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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2011-10-30 15:16:07 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2011-10-30 15:16:15 +0100
commita45aff5285871bf7be1781d9462d3fdbb6c913f9 (patch)
tree3f0f0e58644707f4ac15b57f420952a68ecc1a96
parentcaa04f69df9a5d4c10867b475006cf6f2f1e8500 (diff)
[S390] user per registers vs. ptrace single stepping
git commit 5e9a2692 "[S390] ptrace cleanup" introduced a regression for the case when both a user PER set (e.g. a storage alteration trace) and PTRACE_SINGLESTEP are active. The new code will overrule the user PER set with a instruction-fetch PER set over the whole address space for ptrace single stepping. The inferior process will be stopped after each instruction with an instruction fetch event. Any other events that may have occurred concurrently are not reported (e.g. storage alteration event) because the control bits for them are not set. The solution is to merge the PER control bits of the user PER set with the PER_EVENT_IFETCH control bit for PTRACE_SINGLESTEP. Cc: stable@kernel.org Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
-rw-r--r--arch/s390/kernel/ptrace.c30
1 files changed, 16 insertions, 14 deletions
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index ef86ad243986..ae0e14b8880c 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -47,29 +47,31 @@ enum s390_regset {
void update_per_regs(struct task_struct *task)
{
- static const struct per_regs per_single_step = {
- .control = PER_EVENT_IFETCH,
- .start = 0,
- .end = PSW_ADDR_INSN,
- };
struct pt_regs *regs = task_pt_regs(task);
struct thread_struct *thread = &task->thread;
- const struct per_regs *new;
- struct per_regs old;
-
- /* TIF_SINGLE_STEP overrides the user specified PER registers. */
- new = test_tsk_thread_flag(task, TIF_SINGLE_STEP) ?
- &per_single_step : &thread->per_user;
+ struct per_regs old, new;
+
+ /* Copy user specified PER registers */
+ new.control = thread->per_user.control;
+ new.start = thread->per_user.start;
+ new.end = thread->per_user.end;
+
+ /* merge TIF_SINGLE_STEP into user specified PER registers. */
+ if (test_tsk_thread_flag(task, TIF_SINGLE_STEP)) {
+ new.control |= PER_EVENT_IFETCH;
+ new.start = 0;
+ new.end = PSW_ADDR_INSN;
+ }
/* Take care of the PER enablement bit in the PSW. */
- if (!(new->control & PER_EVENT_MASK)) {
+ if (!(new.control & PER_EVENT_MASK)) {
regs->psw.mask &= ~PSW_MASK_PER;
return;
}
regs->psw.mask |= PSW_MASK_PER;
__ctl_store(old, 9, 11);
- if (memcmp(new, &old, sizeof(struct per_regs)) != 0)
- __ctl_load(*new, 9, 11);
+ if (memcmp(&new, &old, sizeof(struct per_regs)) != 0)
+ __ctl_load(new, 9, 11);
}
void user_enable_single_step(struct task_struct *task)