tools/testing/selftests/powerpc/security/rfi_flush.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/powerpc/security/rfi_flush.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/powerpc/security/rfi_flush.c
Extension
.c
Size
3464 bytes
Lines
143
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (entry_flush_orig != 0) {
			if (write_debugfs_int("powerpc/entry_flush", 0) < 0) {
				perror("error writing to powerpc/entry_flush debugfs file");
				return 1;
			}
		}
	}

	rfi_flush = rfi_flush_orig;

	fd = perf_event_open_counter(PERF_TYPE_HW_CACHE, PERF_L1D_READ_MISS_CONFIG, -1);
	FAIL_IF(fd < 0);

	p = (char *)memalign(zero_size, CACHELINE_SIZE);

	FAIL_IF(perf_event_enable(fd));

	// disable L1 prefetching
	set_dscr(1);

	iter = repetitions;

	/*
	 * We expect to see l1d miss for each cacheline access when rfi_flush
	 * is set. Allow a small variation on this.
	 */
	l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);

again:
	FAIL_IF(perf_event_reset(fd));

	syscall_loop(p, iterations, zero_size);

	FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));

	if (rfi_flush && v.l1d_misses >= l1d_misses_expected)
		passes++;
	else if (!rfi_flush && v.l1d_misses < (l1d_misses_expected / 2))
		passes++;

	l1d_misses_total += v.l1d_misses;

	while (--iter)
		goto again;

	if (passes < repetitions) {
		printf("FAIL (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d failures]\n",
		       rfi_flush, l1d_misses_total, rfi_flush ? '<' : '>',
		       rfi_flush ? repetitions * l1d_misses_expected :
		       repetitions * l1d_misses_expected / 2,
		       repetitions - passes, repetitions);
		rc = 1;
	} else
		printf("PASS (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d pass]\n",
		       rfi_flush, l1d_misses_total, rfi_flush ? '>' : '<',
		       rfi_flush ? repetitions * l1d_misses_expected :
		       repetitions * l1d_misses_expected / 2,
		       passes, repetitions);

	if (rfi_flush == rfi_flush_orig) {
		rfi_flush = !rfi_flush_orig;
		if (write_debugfs_int("powerpc/rfi_flush", rfi_flush) < 0) {
			perror("error writing to powerpc/rfi_flush debugfs file");
			return 1;
		}
		iter = repetitions;
		l1d_misses_total = 0;
		passes = 0;
		goto again;
	}

	perf_event_disable(fd);
	close(fd);

	set_dscr(0);

	if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
		perror("unable to restore original value of powerpc/rfi_flush debugfs file");
		return 1;
	}

	if (have_entry_flush) {
		if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
			perror("unable to restore original value of powerpc/entry_flush "
			       "debugfs file");
			return 1;
		}
	}

	return rc;

Annotation

Implementation Notes