1 //===-- sanitizer_tls_get_addr.cc -----------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Handle the __tls_get_addr call.
12 //===----------------------------------------------------------------------===//
14 #include "sanitizer_tls_get_addr.h"
16 #include "sanitizer_flags.h"
17 #include "sanitizer_platform_interceptors.h"
19 namespace __sanitizer {
20 #if SANITIZER_INTERCEPT_TLS_GET_ADDR
22 // The actual parameter that comes to __tls_get_addr
23 // is a pointer to a struct with two words in it:
24 struct TlsGetAddrParam {
29 // Glibc starting from 2.19 allocates tls using __signal_safe_memalign,
30 // which has such header.
31 struct Glibc_2_19_tls_header {
36 // This must be static TLS
37 __attribute__((tls_model("initial-exec")))
38 static __thread DTLS dtls;
40 // Make sure we properly destroy the DTLS objects:
41 // this counter should never get too large.
42 static atomic_uintptr_t number_of_live_dtls;
44 static const uptr kDestroyedThread = -1;
46 static inline void DTLS_Deallocate(DTLS::DTV *dtv, uptr size) {
48 VPrintf(2, "__tls_get_addr: DTLS_Deallocate %p %zd\n", dtv, size);
49 UnmapOrDie(dtv, size * sizeof(DTLS::DTV));
50 atomic_fetch_sub(&number_of_live_dtls, 1, memory_order_relaxed);
53 static inline void DTLS_Resize(uptr new_size) {
54 if (dtls.dtv_size >= new_size) return;
55 new_size = RoundUpToPowerOfTwo(new_size);
56 new_size = Max(new_size, 4096UL / sizeof(DTLS::DTV));
58 (DTLS::DTV *)MmapOrDie(new_size * sizeof(DTLS::DTV), "DTLS_Resize");
60 atomic_fetch_add(&number_of_live_dtls, 1, memory_order_relaxed);
61 VPrintf(2, "__tls_get_addr: DTLS_Resize %p %zd\n", &dtls, num_live_dtls);
62 CHECK_LT(num_live_dtls, 1 << 20);
63 uptr old_dtv_size = dtls.dtv_size;
64 DTLS::DTV *old_dtv = dtls.dtv;
66 internal_memcpy(new_dtv, dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
68 dtls.dtv_size = new_size;
70 DTLS_Deallocate(old_dtv, old_dtv_size);
74 if (!common_flags()->intercept_tls_get_addr) return;
75 VPrintf(2, "__tls_get_addr: DTLS_Destroy %p %zd\n", &dtls, dtls.dtv_size);
76 uptr s = dtls.dtv_size;
77 dtls.dtv_size = kDestroyedThread; // Do this before unmap for AS-safety.
78 DTLS_Deallocate(dtls.dtv, s);
81 DTLS::DTV *DTLS_on_tls_get_addr(void *arg_void, void *res,
82 uptr static_tls_begin, uptr static_tls_end) {
83 if (!common_flags()->intercept_tls_get_addr) return 0;
84 TlsGetAddrParam *arg = reinterpret_cast<TlsGetAddrParam *>(arg_void);
85 uptr dso_id = arg->dso_id;
86 if (dtls.dtv_size == kDestroyedThread) return 0;
87 DTLS_Resize(dso_id + 1);
88 if (dtls.dtv[dso_id].beg) return 0;
90 uptr tls_beg = reinterpret_cast<uptr>(res) - arg->offset;
91 VPrintf(2, "__tls_get_addr: %p {%p,%p} => %p; tls_beg: %p; sp: %p "
92 "num_live_dtls %zd\n",
93 arg, arg->dso_id, arg->offset, res, tls_beg, &tls_beg,
94 atomic_load(&number_of_live_dtls, memory_order_relaxed));
95 if (dtls.last_memalign_ptr == tls_beg) {
96 tls_size = dtls.last_memalign_size;
97 VPrintf(2, "__tls_get_addr: glibc <=2.18 suspected; tls={%p,%p}\n",
99 } else if (tls_beg >= static_tls_begin && tls_beg < static_tls_end) {
100 // This is the static TLS block which was initialized / unpoisoned at thread
102 VPrintf(2, "__tls_get_addr: static tls: %p\n", tls_beg);
104 } else if ((tls_beg % 4096) == sizeof(Glibc_2_19_tls_header)) {
105 // We may want to check gnu_get_libc_version().
106 Glibc_2_19_tls_header *header = (Glibc_2_19_tls_header *)tls_beg - 1;
107 tls_size = header->size;
108 tls_beg = header->start;
109 VPrintf(2, "__tls_get_addr: glibc >=2.19 suspected; tls={%p %p}\n",
112 VPrintf(2, "__tls_get_addr: Can't guess glibc version\n");
113 // This may happen inside the DTOR of main thread, so just ignore it.
116 dtls.dtv[dso_id].beg = tls_beg;
117 dtls.dtv[dso_id].size = tls_size;
118 return dtls.dtv + dso_id;
121 void DTLS_on_libc_memalign(void *ptr, uptr size) {
122 if (!common_flags()->intercept_tls_get_addr) return;
123 VPrintf(2, "DTLS_on_libc_memalign: %p %p\n", ptr, size);
124 dtls.last_memalign_ptr = reinterpret_cast<uptr>(ptr);
125 dtls.last_memalign_size = size;
128 DTLS *DTLS_Get() { return &dtls; }
131 void DTLS_on_libc_memalign(void *ptr, uptr size) {}
132 DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res) { return 0; }
133 DTLS *DTLS_Get() { return 0; }
134 void DTLS_Destroy() {}
135 #endif // SANITIZER_INTERCEPT_TLS_GET_ADDR
137 } // namespace __sanitizer