Add 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.
Introduce a common utility assembly trampoline function to invoke a
sigreturn while placing the provided sigframe at wanted alignment and
also an helper to make space when needed inside the sigframe reserved
area.
Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
---
v3 --> v4
- fix commit
- fix signal.S, handle misalign requests too
- remove unneeded comments
- add signal.h include
- added get_starting_head() helper
- added test description
---
tools/testing/selftests/arm64/signal/Makefile | 2 +-
.../testing/selftests/arm64/signal/signals.S | 62 +++++++++++++++++++
.../arm64/signal/test_signals_utils.h | 1 +
.../testcases/fake_sigreturn_bad_magic.c | 54 ++++++++++++++++
.../arm64/signal/testcases/testcases.c | 28 +++++++++
.../arm64/signal/testcases/testcases.h | 4 ++
6 files changed, 150 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 f78f5190e3d4..b497cfea4643 100644
--- a/tools/testing/selftests/arm64/signal/Makefile
+++ b/tools/testing/selftests/arm64/signal/Makefile
@@ -28,5 +28,5 @@ clean:
# 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
$(CC) $(CFLAGS) $^ -o $@
diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S
new file mode 100644
index 000000000000..b89fec0d5ba0
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/signals.S
@@ -0,0 +1,62 @@
+/* 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 SP @%08lX\n"
+
+.text
+
+.globl fake_sigreturn
+
+/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */
+fake_sigreturn:
+ mov x20, x0
+ mov x21, x1
+ mov x22, x2
+ mov x23, sp
+
+ /* create space on the stack for fake sigframe 16 bytes-aligned */
+ add x0, x21, #16
+ bic x0, x0, #15
+ sub x23, x23, x0
+ /* any misalignment requested ? */
+ add x23, x23, x22
+
+ 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 possibly 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 ce35be8ebc8e..68930f1e46e5 100644
--- a/tools/testing/selftests/arm64/signal/test_signals_utils.h
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h
@@ -12,4 +12,5 @@ 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 misalign_bytes);
#endif
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..7fb700b9801b
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 ARM Limited
+ *
+ * Place a fake sigframe on the stack including a BAD Unknown magic
+ * record: on sigreturn Kernel must spot this attempt and the test
+ * case is expected to be terminated via SEGV.
+ */
+
+#include <signal.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, need_sz;
+ 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);
+ /* need at least 2*HDR_SZ space: KSFT_BAD_MAGIC + terminator. */
+ need_sz = HDR_SZ * 2;
+ head = get_starting_head(shead, need_sz, resv_sz, NULL);
+ if (head) {
+ /*
+ * 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), 0);
+ }
+
+ return 1;
+}
+
+struct tdescr tde = {
+ .name = "FAKE_SIGRETURN_BAD_MAGIC",
+ .descr = "Trigger a sigreturn with a sigframe with a bad magic",
+ .sig_ok = SIGSEGV,
+ .timeout = 3,
+ .run = fake_sigreturn_bad_magic_run,
+};
diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c
index 72e3f482b177..2effb8ded935 100644
--- a/tools/testing/selftests/arm64/signal/testcases/testcases.c
+++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c
@@ -149,3 +149,31 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
return true;
}
+
+struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead,
+ size_t need_sz, size_t resv_sz,
+ size_t *offset)
+{
+ size_t offs = 0;
+ struct _aarch64_ctx *head;
+
+ head = get_terminator(shead, resv_sz, &offs);
+ /* not found a terminator...no need to update offset if any */
+ if (!head)
+ return head;
+ if (resv_sz - offs < need_sz) {
+ fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",
+ resv_sz - offs);
+ head = get_header(shead, EXTRA_MAGIC, resv_sz, &offs);
+ if (!head || resv_sz - offs < need_sz) {
+ fprintf(stderr,
+ "Failed to reclaim space on sigframe.\n");
+ return NULL;
+ }
+ }
+
+ fprintf(stderr, "Available space:%zd\n", resv_sz - offs);
+ if (offset)
+ *offset = offs;
+ return head;
+}
diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.h b/tools/testing/selftests/arm64/signal/testcases/testcases.h
index 00618c3202bb..7653f8a64b3d 100644
--- a/tools/testing/selftests/arm64/signal/testcases/testcases.h
+++ b/tools/testing/selftests/arm64/signal/testcases/testcases.h
@@ -83,4 +83,8 @@ static inline void write_terminator_record(struct _aarch64_ctx *tail)
tail->size = 0;
}
}
+
+struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead,
+ size_t need_sz, size_t resv_sz,
+ size_t *offset);
#endif
--
2.17.1
