1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Provide kernel BTF information for introspection and use by eBPF tools. 4 */ 5 #include <linux/kernel.h> 6 #include <linux/module.h> 7 #include <linux/kobject.h> 8 #include <linux/init.h> 9 #include <linux/sysfs.h> 10 #include <linux/mm.h> 11 #include <linux/io.h> 12 #include <linux/btf.h> 13 14 /* See scripts/link-vmlinux.sh, gen_btf() func for details */ 15 extern char __start_BTF[]; 16 extern char __stop_BTF[]; 17 18 static int btf_sysfs_vmlinux_mmap(struct file *filp, struct kobject *kobj, 19 const struct bin_attribute *attr, 20 struct vm_area_struct *vma) 21 { 22 unsigned long pages = PAGE_ALIGN(attr->size) >> PAGE_SHIFT; 23 size_t vm_size = vma->vm_end - vma->vm_start; 24 phys_addr_t addr = virt_to_phys(__start_BTF); 25 unsigned long pfn = addr >> PAGE_SHIFT; 26 27 if (attr->private != __start_BTF || !PAGE_ALIGNED(addr)) 28 return -EINVAL; 29 30 if (vma->vm_pgoff) 31 return -EINVAL; 32 33 if (vma->vm_flags & (VM_WRITE | VM_EXEC | VM_MAYSHARE)) 34 return -EACCES; 35 36 if (pfn + pages < pfn) 37 return -EINVAL; 38 39 if ((vm_size >> PAGE_SHIFT) > pages) 40 return -EINVAL; 41 42 vm_flags_mod(vma, VM_DONTDUMP, VM_MAYEXEC | VM_MAYWRITE); 43 return remap_pfn_range(vma, vma->vm_start, pfn, vm_size, vma->vm_page_prot); 44 } 45 46 static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = { 47 .attr = { .name = "vmlinux", .mode = 0444, }, 48 .read_new = sysfs_bin_attr_simple_read, 49 .mmap = btf_sysfs_vmlinux_mmap, 50 }; 51 52 struct kobject *btf_kobj; 53 54 static int __init btf_vmlinux_init(void) 55 { 56 bin_attr_btf_vmlinux.private = __start_BTF; 57 bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF; 58 59 if (bin_attr_btf_vmlinux.size == 0) 60 return 0; 61 62 btf_kobj = kobject_create_and_add("btf", kernel_kobj); 63 if (!btf_kobj) 64 return -ENOMEM; 65 66 return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_vmlinux); 67 } 68 69 subsys_initcall(btf_vmlinux_init); 70