powerpc/ptrace: Enable support for NT_PPC_CVSX

This patch enables support for TM checkpointed VSX register
set ELF core note NT_PPC_CVSX based ptrace requests through
PTRACE_GETREGSET, PTRACE_SETREGSET calls. This is achieved
through adding a register set REGSET_CVSX 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/include/uapi/asm/elf.h

@@ -92,6 +92,7 @@
 #define ELF_NGREG	48	/* includes nip, msr, lr, etc. */
 #define ELF_NFPREG	33	/* includes fpscr */
 #define ELF_NVMX	34	/* includes all vector registers */
+#define ELF_NVSX	32	/* includes all VSX registers */
 
 typedef unsigned long elf_greg_t64;
 typedef elf_greg_t64 elf_gregset_t64[ELF_NGREG];

arch/powerpc/kernel/ptrace.c

@@ -65,6 +65,7 @@ struct pt_regs_offset {
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
 #define TVSO(f)	(offsetof(struct thread_vr_state, f))
+#define TFSO(f)	(offsetof(struct thread_fp_state, f))
 
 static const struct pt_regs_offset regoffset_table[] = {
 	GPR_OFFSET_NAME(0),
@@ -1294,6 +1295,123 @@ static int tm_cvmx_set(struct task_struct *target,
 
 	return ret;
 }
+
+/**
+ * tm_cvsx_active - get active number of registers in CVSX
+ * @target:	The target task.
+ * @regset:	The user regset structure.
+ *
+ * This function checks for the active number of available
+ * regisers in transaction checkpointed VSX category.
+ */
+static int tm_cvsx_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;
+
+	flush_vsx_to_thread(target);
+	return target->thread.used_vsr ? regset->n : 0;
+}
+
+/**
+ * tm_cvsx_get - get CVSX 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 VSX 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 VSX registers.
+ * The userspace interface buffer layout is as follows.
+ *
+ * struct data {
+ *	u64	vsx[32];
+ *};
+ */
+static int tm_cvsx_get(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			void *kbuf, void __user *ubuf)
+{
+	u64 buf[32];
+	int ret, i;
+
+	if (!cpu_has_feature(CPU_FTR_TM))
+		return -ENODEV;
+
+	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
+		return -ENODATA;
+
+	/* Flush the state */
+	flush_fp_to_thread(target);
+	flush_altivec_to_thread(target);
+	flush_tmregs_to_thread(target);
+	flush_vsx_to_thread(target);
+
+	for (i = 0; i < 32 ; i++)
+		buf[i] = target->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  buf, 0, 32 * sizeof(double));
+
+	return ret;
+}
+
+/**
+ * tm_cvsx_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 VSX registers.
+ *
+ * When the transaction is active 'fp_state' holds the checkpointed
+ * VSX 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	vsx[32];
+ *};
+ */
+static int tm_cvsx_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[32];
+	int ret, i;
+
+	if (!cpu_has_feature(CPU_FTR_TM))
+		return -ENODEV;
+
+	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
+		return -ENODATA;
+
+	/* Flush the state */
+	flush_fp_to_thread(target);
+	flush_altivec_to_thread(target);
+	flush_tmregs_to_thread(target);
+	flush_vsx_to_thread(target);
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 buf, 0, 32 * sizeof(double));
+	for (i = 0; i < 32 ; i++)
+		target->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
+
+	return ret;
+}
 #endif
 
 /*
@@ -1315,6 +1433,7 @@ enum powerpc_regset {
 	REGSET_TM_CGPR,		/* TM checkpointed GPR registers */
 	REGSET_TM_CFPR,		/* TM checkpointed FPR registers */
 	REGSET_TM_CVMX,		/* TM checkpointed VMX registers */
+	REGSET_TM_CVSX,		/* TM checkpointed VSX registers */
 #endif
 };
 
@@ -1366,6 +1485,11 @@ static const struct user_regset native_regsets[] = {
 		.size = sizeof(vector128), .align = sizeof(vector128),
 		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
 	},
+	[REGSET_TM_CVSX] = {
+		.core_note_type = NT_PPC_TM_CVSX, .n = ELF_NVSX,
+		.size = sizeof(double), .align = sizeof(double),
+		.active = tm_cvsx_active, .get = tm_cvsx_get, .set = tm_cvsx_set
+	},
 #endif
 };
 
@@ -1608,6 +1732,11 @@ static const struct user_regset compat_regsets[] = {
 		.size = sizeof(vector128), .align = sizeof(vector128),
 		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
 	},
+	[REGSET_TM_CVSX] = {
+		.core_note_type = NT_PPC_TM_CVSX, .n = ELF_NVSX,
+		.size = sizeof(double), .align = sizeof(double),
+		.active = tm_cvsx_active, .get = tm_cvsx_get, .set = tm_cvsx_set
+	},
 #endif
 };