powerpc: fixing ptrace_get_reg to return an error

Currently ptrace_get_reg returns error as a value
what make impossible to tell whether it is a correct value or error code.

The patch adds a parameter which points to the real return data and
returns an error code.

As get_user_msr() never fails and it is used in multiple places so it has not
been changed by this patch.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>

1 files changed, 12 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index c0244e766834..f51599e941c7 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -95,7 +95,9 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 
                 CHECK_FULL_REGS(child->thread.regs);
                 if (index < PT_FPR0) {
-                        tmp = ptrace_get_reg(child, index);
+                        ret = ptrace_get_reg(child, index, &tmp);
+                        if (ret)
+                                break;
                 } else {
                         flush_fp_to_thread(child);
                         /*
@@ -148,7 +150,11 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         tmp = ((u64 *)child->thread.fpr)
                                 [FPRINDEX_3264(numReg)];
                 } else { /* register within PT_REGS struct */
-                        tmp = ptrace_get_reg(child, numReg);
+                        unsigned long tmp2;
+                        ret = ptrace_get_reg(child, numReg, &tmp2);
+                        if (ret)
+                                break;
+                        tmp = tmp2;
                 } 
                 reg32bits = ((u32*)&tmp)[part];
                 ret = put_user(reg32bits, (u32 __user *)data);
@@ -232,7 +238,10 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         break;
                 CHECK_FULL_REGS(child->thread.regs);
                 if (numReg < PT_FPR0) {
-                        unsigned long freg = ptrace_get_reg(child, numReg);
+                        unsigned long freg;
+                        ret = ptrace_get_reg(child, numReg, &freg);
+                        if (ret)
+                                break;
                         if (index % 2)
                                 freg = (freg & ~0xfffffffful) | (data & 0xfffffffful);
                         else