Added a simple fake_sigreturn testcase which builds a ucontext_t
with a bad magic header and place it onto the stack.
Expects a SIGSEGV on test PASS.
This commit also introduces a common utility assembly function to
invoke a sigreturn using a fake provided sigframe.
Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
---
tools/testing/selftests/arm64/signal/Makefile | 2 +-
.../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++
.../arm64/signal/test_signals_utils.h | 1 +
.../arm64/signal/testcases/.gitignore | 1 +
.../testcases/fake_sigreturn_bad_magic.c | 63 ++++++++++++++++++
5 files changed, 130 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/arm64/signal/signals.S
create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile
index 5ec92a4dba48..fbef7986f8c8 100644
--- a/tools/testing/selftests/arm64/signal/Makefile
+++ b/tools/testing/selftests/arm64/signal/Makefile
@@ -78,7 +78,7 @@ endif
# Common test-unit targets to build common-layout test-cases executables
# Needs secondary expansion to properly include the testcase c-file in pre-reqs
.SECONDEXPANSION:
-$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h
+$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h
@if [ ! -d $(khdr_dir) ]; then \
echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \
echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \
diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S
new file mode 100644
index 000000000000..6262b877400b
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/signals.S
@@ -0,0 +1,64 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0
+ * Copyright (C) 2019 ARM Limited
+ */
+
+#include <asm/unistd.h>
+
+.section ".rodata", "a"
+call_fmt:
+ .asciz "Calling sigreturn with fake sigframe sized:%zd at calculated SP @%08lX\n"
+
+.text
+
+.globl fake_sigreturn
+
+/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:alignment_SP */
+fake_sigreturn:
+ mov x20, x0
+ mov x21, x1
+ mov x22, x2
+ mov x23, sp
+
+ /* create space on the stack for fake sigframe..."x22"-aligned */
+ mov x0, #0
+ add x0, x21, x22
+ sub x22, x22, #1
+ bic x0, x0, x22
+ sub x23, x23, x0
+
+ ldr x0, =call_fmt
+ mov x1, x21
+ mov x2, x23
+ bl printf
+
+ mov sp, x23
+
+ /* now fill it with the provided content... */
+ mov x0, sp
+ mov x1, x20
+ mov x2, x21
+ bl memcpy
+
+ /*
+ * Here saving a last minute SP to current->token acts as a marker:
+ * if we got here, we are successfully faking a sigreturn; in other
+ * words we are sure no bad fatal signal has been raised till now
+ * for unrelated reasons, so we should consider the possibl observed
+ * fatal signal like SEGV coming from Kernel restore_sigframe() and
+ * triggered as expected from our test-case.
+ * For simplicity this assumes that current field 'token' is laid out
+ * as first in struct tdescr
+ */
+ ldr x0, current
+ str x23, [x0]
+ /* SP is already pointing back to the just built fake sigframe here */
+ mov x8, #__NR_rt_sigreturn
+ svc #0
+
+ /*
+ * Above sigreturn should not return...looping here leads to a timeout
+ * and ensure proper and clean test failure, instead of jumping around
+ * on a potentially corrupted stack.
+ */
+ b .
diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h
index b37167c98ccd..cdf3018aa1aa 100644
--- a/tools/testing/selftests/arm64/signal/test_signals_utils.h
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h
@@ -27,4 +27,5 @@ int test_run(struct tdescr *td);
void test_result(struct tdescr *td);
bool get_current_context(struct tdescr *td, ucontext_t *dest_uc);
+int fake_sigreturn(void *sigframe, size_t sz, int alignment);
#endif
diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore
index a48a118b1a1a..0ea6fdc3765c 100644
--- a/tools/testing/selftests/arm64/signal/testcases/.gitignore
+++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore
@@ -4,3 +4,4 @@ mangle_pstate_invalid_mode_el1
mangle_pstate_invalid_mode_el2
mangle_pstate_invalid_mode_el3
mangle_pstate_ssbs_regs
+fake_sigreturn_bad_magic
diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
new file mode 100644
index 000000000000..b4c063e02a7a
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2019 ARM Limited */
+
+#include <stdio.h>
+#include <ucontext.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+struct fake_sigframe sf;
+
+static int fake_sigreturn_bad_magic_run(struct tdescr *td,
+ siginfo_t *si, ucontext_t *uc)
+{
+ size_t resv_sz, offset;
+ struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head;
+
+ /* 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);
+ /*
+ * find the terminator, preserving existing headers
+ * and verify amount of spare room in __reserved area.
+ */
+ head = get_terminator(shead, resv_sz, &offset);
+ /*
+ * try stripping extra_context header when low on space:
+ * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC
+ * and the other for the usual terminator.
+ */
+ if (head && resv_sz - offset < HDR_SZ * 2) {
+ fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",
+ resv_sz - offset);
+ head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset);
+ }
+ /* just give up and timeout if still not enough space */
+ if (head && resv_sz - offset >= HDR_SZ) {
+ fprintf(stderr, "Mangling template header. Spare space:%zd\n",
+ resv_sz - offset);
+ /*
+ * use a well known NON existent bad magic...something
+ * we should pretty sure won't be ever defined in Kernel
+ */
+ head->magic = KSFT_BAD_MAGIC;
+ head->size = HDR_SZ;
+ write_terminator_record(GET_RESV_NEXT_HEAD(head));
+
+ ASSERT_BAD_CONTEXT(&sf.uc);
+ fake_sigreturn(&sf, sizeof(sf), 16);
+ }
+
+ return 1;
+}
+
+struct tdescr tde = {
+ .name = "FAKE_SIGRETURN_BAD_MAGIC",
+ .descr = "Triggers a fake sigreturn with a sigframe including a bad non-existent magic",
+ .sig_ok = SIGSEGV,
+ .timeout = 3,
+ .run = fake_sigreturn_bad_magic_run,
+};
--
2.17.1
