[PATCH v3 4/9] execmem: don't remove ROX cache from the direct map
From: Mike Rapoport <rppt@kernel.org>
Date: 2025-01-26 07:48:33
Also in:
linux-kselftest, linux-mm, linux-modules, linux-um, live-patching, lkml
Subsystem:
memory management, memory management - execmem, the rest · Maintainers:
Andrew Morton, Mike Rapoport, Linus Torvalds
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org> The memory allocated for the ROX cache was removed from the direct map to reduce amount of direct map updates, however this cannot be tolerated by /proc/kcore that accesses module memory using vread_iter() and the latter does vmalloc_to_page() and copy_page_to_iter_nofault(). Instead of removing ROX cache memory from the direct map and mapping it as ROX in vmalloc space, simply call set_memory_rox() that will take care of proper permissions on both vmalloc and in the direct map. Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> --- mm/execmem.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/mm/execmem.c b/mm/execmem.c
index 317b6a8d35be..04b0bf1b5025 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c@@ -257,7 +257,6 @@ static void *__execmem_cache_alloc(struct execmem_range *range, size_t size) static int execmem_cache_populate(struct execmem_range *range, size_t size) { unsigned long vm_flags = VM_ALLOW_HUGE_VMAP; - unsigned long start, end; struct vm_struct *vm; size_t alloc_size; int err = -ENOMEM;
@@ -275,26 +274,18 @@ static int execmem_cache_populate(struct execmem_range *range, size_t size) /* fill memory with instructions that will trap */ execmem_fill_trapping_insns(p, alloc_size, /* writable = */ true); - start = (unsigned long)p; - end = start + alloc_size; - - vunmap_range(start, end); - - err = execmem_set_direct_map_valid(vm, false); - if (err) - goto err_free_mem; - - err = vmap_pages_range_noflush(start, end, range->pgprot, vm->pages, - PMD_SHIFT); + err = set_memory_rox((unsigned long)p, vm->nr_pages); if (err) goto err_free_mem; err = execmem_cache_add(p, alloc_size); if (err) - goto err_free_mem; + goto err_reset_direct_map; return 0; +err_reset_direct_map: + execmem_set_direct_map_valid(vm, true); err_free_mem: vfree(p); return err;
--
2.45.2