b81980a376
Fix the logic used to calculate page boundaries in clear_cache_test to use correct masks -- e.g. -4096 rather than -4095. The latter gives incorrect result since: -4095 -> 0xfffff001 -4096 -> 0xfffff000 (== ~4095) The issue went unnoticed so far because the array alignment caused the last bit not to be set. However, on 32-bit x86 no such alignment is enforced and the wrong page address caused the test to fail. Furthermore, obtain the page size from the system instead of hardcoding 4096. Differential Revision: https://reviews.llvm.org/D28849 llvm-svn: 292729
98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
//===-- clear_cache_test.c - Test clear_cache -----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include <stdio.h>
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#include <string.h>
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#include <stdint.h>
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#if defined(_WIN32)
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#include <windows.h>
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void __clear_cache(void* start, void* end)
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{
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if (!FlushInstructionCache(GetCurrentProcess(), start, end-start))
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exit(1);
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}
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static uintptr_t get_page_size() {
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SYSTEM_INFO si;
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GetSystemInfo(&si);
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return si.dwPageSize;
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}
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#else
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#include <unistd.h>
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#include <sys/mman.h>
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extern void __clear_cache(void* start, void* end);
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static uintptr_t get_page_size() {
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return sysconf(_SC_PAGE_SIZE);
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}
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#endif
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typedef int (*pfunc)(void);
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int func1()
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{
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return 1;
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}
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int func2()
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{
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return 2;
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}
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void *__attribute__((noinline))
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memcpy_f(void *dst, const void *src, size_t n) {
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// ARM and MIPS nartually align functions, but use the LSB for ISA selection
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// (THUMB, MIPS16/uMIPS respectively). Ensure that the ISA bit is ignored in
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// the memcpy
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#if defined(__arm__) || defined(__mips__)
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return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) |
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((uintptr_t)src & 1));
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#else
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return memcpy(dst, (void *)((uintptr_t)src), n);
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#endif
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}
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unsigned char execution_buffer[128];
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int main()
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{
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// make executable the page containing execution_buffer
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uintptr_t page_size = get_page_size();
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char* start = (char*)((uintptr_t)execution_buffer & (-page_size));
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char* end = (char*)((uintptr_t)(&execution_buffer[128+page_size]) & (-page_size));
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#if defined(_WIN32)
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DWORD dummy_oldProt;
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MEMORY_BASIC_INFORMATION b;
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if (!VirtualQuery(start, &b, sizeof(b)))
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return 1;
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if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
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#else
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if (mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
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#endif
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return 1;
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// verify you can copy and execute a function
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pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
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__clear_cache(execution_buffer, &execution_buffer[128]);
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if ((*f1)() != 1)
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return 1;
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// verify you can overwrite a function with another
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pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
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__clear_cache(execution_buffer, &execution_buffer[128]);
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if ((*f2)() != 2)
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return 1;
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return 0;
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}
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