tests/tcg/linux-test: Add linux-madvise test

Add a test that checks madvise(MADV_DONTNEED) behavior with anonymous
and file mappings in order to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220906000839.1672934-6-iii@linux.ibm.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

tests/tcg/multiarch/linux/linux-madvise.c

@@ -0,0 +1,70 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+static void test_anonymous(void)
+{
+    int pagesize = getpagesize();
+    char *page;
+    int ret;
+
+    page = mmap(NULL, pagesize, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+    assert(page != MAP_FAILED);
+
+    /* Check that mprotect() does not interfere with MADV_DONTNEED. */
+    ret = mprotect(page, pagesize, PROT_READ | PROT_WRITE);
+    assert(ret == 0);
+
+    /* Check that MADV_DONTNEED clears the page. */
+    *page = 42;
+    ret = madvise(page, pagesize, MADV_DONTNEED);
+    assert(ret == 0);
+    assert(*page == 0);
+
+    ret = munmap(page, pagesize);
+    assert(ret == 0);
+}
+
+static void test_file(void)
+{
+    char tempname[] = "/tmp/.cmadviseXXXXXX";
+    int pagesize = getpagesize();
+    ssize_t written;
+    char c = 42;
+    char *page;
+    int ret;
+    int fd;
+
+    fd = mkstemp(tempname);
+    assert(fd != -1);
+    ret = unlink(tempname);
+    assert(ret == 0);
+    written = write(fd, &c, sizeof(c));
+    assert(written == sizeof(c));
+    page = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE, fd, 0);
+    assert(page != MAP_FAILED);
+
+    /* Check that mprotect() does not interfere with MADV_DONTNEED. */
+    ret = mprotect(page, pagesize, PROT_READ | PROT_WRITE);
+    assert(ret == 0);
+
+    /* Check that MADV_DONTNEED resets the page. */
+    *page = 0;
+    ret = madvise(page, pagesize, MADV_DONTNEED);
+    assert(ret == 0);
+    assert(*page == c);
+
+    ret = munmap(page, pagesize);
+    assert(ret == 0);
+    ret = close(fd);
+    assert(ret == 0);
+}
+
+int main(void)
+{
+    test_anonymous();
+    test_file();
+
+    return EXIT_SUCCESS;
+}