s390/uprobes: fix user space PER events
If uprobes are single stepped for example with gdb, the behavior should
now be correct. Before this patch, when gdb was single stepping a uprobe,
the result was a SIGILL.
When PER is active for any storage alteration and a uprobe is hit, a storage
alteration event is indicated. These over indications are filterd out by gdb,
if no change has happened within the observed area.
Signed-off-by: Jan Willeke <willeke@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c
index f6b3cd0..cc73280 100644
--- a/arch/s390/kernel/uprobes.c
+++ b/arch/s390/kernel/uprobes.c
@@ -48,6 +48,30 @@
return false;
}
+static int check_per_event(unsigned short cause, unsigned long control,
+ struct pt_regs *regs)
+{
+ if (!(regs->psw.mask & PSW_MASK_PER))
+ return 0;
+ /* user space single step */
+ if (control == 0)
+ return 1;
+ /* over indication for storage alteration */
+ if ((control & 0x20200000) && (cause & 0x2000))
+ return 1;
+ if (cause & 0x8000) {
+ /* all branches */
+ if ((control & 0x80800000) == 0x80000000)
+ return 1;
+ /* branch into selected range */
+ if (((control & 0x80800000) == 0x80800000) &&
+ regs->psw.addr >= current->thread.per_user.start &&
+ regs->psw.addr <= current->thread.per_user.end)
+ return 1;
+ }
+ return 0;
+}
+
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
int fixup = probe_get_fixup_type(auprobe->insn);
@@ -71,9 +95,13 @@
if (regs->psw.addr - utask->xol_vaddr == ilen)
regs->psw.addr = utask->vaddr + ilen;
}
- /* If per tracing was active generate trap */
- if (regs->psw.mask & PSW_MASK_PER)
- do_per_trap(regs);
+ if (check_per_event(current->thread.per_event.cause,
+ current->thread.per_user.control, regs)) {
+ /* fix per address */
+ current->thread.per_event.address = utask->vaddr;
+ /* trigger per event */
+ set_pt_regs_flag(regs, PIF_PER_TRAP);
+ }
return 0;
}
@@ -106,6 +134,7 @@
clear_thread_flag(TIF_UPROBE_SINGLESTEP);
regs->int_code = auprobe->saved_int_code;
regs->psw.addr = current->utask->vaddr;
+ current->thread.per_event.address = current->utask->vaddr;
}
unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
@@ -146,17 +175,20 @@
__rc; \
})
-#define emu_store_ril(ptr, input) \
+#define emu_store_ril(regs, ptr, input) \
({ \
unsigned int mask = sizeof(*(ptr)) - 1; \
+ __typeof__(ptr) __ptr = (ptr); \
int __rc = 0; \
\
if (!test_facility(34)) \
__rc = EMU_ILLEGAL_OP; \
- else if ((u64 __force)ptr & mask) \
+ else if ((u64 __force)__ptr & mask) \
__rc = EMU_SPECIFICATION; \
- else if (put_user(*(input), ptr)) \
+ else if (put_user(*(input), __ptr)) \
__rc = EMU_ADDRESSING; \
+ if (__rc == 0) \
+ sim_stor_event(regs, __ptr, mask + 1); \
__rc; \
})
@@ -198,6 +230,25 @@
};
/*
+ * If user per registers are setup to trace storage alterations and an
+ * emulated store took place on a fitting address a user trap is generated.
+ */
+static void sim_stor_event(struct pt_regs *regs, void *addr, int len)
+{
+ if (!(regs->psw.mask & PSW_MASK_PER))
+ return;
+ if (!(current->thread.per_user.control & PER_EVENT_STORE))
+ return;
+ if ((void *)current->thread.per_user.start > (addr + len))
+ return;
+ if ((void *)current->thread.per_user.end < addr)
+ return;
+ current->thread.per_event.address = regs->psw.addr;
+ current->thread.per_event.cause = PER_EVENT_STORE >> 16;
+ set_pt_regs_flag(regs, PIF_PER_TRAP);
+}
+
+/*
* pc relative instructions are emulated, since parameters may not be
* accessible from the xol area due to range limitations.
*/
@@ -249,13 +300,13 @@
rc = emu_load_ril((u32 __user *)uptr, &rx->u64);
break;
case 0x07: /* sthrl */
- rc = emu_store_ril((u16 __user *)uptr, &rx->u16[3]);
+ rc = emu_store_ril(regs, (u16 __user *)uptr, &rx->u16[3]);
break;
case 0x0b: /* stgrl */
- rc = emu_store_ril((u64 __user *)uptr, &rx->u64);
+ rc = emu_store_ril(regs, (u64 __user *)uptr, &rx->u64);
break;
case 0x0f: /* strl */
- rc = emu_store_ril((u32 __user *)uptr, &rx->u32[1]);
+ rc = emu_store_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
break;
}
break;