1 //===-- sanitizer_coverage_win_sections.cc --------------------------------===// 2 // 3 // This file is distributed under the University of Illinois Open Source 4 // License. See LICENSE.TXT for details. 5 // 6 //===----------------------------------------------------------------------===// 7 // 8 // This file defines delimiters for Sanitizer Coverage's section. It contains 9 // Windows specific tricks to coax the linker into giving us the start and stop 10 // addresses of a section, as ELF linkers can do, to get the size of certain 11 // arrays. According to https://msdn.microsoft.com/en-us/library/7977wcck.aspx 12 // sections with the same name before "$" are sorted alphabetically by the 13 // string that comes after "$" and merged into one section. We take advantage 14 // of this by putting data we want the size of into the middle (M) of a section, 15 // by using the letter "M" after "$". We get the start of this data (ie: 16 // __start_section_name) by making the start variable come at the start of the 17 // section (using the letter A after "$"). We do the same to get the end of the 18 // data by using the letter "Z" after "$" to make the end variable come after 19 // the data. Note that because of our technique the address of the start 20 // variable is actually the address of data that comes before our middle 21 // section. We also need to prevent the linker from adding any padding. Each 22 // technique we use for this is explained in the comments below. 23 //===----------------------------------------------------------------------===// 24 25 #include "sanitizer_platform.h" 26 #if SANITIZER_WINDOWS 27 #include <stdint.h> 28 extern "C" { 29 // The Guard array and counter array should both be merged into the .data 30 // section to reduce the number of PE sections However, because PCTable is 31 // constant it should be merged with the .rdata section. 32 #pragma section(".SCOV$GA", read, write) // NOLINT 33 // Use align(1) to avoid adding any padding that will mess up clients trying to 34 // determine the start and end of the array. 35 __declspec(allocate(".SCOV$GA")) __declspec(align(1)) uint64_t 36 __start___sancov_guards = 0; 37 #pragma section(".SCOV$GZ", read, write) // NOLINT 38 __declspec(allocate(".SCOV$GZ")) __declspec(align(1)) uint64_t 39 __stop___sancov_guards = 0; 40 41 #pragma section(".SCOV$CA", read, write) // NOLINT 42 __declspec(allocate(".SCOV$CA")) __declspec(align(1)) uint64_t 43 __start___sancov_cntrs = 0; 44 #pragma section(".SCOV$CZ", read, write) // NOLINT 45 __declspec(allocate(".SCOV$CZ")) __declspec(align(1)) uint64_t 46 __stop___sancov_cntrs = 0; 47 48 #pragma comment(linker, "/MERGE:.SCOV=.data") 49 50 // Use uint64_t so there won't be any issues if the linker tries to word align 51 // the pc array. 52 #pragma section(".SCOVP$A", read) // NOLINT 53 __declspec(allocate(".SCOVP$A")) __declspec(align(1)) uint64_t 54 __start___sancov_pcs = 0; 55 #pragma section(".SCOVP$Z", read) // NOLINT 56 __declspec(allocate(".SCOVP$Z")) __declspec(align(1)) uint64_t 57 __stop___sancov_pcs = 0; 58 59 #pragma comment(linker, "/MERGE:.SCOVP=.rdata") 60 } 61 #endif // SANITIZER_WINDOWS 62