arm64: ptrace: remove addr_limit manipulation

We transiently switch to KERNEL_DS in compat_ptrace_gethbpregs() and
compat_ptrace_sethbpregs(), but in either case this is pointless as we
don't perform any uaccess during this window.

let's rip out the redundant addr_limit manipulation.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 0 insertions, 6 deletions

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 71d99af24ef2..7a832ce6552f 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1458,9 +1458,7 @@ static int compat_ptrace_gethbpregs(struct task_struct *tsk, compat_long_t num,
 {
         int ret;
         u32 kdata;
-        mm_segment_t old_fs = get_fs();
 
-        set_fs(KERNEL_DS);
         /* Watchpoint */
         if (num < 0) {
                 ret = compat_ptrace_hbp_get(NT_ARM_HW_WATCH, tsk, num, &kdata);
@@ -1471,7 +1469,6 @@ static int compat_ptrace_gethbpregs(struct task_struct *tsk, compat_long_t num,
         } else {
                 ret = compat_ptrace_hbp_get(NT_ARM_HW_BREAK, tsk, num, &kdata);
         }
-        set_fs(old_fs);
 
         if (!ret)
                 ret = put_user(kdata, data);
@@ -1484,7 +1481,6 @@ static int compat_ptrace_sethbpregs(struct task_struct *tsk, compat_long_t num,
 {
         int ret;
         u32 kdata = 0;
-        mm_segment_t old_fs = get_fs();
 
         if (num == 0)
                 return 0;
@@ -1493,12 +1489,10 @@ static int compat_ptrace_sethbpregs(struct task_struct *tsk, compat_long_t num,
         if (ret)
                 return ret;
 
-        set_fs(KERNEL_DS);
         if (num < 0)
                 ret = compat_ptrace_hbp_set(NT_ARM_HW_WATCH, tsk, num, &kdata);
         else
                 ret = compat_ptrace_hbp_set(NT_ARM_HW_BREAK, tsk, num, &kdata);
-        set_fs(old_fs);
 
         return ret;
 }