s390/ptrace: add runtime instrumention register get/set

Add runtime instrumention register get and set which allows to read
and modify the runtime instrumention control block.

Signed-off-by: Alice Frosi <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/kernel/ptrace.c

···
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/switch_to.h>
+#include <asm/runtime_instr.h>
+#include <asm/facility.h>
+
 #include "entry.h"
 
 #ifdef CONFIG_COMPAT
···
 				  data, 0, sizeof(struct gs_cb));
 }
 
+static bool is_ri_cb_valid(struct runtime_instr_cb *cb)
+{
+	return (cb->rca & 0x1f) == 0 &&
+		(cb->roa & 0xfff) == 0 &&
+		(cb->rla & 0xfff) == 0xfff &&
+		cb->s == 1 &&
+		cb->k == 1 &&
+		cb->h == 0 &&
+		cb->reserved1 == 0 &&
+		cb->ps == 1 &&
+		cb->qs == 0 &&
+		cb->pc == 1 &&
+		cb->qc == 0 &&
+		cb->reserved2 == 0 &&
+		cb->key == PAGE_DEFAULT_KEY &&
+		cb->reserved3 == 0 &&
+		cb->reserved4 == 0 &&
+		cb->reserved5 == 0 &&
+		cb->reserved6 == 0 &&
+		cb->reserved7 == 0 &&
+		cb->reserved8 == 0 &&
+		cb->rla >= cb->roa &&
+		cb->rca >= cb->roa &&
+		cb->rca <= cb->rla+1 &&
+		cb->m < 3;
+}
+
+static int s390_runtime_instr_get(struct task_struct *target,
+				const struct user_regset *regset,
+				unsigned int pos, unsigned int count,
+				void *kbuf, void __user *ubuf)
+{
+	struct runtime_instr_cb *data = target->thread.ri_cb;
+
+	if (!test_facility(64))
+		return -ENODEV;
+	if (!data)
+		return -ENODATA;
+
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				   data, 0, sizeof(struct runtime_instr_cb));
+}
+
+static int s390_runtime_instr_set(struct task_struct *target,
+				  const struct user_regset *regset,
+				  unsigned int pos, unsigned int count,
+				  const void *kbuf, const void __user *ubuf)
+{
+	struct runtime_instr_cb ri_cb = { }, *data = NULL;
+	int rc;
+
+	if (!test_facility(64))
+		return -ENODEV;
+
+	if (!target->thread.ri_cb) {
+		data = kzalloc(sizeof(*data), GFP_KERNEL);
+		if (!data)
+			return -ENOMEM;
+	}
+
+	if (target->thread.ri_cb) {
+		if (target == current)
+			store_runtime_instr_cb(&ri_cb);
+		else
+			ri_cb = *target->thread.ri_cb;
+	}
+
+	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				&ri_cb, 0, sizeof(struct runtime_instr_cb));
+	if (rc) {
+		kfree(data);
+		return -EFAULT;
+	}
+
+	if (!is_ri_cb_valid(&ri_cb)) {
+		kfree(data);
+		return -EINVAL;
+	}
+
+	preempt_disable();
+	if (!target->thread.ri_cb)
+		target->thread.ri_cb = data;
+	*target->thread.ri_cb = ri_cb;
+	if (target == current)
+		load_runtime_instr_cb(target->thread.ri_cb);
+	preempt_enable();
+
+	return 0;
+}
+
 static const struct user_regset s390_regsets[] = {
 	{
 		.core_note_type = NT_PRSTATUS,
···
 		.align = sizeof(__u64),
 		.get = s390_gs_bc_get,
 		.set = s390_gs_bc_set,
+	},
+	{
+		.core_note_type = NT_S390_RI_CB,
+		.n = sizeof(struct runtime_instr_cb) / sizeof(__u64),
+		.size = sizeof(__u64),
+		.align = sizeof(__u64),
+		.get = s390_runtime_instr_get,
+		.set = s390_runtime_instr_set,
 	},
 };
 
···
 		.align = sizeof(__u64),
 		.get = s390_gs_cb_get,
 		.set = s390_gs_cb_set,
+	},
+	{
+		.core_note_type = NT_S390_RI_CB,
+		.n = sizeof(struct runtime_instr_cb) / sizeof(__u64),
+		.size = sizeof(__u64),
+		.align = sizeof(__u64),
+		.get = s390_runtime_instr_get,
+		.set = s390_runtime_instr_set,
 	},
 };
 

include/uapi/linux/elf.h

···
 #define NT_S390_VXRS_HIGH	0x30a	/* s390 vector registers 16-31 */
 #define NT_S390_GS_CB	0x30b		/* s390 guarded storage registers */
 #define NT_S390_GS_BC	0x30c		/* s390 guarded storage broadcast control block */
+#define NT_S390_RI_CB	0x30d		/* s390 runtime instrumentation */
 #define NT_ARM_VFP	0x400		/* ARM VFP/NEON registers */
 #define NT_ARM_TLS	0x401		/* ARM TLS register */
 #define NT_ARM_HW_BREAK	0x402		/* ARM hardware breakpoint registers */