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>

2 files changed, 130 insertions, 0 deletions

diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
index ecb4e84cb22c..1549172aa258 100644
--- a/arch/powerpc/include/uapi/asm/elf.h
+++ b/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];
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 6e42137c0175..df6afe7da4da 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/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
 };