[PATCH 1/1] alloc_tag: avoid execmem_vmap() when !MMU

[Suren Baghdasaryan <surenb@google.com>]

With CONFIG_MMU=n __get_vm_area_node() is not available and memory for the
allocation tags cannot be populated as needed. For this case, populate the
required memory at initialization time.

Fixes: 57bc3834fb6f ("alloc_tag: populate memory for module tags as needed")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410250808.dQGyYjlk-lkp@intel.com/
Closes: https://lore.kernel.org/oe-lkp/202410251525.9f85854d-oliver.sang@intel.com
Closes: https://lore.kernel.org/oe-kbuild-all/202410261016.IO7C6Cml-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202410270919.LebQlmxD-lkp@intel.com/
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/execmem.h |  2 ++
 lib/alloc_tag.c         | 23 ++++++++++++++++++++++-
 mm/execmem.c            | 32 ++++++++++++++++----------------
 3 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/include/linux/execmem.h b/include/linux/execmem.h
index 5a5e2917f870..64130ae19690 100644
--- a/include/linux/execmem.h
+++ b/include/linux/execmem.h
@@ -139,6 +139,7 @@ void *execmem_alloc(enum execmem_type type, size_t size);
  */
 void execmem_free(void *ptr);
 
+#ifdef CONFIG_MMU
 /**
  * execmem_vmap - create virtual mapping for EXECMEM_MODULE_DATA memory
  * @size: size of the virtual mapping in bytes
@@ -148,6 +149,7 @@ void execmem_free(void *ptr);
  * Return: the area descriptor on success or %NULL on failure.
  */
 struct vm_struct *execmem_vmap(size_t size);
+#endif
 
 /**
  * execmem_update_copy - copy an update to executable memory
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index c1ddac2d29f0..1c74942e6dfd 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -268,7 +268,6 @@ void __init alloc_tag_sec_init(void)
 #ifdef CONFIG_MODULES
 
 static struct maple_tree mod_area_mt = MTREE_INIT(mod_area_mt, MT_FLAGS_ALLOC_RANGE);
-static struct vm_struct *vm_module_tags;
 /* A dummy object used to indicate an unloaded module */
 static struct module unloaded_mod;
 /* A dummy object used to indicate a module prepended area */
@@ -391,6 +390,9 @@ static bool find_aligned_area(struct ma_state *mas, unsigned long section_size,
 	return false;
 }
 
+#ifdef CONFIG_MMU
+static struct vm_struct *vm_module_tags;
+
 static int vm_module_tags_populate(void)
 {
 	unsigned long phys_size = vm_module_tags->nr_pages << PAGE_SHIFT;
@@ -417,6 +419,13 @@ static int vm_module_tags_populate(void)
 
 	return 0;
 }
+#else
+static int vm_module_tags_populate(void)
+{
+	/* Memory was already allocated */
+	return 0;
+}
+#endif
 
 static void *reserve_module_tags(struct module *mod, unsigned long size,
 				 unsigned int prepend, unsigned long align)
@@ -561,6 +570,7 @@ static void replace_module(struct module *mod, struct module *new_mod)
 
 static int __init alloc_mod_tags_mem(void)
 {
+#ifdef CONFIG_MMU
 	/* Map space to copy allocation tags */
 	vm_module_tags = execmem_vmap(MODULE_ALLOC_TAG_VMAP_SIZE);
 	if (!vm_module_tags) {
@@ -578,6 +588,13 @@ static int __init alloc_mod_tags_mem(void)
 	}
 
 	module_tags.start_addr = (unsigned long)vm_module_tags->addr;
+#else
+	/* Allocate space to copy allocation tags */
+	module_tags.start_addr = (unsigned long)execmem_alloc(EXECMEM_MODULE_DATA,
+							      MODULE_ALLOC_TAG_VMAP_SIZE);
+	if (!module_tags.start_addr)
+		return -ENOMEM;
+#endif
 	module_tags.end_addr = module_tags.start_addr + MODULE_ALLOC_TAG_VMAP_SIZE;
 	/* Ensure the base is alloc_tag aligned when required for indexing */
 	module_tags.start_addr = alloc_tag_align(module_tags.start_addr);
@@ -587,6 +604,7 @@ static int __init alloc_mod_tags_mem(void)
 
 static void __init free_mod_tags_mem(void)
 {
+#ifdef CONFIG_MMU
 	int i;
 
 	module_tags.start_addr = 0;
@@ -594,6 +612,9 @@ static void __init free_mod_tags_mem(void)
 		__free_page(vm_module_tags->pages[i]);
 	kfree(vm_module_tags->pages);
 	free_vm_area(vm_module_tags);
+#else
+	execmem_free((void *)module_tags.start_addr);
+#endif
 }
 
 #else /* CONFIG_MODULES */
diff --git a/mm/execmem.c b/mm/execmem.c
index 5c0f9f2d6f83..317b6a8d35be 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -64,6 +64,22 @@ static void *execmem_vmalloc(struct execmem_range *range, size_t size,
 
 	return p;
 }
+
+struct vm_struct *execmem_vmap(size_t size)
+{
+	struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
+	struct vm_struct *area;
+
+	area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
+				  range->start, range->end, NUMA_NO_NODE,
+				  GFP_KERNEL, __builtin_return_address(0));
+	if (!area && range->fallback_start)
+		area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
+					  range->fallback_start, range->fallback_end,
+					  NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
+
+	return area;
+}
 #else
 static void *execmem_vmalloc(struct execmem_range *range, size_t size,
 			     pgprot_t pgprot, unsigned long vm_flags)
@@ -368,22 +384,6 @@ void execmem_free(void *ptr)
 		vfree(ptr);
 }
 
-struct vm_struct *execmem_vmap(size_t size)
-{
-	struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
-	struct vm_struct *area;
-
-	area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
-				  range->start, range->end, NUMA_NO_NODE,
-				  GFP_KERNEL, __builtin_return_address(0));
-	if (!area && range->fallback_start)
-		area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
-					  range->fallback_start, range->fallback_end,
-					  NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
-
-	return area;
-}
-
 void *execmem_update_copy(void *dst, const void *src, size_t size)
 {
 	return text_poke_copy(dst, src, size);

base-commit: 92409df3e00a17d6fd5bb27732fa186749725ed5
-- 
2.47.0.163.g1226f6d8fa-goog