Validate stack switching and recursion depth.
Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
tests/tcg/aarch64/gcs.h | 9 ++++
tests/tcg/aarch64/gcsss.c | 74 +++++++++++++++++++++++++++++++
tests/tcg/aarch64/Makefile.target | 2 +-
3 files changed, 84 insertions(+), 1 deletion(-)
create mode 100644 tests/tcg/aarch64/gcsss.c
diff --git a/tests/tcg/aarch64/gcs.h b/tests/tcg/aarch64/gcs.h
index 99cb4d4e38..e821963cb8 100644
--- a/tests/tcg/aarch64/gcs.h
+++ b/tests/tcg/aarch64/gcs.h
@@ -69,3 +69,12 @@
#define gcspr() \
({ uint64_t *r; asm volatile("mrs %0, s3_3_c2_c5_1" : "=r"(r)); r; })
+
+#define gcsss1(val) \
+ do { \
+ asm volatile("sys #3, c7, c7, #2, %0" : : "r"(val) : "memory"); \
+ } while (0)
+
+#define gcsss2() \
+ ({ uint64_t *r; \
+ asm volatile("sysl %0, #3, c7, c7, #3" : "=r"(r) : : "memory"); r; })
diff --git a/tests/tcg/aarch64/gcsss.c b/tests/tcg/aarch64/gcsss.c
new file mode 100644
index 0000000000..9550c68e7e
--- /dev/null
+++ b/tests/tcg/aarch64/gcsss.c
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "gcs.h"
+
+#define IN_PROGRESS(X) ((uint64_t)(X) | 5)
+#define CAP(X) (((uint64_t)(X) & ~0xfff) + 1)
+
+static uint64_t * __attribute__((noinline)) recurse(size_t index)
+{
+ if (index == 0) {
+ return gcspr();
+ }
+ return recurse(index - 1);
+}
+
+int main()
+{
+ void *tmp;
+ uint64_t *alt_stack, *alt_cap;
+ uint64_t *orig_pr, *orig_cap;
+ uint64_t *bottom;
+ size_t pagesize = getpagesize();
+ size_t words;
+
+ enable_gcs(0);
+ orig_pr = gcspr();
+
+ /* Allocate a guard page before and after. */
+ tmp = mmap(0, 3 * pagesize, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+ assert(tmp != MAP_FAILED);
+
+ /* map_shadow_stack won't replace existing mappings */
+ munmap(tmp + pagesize, pagesize);
+
+ /* Allocate a new stack between the guards. */
+ alt_stack = (uint64_t *)
+ syscall(__NR_map_shadow_stack, tmp + pagesize, pagesize,
+ SHADOW_STACK_SET_TOKEN);
+ assert(alt_stack == tmp + pagesize);
+
+ words = pagesize / 8;
+ alt_cap = alt_stack + words - 1;
+
+ /* SHADOW_STACK_SET_TOKEN set the cap. */
+ assert(*alt_cap == CAP(alt_cap));
+
+ /* Swap to the alt stack, one step at a time. */
+ gcsss1(alt_cap);
+
+ assert(gcspr() == alt_cap);
+ assert(*alt_cap == IN_PROGRESS(orig_pr));
+
+ orig_cap = gcsss2();
+
+ assert(orig_cap == orig_pr - 1);
+ assert(*orig_cap == CAP(orig_cap));
+ assert(gcspr() == alt_stack + words);
+
+ /* We should be able to use the whole stack. */
+ bottom = recurse(words - 1);
+ assert(bottom == alt_stack);
+
+ /* We should be back where we started. */
+ assert(gcspr() == alt_stack + words);
+
+ /* Swap back to the original stack. */
+ gcsss1(orig_cap);
+ tmp = gcsss2();
+
+ assert(gcspr() == orig_pr);
+ assert(tmp == alt_cap);
+
+ exit(0);
+}
diff --git a/tests/tcg/aarch64/Makefile.target
b/tests/tcg/aarch64/Makefile.target
index c6f401c317..b858f8692e 100644
--- a/tests/tcg/aarch64/Makefile.target
+++ b/tests/tcg/aarch64/Makefile.target
@@ -76,7 +76,7 @@ $(SME_TESTS): CFLAGS += $(CROSS_AS_HAS_ARMV9_SME)
endif
# GCS Tests
-GCS_TESTS += gcsstr gcspushm
+GCS_TESTS += gcsstr gcspushm gcsss
AARCH64_TESTS += $(GCS_TESTS)
$(GCS_TESTS): gcs.h
--
2.43.0
