kselftest: arm64: fake_sigreturn_missing_fpsimd

Add a simple fake_sigreturn testcase which builds a ucontext_t without
the required fpsimd_context and place it onto the stack.
Expects a SIGSEGV on test PASS.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c
new file mode 100644 (file)
index 0000000..08ecd80
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 ARM Limited
+ *
+ * Place a fake sigframe on the stack missing the mandatory FPSIMD
+ * record: on sigreturn Kernel must spot this attempt and the test
+ * case is expected to be terminated via SEGV.
+ */
+
+#include <stdio.h>
+#include <signal.h>
+#include <ucontext.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+struct fake_sigframe sf;
+
+static int fake_sigreturn_missing_fpsimd_run(struct tdescr *td,
+                                            siginfo_t *si, ucontext_t *uc)
+{
+       size_t resv_sz, offset;
+       struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf);
+
+       /* just to fill the ucontext_t with something real */
+       if (!get_current_context(td, &sf.uc))
+               return 1;
+
+       resv_sz = GET_SF_RESV_SIZE(sf);
+       head = get_header(head, FPSIMD_MAGIC, resv_sz, &offset);
+       if (head && resv_sz - offset >= HDR_SZ) {
+               fprintf(stderr, "Mangling template header. Spare space:%zd\n",
+                       resv_sz - offset);
+               /* Just overwrite fpsmid_context */
+               write_terminator_record(head);
+
+               ASSERT_BAD_CONTEXT(&sf.uc);
+               fake_sigreturn(&sf, sizeof(sf), 0);
+       }
+
+       return 1;
+}
+
+struct tdescr tde = {
+               .name = "FAKE_SIGRETURN_MISSING_FPSIMD",
+               .descr = "Triggers a sigreturn with a missing fpsimd_context",
+               .sig_ok = SIGSEGV,
+               .timeout = 3,
+               .run = fake_sigreturn_missing_fpsimd_run,
+};