arm64: add support for kernel ASLR

[cascardo/linux.git] / arch / arm64 / kernel / module.c

diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 93e9702..7f31698 100644 (file)
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -34,10 +34,26 @@ void *module_alloc(unsigned long size)
 {
        void *p;
 
-       p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
+       p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
+                               module_alloc_base + MODULES_VSIZE,
                                GFP_KERNEL, PAGE_KERNEL_EXEC, 0,
                                NUMA_NO_NODE, __builtin_return_address(0));
 
+       if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
+           !IS_ENABLED(CONFIG_KASAN))
+               /*
+                * KASAN can only deal with module allocations being served
+                * from the reserved module region, since the remainder of
+                * the vmalloc region is already backed by zero shadow pages,
+                * and punching holes into it is non-trivial. Since the module
+                * region is not randomized when KASAN is enabled, it is even
+                * less likely that the module region gets exhausted, so we
+                * can simply omit this fallback in that case.
+                */
+               p = __vmalloc_node_range(size, MODULE_ALIGN, VMALLOC_START,
+                               VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_EXEC, 0,
+                               NUMA_NO_NODE, __builtin_return_address(0));
+
        if (p && (kasan_module_alloc(p, size) < 0)) {
                vfree(p);
                return NULL;
@@ -361,6 +377,13 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
                case R_AARCH64_CALL26:
                        ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 26,
                                             AARCH64_INSN_IMM_26);
+
+                       if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
+                           ovf == -ERANGE) {
+                               val = module_emit_plt_entry(me, &rel[i], sym);
+                               ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2,
+                                                    26, AARCH64_INSN_IMM_26);
+                       }
                        break;
 
                default: