dump: use MEMBARRIER_CMD_GET_REGISTRATIONS when available

MEMBARRIER_CMD_GET_REGISTRATIONS can tell us whether or not the process used MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED unlike the old probing method. Falls back to the old method when MEMBARRIER_CMD_GET_REGISTRATIONS is unavailable. Signed-off-by: Michal Clapinski <mclapinski@google.com>
checkpoint-restore · Sep 12, 2023 · 2926651 · 2926651
1 parent 82bfb67
commit 2926651
Show file tree

Hide file tree

Showing 5 changed files with 59 additions and 13 deletions.
diff --git a/criu/include/kerndat.h b/criu/include/kerndat.h
@@ -85,6 +85,7 @@ struct kerndat_s {
 	bool has_ptrace_get_rseq_conf;
 	struct __ptrace_rseq_configuration libc_rseq_conf;
 	bool has_ipv6_freebind;
+	bool has_membarrier_get_registrations;
 };
 
 extern struct kerndat_s kdat;

diff --git a/criu/include/parasite.h b/criu/include/parasite.h
@@ -118,6 +118,8 @@ static inline int posix_timers_dump_size(int timer_n)
  */
 
 struct parasite_dump_misc {
+	bool has_membarrier_get_registrations; // this is sent from criu to parasite.
+
 	unsigned long brk;
 
 	u32 pid;

diff --git a/criu/kerndat.c b/criu/kerndat.c
@@ -17,6 +17,7 @@
 #include <sys/inotify.h>
 #include <sched.h>
 #include <sys/mount.h>
+#include <linux/membarrier.h>
 
 #if defined(CONFIG_HAS_NFTABLES_LIB_API_0) || defined(CONFIG_HAS_NFTABLES_LIB_API_1)
 #include <nftables/libnftables.h>
@@ -1636,6 +1637,23 @@ static int kerndat_has_ipv6_freebind(void)
 	return ret;
 }
 
+static int kerndat_has_membarrier_get_registrations(void)
+{
+	const int cmd_get_registrations = 1 << 9;
+	int ret = syscall(__NR_membarrier, cmd_get_registrations, 0);
+	if (ret < 0) {
+		if (errno != EINVAL) {
+			return ret;
+		}
+
+		kdat.has_membarrier_get_registrations = false;
+	} else {
+		kdat.has_membarrier_get_registrations = true;
+	}
+
+	return 0;
+}
+
 /*
  * Some features depend on resource that can be dynamically changed
  * at the OS runtime. There are cases that we cannot determine the
@@ -1879,6 +1897,10 @@ int kerndat_init(void)
 		pr_err("kerndat_has_ipv6_freebind failed when initializing kerndat.\n");
 		ret = -1;
 	}
+	if (!ret && kerndat_has_membarrier_get_registrations()) {
+		pr_err("kerndat_has_membarrier_get_registrations failed when initializing kerndat.\n");
+		ret = -1;
+	}
 
 	kerndat_lsm();
 	kerndat_mmap_min_addr();

diff --git a/criu/parasite-syscall.c b/criu/parasite-syscall.c
@@ -433,6 +433,7 @@ int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_mis
 	struct parasite_dump_misc *ma;
 
 	ma = compel_parasite_args(ctl, struct parasite_dump_misc);
+	ma->has_membarrier_get_registrations = kdat.has_membarrier_get_registrations;
 	if (compel_rpc_call_sync(PARASITE_CMD_DUMP_MISC, ctl) < 0)
 		return -1;
 

diff --git a/criu/pie/parasite.c b/criu/pie/parasite.c
@@ -246,6 +246,27 @@ static int get_membarrier_registration_mask(int cmd_bit)
 #define MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED	      3
 #define MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_SYNC_CORE 5
 #define MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_RSEQ      7
+#define MEMBARRIER_CMDBIT_GET_REGISTRATIONS	      9
+
+static int dump_membarrier_compat(int *membarrier_registration_mask)
+{
+	int ret;
+
+	*membarrier_registration_mask = 0;
+	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED);
+	if (ret < 0)
+		return -1;
+	*membarrier_registration_mask |= ret;
+	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_SYNC_CORE);
+	if (ret < 0)
+		return -1;
+	*membarrier_registration_mask |= ret;
+	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_RSEQ);
+	if (ret < 0)
+		return -1;
+	*membarrier_registration_mask |= ret;
+	return 0;
+}
 
 static int dump_misc(struct parasite_dump_misc *args)
 {
@@ -261,19 +282,18 @@ static int dump_misc(struct parasite_dump_misc *args)
 	args->dumpable = sys_prctl(PR_GET_DUMPABLE, 0, 0, 0, 0);
 	args->thp_disabled = sys_prctl(PR_GET_THP_DISABLE, 0, 0, 0, 0);
 
-	args->membarrier_registration_mask = 0;
-	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED);
-	if (ret < 0)
-		return -1;
-	args->membarrier_registration_mask |= ret;
-	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_SYNC_CORE);
-	if (ret < 0)
-		return -1;
-	args->membarrier_registration_mask |= ret;
-	ret = get_membarrier_registration_mask(MEMBARRIER_CMDBIT_PRIVATE_EXPEDITED_RSEQ);
-	if (ret < 0)
-		return -1;
-	args->membarrier_registration_mask |= ret;
+	if (args->has_membarrier_get_registrations) {
+		ret = sys_membarrier(1 << MEMBARRIER_CMDBIT_GET_REGISTRATIONS, 0, 0);
+		if (ret < 0) {
+			pr_err("membarrier(1 << %d) returned %d\n", MEMBARRIER_CMDBIT_GET_REGISTRATIONS, ret);
+			return -1;
+		}
+		args->membarrier_registration_mask = ret;
+	} else {
+		ret = dump_membarrier_compat(&args->membarrier_registration_mask);
+		if (ret)
+			return ret;
+	}
 
 	ret = sys_prctl(PR_GET_CHILD_SUBREAPER, (unsigned long)&args->child_subreaper, 0, 0, 0);
 	if (ret)