Implement the architecture-specific execmem_fill_trapping_insns() helper to poison executable memory regions. When CONFIG_ARCH_HAS_EXECMEM_ROX is enabled, the execmem subsystem requires a way to fill unused or freed executable memory with architecture-specific trapping instructions. This implementation fills the specified region with AARCH64_BREAK_FAULT instructions and flushes the icache to ensure the traps are immediately visible to execution. Signed-off-by: Adrian Barnaś --- arch/arm64/mm/init.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index c673a9a839dd..71aa745e0bef 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -408,6 +408,20 @@ void dump_mem_limit(void) } #ifdef CONFIG_EXECMEM + +#ifdef CONFIG_ARCH_HAS_EXECMEM_ROX +void execmem_fill_trapping_insns(void *ptr, size_t size) +{ + int nr_inst = size / AARCH64_INSN_SIZE; + __le32 *updptr = ptr; + + for (int i = 0; i < nr_inst; i++) + updptr[i] = cpu_to_le32(AARCH64_BREAK_FAULT); + + flush_icache_range((unsigned long)ptr, (unsigned long)ptr + size); +} +#endif + static u64 module_direct_base __ro_after_init = 0; static u64 module_plt_base __ro_after_init = 0; -- 2.54.0.1136.gdb2ca164c4-goog