s390: Add guarded-storage support

Dump and restore tasks with GS control blocks. Guarded-storage is a new
s390 feature to improve garbage collecting languages like Java.

There are two control blocks in the CPU:

 - GS control block
 - GS broadcast control block

Both control blocks have to be dumped and restored for all threads.
Signed-off-by: Alice Frosi <alice@linux.vnet.ibm.com>
Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

compel/arch/s390/src/lib/include/uapi/asm/infect-types.h

@@ -38,12 +38,18 @@ struct prfpreg {
 };
 
 #define USER_FPREGS_VXRS	0x000000001
+/* Guarded-storage control block */
+#define USER_GS_CB		0x000000002
+/* Guarded-storage broadcast control block */
+#define USER_GS_BC		0x000000004
 
 typedef struct {
 	uint32_t	flags;
 	struct prfpreg	prfpreg;
 	uint64_t	vxrs_low[16];
 	vector128_t	vxrs_high[16];
+	uint64_t	gs_cb[4];
+	uint64_t	gs_bc[4];
 } user_fpregs_struct_t;
 
 typedef struct {

compel/arch/s390/src/lib/infect.c

@@ -19,6 +19,8 @@
 #define NT_PRFPREG		2
 #define NT_S390_VXRS_LOW	0x309
 #define NT_S390_VXRS_HIGH	0x30a
+#define NT_S390_GS_CB		0x30b
+#define NT_S390_GS_BC		0x30c
 
 /*
  * Print general purpose and access registers
@@ -40,17 +42,12 @@ static void print_user_regs_struct(const char *msg, int pid,
 }
 
 /*
- * Print floating point and vector registers
+ * Print vector registers
  */
-static void print_user_fpregs_struct(const char *msg, int pid,
-				     user_fpregs_struct_t *fpregs)
+static void print_vxrs(user_fpregs_struct_t *fpregs)
 {
 	int i;
 
-	pr_debug("%s: FP registers for pid=%d\n", msg, pid);
-	pr_debug("       fpc %08x\n", fpregs->prfpreg.fpc);
-	for (i = 0; i < 16; i++)
-		pr_debug("       f%02d %016lx\n", i, fpregs->prfpreg.fprs[i]);
 	if (!(fpregs->flags & USER_FPREGS_VXRS)) {
 		pr_debug("       No VXRS\n");
 		return;
@@ -63,6 +60,53 @@ static void print_user_fpregs_struct(const char *msg, int pid,
 			 fpregs->vxrs_high[i].part2);
 }
 
+/*
+ * Print guarded-storage control block
+ */
+static void print_gs_cb(user_fpregs_struct_t *fpregs)
+{
+	int i;
+
+	if (!(fpregs->flags & USER_GS_CB)) {
+		pr_debug("       No GS_CB\n");
+		return;
+	}
+	for (i = 0; i < 4; i++)
+		pr_debug("  gs_cb%02d %016lx\n", i, fpregs->gs_cb[i]);
+}
+
+/*
+ * Print guarded-storage broadcast control block
+ */
+static void print_gs_bc(user_fpregs_struct_t *fpregs)
+{
+	int i;
+
+	if (!(fpregs->flags & USER_GS_BC)) {
+		pr_debug("       No GS_BC\n");
+		return;
+	}
+	for (i = 0; i < 4; i++)
+		pr_debug("  gs_bc%02d %016lx\n", i, fpregs->gs_bc[i]);
+}
+
+/*
+ * Print FP registers, VX registers, and guarded storage
+ */
+static void print_user_fpregs_struct(const char *msg, int pid,
+				     user_fpregs_struct_t *fpregs)
+{
+	int i;
+
+	pr_debug("%s: FP registers for pid=%d\n", msg, pid);
+	pr_debug("       fpc %08x\n", fpregs->prfpreg.fpc);
+	for (i = 0; i < 16; i++)
+		pr_debug("       f%02d %016lx\n", i, fpregs->prfpreg.fprs[i]);
+	print_vxrs(fpregs);
+	print_gs_cb(fpregs);
+	print_gs_bc(fpregs);
+}
+
 int sigreturn_prep_regs_plain(struct rt_sigframe *sigframe,
 			      user_regs_struct_t *regs,
 			      user_fpregs_struct_t *fpregs)
@@ -148,7 +192,47 @@ int get_vx_regs(pid_t pid, user_fpregs_struct_t *fpregs)
 	return 0;
 }
 
+/*
+ * Get guarded-storage control block
+ */
+int get_gs_cb(pid_t pid, user_fpregs_struct_t *fpregs)
+{
+	struct iovec iov;
 
+	fpregs->flags &= ~(USER_GS_CB | USER_GS_BC);
+	iov.iov_base = &fpregs->gs_cb;
+	iov.iov_len = sizeof(fpregs->gs_cb);
+	if (ptrace(PTRACE_GETREGSET, pid, NT_S390_GS_CB, &iov) < 0) {
+		switch (errno) {
+		case EINVAL:
+		case ENODEV:
+			memset(&fpregs->gs_cb, 0, sizeof(fpregs->gs_cb));
+			memset(&fpregs->gs_bc, 0, sizeof(fpregs->gs_bc));
+			pr_debug("GS_CB not supported\n");
+			return 0;
+		case ENODATA:
+			pr_debug("GS_CB not set\n");
+			break;
+		default:
+			return -1;
+		}
+	} else {
+		fpregs->flags |= USER_GS_CB;
+	}
+	iov.iov_base = &fpregs->gs_bc;
+	iov.iov_len = sizeof(fpregs->gs_bc);
+	if (ptrace(PTRACE_GETREGSET, pid, NT_S390_GS_BC, &iov) < 0) {
+		if (errno == ENODATA) {
+			pr_debug("GS_BC not set\n");
+			return 0;
+		}
+		pr_perror("Couldn't get GS_BC\n");
+		return -1;
+	}
+	fpregs->flags |= USER_GS_BC;
+
+	return 0;
+}
 /*
  * Prepare task registers for restart
  */
@@ -172,6 +256,10 @@ int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
 		pr_perror("Couldn't get vector registers");
 		return -1;
 	}
+	if (get_gs_cb(pid, &fpregs)) {
+		pr_perror("Couldn't get guarded-storage");
+		return -1;
+	}
 	print_user_fpregs_struct("get_task_regs", pid, &fpregs);
 	/* Check for system call restarting. */
 	if (regs->system_call) {

images/core-s390.proto

@@ -30,10 +30,16 @@ message user_s390_fpregs_entry {
 	repeated uint64			fprs		= 2;
 }
 
+message user_s390_gs_cb_entry {
+	repeated uint64			regs		= 1;
+}
+
 message thread_info_s390 {
 	required uint64				clear_tid_addr	= 1[(criu).hex = true];
 	required user_s390_regs_entry		gpregs		= 2[(criu).hex = true];
 	required user_s390_fpregs_entry		fpregs		= 3[(criu).hex = true];
 	optional user_s390_vxrs_low_entry	vxrs_low	= 4[(criu).hex = true];
 	optional user_s390_vxrs_high_entry	vxrs_high	= 5[(criu).hex = true];
+	optional user_s390_gs_cb_entry		gs_cb		= 6[(criu).hex = true];
+	optional user_s390_gs_cb_entry		gs_bc		= 7[(criu).hex = true];
 }