bb3a3da38d
Unmapping and remapping is dangerous since another thread could touch the shadow memory while it is unmapped. But there is really no need to unmap anyway, since mmap(MAP_FIXED) will happily clobber the existing mapping with zeroes. This is thread-safe since the mmap() is done under the same kernel lock as page faults are done. Reviewed By: vitalybuka Differential Revision: https://reviews.llvm.org/D85947
37 lines
1018 B
C
37 lines
1018 B
C
// Tests that doing dfsan_flush() while another thread is executing doesn't
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// segfault.
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// RUN: %clang_dfsan %s -o %t && %run %t
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#include <assert.h>
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#include <pthread.h>
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#include <sanitizer/dfsan_interface.h>
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#include <stdlib.h>
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static unsigned char GlobalBuf[4096];
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static int ShutDownThread;
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static int StartFlush;
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// Access GlobalBuf continuously, causing its shadow to be touched as well.
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// When main() calls dfsan_flush(), no segfault should be triggered.
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static void *accessGlobalInBackground(void *Arg) {
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__atomic_store_n(&StartFlush, 1, __ATOMIC_RELEASE);
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while (!__atomic_load_n(&ShutDownThread, __ATOMIC_ACQUIRE))
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for (unsigned I = 0; I < sizeof(GlobalBuf); ++I)
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++GlobalBuf[I];
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return NULL;
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}
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int main() {
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pthread_t Thread;
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pthread_create(&Thread, NULL, accessGlobalInBackground, NULL);
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while (!__atomic_load_n(&StartFlush, __ATOMIC_ACQUIRE))
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; // Spin
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dfsan_flush();
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__atomic_store_n(&ShutDownThread, 1, __ATOMIC_RELEASE);
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pthread_join(Thread, NULL);
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return 0;
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}
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