powerpc/ptrace: Enable support for NT_PPC_CFPR

This patch enables support for TM checkpointed FPR register
set ELF core note NT_PPC_CFPR based ptrace requests through
PTRACE_GETREGSET, PTRACE_SETREGSET calls. This is achieved
through adding a register set REGSET_CFPR in powerpc
corresponding to the ELF core note section added. It
implements the get, set and active functions for this new
register set added.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/ptrace.c

@@ -1032,6 +1032,121 @@ static int tm_cgpr_set(struct task_struct *target,
 
 	return ret;
 }
+
+/**
+ * tm_cfpr_active - get active number of registers in CFPR
+ * @target:	The target task.
+ * @regset:	The user regset structure.
+ *
+ * This function checks for the active number of available
+ * regisers in transaction checkpointed FPR category.
+ */
+static int tm_cfpr_active(struct task_struct *target,
+				const struct user_regset *regset)
+{
+	if (!cpu_has_feature(CPU_FTR_TM))
+		return -ENODEV;
+
+	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
+		return 0;
+
+	return regset->n;
+}
+
+/**
+ * tm_cfpr_get - get CFPR registers
+ * @target:	The target task.
+ * @regset:	The user regset structure.
+ * @pos:	The buffer position.
+ * @count:	Number of bytes to copy.
+ * @kbuf:	Kernel buffer to copy from.
+ * @ubuf:	User buffer to copy into.
+ *
+ * This function gets in transaction checkpointed FPR registers.
+ *
+ * When the transaction is active 'fp_state' holds the checkpointed
+ * values for the current transaction to fall back on if it aborts
+ * in between. This function gets those checkpointed FPR registers.
+ * The userspace interface buffer layout is as follows.
+ *
+ * struct data {
+ *	u64	fpr[32];
+ *	u64	fpscr;
+ *};
+ */
+static int tm_cfpr_get(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			void *kbuf, void __user *ubuf)
+{
+	u64 buf[33];
+	int i;
+
+	if (!cpu_has_feature(CPU_FTR_TM))
+		return -ENODEV;
+
+	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
+		return -ENODATA;
+
+	flush_fp_to_thread(target);
+	flush_altivec_to_thread(target);
+	flush_tmregs_to_thread(target);
+
+	/* copy to local buffer then write that out */
+	for (i = 0; i < 32 ; i++)
+		buf[i] = target->thread.TS_FPR(i);
+	buf[32] = target->thread.fp_state.fpscr;
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
+}
+
+/**
+ * tm_cfpr_set - set CFPR registers
+ * @target:	The target task.
+ * @regset:	The user regset structure.
+ * @pos:	The buffer position.
+ * @count:	Number of bytes to copy.
+ * @kbuf:	Kernel buffer to copy into.
+ * @ubuf:	User buffer to copy from.
+ *
+ * This function sets in transaction checkpointed FPR registers.
+ *
+ * When the transaction is active 'fp_state' holds the checkpointed
+ * FPR register values for the current transaction to fall back on
+ * if it aborts in between. This function sets these checkpointed
+ * FPR registers. The userspace interface buffer layout is as follows.
+ *
+ * struct data {
+ *	u64	fpr[32];
+ *	u64	fpscr;
+ *};
+ */
+static int tm_cfpr_set(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			const void *kbuf, const void __user *ubuf)
+{
+	u64 buf[33];
+	int i;
+
+	if (!cpu_has_feature(CPU_FTR_TM))
+		return -ENODEV;
+
+	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
+		return -ENODATA;
+
+	flush_fp_to_thread(target);
+	flush_altivec_to_thread(target);
+	flush_tmregs_to_thread(target);
+
+	/* copy to local buffer then write that out */
+	i = user_regset_copyin(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
+	if (i)
+		return i;
+	for (i = 0; i < 32 ; i++)
+		target->thread.TS_FPR(i) = buf[i];
+	target->thread.fp_state.fpscr = buf[32];
+	return 0;
+}
 #endif
 
 /*
@@ -1051,6 +1166,7 @@ enum powerpc_regset {
 #endif
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 	REGSET_TM_CGPR,		/* TM checkpointed GPR registers */
+	REGSET_TM_CFPR,		/* TM checkpointed FPR registers */
 #endif
 };
 
@@ -1092,6 +1208,11 @@ static const struct user_regset native_regsets[] = {
 		.size = sizeof(long), .align = sizeof(long),
 		.active = tm_cgpr_active, .get = tm_cgpr_get, .set = tm_cgpr_set
 	},
+	[REGSET_TM_CFPR] = {
+		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
+		.size = sizeof(double), .align = sizeof(double),
+		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
+	},
 #endif
 };
 
@@ -1324,6 +1445,11 @@ static const struct user_regset compat_regsets[] = {
 		.active = tm_cgpr_active,
 		.get = tm_cgpr32_get, .set = tm_cgpr32_set
 	},
+	[REGSET_TM_CFPR] = {
+		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
+		.size = sizeof(double), .align = sizeof(double),
+		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
+	},
 #endif
 };