parse_vdso.c is crashing on 5.8-rc5 s390x, because it wrongly reads nbucket as 0: Program received signal SIGFPE, Arithmetic exception. 0x0000000001000f3e in vdso_sym (version=0x1001280 "LINUX_2.6", name=0x100128a "__vdso_getcpu") at parse_vdso.c:207 207 ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; (gdb) p vdso_info.nbucket $1 = 0
Per readelf source: https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=binutils/readelf.c;h=2406304fe35a832ac53aa7b1a367f3f7afed4264;hb=HEAD#l10027 and objdump output hash entries are double size on 64bit s390 and alpha: 0000000000000120 <.hash>: 120: 00 00 00 00 .long 0x00000000 124: 00 00 00 03 .long 0x00000003 128: 00 00 00 00 .long 0x00000000 12c: 00 00 00 07 .long 0x00000007 130: 00 00 00 00 .long 0x00000000 134: 00 00 00 01 .long 0x00000001 138: 00 00 00 00 .long 0x00000000 13c: 00 00 00 05 .long 0x00000005 140: 00 00 00 00 .long 0x00000000 144: 00 00 00 06 .long 0x00000006 ... 16c: 00 00 00 02 .long 0x00000002 170: 00 00 00 00 .long 0x00000000 174: 00 00 00 03 .long 0x00000003 178: 00 00 00 00 .long 0x00000000 17c: 00 00 00 04 .long 0x00000004 Do similar check in parse_vdso.c and treat hash entries as double word. Signed-off-by: Jan Stancek <jstan...@redhat.com> --- tools/testing/selftests/vDSO/parse_vdso.c | 48 +++++++++++++++++++---- 1 file changed, 40 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c index 413f75620a35..e23efcbd1c88 100644 --- a/tools/testing/selftests/vDSO/parse_vdso.c +++ b/tools/testing/selftests/vDSO/parse_vdso.c @@ -47,8 +47,9 @@ static struct vdso_info /* Symbol table */ ELF(Sym) *symtab; const char *symstrings; - ELF(Word) *bucket, *chain; + void *bucket, *chain; ELF(Word) nbucket, nchain; + bool hash_ent_is_dword; /* Version table */ ELF(Versym) *versym; @@ -69,6 +70,28 @@ static unsigned long elf_hash(const unsigned char *name) return h; } +/* return value of hash table entry */ +ELF(Word) get_hash_val(void *ptr, ELF(Word) idx) +{ + if (vdso_info.hash_ent_is_dword) { + ELF(Xword) *table = ptr; + /* for vdso assume all values fit in Elf Word */ + return (ELF(Word)) table[idx]; + } + + ELF(Word) *table = ptr; + return table[idx]; +} + +/* return pointer to hash table entry */ +void *get_hash_ptr(void *ptr, ELF(Word) idx) +{ + if (vdso_info.hash_ent_is_dword) + return &((ELF(Xword) *) ptr)[idx]; + + return &((ELF(Word) *) ptr)[idx]; +} + void vdso_init_from_sysinfo_ehdr(uintptr_t base) { size_t i; @@ -84,6 +107,14 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) return; /* Wrong ELF class -- check ELF_BITS */ } + /* 64bit s390 and alpha have hash entry size of 8 bytes */ + if ((hdr->e_machine == EM_ALPHA + || hdr->e_machine == EM_S390) + && hdr->e_ident[EI_CLASS] == ELFCLASS64) + vdso_info.hash_ent_is_dword = true; + else + vdso_info.hash_ent_is_dword = false; + ELF(Phdr) *pt = (ELF(Phdr)*)(vdso_info.load_addr + hdr->e_phoff); ELF(Dyn) *dyn = 0; @@ -149,11 +180,11 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) if (!vdso_info.verdef) vdso_info.versym = 0; - /* Parse the hash table header. */ - vdso_info.nbucket = hash[0]; - vdso_info.nchain = hash[1]; - vdso_info.bucket = &hash[2]; - vdso_info.chain = &hash[vdso_info.nbucket + 2]; + + vdso_info.nbucket = get_hash_val(hash, 0); + vdso_info.nchain = get_hash_val(hash, 1); + vdso_info.bucket = get_hash_ptr(hash, 2); + vdso_info.chain = get_hash_ptr(hash, vdso_info.nbucket + 2); /* That's all we need. */ vdso_info.valid = true; @@ -204,9 +235,10 @@ void *vdso_sym(const char *version, const char *name) return 0; ver_hash = elf_hash(version); - ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; + ELF(Word) chain = get_hash_val(vdso_info.bucket, + elf_hash(name) % vdso_info.nbucket); - for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) { + for (; chain != STN_UNDEF; chain = get_hash_val(vdso_info.chain, chain)) { ELF(Sym) *sym = &vdso_info.symtab[chain]; /* Check for a defined global or weak function w/ right name. */ -- 2.18.1
