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Subject[PATCH 4.3 087/125] s390/kernel: fix ptrace peek/poke for floating point registers
Date
4.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

commit 55a423b6f105fa323168f15f4bb67f23b21da44e upstream.

git commit 155e839a814834a3b4b31e729f4716e59d3d2dd4
"s390/kernel: dynamically allocate FP register save area"
introduced a regression in regard to ptrace.

If the vector register extension is not present or unused the
ptrace peek of a floating pointer register return incorrect data
and the ptrace poke to a floating pointer register overwrites the
task structure starting at task->thread.fpu.fprs.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/kernel/ptrace.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -244,7 +244,7 @@ static unsigned long __peek_user(struct
((addr_t) child->thread.fpu.vxrs + 2*offset);
else
tmp = *(addr_t *)
- ((addr_t) &child->thread.fpu.fprs + offset);
+ ((addr_t) child->thread.fpu.fprs + offset);

} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
/*
@@ -388,7 +388,7 @@ static int __poke_user(struct task_struc
child->thread.fpu.vxrs + 2*offset) = data;
else
*(addr_t *)((addr_t)
- &child->thread.fpu.fprs + offset) = data;
+ child->thread.fpu.fprs + offset) = data;

} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
/*
@@ -622,7 +622,7 @@ static u32 __peek_user_compat(struct tas
((addr_t) child->thread.fpu.vxrs + 2*offset);
else
tmp = *(__u32 *)
- ((addr_t) &child->thread.fpu.fprs + offset);
+ ((addr_t) child->thread.fpu.fprs + offset);

} else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
/*
@@ -747,7 +747,7 @@ static int __poke_user_compat(struct tas
child->thread.fpu.vxrs + 2*offset) = tmp;
else
*(__u32 *)((addr_t)
- &child->thread.fpu.fprs + offset) = tmp;
+ child->thread.fpu.fprs + offset) = tmp;

} else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
/*



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