From a45aff5285871bf7be1781d9462d3fdbb6c913f9 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Sun, 30 Oct 2011 15:16:07 +0100 Subject: [PATCH] [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 --- arch/s390/kernel/ptrace.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 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; + struct per_regs old, new; - /* TIF_SINGLE_STEP overrides the user specified PER registers. */ - new = test_tsk_thread_flag(task, TIF_SINGLE_STEP) ? - &per_single_step : &thread->per_user; + /* 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)