[S390] kprobes: single step cleanup
The saved interrupt mask and the saved control registers are only
relevant while single stepping is set up. A secondary kprobe while
kprobe single stepping is active may not occur. That makes is safe
to remove the save and restore of kprobe_saved_imask / kprobe_save_ctl
from save_previous_kprobe and restore_previous_kprobe.
Move all single step related code to two functions, enable_singlestep
and disable_singlestep.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/kprobes.h b/arch/s390/include/asm/kprobes.h
index 330f68c..15d0dec 100644
--- a/arch/s390/include/asm/kprobes.h
+++ b/arch/s390/include/asm/kprobes.h
@@ -72,9 +72,6 @@
struct prev_kprobe {
struct kprobe *kp;
unsigned long status;
- unsigned long saved_psw;
- unsigned long kprobe_saved_imask;
- unsigned long kprobe_saved_ctl[3];
};
/* per-cpu kprobe control block */
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index b8e5175..91c611f 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -198,51 +198,58 @@
}
}
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb,
+ struct pt_regs *regs,
+ unsigned long ip)
{
per_cr_bits kprobe_per_regs[1];
- memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
- regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
-
/* Set up the per control reg info, will pass to lctl */
+ memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
kprobe_per_regs[0].em_instruction_fetch = 1;
- kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
- kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
+ kprobe_per_regs[0].starting_addr = ip;
+ kprobe_per_regs[0].ending_addr = ip;
- /* Set the PER control regs, turns on single step for this address */
+ /* Save control regs and psw mask */
+ __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
+ kcb->kprobe_saved_imask = regs->psw.mask &
+ (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
+
+ /* Set PER control regs, turns on single step for the given address */
__ctl_load(kprobe_per_regs, 9, 11);
regs->psw.mask |= PSW_MASK_PER;
regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
+ regs->psw.addr = ip | PSW_ADDR_AMODE;
}
+static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb,
+ struct pt_regs *regs,
+ unsigned long ip)
+{
+ /* Restore control regs and psw mask, set new psw address */
+ __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
+ regs->psw.mask &= ~PSW_MASK_PER;
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+ regs->psw.addr = ip | PSW_ADDR_AMODE;
+}
+
+
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
- kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
- memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
- sizeof(kcb->kprobe_saved_ctl));
}
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
- kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
- memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
- sizeof(kcb->kprobe_saved_ctl));
}
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = p;
- /* Save the interrupt and per flags */
- kcb->kprobe_saved_imask = regs->psw.mask &
- (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
- /* Save the control regs that govern PER */
- __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
@@ -282,7 +289,8 @@
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p);
- prepare_singlestep(p, regs);
+ enable_singlestep(kcb, regs,
+ (unsigned long) p->ainsn.insn);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
@@ -311,7 +319,7 @@
return 1;
ss_probe:
- prepare_singlestep(p, regs);
+ enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;
@@ -433,31 +441,20 @@
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- regs->psw.addr &= PSW_ADDR_INSN;
+ unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;
if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
- regs->psw.addr = (unsigned long)p->addr +
- ((unsigned long)regs->psw.addr -
- (unsigned long)p->ainsn.insn);
+ ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
- if ((unsigned long)regs->psw.addr -
- (unsigned long)p->ainsn.insn == p->ainsn.ilen)
- regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
+ if (ip - (unsigned long) p->ainsn.insn == p->ainsn.ilen)
+ ip = (unsigned long) p->addr + p->ainsn.ilen;
if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
- regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
- (regs->gprs[p->ainsn.reg] -
- (unsigned long)p->ainsn.insn))
- | PSW_ADDR_AMODE;
+ regs->gprs[p->ainsn.reg] += (unsigned long) p->addr -
+ (unsigned long) p->ainsn.insn;
- regs->psw.addr |= PSW_ADDR_AMODE;
- /* turn off PER mode */
- regs->psw.mask &= ~PSW_MASK_PER;
- /* Restore the original per control regs */
- __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
- regs->psw.mask |= kcb->kprobe_saved_imask;
+ disable_singlestep(kcb, regs, ip);
}
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
@@ -515,9 +512,7 @@
* and allow the page fault handler to continue as a
* normal page fault.
*/
- regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
- regs->psw.mask &= ~PSW_MASK_PER;
- regs->psw.mask |= kcb->kprobe_saved_imask;
+ disable_singlestep(kcb, regs, (unsigned long) cur->addr);
if (kcb->kprobe_status == KPROBE_REENTER)
restore_previous_kprobe(kcb);
else {