: arm64: set uwtable llvm module flag for CONFIG_UNWIND_TABLES Due to a rustc bug [1] the -Cforce-unwind-tables=y flag only emits the uwtable annotation for functions, but not for the module. This means that compiler-generated functions such as 'asan.module_ctor' do not receive the uwtable annotation. When CONFIG_UNWIND_PATCH_PAC_INTO_SCS is enabled, this leads to boot failures because the dwarf information emitted for the kasan constructors is wrong, which causes the SCS boot patching code to patch the constructor in an illegal manner. Specifically, the paciasp instruction is patched, but the autiasp instruction is not. This mismatch leads to a crash when the constructor is called during boot. ================================================================== BUG: KASAN: global-out-of-bounds in do_basic_setup+0x4c/0x90 Read of size 8 at addr ffffffe3cc7eb488 by task swapper/0/1 Specifically the faulting instruction is the (*fn)() to invoke the constructor in do_ctors() of the init/main.c file. Once the fix lands in rustc, this flag can be made conditional on the rustc version. Note that passing the flag on a rustc with the fix present has no effect. [ The fix [1] has landed for Rust 1.98.0 (expected release on 2026-08-20). Thus add a version check as discussed. - Miguel ] Fixes: d077242d68a3 ("rust: support for shadow call stack sanitizer") Cc: stable@kernel.org Link: https://github.com/rust-lang/rust/pull/156973 [1] Reported-by: Bo Ye Debugged-by: Isaac Manjarres Debugged-by: Sami Tolvanen Tested-by: Isaac Manjarres Signed-off-by: Alice Ryhl Link: https://patch.msgid.link/20260527-uwtable-module-flag-v1-1-caa41342be4b@google.com [ Adjusted link and comment. - Miguel ] Signed-off-by: Miguel Ojeda --- diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 73a10f65ce8bc..6b005c8fef706 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -63,6 +63,9 @@ else KBUILD_CFLAGS += -fasynchronous-unwind-tables KBUILD_AFLAGS += -fasynchronous-unwind-tables KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n +# Work around rustc bug on compilers without +# https://github.com/rust-lang/rust/pull/156973. +KBUILD_RUSTFLAGS += $(if $(call rustc-min-version,109800),,-Zllvm_module_flag=uwtable:u32:2:max) endif ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)