[IA64] Fix convert_to_non_syscall() so gdb inferior calls work again

Fix convert_to_non_syscall() so it arranges for the kernel to be left
via ia64_leave_kernel() rather than ia64_leave_syscall().  The latter
no longer tolerates being called with pSys=0 and pNonSys=1.

Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 21 insertions, 1 deletions

diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index c253fd5914fc..9e730c7bf0cd 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -705,12 +705,32 @@ convert_to_non_syscall (struct task_struct *child, struct pt_regs  *pt,
                         break;
         }
 
+        /*
+         * Note: at the time of this call, the target task is blocked
+         * in notify_resume_user() and by clearling PRED_LEAVE_SYSCALL
+         * (aka, "pLvSys") we redirect execution from
+         * .work_pending_syscall_end to .work_processed_kernel.
+         */
         unw_get_pr(&prev_info, &pr);
-        pr &= ~(1UL << PRED_SYSCALL);
+        pr &= ~((1UL << PRED_SYSCALL) | (1UL << PRED_LEAVE_SYSCALL));
         pr |=  (1UL << PRED_NON_SYSCALL);
         unw_set_pr(&prev_info, pr);
 
         pt->cr_ifs = (1UL << 63) | cfm;
+        /*
+         * Clear the memory that is NOT written on syscall-entry to
+         * ensure we do not leak kernel-state to user when execution
+         * resumes.
+         */
+        pt->r2 = 0;
+        pt->r3 = 0;
+        pt->r14 = 0;
+        memset(&pt->r16, 0, 16*8);      /* clear r16-r31 */
+        memset(&pt->f6, 0, 6*16);       /* clear f6-f11 */
+        pt->b7 = 0;
+        pt->ar_ccv = 0;
+        pt->ar_csd = 0;
+        pt->ar_ssd = 0;
 }
 
 static int