[compiler-rt] r200384 - [asan] experimental intercetor for __tls_get_addr. So far it does nothing interesting, actual usage will come later. See https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM for background
Alexander Potapenko
glider at google.com
Wed Jan 29 02:16:38 PST 2014
Note that __tls_get_addr is unavailable on OSX
On Wed, Jan 29, 2014 at 1:29 PM, Kostya Serebryany <kcc at google.com> wrote:
> Author: kcc
> Date: Wed Jan 29 03:29:16 2014
> New Revision: 200384
>
> URL: http://llvm.org/viewvc/llvm-project?rev=200384&view=rev
> Log:
> [asan] experimental intercetor for __tls_get_addr. So far it does nothing interesting, actual usage will come later. See https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM for background
>
> Added:
> compiler-rt/trunk/lib/asan/lit_tests/TestCases/Linux/stress_dtls.c
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.cc
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.h
> Modified:
> compiler-rt/trunk/lib/asan/asan_malloc_linux.cc
> compiler-rt/trunk/lib/asan/asan_thread.cc
> compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_interceptors.h
>
> Modified: compiler-rt/trunk/lib/asan/asan_malloc_linux.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_malloc_linux.cc?rev=200384&r1=200383&r2=200384&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/asan_malloc_linux.cc (original)
> +++ compiler-rt/trunk/lib/asan/asan_malloc_linux.cc Wed Jan 29 03:29:16 2014
> @@ -17,6 +17,7 @@
> #include "sanitizer_common/sanitizer_platform.h"
> #if SANITIZER_LINUX
>
> +#include "sanitizer_common/sanitizer_tls_get_addr.h"
> #include "asan_allocator.h"
> #include "asan_interceptors.h"
> #include "asan_internal.h"
> @@ -101,8 +102,12 @@ INTERCEPTOR(void*, memalign, uptr bounda
> return asan_memalign(boundary, size, &stack, FROM_MALLOC);
> }
>
> -INTERCEPTOR(void*, __libc_memalign, uptr align, uptr s)
> - ALIAS("memalign");
> +INTERCEPTOR(void*, __libc_memalign, uptr boundary, uptr size) {
> + GET_STACK_TRACE_MALLOC;
> + void *res = asan_memalign(boundary, size, &stack, FROM_MALLOC);
> + DTLS_on_libc_memalign(res, size * boundary);
> + return res;
> +}
>
> INTERCEPTOR(uptr, malloc_usable_size, void *ptr) {
> GET_CURRENT_PC_BP_SP;
>
> Modified: compiler-rt/trunk/lib/asan/asan_thread.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_thread.cc?rev=200384&r1=200383&r2=200384&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/asan_thread.cc (original)
> +++ compiler-rt/trunk/lib/asan/asan_thread.cc Wed Jan 29 03:29:16 2014
> @@ -20,6 +20,7 @@
> #include "sanitizer_common/sanitizer_common.h"
> #include "sanitizer_common/sanitizer_placement_new.h"
> #include "sanitizer_common/sanitizer_stackdepot.h"
> +#include "sanitizer_common/sanitizer_tls_get_addr.h"
> #include "lsan/lsan_common.h"
>
> namespace __asan {
> @@ -107,6 +108,7 @@ void AsanThread::Destroy() {
> DeleteFakeStack(tid);
> uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
> UnmapOrDie(this, size);
> + DTLS_Destroy();
> }
>
> // We want to create the FakeStack lazyly on the first use, but not eralier
>
> Added: compiler-rt/trunk/lib/asan/lit_tests/TestCases/Linux/stress_dtls.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/lit_tests/TestCases/Linux/stress_dtls.c?rev=200384&view=auto
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/lit_tests/TestCases/Linux/stress_dtls.c (added)
> +++ compiler-rt/trunk/lib/asan/lit_tests/TestCases/Linux/stress_dtls.c Wed Jan 29 03:29:16 2014
> @@ -0,0 +1,102 @@
> +// REQUIRES: asan-64-bits
> +// Stress test dynamic TLS + dlopen + threads.
> +//
> +// Note that glibc 2.15 seems utterly broken on this test,
> +// it fails with ~17 DSOs dlopen-ed.
> +// glibc 2.19 seems fine.
> +//
> +//
> +// RUN: %clangxx_asan -x c -DSO_NAME=f0 %s -shared -o %t-f0.so -fPIC
> +// RUN: %clangxx_asan -x c -DSO_NAME=f1 %s -shared -o %t-f1.so -fPIC
> +// RUN: %clangxx_asan -x c -DSO_NAME=f2 %s -shared -o %t-f2.so -fPIC
> +// RUN: %clangxx_asan %s -o %t
> +// RUN: %t 0 3
> +// RUN: %t 2 3
> +// RUN: ASAN_OPTIONS=verbosity=2 %t 2 2 2>&1 | FileCheck %s
> +// CHECK: __tls_get_addr
> +// CHECK: __tls_get_addr
> +// CHECK: __tls_get_addr
> +// CHECK: __tls_get_addr
> +// CHECK: __tls_get_addr
> +/*
> +cc=your-compiler
> +
> +$cc stress_dtls.c -lpthread -ldl
> +for((i=0;i<100;i++)); do
> + $cc -fPIC -shared -DSO_NAME=f$i -o a.out-f$i.so stress_dtls.c;
> +done
> +./a.out 2 4 # <<<<<< 2 threads, 4 libs
> +./a.out 3 50 # <<<<<< 3 threads, 50 libs
> +*/
> +#ifndef SO_NAME
> +#define _GNU_SOURCE
> +#include <assert.h>
> +#include <dlfcn.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <pthread.h>
> +#include <stdint.h>
> +
> +typedef void **(*f_t)();
> +
> +__thread int my_tls;
> +
> +#define MAX_N_FUNCTIONS 1000
> +f_t Functions[MAX_N_FUNCTIONS];
> +
> +void *PrintStuff(void *unused) {
> + uintptr_t stack;
> + // fprintf(stderr, "STACK: %p TLS: %p SELF: %p\n", &stack, &my_tls,
> + // (void *)pthread_self());
> + int i;
> + for (i = 0; i < MAX_N_FUNCTIONS; i++) {
> + if (!Functions[i]) break;
> + uintptr_t dtls = (uintptr_t)Functions[i]();
> + fprintf(stderr, " dtls[%03d]: %lx\n", i, dtls);
> + *(long*)dtls = 42; // check that this is writable.
> + }
> + return NULL;
> +}
> +
> +int main(int argc, char *argv[]) {
> + int num_threads = 1;
> + int num_libs = 1;
> + if (argc >= 2)
> + num_threads = atoi(argv[1]);
> + if (argc >= 3)
> + num_libs = atoi(argv[2]);
> + assert(num_libs <= MAX_N_FUNCTIONS);
> +
> + int lib;
> + for (lib = 0; lib < num_libs; lib++) {
> + char buf[4096];
> + snprintf(buf, sizeof(buf), "%s-f%d.so", argv[0], lib);
> + void *handle = dlopen(buf, RTLD_LAZY);
> + if (!handle) {
> + fprintf(stderr, "%s\n", dlerror());
> + exit(1);
> + }
> + snprintf(buf, sizeof(buf), "f%d", lib);
> + Functions[lib] = (f_t)dlsym(handle, buf);
> + if (!Functions[lib]) {
> + fprintf(stderr, "%s\n", dlerror());
> + exit(1);
> + }
> + fprintf(stderr, "LIB[%03d] %s: %p\n", lib, buf, Functions[lib]);
> + PrintStuff(0);
> +
> + int i;
> + for (i = 0; i < num_threads; i++) {
> + pthread_t t;
> + pthread_create(&t, 0, PrintStuff, 0);
> + pthread_join(t, 0);
> + }
> + }
> + return 0;
> +}
> +#else // SO_NAME
> +__thread void *huge_thread_local_array[1 << 17];
> +void **SO_NAME() {
> + return &huge_thread_local_array[0];
> +}
> +#endif
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt?rev=200384&r1=200383&r2=200384&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt Wed Jan 29 03:29:16 2014
> @@ -22,6 +22,7 @@ set(SANITIZER_SOURCES
> sanitizer_symbolizer.cc
> sanitizer_symbolizer_libbacktrace.cc
> sanitizer_symbolizer_win.cc
> + sanitizer_tls_get_addr.cc
> sanitizer_thread_registry.cc
> sanitizer_win.cc)
>
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc?rev=200384&r1=200383&r2=200384&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc Wed Jan 29 03:29:16 2014
> @@ -29,6 +29,7 @@
> //===----------------------------------------------------------------------===//
> #include "interception/interception.h"
> #include "sanitizer_platform_interceptors.h"
> +#include "sanitizer_tls_get_addr.h"
>
> #include <stdarg.h>
>
> @@ -3063,10 +3064,23 @@ INTERCEPTOR(__sanitizer_clock_t, times,
> return res;
> }
> #define INIT_TIMES COMMON_INTERCEPT_FUNCTION(times);
> +INTERCEPTOR(void *, __tls_get_addr, void *arg) {
> + void *ctx;
> + COMMON_INTERCEPTOR_ENTER(ctx, __tls_get_addr, arg);
> + void *res = REAL(__tls_get_addr)(arg);
> + DTLS_on_tls_get_addr(arg, res);
> + return res;
> +}
> #else
> #define INIT_TIMES
> #endif
>
> +#if SANITIZER_INTERCEPT_TLS_GET_ADDR
> +#define INIT_TLS_GET_ADDR COMMON_INTERCEPT_FUNCTION(__tls_get_addr)
> +#else
> +#define INIT_TLS_GET_ADDR
> +#endif
> +
> #define SANITIZER_COMMON_INTERCEPTORS_INIT \
> INIT_TEXTDOMAIN; \
> INIT_STRCMP; \
> @@ -3182,4 +3196,5 @@ INTERCEPTOR(__sanitizer_clock_t, times,
> INIT_GETLINE; \
> INIT_ICONV; \
> INIT_TIMES; \
> + INIT_TLS_GET_ADDR; \
> /**/
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_interceptors.h
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_interceptors.h?rev=200384&r1=200383&r2=200384&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_interceptors.h (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_interceptors.h Wed Jan 29 03:29:16 2014
> @@ -177,4 +177,6 @@
> #define SANITIZER_INTERCEPT_PTHREAD_COND SI_NOT_WINDOWS
> #define SANITIZER_INTERCEPT_PTHREAD_SETNAME_NP SI_LINUX_NOT_ANDROID
>
> +#define SANITIZER_INTERCEPT_TLS_GET_ADDR SI_LINUX_NOT_ANDROID
> +
> #endif // #ifndef SANITIZER_PLATFORM_INTERCEPTORS_H
>
> Added: compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.cc?rev=200384&view=auto
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.cc (added)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.cc Wed Jan 29 03:29:16 2014
> @@ -0,0 +1,114 @@
> +//===-- sanitizer_tls_get_addr.cc -----------------------------------------===//
> +//
> +// The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// Handle the __tls_get_addr call.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#include "sanitizer_tls_get_addr.h"
> +
> +#include "sanitizer_flags.h"
> +#include "sanitizer_platform_interceptors.h"
> +
> +namespace __sanitizer {
> +#if SANITIZER_INTERCEPT_TLS_GET_ADDR
> +
> +// The actual parameter that comes to __tls_get_addr
> +// is a pointer to a struct with two words in it:
> +struct TlsGetAddrParam {
> + uptr dso_id;
> + uptr offset;
> +};
> +
> +// Glibc starting from 2.19 allocates tls using __signal_safe_memalign,
> +// which has such header.
> +struct Glibc_2_19_tls_header {
> + uptr size;
> + uptr start;
> +};
> +
> +// This must be static TLS, i.e. the run-time should be build with
> +// -ftls-model=initial-exec or equivalent.
> +static __thread DTLS dtls;
> +
> +// Make sure we properly destroy the DTLS objects:
> +// this counter should never get too large.
> +static atomic_uintptr_t number_of_live_dtls;
> +
> +static const uptr kDestroyedThread = -1;
> +
> +static inline void DTLS_Resize(uptr new_size) {
> + if (dtls.dtv_size >= new_size) return;
> + new_size = RoundUpToPowerOfTwo(new_size);
> + new_size = Max(new_size, 4096UL / sizeof(DTLS::DTV));
> + DTLS::DTV *new_dtv =
> + (DTLS::DTV *)MmapOrDie(new_size * sizeof(DTLS::DTV), "DTLS_Resize");
> + CHECK_LT(atomic_fetch_add(&number_of_live_dtls, 1, memory_order_relaxed),
> + 1 << 20);
> + if (dtls.dtv_size)
> + internal_memcpy(new_dtv, dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
> + DTLS_Destroy();
> + dtls.dtv = new_dtv;
> + dtls.dtv_size = new_size;
> +}
> +
> +void DTLS_Destroy() {
> + if (!dtls.dtv_size) return;
> + UnmapOrDie(dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
> + atomic_fetch_sub(&number_of_live_dtls, 1, memory_order_relaxed);
> + dtls.dtv_size = kDestroyedThread;
> +}
> +
> +void DTLS_on_tls_get_addr(void *arg_void, void *res) {
> + TlsGetAddrParam *arg = reinterpret_cast<TlsGetAddrParam *>(arg_void);
> + uptr dso_id = arg->dso_id;
> + if (dtls.dtv_size == kDestroyedThread) return;
> + DTLS_Resize(dso_id + 1);
> + if (dtls.dtv[dso_id].beg)
> + return;
> + uptr tls_size = 0;
> + uptr tls_beg = reinterpret_cast<uptr>(res) - arg->offset;
> + VPrintf(2, "__tls_get_addr: %p {%p,%p} => %p; tls_beg: %p\n", arg,
> + arg->dso_id, arg->offset, res, tls_beg);
> + if (dtls.last_memalign_ptr == tls_beg) {
> + tls_size = dtls.last_memalign_size;
> + VPrintf(2, "__tls_get_addr: glibc <=2.18 suspected; tls={%p,%p}\n", tls_beg,
> + tls_size);
> + } else if ((tls_beg % 4096) == sizeof(Glibc_2_19_tls_header)) {
> + // We may want to check gnu_get_libc_version().
> + Glibc_2_19_tls_header *header = (Glibc_2_19_tls_header *)tls_beg - 1;
> + tls_size = header->size;
> + tls_beg = header->start;
> + VPrintf(2, "__tls_get_addr: glibc >=2.19 suspected; tls={%p %p}\n", tls_beg,
> + tls_size);
> + } else {
> + VPrintf(2, "__tls_get_addr: Can't guess glibc version\n");
> + // This may happen inside the DTOR of main thread, so just ignore it.
> + tls_size = 0;
> + }
> + dtls.dtv[dso_id].beg = tls_beg;
> + dtls.dtv[dso_id].size = tls_size;
> +}
> +
> +void DTLS_on_libc_memalign(void *ptr, uptr size) {
> + VPrintf(2, "DTLS_on_libc_memalign: %p %p\n", ptr, size);
> + dtls.last_memalign_ptr = reinterpret_cast<uptr>(ptr);
> + dtls.last_memalign_size = size;
> +}
> +
> +DTLS *DTLS_Get() { return &dtls; }
> +
> +#else
> +void DTLS_on_libc_memalign(void *ptr, uptr size) {}
> +void DTLS_on_tls_get_addr(void *arg, void *res) {}
> +DTLS *DTLS_Get() { return 0; }
> +void DTLS_Destroy() {}
> +#endif // SANITIZER_INTERCEPT_TLS_GET_ADDR
> +
> +} // namespace __sanitizer
>
> Added: compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.h
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.h?rev=200384&view=auto
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.h (added)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_tls_get_addr.h Wed Jan 29 03:29:16 2014
> @@ -0,0 +1,58 @@
> +//===-- sanitizer_tls_get_addr.h --------------------------------*- C++ -*-===//
> +//
> +// The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// Handle the __tls_get_addr call.
> +//
> +// All this magic is specific to glibc and is required to workaround
> +// the lack of interface that would tell us about the Dynamic TLS (DTLS).
> +// https://sourceware.org/bugzilla/show_bug.cgi?id=16291
> +//
> +// The matters get worse because the glibc implementation changed between
> +// 2.18 and 2.19:
> +// https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM
> +//
> +// Before 2.19, every DTLS chunk is allocated with __libc_memalign,
> +// which we intercept and thus know where is the DTLS.
> +// Since 2.19, DTLS chunks are allocated with __signal_safe_memalign,
> +// which is an internal function that wraps a mmap call, neither of which
> +// we can intercept. Luckily, __signal_safe_memalign has a simple parseable
> +// header which we can use.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#ifndef SANITIZER_TLS_GET_ADDR_H
> +#define SANITIZER_TLS_GET_ADDR_H
> +
> +#include "sanitizer_common.h"
> +
> +namespace __sanitizer {
> +
> +struct DTLS {
> + // Array of DTLS chunks for the current Thread.
> + // If beg == 0, the chunk is unused.
> + struct DTV {
> + uptr beg, size;
> + };
> +
> + uptr dtv_size;
> + DTV *dtv; // dtv_size elements, allocated by MmapOrDie.
> +
> + // Auxilary fields, don't access them outside sanitizer_tls_get_addr.cc
> + uptr last_memalign_size;
> + uptr last_memalign_ptr;
> +};
> +
> +void DTLS_on_tls_get_addr(void *arg, void *res);
> +void DTLS_on_libc_memalign(void *ptr, uptr size);
> +DTLS *DTLS_Get();
> +void DTLS_Destroy(); // Make sure to call this before the thread is destroyed.
> +
> +} // namespace __sanitizer
> +
> +#endif // SANITIZER_TLS_GET_ADDR_H
>
>
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> llvm-commits at cs.uiuc.edu
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--
Alexander Potapenko
Software Engineer
Google Moscow
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