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Message-Id: <20231009-arm64-gcs-v6-36-78e55deaa4dd@kernel.org>
Date: Mon, 09 Oct 2023 13:09:10 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Jonathan Corbet <corbet@....net>,
Andrew Morton <akpm@...ux-foundation.org>,
Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
James Morse <james.morse@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Arnd Bergmann <arnd@...db.de>, Oleg Nesterov <oleg@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Shuah Khan <shuah@...nel.org>,
"Rick P. Edgecombe" <rick.p.edgecombe@...el.com>,
Deepak Gupta <debug@...osinc.com>,
Ard Biesheuvel <ardb@...nel.org>,
Szabolcs Nagy <Szabolcs.Nagy@....com>
Cc: "H.J. Lu" <hjl.tools@...il.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Florian Weimer <fweimer@...hat.com>,
Christian Brauner <brauner@...nel.org>,
linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
kvmarm@...ts.linux.dev, linux-fsdevel@...r.kernel.org,
linux-arch@...r.kernel.org, linux-mm@...ck.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH v6 36/38] selftests/arm64: Add GCS signal tests
Do some testing of the signal handling for GCS, checking that a GCS
frame has the expected information in it and that the expected signals
are delivered with invalid operations.
Signed-off-by: Mark Brown <broonie@...nel.org>
---
tools/testing/selftests/arm64/signal/.gitignore | 1 +
.../selftests/arm64/signal/test_signals_utils.h | 10 +++
.../arm64/signal/testcases/gcs_exception_fault.c | 59 ++++++++++++++++
.../selftests/arm64/signal/testcases/gcs_frame.c | 78 ++++++++++++++++++++++
.../arm64/signal/testcases/gcs_write_fault.c | 67 +++++++++++++++++++
5 files changed, 215 insertions(+)
diff --git a/tools/testing/selftests/arm64/signal/.gitignore b/tools/testing/selftests/arm64/signal/.gitignore
index 839e3a252629..26de12918890 100644
--- a/tools/testing/selftests/arm64/signal/.gitignore
+++ b/tools/testing/selftests/arm64/signal/.gitignore
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
mangle_*
fake_sigreturn_*
+gcs_*
sme_*
ssve_*
sve_*
diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h
index 1e80808ee105..36fc12b3cd60 100644
--- a/tools/testing/selftests/arm64/signal/test_signals_utils.h
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h
@@ -6,6 +6,7 @@
#include <assert.h>
#include <stdio.h>
+#include <stdint.h>
#include <string.h>
#include <linux/compiler.h>
@@ -47,6 +48,15 @@ void test_result(struct tdescr *td);
_arg1; \
})
+static inline __attribute__((always_inline)) uint64_t get_gcspr_el0(void)
+{
+ uint64_t val;
+
+ asm volatile("mrs %0, S3_3_C2_C5_1" : "=r" (val));
+
+ return val;
+}
+
static inline bool feats_ok(struct tdescr *td)
{
if (td->feats_incompatible & td->feats_supported)
diff --git a/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c b/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c
new file mode 100644
index 000000000000..532d533592a1
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Limited
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+/* This should be includable from some standard header, but which? */
+#ifndef SEGV_CPERR
+#define SEGV_CPERR 10
+#endif
+
+static inline void gcsss1(uint64_t Xt)
+{
+ asm volatile (
+ "sys #3, C7, C7, #2, %0\n"
+ :
+ : "rZ" (Xt)
+ : "memory");
+}
+
+static int gcs_op_fault_trigger(struct tdescr *td)
+{
+ /*
+ * The slot below our current GCS should be in a valid GCS but
+ * must not have a valid cap in it.
+ */
+ gcsss1(get_gcspr_el0() - 8);
+
+ return 0;
+}
+
+static int gcs_op_fault_signal(struct tdescr *td, siginfo_t *si,
+ ucontext_t *uc)
+{
+ ASSERT_GOOD_CONTEXT(uc);
+
+ return 1;
+}
+
+struct tdescr tde = {
+ .name = "Invalid GCS operation",
+ .descr = "An invalid GCS operation generates the expected signal",
+ .feats_required = FEAT_GCS,
+ .timeout = 3,
+ .sig_ok = SIGSEGV,
+ .sig_ok_code = SEGV_CPERR,
+ .sanity_disabled = true,
+ .trigger = gcs_op_fault_trigger,
+ .run = gcs_op_fault_signal,
+};
diff --git a/tools/testing/selftests/arm64/signal/testcases/gcs_frame.c b/tools/testing/selftests/arm64/signal/testcases/gcs_frame.c
new file mode 100644
index 000000000000..d67cb26195a6
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/gcs_frame.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Limited
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+static union {
+ ucontext_t uc;
+ char buf[1024 * 64];
+} context;
+
+static int gcs_regs(struct tdescr *td, siginfo_t *si, ucontext_t *uc)
+{
+ size_t offset;
+ struct _aarch64_ctx *head = GET_BUF_RESV_HEAD(context);
+ struct gcs_context *gcs;
+ unsigned long expected, gcspr;
+ int ret;
+
+ ret = prctl(PR_GET_SHADOW_STACK_STATUS, &expected, 0, 0, 0);
+ if (ret != 0) {
+ fprintf(stderr, "Unable to query GCS status\n");
+ return 1;
+ }
+
+ /* We expect a cap to be added to the GCS in the signal frame */
+ gcspr = get_gcspr_el0();
+ gcspr -= 8;
+ fprintf(stderr, "Expecting GCSPR_EL0 %lx\n", gcspr);
+
+ if (!get_current_context(td, &context.uc, sizeof(context))) {
+ fprintf(stderr, "Failed getting context\n");
+ return 1;
+ }
+ fprintf(stderr, "Got context\n");
+
+ head = get_header(head, GCS_MAGIC, GET_BUF_RESV_SIZE(context),
+ &offset);
+ if (!head) {
+ fprintf(stderr, "No GCS context\n");
+ return 1;
+ }
+
+ gcs = (struct gcs_context *)head;
+
+ /* Basic size validation is done in get_current_context() */
+
+ if (gcs->features_enabled != expected) {
+ fprintf(stderr, "Features enabled %llx but expected %lx\n",
+ gcs->features_enabled, expected);
+ return 1;
+ }
+
+ if (gcs->gcspr != gcspr) {
+ fprintf(stderr, "Got GCSPR %llx but expected %lx\n",
+ gcs->gcspr, gcspr);
+ return 1;
+ }
+
+ fprintf(stderr, "GCS context validated\n");
+ td->pass = 1;
+
+ return 0;
+}
+
+struct tdescr tde = {
+ .name = "GCS basics",
+ .descr = "Validate a GCS signal context",
+ .feats_required = FEAT_GCS,
+ .timeout = 3,
+ .run = gcs_regs,
+};
diff --git a/tools/testing/selftests/arm64/signal/testcases/gcs_write_fault.c b/tools/testing/selftests/arm64/signal/testcases/gcs_write_fault.c
new file mode 100644
index 000000000000..126b1a294a29
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/gcs_write_fault.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Limited
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+static uint64_t *gcs_page;
+
+#ifndef __NR_map_shadow_stack
+#define __NR_map_shadow_stack 452
+#endif
+
+static bool alloc_gcs(struct tdescr *td)
+{
+ long page_size = sysconf(_SC_PAGE_SIZE);
+
+ gcs_page = (void *)syscall(__NR_map_shadow_stack, 0,
+ page_size, 0);
+ if (gcs_page == MAP_FAILED) {
+ fprintf(stderr, "Failed to map %ld byte GCS: %d\n",
+ page_size, errno);
+ return false;
+ }
+
+ return true;
+}
+
+static int gcs_write_fault_trigger(struct tdescr *td)
+{
+ /* Verify that the page is readable (ie, not completely unmapped) */
+ fprintf(stderr, "Read value 0x%lx\n", gcs_page[0]);
+
+ /* A regular write should trigger a fault */
+ gcs_page[0] = EINVAL;
+
+ return 0;
+}
+
+static int gcs_write_fault_signal(struct tdescr *td, siginfo_t *si,
+ ucontext_t *uc)
+{
+ ASSERT_GOOD_CONTEXT(uc);
+
+ return 1;
+}
+
+
+struct tdescr tde = {
+ .name = "GCS write fault",
+ .descr = "Normal writes to a GCS segfault",
+ .feats_required = FEAT_GCS,
+ .timeout = 3,
+ .sig_ok = SIGSEGV,
+ .sanity_disabled = true,
+ .init = alloc_gcs,
+ .trigger = gcs_write_fault_trigger,
+ .run = gcs_write_fault_signal,
+};
--
2.30.2
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