[PATCH 3.16 246/370] powerpc/ptrace: Preserve previous fprs/vsrs on short regset write

Ben Hutchings
2017-03-10T12:20:25Z

From: Dave Martin <Dave.Martin@arm.com>

commit 99dfe80a2a246c600440a815741fd2e74a8b4977 upstream.

Ensure that if userspace supplies insufficient data to PTRACE_SETREGSET
to fill all the registers, the thread's old registers are preserved.

Fixes: c6e6771b87d4 ("powerpc: Introduce VSX thread_struct and CONFIG_VSX")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/powerpc/kernel/ptrace.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -394,6 +394,10 @@ static int fpr_set(struct task_struct *t
flush_fp_to_thread(target);

#ifdef CONFIG_VSX
+ for (i = 0; i < 32 ; i++)
+ buf[i] = target->thread.TS_FPR(i);
+ buf[32] = target->thread.fp_state.fpscr;
+
/* copy to local buffer then write that out */
i = user_regset_copyin(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
if (i)
@@ -537,6 +541,9 @@ static int vsr_set(struct task_struct *t

flush_vsx_to_thread(target);

+ for (i = 0; i < 32 ; i++)
+ buf[i] = target->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
+
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
buf, 0, 32 * sizeof(double));
for (i = 0; i < 32 ; i++)