The current implementation of 'free_init_memory()' fills the freed '__init' and '__initdata' memory regions with a faulting instruction before unmapping and returning them to the heap. However, after unmapping, any access to this region will result in a page fault, making the instruction fill redundant.
Replace the instruction fill with a call to 'memset()', zeroing the entire region before it is unmapped and returned to the allocator. Additionally, this change resolves a violation of MISRA C:2012 Rule 11.3 (cast between pointer to object type and pointer to a different object type), caused by performing a cast from a 'char *' to a 'uint32_t *' pointer to write instructions directly into memory, which is not compliant with MISRA guidelines. No functional changes. Signed-off-by: Dmytro Prokopchuk <[email protected]> --- Changes in v2: - replaced the instruction fill with a call to 'memset()' - changed commit message appropriately Link to v1: https://patchew.org/Xen/680a7418c445381d68fc95f0e3cd03f574fdda86.1761672602.git.dmytro._5fprokopch...@epam.com/ Test CI pipeline: https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/2132383252 --- xen/arch/arm/mmu/setup.c | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-) diff --git a/xen/arch/arm/mmu/setup.c b/xen/arch/arm/mmu/setup.c index eb8ed19ca1..9b874f8ab2 100644 --- a/xen/arch/arm/mmu/setup.c +++ b/xen/arch/arm/mmu/setup.c @@ -479,9 +479,6 @@ void free_init_memory(void) { paddr_t pa = virt_to_maddr(__init_begin); unsigned long len = __init_end - __init_begin; - uint32_t insn; - unsigned int i, nr = len / sizeof(insn); - uint32_t *p; int rc; rc = modify_xen_mappings((unsigned long)__init_begin, @@ -495,15 +492,8 @@ void free_init_memory(void) */ invalidate_icache_local(); -#ifdef CONFIG_ARM_32 - /* udf instruction i.e (see A8.8.247 in ARM DDI 0406C.c) */ - insn = 0xe7f000f0; -#else - insn = AARCH64_BREAK_FAULT; -#endif - p = (uint32_t *)__init_begin; - for ( i = 0; i < nr; i++ ) - *(p + i) = insn; + /* Zeroing the memory before returning it */ + memset(__init_begin, 0, len); rc = destroy_xen_mappings((unsigned long)__init_begin, (unsigned long)__init_end); -- 2.43.0
