[RFC PATCH v2 2/2] selftests: rseq: test abort-at-ip extension on x86

Mathieu Desnoyers
2022-01-10T17:16:27Z

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
---
tools/testing/selftests/rseq/.gitignore | 1 +
tools/testing/selftests/rseq/Makefile | 3 +-
tools/testing/selftests/rseq/rseq.c | 21 ++
tools/testing/selftests/rseq/rseq.h | 12 +
.../selftests/rseq/rseq_ext_abort_at_ip.c | 285 ++++++++++++++++++
5 files changed, 321 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/rseq/rseq_ext_abort_at_ip.c

diff --git a/tools/testing/selftests/rseq/.gitignore b/tools/testing/selftests/rseq/.gitignore
index 5910888ebfe1..472152afab77 100644
--- a/tools/testing/selftests/rseq/.gitignore
+++ b/tools/testing/selftests/rseq/.gitignore
@@ -5,3 +5,4 @@ basic_rseq_op_test
param_test
param_test_benchmark
param_test_compare_twice
+rseq_ext_abort_at_ip
diff --git a/tools/testing/selftests/rseq/Makefile b/tools/testing/selftests/rseq/Makefile
index 2af9d39a9716..dae0dba7552b 100644
--- a/tools/testing/selftests/rseq/Makefile
+++ b/tools/testing/selftests/rseq/Makefile
@@ -13,7 +13,8 @@ LDLIBS += -lpthread
OVERRIDE_TARGETS = 1

TEST_GEN_PROGS = basic_test basic_percpu_ops_test param_test \
- param_test_benchmark param_test_compare_twice
+ param_test_benchmark param_test_compare_twice \
+ rseq_ext_abort_at_ip

TEST_GEN_PROGS_EXTENDED = librseq.so

diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 7159eb777fd3..3e012f581ddb 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -73,6 +73,27 @@ static int sys_rseq(volatile struct rseq *rseq_abi, uint32_t rseq_len,
return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
}

+/*
+ * Return 0 if extension is available, negative error otherwise.
+ */
+int rseq_query_extension(enum rseq_extension ext)
+{
+ int ret;
+ unsigned int flags;
+
+ switch (ext) {
+ case RSEQ_EXT_ABORT_AT_IP:
+ flags = RSEQ_FLAG_QUERY_ABORT_AT_IP;
+ break;
+ default:
+ return -EINVAL;
+ }
+ ret = sys_rseq(NULL, 0, flags, 0);
+ if (!ret)
+ return 0;
+ return -errno;
+}
+
int rseq_register_current_thread(void)
{
int rc, ret = 0;
diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index 3f63eb362b92..34c80402c078 100644
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -67,6 +67,12 @@ extern int __rseq_handled;
abort(); \
} while (0)

+enum rseq_extension {
+ RSEQ_EXT_ABORT_AT_IP = 0,
+};
+
+#define ASM_RSEQ_CS_FLAG_ABORT_AT_IP (1U << 3)
+
#if defined(__x86_64__) || defined(__i386__)
#include <rseq-x86.h>
#elif defined(__ARMEL__)
@@ -162,4 +168,10 @@ static inline void rseq_prepare_unload(void)
rseq_clear_rseq_cs();
}

+/*
+ * Query whether rseq extension is available. Return 0 if available, negative
+ * error value otherwise.
+ */
+int rseq_query_extension(enum rseq_extension ext);
+
#endif /* RSEQ_H_ */
diff --git a/tools/testing/selftests/rseq/rseq_ext_abort_at_ip.c b/tools/testing/selftests/rseq/rseq_ext_abort_at_ip.c
new file mode 100644
index 000000000000..4cddf7433cc3
--- /dev/null
+++ b/tools/testing/selftests/rseq/rseq_ext_abort_at_ip.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * RSEQ abort-at-ip extension test.
+ *
+ * The test test_abort_at_ip_loop() implements an infinite loop which only exits when
+ * aborted. This rseq critical section is defined with the abort-at-ip
+ * extension, which requires the userspace abort handler to reajust the stack pointer.
+ * This test validates that the abort-at-ip value is within the address range of the
+ * rseq critical section.
+ *
+ * The test test_abort_at_ip_undo() validates that when aborted between two
+ * consecutive increments of two distinct variables, those variables are indeed one
+ * value apart. This validates that abort undo operations based on the abort-at-ip
+ * work as expected.
+ */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include "rseq.h"
+
+const int nr_iter = 10;
+
+#ifdef __x86_64__
+static void test_abort_at_ip_loop(void)
+{
+ void *abort_ip_addr, *abort_ip_start, *abort_ip_end;
+
+ printf("Testing abort_at_ip infinite loop\n");
+
+ __asm__ __volatile__ goto (
+ __RSEQ_ASM_DEFINE_TABLE(3, 0x0, ASM_RSEQ_CS_FLAG_ABORT_AT_IP, 1f, (2f - 1f), 4f) /* start, post_commit_offset, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
+ "rep; nop\n\t" /* cpu_relax for busy loop. */
+ "jmp 1b\n\t" /* infinite loop. */
+ "2:\n\t"
+ RSEQ_ASM_DEFINE_ABORT(4,
+ /* abort-at-ip must be pop from the stack. */
+ "popq %%rcx\n\t"
+ "addq $128, %%rsp\n\t" /* x86-64 redzone */
+ "movq %%rcx, %[abort_ip_addr]\n\t"
+ "lea 1b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[abort_ip_start]\n\t"
+ "lea 2b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[abort_ip_end]\n\t",
+ abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_abi] "r" (&__rseq_abi),
+ [abort_ip_addr] "m" (abort_ip_addr),
+ [abort_ip_start] "m" (abort_ip_start),
+ [abort_ip_end] "m" (abort_ip_end)
+ : "memory", "cc", "rcx"
+ : abort
+ );
+ fprintf(stderr, "Error: infinite loop should never exit gracefully.\n");
+ abort();
+
+abort:
+ printf("Critical section aborted (as expected) at ip %p, within range [%p,%p[\n",
+ abort_ip_addr, abort_ip_start, abort_ip_end);
+ if (abort_ip_addr < abort_ip_start || abort_ip_addr >= abort_ip_end) {
+ fprintf(stderr, "Error: abort-ip is outside of expected range\n");
+ abort();
+ }
+}
+
+static void test_abort_at_ip_undo(void)
+{
+ void *abort_ip_addr, *abort_ip_start, *abort_ip_end, *ip_after_first_inc, *ip_after_second_inc;
+ unsigned long v[2] = { 0, 0 };
+
+ printf("Testing abort_at_ip undo\n");
+
+ __asm__ __volatile__ goto (
+ __RSEQ_ASM_DEFINE_TABLE(3, 0x0, ASM_RSEQ_CS_FLAG_ABORT_AT_IP, 1f, (2f - 1f), 4f) /* start, post_commit_offset, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
+ "incq %[v0]\n\t"
+ "10:\n\t"
+ "rep; nop\n\t"
+ "incq %[v1]\n\t"
+ "20:\n\t"
+ "rep; nop\n\t"
+ "jmp 1b\n\t" /* infinite loop. */
+ "2:\n\t"
+ RSEQ_ASM_DEFINE_ABORT(4,
+ /* abort-at-ip must be pop from the stack. */
+ "popq %%rcx\n\t"
+ "addq $128, %%rsp\n\t" /* x86-64 redzone */
+ "movq %%rcx, %[abort_ip_addr]\n\t"
+ "lea 1b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[abort_ip_start]\n\t"
+ "lea 2b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[abort_ip_end]\n\t"
+ "lea 10b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[ip_after_first_inc]\n\t"
+ "lea 20b(%%rip), %%rcx\n\t"
+ "movq %%rcx, %[ip_after_second_inc]\n\t",
+ abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_abi] "r" (&__rseq_abi),
+ [abort_ip_addr] "m" (abort_ip_addr),
+ [abort_ip_start] "m" (abort_ip_start),
+ [abort_ip_end] "m" (abort_ip_end),
+ [ip_after_first_inc] "m" (ip_after_first_inc),
+ [ip_after_second_inc] "m" (ip_after_second_inc),
+ [v0] "m" (v[0]),
+ [v1] "m" (v[1])
+ : "memory", "cc", "rcx"
+ : abort
+ );
+ fprintf(stderr, "Error: infinite loop should never exit gracefully.\n");
+ abort();
+
+abort:
+ printf("Critical section aborted (as expected) at ip %p, within range [%p,%p[\n",
+ abort_ip_addr, abort_ip_start, abort_ip_end);
+ if (abort_ip_addr < abort_ip_start || abort_ip_addr >= abort_ip_end) {
+ fprintf(stderr, "Error: abort-ip is outside of expected range\n");
+ abort();
+ }
+ printf("ip after first inc: %p, ip after second inc: %p\n",
+ ip_after_first_inc, ip_after_second_inc);
+ printf("Counter values: v0: %lu v1: %lu\n", v[0], v[1]);
+ if (abort_ip_addr < ip_after_first_inc || abort_ip_addr >= ip_after_second_inc) {
+ if (v[0] != v[1])
+ abort();
+ } else {
+ if (v[0] != v[1] + 1)
+ abort();
+ }
+}
+#elif defined (__i386__)
+static void test_abort_at_ip_loop(void)
+{
+ void *abort_ip_addr, *abort_ip_start, *abort_ip_end;
+
+ printf("Testing abort_at_ip infinite loop\n");
+
+ __asm__ __volatile__ goto (
+ __RSEQ_ASM_DEFINE_TABLE(3, 0x0, ASM_RSEQ_CS_FLAG_ABORT_AT_IP, 1f, (2f - 1f), 4f) /* start, post_commit_offset, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
+ "rep; nop\n\t" /* cpu_relax for busy loop. */
+ "jmp 1b\n\t" /* infinite loop. */
+ "2:\n\t"
+ RSEQ_ASM_DEFINE_ABORT(4,
+ /* abort-at-ip must be pop from the stack. */
+ "popl %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_addr]\n\t"
+ "movl $1b, %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_start]\n\t"
+ "movl $2b, %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_end]\n\t",
+ abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_abi] "r" (&__rseq_abi),
+ [abort_ip_addr] "m" (abort_ip_addr),
+ [abort_ip_start] "m" (abort_ip_start),
+ [abort_ip_end] "m" (abort_ip_end)
+ : "memory", "cc", "ecx"
+ : abort
+ );
+ fprintf(stderr, "Error: infinite loop should never exit gracefully.\n");
+ abort();
+
+abort:
+ printf("Critical section aborted (as expected) at ip %p, within range [%p,%p[\n",
+ abort_ip_addr, abort_ip_start, abort_ip_end);
+ if (abort_ip_addr < abort_ip_start || abort_ip_addr >= abort_ip_end) {
+ fprintf(stderr, "Error: abort-ip is outside of expected range\n");
+ abort();
+ }
+}
+
+static void test_abort_at_ip_undo(void)
+{
+ void *abort_ip_addr, *abort_ip_start, *abort_ip_end, *ip_after_first_inc, *ip_after_second_inc;
+ unsigned long v[2] = { 0, 0 };
+
+ printf("Testing abort_at_ip undo\n");
+
+ __asm__ __volatile__ goto (
+ __RSEQ_ASM_DEFINE_TABLE(3, 0x0, ASM_RSEQ_CS_FLAG_ABORT_AT_IP, 1f, (2f - 1f), 4f) /* start, post_commit_offset, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
+ "incl %[v0]\n\t"
+ "10:\n\t"
+ "rep; nop\n\t"
+ "incl %[v1]\n\t"
+ "20:\n\t"
+ "rep; nop\n\t"
+ "jmp 1b\n\t" /* infinite loop. */
+ "2:\n\t"
+ RSEQ_ASM_DEFINE_ABORT(4,
+ /* abort-at-ip must be pop from the stack. */
+ "popl %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_addr]\n\t"
+ "movl $1b, %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_start]\n\t"
+ "movl $2b, %%ecx\n\t"
+ "movl %%ecx, %[abort_ip_end]\n\t"
+ "movl $10b, %%ecx\n\t"
+ "movl %%ecx, %[ip_after_first_inc]\n\t"
+ "movl $20b, %%ecx\n\t"
+ "movl %%ecx, %[ip_after_second_inc]\n\t",
+ abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_abi] "r" (&__rseq_abi),
+ [abort_ip_addr] "m" (abort_ip_addr),
+ [abort_ip_start] "m" (abort_ip_start),
+ [abort_ip_end] "m" (abort_ip_end),
+ [ip_after_first_inc] "m" (ip_after_first_inc),
+ [ip_after_second_inc] "m" (ip_after_second_inc),
+ [v0] "m" (v[0]),
+ [v1] "m" (v[1])
+ : "memory", "cc", "rcx"
+ : abort
+ );
+ fprintf(stderr, "Error: infinite loop should never exit gracefully.\n");
+ abort();
+
+abort:
+ printf("Critical section aborted (as expected) at ip %p, within range [%p,%p[\n",
+ abort_ip_addr, abort_ip_start, abort_ip_end);
+ if (abort_ip_addr < abort_ip_start || abort_ip_addr >= abort_ip_end) {
+ fprintf(stderr, "Error: abort-ip is outside of expected range\n");
+ abort();
+ }
+ printf("ip after first inc: %p, ip after second inc: %p\n",
+ ip_after_first_inc, ip_after_second_inc);
+ printf("Counter values: v0: %lu v1: %lu\n", v[0], v[1]);
+ if (abort_ip_addr < ip_after_first_inc || abort_ip_addr >= ip_after_second_inc) {
+ if (v[0] != v[1])
+ abort();
+ } else {
+ if (v[0] != v[1] + 1)
+ abort();
+ }
+}
+#else
+static void test_abort_at_ip_loop(void)
+{
+ abort();
+}
+static void test_abort_at_ip_undo(void)
+{
+ abort();
+}
+#endif
+
+int main(int argc, char **argv)
+{
+ int i;
+
+ if (rseq_register_current_thread()) {
+ fprintf(stderr, "Error: rseq_register_current_thread(...) failed(%d): %s\n",
+ errno, strerror(errno));
+ goto init_thread_error;
+ }
+ printf("testing abort-at-ip extension\n");
+ if (rseq_query_extension(RSEQ_EXT_ABORT_AT_IP) != 0) {
+ fprintf(stderr, "RSEQ abort-at-ip extension is not supported, skipping test.\n");
+ return 0;
+ }
+ for (i = 0; i < nr_iter; i++)
+ test_abort_at_ip_loop();
+ for (i = 0; i < nr_iter; i++)
+ test_abort_at_ip_undo();
+ if (rseq_unregister_current_thread()) {
+ fprintf(stderr, "Error: rseq_unregister_current_thread(...) failed(%d): %s\n",
+ errno, strerror(errno));
+ goto init_thread_error;
+ }
+ return 0;
+
+init_thread_error:
+ return -1;
+}
--
2.17.1