diff options
Diffstat (limited to 'compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cpp')
-rw-r--r-- | compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cpp | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cpp new file mode 100644 index 000000000000..e7d6563393cf --- /dev/null +++ b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cpp @@ -0,0 +1,67 @@ +//===-- sanitizer_coverage_win_sections.cpp -------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file defines delimiters for Sanitizer Coverage's section. It contains +// Windows specific tricks to coax the linker into giving us the start and stop +// addresses of a section, as ELF linkers can do, to get the size of certain +// arrays. According to https://msdn.microsoft.com/en-us/library/7977wcck.aspx +// sections with the same name before "$" are sorted alphabetically by the +// string that comes after "$" and merged into one section. We take advantage +// of this by putting data we want the size of into the middle (M) of a section, +// by using the letter "M" after "$". We get the start of this data (ie: +// __start_section_name) by making the start variable come at the start of the +// section (using the letter A after "$"). We do the same to get the end of the +// data by using the letter "Z" after "$" to make the end variable come after +// the data. Note that because of our technique the address of the start +// variable is actually the address of data that comes before our middle +// section. We also need to prevent the linker from adding any padding. Each +// technique we use for this is explained in the comments below. +//===----------------------------------------------------------------------===// + +#include "sanitizer_platform.h" +#if SANITIZER_WINDOWS +#include <stdint.h> + +extern "C" { +// Use uint64_t so the linker won't need to add any padding if it tries to word +// align the start of the 8-bit counters array. The array will always start 8 +// bytes after __start_sancov_cntrs. +#pragma section(".SCOV$CA", read, write) +__declspec(allocate(".SCOV$CA")) uint64_t __start___sancov_cntrs = 0; + +// Even though we said not to align __stop__sancov_cntrs (using the "align" +// declspec), MSVC's linker may try to align the section, .SCOV$CZ, containing +// it. This can cause a mismatch between the number of PCs and counters since +// each PCTable element is 8 bytes (unlike counters which are 1 byte) so no +// padding would be added to align .SCOVP$Z, However, if .SCOV$CZ section is 1 +// byte, the linker won't try to align it on an 8-byte boundary, so use a +// uint8_t for __stop_sancov_cntrs. +#pragma section(".SCOV$CZ", read, write) +__declspec(allocate(".SCOV$CZ")) __declspec(align(1)) uint8_t + __stop___sancov_cntrs = 0; + +#pragma section(".SCOV$GA", read, write) +__declspec(allocate(".SCOV$GA")) uint64_t __start___sancov_guards = 0; +#pragma section(".SCOV$GZ", read, write) +__declspec(allocate(".SCOV$GZ")) __declspec(align(1)) uint8_t + __stop___sancov_guards = 0; + +// The guard array and counter array should both be merged into the .data +// section to reduce the number of PE sections. However, because PCTable is +// constant it should be merged with the .rdata section. +#pragma comment(linker, "/MERGE:.SCOV=.data") + +#pragma section(".SCOVP$A", read) +__declspec(allocate(".SCOVP$A")) uint64_t __start___sancov_pcs = 0; +#pragma section(".SCOVP$Z", read) +__declspec(allocate(".SCOVP$Z")) __declspec(align(1)) uint8_t + __stop___sancov_pcs = 0; + +#pragma comment(linker, "/MERGE:.SCOVP=.rdata") +} +#endif // SANITIZER_WINDOWS |