[RFC PATCH 3/5] powerpc: Fix pmu get/set functions

[Pedro Franco de Carvalho]

The PMU regset exposed through ptrace has 5 64-bit words, which are
all copied in and out. However, mmcr0 in the thread_struct is an
unsigned, which causes pmu_set to clobber the next variable in the
thread_struct (used_ebb), and pmu_get to return the same variable in
one half of the mmcr0 slot.
---
 arch/powerpc/kernel/ptrace.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index be8ca03a0bd5..69123feaef9e 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1733,6 +1733,9 @@ static int pmu_get(struct task_struct *target,
                      unsigned int pos, unsigned int count,
                      void *kbuf, void __user *ubuf)
 {
+       int ret = 0;
+       unsigned long mmcr0 = target->thread.mmcr0;
+
        /* Build tests */
        BUILD_BUG_ON(TSO(siar) + sizeof(unsigned long) != TSO(sdar));
        BUILD_BUG_ON(TSO(sdar) + sizeof(unsigned long) != TSO(sier));
@@ -1742,9 +1745,16 @@ static int pmu_get(struct task_struct *target,
        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
                return -ENODEV;
 
-       return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                       &target->thread.siar, 0,
+       ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+               &target->thread.siar, 0,
+               4 * sizeof(unsigned long));
+
+       if (!ret)
+               ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+                       &mmcr0, 4 * sizeof(unsigned long),
                        5 * sizeof(unsigned long));
+
+       return ret;
 }
 
 static int pmu_set(struct task_struct *target,
@@ -1754,6 +1764,12 @@ static int pmu_set(struct task_struct *target,
 {
        int ret = 0;
 
+#ifdef __BIG_ENDIAN
+       int mmcr0_offset = sizeof(unsigned);
+#else
+       int mmcr0_offset = 0;
+#endif
+
        /* Build tests */
        BUILD_BUG_ON(TSO(siar) + sizeof(unsigned long) != TSO(sdar));
        BUILD_BUG_ON(TSO(sdar) + sizeof(unsigned long) != TSO(sier));
@@ -1783,9 +1799,16 @@ static int pmu_set(struct task_struct *target,
                        4 * sizeof(unsigned long));
 
        if (!ret)
+               ret = user_regset_copyin_ignore(&pos, &count, &kbuf,
+                       &ubuf, 4 * sizeof(unsigned long),
+                       4 * sizeof(unsigned long) + mmcr0_offset);
+
+       if (!ret)
                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-                       &target->thread.mmcr0, 4 * sizeof(unsigned long),
-                       5 * sizeof(unsigned long));
+                       &target->thread.mmcr0,
+                       4 * sizeof(unsigned long) + mmcr0_offset,
+                       4 * sizeof(unsigned long) + mmcr0_offset
+                       + sizeof (unsigned));
        return ret;
 }
 #endif
-- 
2.13.6