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builtins test: Move clear_cache_test.c from a mprotect()ed global to a mmap()ed variable 

ld64 in the macOS 10.15 SDK gives __DATA a maxprot of 3, meaning it
can't be made executable at runtime by default.

Change clear_cache_test.c to use mmap()ed data that's mapped as writable
and executable from the beginning, instead of trying to mprotect()ing a
__DATA variable as executable. This fixes the test on macOS with the
10.15 SDK.

PR43407.

Differential Revision: https://reviews.llvm.org/D67929

llvm-svn: 372849
This commit is contained in:
Nico Weber 2019-09-25 11:57:51 +00:00
parent 4d23bd528c
commit cddc153102
1 changed files with 21 additions and 28 deletions
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49
compiler-rt/test/builtins/Unit/clear_cache_test.c
View File

@ -13,25 +13,16 @@
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#if defined(_WIN32)
#include <windows.h>
static uintptr_t get_page_size() {
SYSTEM_INFO si;
GetSystemInfo(&si);
return si.dwPageSize;
}
#else
#include <unistd.h>
#include <sys/mman.h>
static uintptr_t get_page_size() {
return sysconf(_SC_PAGE_SIZE);
}
#endif
extern void __clear_cache(void* start, void* end);
typedef int (*pfunc)(void);
// Make these static to avoid ILT jumps for incremental linking on Windows.
@ -51,34 +42,36 @@ memcpy_f(void *dst, const void *src, size_t n) {
#endif
}
unsigned char execution_buffer[128] __attribute__((aligned(8)));
int main()
{
// make executable the page containing execution_buffer
uintptr_t page_size = get_page_size();
char* start = (char*)((uintptr_t)execution_buffer & (-page_size));
char* end = (char*)((uintptr_t)(&execution_buffer[128+page_size]) & (-page_size));
#if defined(_WIN32)
DWORD dummy_oldProt;
MEMORY_BASIC_INFORMATION b;
if (!VirtualQuery(start, &b, sizeof(b)))
return 1;
if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
const int kSize = 128;
#if !defined(_WIN32)
uint8_t *execution_buffer = mmap(0, kSize,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANON | MAP_PRIVATE, 0, 0);
if (execution_buffer == MAP_FAILED)
return 1;
#else
if (mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
#endif
HANDLE mapping = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
PAGE_EXECUTE_READWRITE, 0, kSize, NULL);
if (mapping == NULL)
return 1;
uint8_t* execution_buffer = MapViewOfFile(
mapping, FILE_MAP_ALL_ACCESS | FILE_MAP_EXECUTE, 0, 0, 0);
if (execution_buffer == NULL)
return 1;
#endif
// verify you can copy and execute a function
pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
__clear_cache(execution_buffer, &execution_buffer[128]);
pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, kSize);
__clear_cache(execution_buffer, execution_buffer + kSize);
if ((*f1)() != 1)
return 1;
// verify you can overwrite a function with another
pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
__clear_cache(execution_buffer, &execution_buffer[128]);
pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, kSize);
__clear_cache(execution_buffer, execution_buffer + kSize);
if ((*f2)() != 2)
return 1;