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Date:   Tue, 23 Mar 2021 13:39:44 -0700
From:   Sami Tolvanen <>
To:     Kees Cook <>
Cc:     Nathan Chancellor <>,
        Nick Desaulniers <>,
        Masahiro Yamada <>,
        Will Deacon <>, Jessica Yu <>,
        Arnd Bergmann <>, Tejun Heo <>,
        "Paul E. McKenney" <>,
        Christoph Hellwig <>,
        Peter Zijlstra <>,,,,,,,,
        Sami Tolvanen <>
Subject: [PATCH v3 15/17] arm64: add __nocfi to __apply_alternatives

__apply_alternatives makes indirect calls to functions whose address
is taken in assembly code using the alternative_cb macro. With
non-canonical CFI, the compiler won't replace these function
references with the jump table addresses, which trips CFI. Disable CFI
checking in the function to work around the issue.

Signed-off-by: Sami Tolvanen <>
Reviewed-by: Kees Cook <>
 arch/arm64/kernel/alternative.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 1184c44ea2c7..abc84636af07 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -133,8 +133,8 @@ static void clean_dcache_range_nopatch(u64 start, u64 end)
 	} while (cur += d_size, cur < end);
-static void __apply_alternatives(void *alt_region,  bool is_module,
-				 unsigned long *feature_mask)
+static void __nocfi __apply_alternatives(void *alt_region,  bool is_module,
+					 unsigned long *feature_mask)
 	struct alt_instr *alt;
 	struct alt_region *region = alt_region;

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