[PATCH 15/17] arm64: add __nocfi to __apply_alternatives

Sami Tolvanen
2021-03-12T00:50:51Z

__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 <samitolvanen@google.com>
---
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;
--
2.31.0.rc2.261.g7f71774620-goog