tools/testing/selftests/vDSO/parse_vdso.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/vDSO/parse_vdso.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/vDSO/parse_vdso.c
Extension
.c
Size
7543 bytes
Lines
300
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (pt[i].p_type == PT_LOAD && !found_vaddr) {
			found_vaddr = true;
			vdso_info.load_offset =	base
				+ (uintptr_t)pt[i].p_offset
				- (uintptr_t)pt[i].p_vaddr;
		} else if (pt[i].p_type == PT_DYNAMIC) {
			dyn = (ELF(Dyn)*)(base + pt[i].p_offset);
		}
	}

	if (!found_vaddr || !dyn)
		return;  /* Failed */

	/*
	 * Fish out the useful bits of the dynamic table.
	 */
	ELF_HASH_ENTRY *hash = 0;
	vdso_info.symstrings = 0;
	vdso_info.gnu_hash = 0;
	vdso_info.symtab = 0;
	vdso_info.versym = 0;
	vdso_info.verdef = 0;
	for (i = 0; dyn[i].d_tag != DT_NULL; i++) {
		switch (dyn[i].d_tag) {
		case DT_STRTAB:
			vdso_info.symstrings = (const char *)
				((uintptr_t)dyn[i].d_un.d_ptr
				 + vdso_info.load_offset);
			break;
		case DT_SYMTAB:
			vdso_info.symtab = (ELF(Sym) *)
				((uintptr_t)dyn[i].d_un.d_ptr
				 + vdso_info.load_offset);
			break;
		case DT_HASH:
			hash = (ELF_HASH_ENTRY *)
				((uintptr_t)dyn[i].d_un.d_ptr
				 + vdso_info.load_offset);
			break;
		case DT_GNU_HASH:
			vdso_info.gnu_hash =
				(ELF(Word) *)((uintptr_t)dyn[i].d_un.d_ptr +
					      vdso_info.load_offset);
			break;
		case DT_VERSYM:
			vdso_info.versym = (ELF(Versym) *)
				((uintptr_t)dyn[i].d_un.d_ptr
				 + vdso_info.load_offset);
			break;
		case DT_VERDEF:
			vdso_info.verdef = (ELF(Verdef) *)
				((uintptr_t)dyn[i].d_un.d_ptr
				 + vdso_info.load_offset);
			break;
		}
	}
	if (!vdso_info.symstrings || !vdso_info.symtab ||
	    (!hash && !vdso_info.gnu_hash))
		return;  /* Failed */

	if (!vdso_info.verdef)
		vdso_info.versym = 0;

	/* Parse the hash table header. */
	if (vdso_info.gnu_hash) {
		vdso_info.nbucket = vdso_info.gnu_hash[0];
		/* The bucket array is located after the header (4 uint32) and the bloom
		 * filter (size_t array of gnu_hash[2] elements).
		 */
		vdso_info.gnu_bucket = vdso_info.gnu_hash + 4 +
				       sizeof(size_t) / 4 * vdso_info.gnu_hash[2];
	} else {
		vdso_info.nbucket = hash[0];
		vdso_info.nchain = hash[1];
		vdso_info.bucket = &hash[2];
		vdso_info.chain = &hash[vdso_info.nbucket + 2];
	}

	/* That's all we need. */
	vdso_info.valid = true;
}

static bool vdso_match_version(ELF(Versym) ver,
			       const char *name, ELF(Word) hash)
{
	/*
	 * This is a helper function to check if the version indexed by
	 * ver matches name (which hashes to hash).
	 *
	 * The version definition table is a mess, and I don't know how

Annotation

Implementation Notes