[PATCH bpf 3/4] module: introduce module_alloc_huge

Song Liu
2022-04-22T05:24:25Z

Introduce module_alloc_huge, which allocates huge page backed memory in
module memory space. The primary user of this memory is bpf_prog_pack
(multiple BPF programs sharing a huge page).

Signed-off-by: Song Liu <song@kernel.org>
---
arch/x86/kernel/module.c | 21 +++++++++++++++++++++
include/linux/moduleloader.h | 5 +++++
kernel/module.c | 8 ++++++++
3 files changed, 34 insertions(+)

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index b98ffcf4d250..63f6a16c70dc 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -86,6 +86,27 @@ void *module_alloc(unsigned long size)
return p;
}

+void *module_alloc_huge(unsigned long size)
+{
+ gfp_t gfp_mask = GFP_KERNEL;
+ void *p;
+
+ if (PAGE_ALIGN(size) > MODULES_LEN)
+ return NULL;
+
+ p = __vmalloc_node_range(size, MODULE_ALIGN,
+ MODULES_VADDR + get_module_load_offset(),
+ MODULES_END, gfp_mask, PAGE_KERNEL,
+ VM_DEFER_KMEMLEAK | VM_ALLOW_HUGE_VMAP,
+ NUMA_NO_NODE, __builtin_return_address(0));
+ if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
+ vfree(p);
+ return NULL;
+ }
+
+ return p;
+}
+
#ifdef CONFIG_X86_32
int apply_relocate(Elf32_Shdr *sechdrs,
const char *strtab,
diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index 9e09d11ffe5b..d34743a88938 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -26,6 +26,11 @@ unsigned int arch_mod_section_prepend(struct module *mod, unsigned int section);
sections. Returns NULL on failure. */
void *module_alloc(unsigned long size);

+/* Allocator used for allocating memory in module memory space. If size is
+ * greater than PMD_SIZE, allow using huge pages. Returns NULL on failure.
+ */
+void *module_alloc_huge(unsigned long size);
+
/* Free memory returned from module_alloc. */
void module_memfree(void *module_region);

diff --git a/kernel/module.c b/kernel/module.c
index 6cea788fd965..2af20ac3209c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2839,6 +2839,14 @@ void * __weak module_alloc(unsigned long size)
NUMA_NO_NODE, __builtin_return_address(0));
}

+void * __weak module_alloc_huge(unsigned long size)
+{
+ return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL, PAGE_KERNEL_EXEC,
+ VM_FLUSH_RESET_PERMS | VM_ALLOW_HUGE_VMAP,
+ NUMA_NO_NODE, __builtin_return_address(0));
+}
+
bool __weak module_init_section(const char *name)
{
return strstarts(name, ".init");
--
2.30.2