[PATCH 33/33] kselftest/riscv: kselftest for user mode cfi
Deepak Gupta
debug at rivosinc.com
Fri Oct 4 11:59:47 PDT 2024
On Wed, Oct 02, 2024 at 05:18:36PM -0600, Shuah Khan wrote:
>On 10/1/24 10:06, Deepak Gupta wrote:
>>Adds kselftest for RISC-V control flow integrity implementation for user
>>mode. There is not a lot going on in kernel for enabling landing pad for
>>user mode. cfi selftest are intended to be compiled with zicfilp and
>>zicfiss enabled compiler. Thus kselftest simply checks if landing pad and
>>shadow stack for the binary and process are enabled or not. selftest then
>>register a signal handler for SIGSEGV. Any control flow violation are
>>reported as SIGSEGV with si_code = SEGV_CPERR. Test will fail on receiving
>>any SEGV_CPERR. Shadow stack part has more changes in kernel and thus there
>>are separate tests for that
>> - Exercise `map_shadow_stack` syscall
>> - `fork` test to make sure COW works for shadow stack pages
>> - gup tests
>> As of today kernel uses FOLL_FORCE when access happens to memory via
>> /proc/<pid>/mem. Not breaking that for shadow stack
>> - signal test. Make sure signal delivery results in token creation on
>> shadow stack and consumes (and verifies) token on sigreturn
>> - shadow stack protection test. attempts to write using regular store
>> instruction on shadow stack memory must result in access faults
>>
>
>Include test output here
Will do that in next rev.
>
>>Signed-off-by: Deepak Gupta <debug at rivosinc.com>
>
>I gave up in the middle. Please send v2 with the following things
>fixed:
>
>- Alignment problems in defines. I pointed out a couple.A
I am sorry, I thought I fixed it. My bad, will fix it and check before sending.
>- Too many debug messages. These make the test report hard to read.
> Take a look at printf() closely and get rid of debug messages.
>- Combine messages. I highlighted a few.
>- Start messages with capital letter
>- Think about messages that can give user information. I highlighted
> a few.
Thanks. I'll take that into account in next rev.
>
>>---
>> tools/testing/selftests/riscv/Makefile | 2 +-
>> tools/testing/selftests/riscv/cfi/.gitignore | 3 +
>> tools/testing/selftests/riscv/cfi/Makefile | 10 +
>> tools/testing/selftests/riscv/cfi/cfi_rv_test.h | 83 +++++
>> tools/testing/selftests/riscv/cfi/riscv_cfi_test.c | 82 +++++
>> tools/testing/selftests/riscv/cfi/shadowstack.c | 362 +++++++++++++++++++++
>> tools/testing/selftests/riscv/cfi/shadowstack.h | 37 +++
>> 7 files changed, 578 insertions(+), 1 deletion(-)
>>
>>diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile
>>index 7ce03d832b64..6e142fe004ab 100644
>>--- a/tools/testing/selftests/riscv/Makefile
>>+++ b/tools/testing/selftests/riscv/Makefile
>>@@ -5,7 +5,7 @@
>> ARCH ?= $(shell uname -m 2>/dev/null || echo not)
>> ifneq (,$(filter $(ARCH),riscv))
>>-RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn
>>+RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn cfi
>> else
>> RISCV_SUBTARGETS :=
>> endif
>>diff --git a/tools/testing/selftests/riscv/cfi/.gitignore b/tools/testing/selftests/riscv/cfi/.gitignore
>>new file mode 100644
>>index 000000000000..ce7623f9da28
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/.gitignore
>>@@ -0,0 +1,3 @@
>>+cfitests
>>+riscv_cfi_test
>>+shadowstack
>>\ No newline at end of file
>
>The above look odd to me.
Noted and will fix.
>
>>diff --git a/tools/testing/selftests/riscv/cfi/Makefile b/tools/testing/selftests/riscv/cfi/Makefile
>>new file mode 100644
>>index 000000000000..b65f7ff38a32
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/Makefile
>>@@ -0,0 +1,10 @@
>>+CFLAGS += -I$(top_srcdir)/tools/include
>>+
>>+CFLAGS += -march=rv64gc_zicfilp_zicfiss
>>+
>>+TEST_GEN_PROGS := cfitests
>>+
>>+include ../../lib.mk
>>+
>>+$(OUTPUT)/cfitests: riscv_cfi_test.c shadowstack.c
>>+ $(CC) -o$@ $(CFLAGS) $(LDFLAGS) $^
>>diff --git a/tools/testing/selftests/riscv/cfi/cfi_rv_test.h b/tools/testing/selftests/riscv/cfi/cfi_rv_test.h
>>new file mode 100644
>>index 000000000000..fa1cf7183672
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/cfi_rv_test.h
>>@@ -0,0 +1,83 @@
>>+/* SPDX-License-Identifier: GPL-2.0-only */
>>+
>>+#ifndef SELFTEST_RISCV_CFI_H
>>+#define SELFTEST_RISCV_CFI_H
>>+#include <stddef.h>
>>+#include <sys/types.h>
>>+#include "shadowstack.h"
>>+
>>+#define RISCV_CFI_SELFTEST_COUNT RISCV_SHADOW_STACK_TESTS
>>+
>>+#define CHILD_EXIT_CODE_SSWRITE 10
>>+#define CHILD_EXIT_CODE_SIG_TEST 11
>
>Align these defines please.
>
>>+
>>+#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
>>+({ \
>>+ register long _num __asm__ ("a7") = (num); \
>>+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
>>+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
>>+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
>>+ register long _arg4 __asm__ ("a3") = (long)(arg4); \
>>+ register long _arg5 __asm__ ("a4") = (long)(arg5); \
>>+ \
>>+ __asm__ volatile ( \
>>+ "ecall\n" \
>>+ : "+r"(_arg1) \
>>+ : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
>>+ "r"(_num) > + : "memory", "cc" \
>>+ ); \
>>+ _arg1; \
>>+})
>>+
>
>This is so hard to read. Can you align the tabs for "\"
>
>
>>+#define my_syscall3(num, arg1, arg2, arg3) \
>>+({ \
>>+ register long _num __asm__ ("a7") = (num); \
>>+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
>>+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
>>+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
>>+ \
>>+ __asm__ volatile ( \
>>+ "ecall\n" \
>>+ : "+r"(_arg1) \
>>+ : "r"(_arg2), "r"(_arg3), \
>>+ "r"(_num) \
>>+ : "memory", "cc" \
>>+ ); \
>>+ _arg1; \
>>+})
>>+
>
>Same here.
>
>>+#ifndef __NR_prctl
>>+#define __NR_prctl 167
>>+#endif
>>+
>>+#ifndef __NR_map_shadow_stack
>>+#define __NR_map_shadow_stack 453
>
>Why do we need to define these? Shouldn't including
>asm-generic/unistd.h sufficient?
>
>>+#endif
>>+
>>+#define CSR_SSP 0x011
>>+
>>+#ifdef __ASSEMBLY__
>>+#define __ASM_STR(x) x
>>+#else
>>+#define __ASM_STR(x) #x
>>+#endif
>>+
>>+#define csr_read(csr) \
>>+({ \
>>+ register unsigned long __v; \
>>+ __asm__ __volatile__ ("csrr %0, " __ASM_STR(csr) \
>>+ : "=r" (__v) : \
>>+ : "memory"); \
>>+ __v; \
>>+})
>>+
>>+#define csr_write(csr, val) \
>>+({ \
>>+ unsigned long __v = (unsigned long) (val); \
>>+ __asm__ __volatile__ ("csrw " __ASM_STR(csr) ", %0" \
>>+ : : "rK" (__v) \
>>+ : "memory"); \
>>+})
>>+
>
>Please fix alignment in the entire file. This is very difficult to read.
>
>>+#endif
>>diff --git a/tools/testing/selftests/riscv/cfi/riscv_cfi_test.c b/tools/testing/selftests/riscv/cfi/riscv_cfi_test.c
>>new file mode 100644
>>index 000000000000..f22b3f0f24de
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/riscv_cfi_test.c
>>@@ -0,0 +1,82 @@
>>+// SPDX-License-Identifier: GPL-2.0-only
>>+
>>+#include "../../kselftest.h"
>>+#include <signal.h>
>>+#include <asm/ucontext.h>
>>+#include <linux/prctl.h>
>>+#include "cfi_rv_test.h"
>>+
>>+/* do not optimize cfi related test functions */
>>+#pragma GCC push_options
>>+#pragma GCC optimize("O0")
>>+
>>+void sigsegv_handler(int signum, siginfo_t *si, void *uc)
>>+{
>>+ struct ucontext *ctx = (struct ucontext *) uc;
>>+
>>+ if (si->si_code == SEGV_CPERR) {
>>+ printf("Control flow violation happened somewhere\n");
>>+ printf("pc where violation happened %lx\n", ctx->uc_mcontext.gregs[0]);
>
>Why do you need two print statements, collapse them.
>
>>+ exit(-1);
>>+ }
>>+
>>+ printf("In sigsegv handler\n");
>
>Remove this - looks like debug message.
>
>>+ /* all other cases are expected to be of shadow stack write case */
>>+ exit(CHILD_EXIT_CODE_SSWRITE);
>>+}
>>+
>>+bool register_signal_handler(void)
>>+{
>>+ struct sigaction sa = {};
>>+
>>+ sa.sa_sigaction = sigsegv_handler;
>>+ sa.sa_flags = SA_SIGINFO;
>>+ if (sigaction(SIGSEGV, &sa, NULL)) {
>>+ printf("registering signal handler for landing pad violation failed\n");
>
>Include strerror() to get the system error message.
>
>>+ return false;
>>+ }
>>+
>>+ return true;
>>+}
>>+
>>+int main(int argc, char *argv[])
>>+{
>>+ int ret = 0;
>>+ unsigned long lpad_status = 0, ss_status = 0;
>>+
>>+ ksft_print_header();
>>+
>>+ ksft_set_plan(RISCV_CFI_SELFTEST_COUNT);
>>+
>>+ ksft_print_msg("starting risc-v tests\n");
>
>Starting instead of starting.
>
>>+
>>+ /*
>>+ * Landing pad test. Not a lot of kernel changes to support landing
>>+ * pad for user mode except lighting up a bit in senvcfg via a prctl
>>+ * Enable landing pad through out the execution of test binary
>>+ */
>>+ ret = my_syscall5(__NR_prctl, PR_GET_INDIR_BR_LP_STATUS, &lpad_status, 0, 0, 0);
>>+ if (ret)
>>+ ksft_exit_skip("Get landing pad status failed with %d\n", ret);
>
>Does this mean __NR_prctl isn't fully supported? It would informative if
>the message says that instead "Get landing pad status failed"
>
>>+
>>+ if (!(lpad_status & PR_INDIR_BR_LP_ENABLE))
>>+ ksft_exit_skip("landing pad is not enabled, should be enabled via glibc\n");
>
>Landing insteads of landing. Use concistent upper case for starting
>messages that go into test report.
>
>>+
>
>
>>+ ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
>>+ if (ret)
>>+ ksft_exit_skip("Get shadow stack failed with %d\n", ret);
>
>Same here. Make this informative - what does this mean? What should
>user do when they see this message?
>
>>+
>>+ if (!(ss_status & PR_SHADOW_STACK_ENABLE))
>>+ ksft_exit_skip("shadow stack is not enabled, should be enabled via glibc\n");
>
>Shadow
>
>>+
>>+ if (!register_signal_handler())
>>+ ksft_exit_skip("registering signal handler for SIGSEGV failed\n");
>
>Registerting
>
>>+
>>+ ksft_print_msg("landing pad and shadow stack are enabled for binary\n");
>>+ ksft_print_msg("starting risc-v shadow stack tests\n");
>
>Do you need the above messages? Collapse them if you really need them
>in the report.
>
>>+ execute_shadow_stack_tests();
>>+
>>+ ksft_finished();
>>+}
>>+
>>+#pragma GCC pop_options
>>diff --git a/tools/testing/selftests/riscv/cfi/shadowstack.c b/tools/testing/selftests/riscv/cfi/shadowstack.c
>>new file mode 100644
>>index 000000000000..2f65eb970c44
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/shadowstack.c
>>@@ -0,0 +1,362 @@
>>+// SPDX-License-Identifier: GPL-2.0-only
>>+
>>+#include "../../kselftest.h"
>>+#include <sys/wait.h>
>>+#include <signal.h>
>>+#include <fcntl.h>
>>+#include <asm-generic/unistd.h>
>>+#include <sys/mman.h>
>>+#include "shadowstack.h"
>>+#include "cfi_rv_test.h"
>>+
>>+/* do not optimize shadow stack related test functions */
>>+#pragma GCC push_options
>>+#pragma GCC optimize("O0")
>>+
>>+void zar(void)
>>+{
>>+ unsigned long ssp = 0;
>>+
>>+ ssp = csr_read(CSR_SSP);
>>+ printf("inside %s and shadow stack ptr is %lx\n", __func__, ssp);
>
>Debug message? get rid of it.
>
>>+}
>>+
>>+void bar(void)
>>+{
>>+ printf("inside %s\n", __func__);
>
>Same here - debug messages make report hard to read.
>
>>+ zar();
>>+}
>>+
>>+void foo(void)
>>+{
>>+ printf("inside %s\n", __func__);
>>+ bar();
>>+}
>>+
>>+void zar_child(void)
>>+{
>>+ unsigned long ssp = 0;
>>+
>>+ ssp = csr_read(CSR_SSP);
>>+ printf("inside %s and shadow stack ptr is %lx\n", __func__, ssp);
>>+}
>>+
>>+void bar_child(void)
>>+{
>>+ printf("inside %s\n", __func__);
>>+ zar_child();
>>+}
>>+
>>+void foo_child(void)
>>+{
>>+ printf("inside %s\n", __func__);
>>+ bar_child();
>>+}
>>+
>>+typedef void (call_func_ptr)(void);
>>+/*
>>+ * call couple of functions to test push pop.
>>+ */
>>+int shadow_stack_call_tests(call_func_ptr fn_ptr, bool parent)
>>+{
>>+ if (parent)
>>+ printf("call test for parent\n");
>>+ else
>>+ printf("call test for child\n");
>>+
>>+ (fn_ptr)();
>>+
>>+ return 0;
>>+}
>>+
>>+/* forks a thread, and ensure shadow stacks fork out */
>>+bool shadow_stack_fork_test(unsigned long test_num, void *ctx)
>>+{
>>+ int pid = 0, child_status = 0, parent_pid = 0, ret = 0;
>>+ unsigned long ss_status = 0;
>>+
>>+ printf("exercising shadow stack fork test\n");
>>+
>>+ ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
>>+ if (ret) {
>>+ printf("shadow stack get status prctl failed with errorcode %d\n", ret);
>>+ return false;
>>+ }
>>+
>>+ if (!(ss_status & PR_SHADOW_STACK_ENABLE))
>>+ ksft_exit_skip("shadow stack is not enabled, should be enabled via glibc\n");
>>+
>>+ parent_pid = getpid();
>>+ pid = fork();
>>+
>>+ if (pid) {
>>+ printf("Parent pid %d and child pid %d\n", parent_pid, pid);
>>+ shadow_stack_call_tests(&foo, true);
>>+ } else
>>+ shadow_stack_call_tests(&foo_child, false);
>>+
>>+ if (pid) {
>>+ printf("waiting on child to finish\n");
>>+ wait(&child_status);
>>+ } else {
>>+ /* exit child gracefully */
>>+ exit(0);
>>+ }
>>+
>>+ if (pid && WIFSIGNALED(child_status)) {
>>+ printf("child faulted");
>>+ return false;
>>+ }
>>+
>>+ return true;
>>+}
>>+
>>+/* exercise `map_shadow_stack`, pivot to it and call some functions to ensure it works */
>>+#define SHADOW_STACK_ALLOC_SIZE 4096
>>+bool shadow_stack_map_test(unsigned long test_num, void *ctx)
>>+{
>>+ unsigned long shdw_addr;
>>+ int ret = 0;
>>+
>>+ shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
>>+
>>+ if (((long) shdw_addr) <= 0) {
>>+ printf("map_shadow_stack failed with error code %d\n", (int) shdw_addr);
>>+ return false;
>>+ }
>>+
>>+ ret = munmap((void *) shdw_addr, SHADOW_STACK_ALLOC_SIZE);
>>+
>>+ if (ret) {
>>+ printf("munmap failed with error code %d\n", ret);
>>+ return false;
>>+ }
>>+
>>+ return true;
>>+}
>>+
>>+/*
>>+ * shadow stack protection tests. map a shadow stack and
>>+ * validate all memory protections work on it
>>+ */
>>+bool shadow_stack_protection_test(unsigned long test_num, void *ctx)
>>+{
>>+ unsigned long shdw_addr;
>>+ unsigned long *write_addr = NULL;
>>+ int ret = 0, pid = 0, child_status = 0;
>>+
>>+ shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
>>+
>>+ if (((long) shdw_addr) <= 0) {
>>+ printf("map_shadow_stack failed with error code %d\n", (int) shdw_addr);
>>+ return false;
>>+ }
>>+
>>+ write_addr = (unsigned long *) shdw_addr;
>>+ pid = fork();
>>+
>>+ /* no child was created, return false */
>>+ if (pid == -1)
>>+ return false;
>>+
>>+ /*
>>+ * try to perform a store from child on shadow stack memory
>>+ * it should result in SIGSEGV
>>+ */
>>+ if (!pid) {
>>+ /* below write must lead to SIGSEGV */
>>+ *write_addr = 0xdeadbeef;
>>+ } else {
>>+ wait(&child_status);
>>+ }
>>+
>>+ /* test fail, if 0xdeadbeef present on shadow stack address */
>>+ if (*write_addr == 0xdeadbeef) {
>>+ printf("write suceeded\n");
>>+ return false;
>>+ }
>>+
>>+ /* if child reached here, then fail */
>>+ if (!pid) {
>>+ printf("child reached unreachable state\n");
>>+ return false;
>>+ }
>>+
>>+ /* if child exited via signal handler but not for write on ss */
>>+ if (WIFEXITED(child_status) &&
>>+ WEXITSTATUS(child_status) != CHILD_EXIT_CODE_SSWRITE) {
>>+ printf("child wasn't signaled for write on shadow stack\n");
>>+ return false;
>>+ }
>>+
>>+ ret = munmap(write_addr, SHADOW_STACK_ALLOC_SIZE);
>>+ if (ret) {
>>+ printf("munmap failed with error code %d\n", ret);
>>+ return false;
>>+ }
>>+
>>+ return true;
>>+}
>>+
>>+#define SS_MAGIC_WRITE_VAL 0xbeefdead
>>+
>>+int gup_tests(int mem_fd, unsigned long *shdw_addr)
>>+{
>>+ unsigned long val = 0;
>>+
>>+ lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
>>+ if (read(mem_fd, &val, sizeof(val)) < 0) {
>>+ printf("reading shadow stack mem via gup failed\n");
>>+ return 1;
>>+ }
>>+
>>+ val = SS_MAGIC_WRITE_VAL;
>>+ lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
>>+ if (write(mem_fd, &val, sizeof(val)) < 0) {
>>+ printf("writing shadow stack mem via gup failed\n");
>>+ return 1;
>>+ }
>>+
>>+ if (*shdw_addr != SS_MAGIC_WRITE_VAL) {
>>+ printf("GUP write to shadow stack memory didn't happen\n");
>>+ return 1;
>>+ }
>>+
>>+ return 0;
>>+}
>>+
>>+bool shadow_stack_gup_tests(unsigned long test_num, void *ctx)
>>+{
>>+ unsigned long shdw_addr = 0;
>>+ unsigned long *write_addr = NULL;
>>+ int fd = 0;
>>+ bool ret = false;
>>+
>>+ shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
>>+
>>+ if (((long) shdw_addr) <= 0) {
>>+ printf("map_shadow_stack failed with error code %d\n", (int) shdw_addr);
>>+ return false;
>>+ }
>>+
>>+ write_addr = (unsigned long *) shdw_addr;
>>+
>>+ fd = open("/proc/self/mem", O_RDWR);
>>+ if (fd == -1)
>>+ return false;
>>+
>>+ if (gup_tests(fd, write_addr)) {
>>+ printf("gup tests failed\n");
>>+ goto out;
>>+ }
>>+
>>+ ret = true;
>>+out:
>>+ if (shdw_addr && munmap(write_addr, SHADOW_STACK_ALLOC_SIZE)) {
>>+ printf("munmap failed with error code %d\n", ret);
>>+ ret = false;
>>+ }
>>+
>>+ return ret;
>>+}
>>+
>>+volatile bool break_loop;
>>+
>>+void sigusr1_handler(int signo)
>>+{
>>+ printf("In sigusr1 handler\n");
>>+ break_loop = true;
>>+}
>>+
>>+bool sigusr1_signal_test(void)
>>+{
>>+ struct sigaction sa = {};
>>+
>>+ sa.sa_handler = sigusr1_handler;
>>+ sa.sa_flags = 0;
>>+ sigemptyset(&sa.sa_mask);
>>+ if (sigaction(SIGUSR1, &sa, NULL)) {
>>+ printf("registering signal handler for SIGUSR1 failed\n");
>>+ return false;
>>+ }
>>+
>>+ return true;
>>+}
>>+/*
>>+ * shadow stack signal test. shadow stack must be enabled.
>>+ * register a signal, fork another thread which is waiting
>>+ * on signal. Send a signal from parent to child, verify
>>+ * that signal was received by child. If not test fails
>>+ */
>>+bool shadow_stack_signal_test(unsigned long test_num, void *ctx)
>>+{
>>+ int pid = 0, child_status = 0, ret = 0;
>>+ unsigned long ss_status = 0;
>>+
>>+ ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
>>+ if (ret) {
>>+ printf("shadow stack get status prctl failed with errorcode %d\n", ret);
>>+ return false;
>>+ }
>>+
>>+ if (!(ss_status & PR_SHADOW_STACK_ENABLE))
>>+ ksft_exit_skip("shadow stack is not enabled, should be enabled via glibc\n");
>>+
>>+ /* this should be caught by signal handler and do an exit */
>>+ if (!sigusr1_signal_test()) {
>>+ printf("registering sigusr1 handler failed\n");
>>+ exit(-1);
>>+ }
>>+
>>+ pid = fork();
>>+
>>+ if (pid == -1) {
>>+ printf("signal test: fork failed\n");
>>+ goto out;
>>+ }
>>+
>>+ if (pid == 0) {
>>+ while (!break_loop)
>>+ sleep(1);
>>+
>>+ exit(11);
>>+ /* child shouldn't go beyond here */
>>+ }
>>+
>>+ /* send SIGUSR1 to child */
>>+ kill(pid, SIGUSR1);
>>+ wait(&child_status);
>>+
>>+out:
>>+
>>+ return (WIFEXITED(child_status) &&
>>+ WEXITSTATUS(child_status) == 11);
>>+}
>>+
>>+int execute_shadow_stack_tests(void)
>>+{
>>+ int ret = 0;
>>+ unsigned long test_count = 0;
>>+ unsigned long shstk_status = 0;
>>+
>>+ printf("Executing RISC-V shadow stack self tests\n");
>>+
>>+ ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &shstk_status, 0, 0, 0);
>>+
>>+ if (ret != 0)
>>+ ksft_exit_skip("Get shadow stack status failed with %d\n", ret);
>>+
>>+ /*
>>+ * If we are here that means get shadow stack status succeeded and
>>+ * thus shadow stack support is baked in the kernel.
>>+ */
>>+ while (test_count < ARRAY_SIZE(shstk_tests)) {
>>+ ksft_test_result((*shstk_tests[test_count].t_func)(test_count, NULL),
>>+ shstk_tests[test_count].name);
>>+ test_count++;
>>+ }
>>+
>>+ return 0;
>>+}
>>+
>>+#pragma GCC pop_options
>>diff --git a/tools/testing/selftests/riscv/cfi/shadowstack.h b/tools/testing/selftests/riscv/cfi/shadowstack.h
>>new file mode 100644
>>index 000000000000..b43e74136a26
>>--- /dev/null
>>+++ b/tools/testing/selftests/riscv/cfi/shadowstack.h
>>@@ -0,0 +1,37 @@
>>+/* SPDX-License-Identifier: GPL-2.0-only */
>>+
>>+#ifndef SELFTEST_SHADOWSTACK_TEST_H
>>+#define SELFTEST_SHADOWSTACK_TEST_H
>>+#include <stddef.h>
>>+#include <linux/prctl.h>
>>+
>>+/*
>>+ * a cfi test returns true for success or false for fail
>>+ * takes a number for test number to index into array and void pointer.
>>+ */
>>+typedef bool (*shstk_test_func)(unsigned long test_num, void *);
>>+
>>+struct shadow_stack_tests {
>>+ char *name;
>>+ shstk_test_func t_func;
>>+};
>>+
>>+bool shadow_stack_fork_test(unsigned long test_num, void *ctx);
>>+bool shadow_stack_map_test(unsigned long test_num, void *ctx);
>>+bool shadow_stack_protection_test(unsigned long test_num, void *ctx);
>>+bool shadow_stack_gup_tests(unsigned long test_num, void *ctx);
>>+bool shadow_stack_signal_test(unsigned long test_num, void *ctx);
>>+
>>+static struct shadow_stack_tests shstk_tests[] = {
>>+ { "shstk fork test\n", shadow_stack_fork_test },
>>+ { "map shadow stack syscall\n", shadow_stack_map_test },
>>+ { "shadow stack gup tests\n", shadow_stack_gup_tests },
>>+ { "shadow stack signal tests\n", shadow_stack_signal_test},
>>+ { "memory protections of shadow stack memory\n", shadow_stack_protection_test }
>>+};
>>+
>>+#define RISCV_SHADOW_STACK_TESTS ARRAY_SIZE(shstk_tests)
>>+
>>+int execute_shadow_stack_tests(void);
>>+
>>+#endif
>>
>
>thanks,
>-- Shuah
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