summaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/ftrace.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/s390/kernel/ftrace.c')
-rw-r--r--arch/s390/kernel/ftrace.c37
1 files changed, 36 insertions, 1 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 21d62d8b6b9a..89c0870d5679 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -159,9 +159,38 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
return 0;
}
+static struct ftrace_hotpatch_trampoline *ftrace_get_trampoline(struct dyn_ftrace *rec)
+{
+ struct ftrace_hotpatch_trampoline *trampoline;
+ struct ftrace_insn insn;
+ s64 disp;
+ u16 opc;
+
+ if (copy_from_kernel_nofault(&insn, (void *)rec->ip, sizeof(insn)))
+ return ERR_PTR(-EFAULT);
+ disp = (s64)insn.disp * 2;
+ trampoline = (void *)(rec->ip + disp);
+ if (get_kernel_nofault(opc, &trampoline->brasl_opc))
+ return ERR_PTR(-EFAULT);
+ if (opc != 0xc015)
+ return ERR_PTR(-EINVAL);
+ return trampoline;
+}
+
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
+ struct ftrace_hotpatch_trampoline *trampoline;
+ u64 old;
+
+ trampoline = ftrace_get_trampoline(rec);
+ if (IS_ERR(trampoline))
+ return PTR_ERR(trampoline);
+ if (get_kernel_nofault(old, &trampoline->interceptor))
+ return -EFAULT;
+ if (old != old_addr)
+ return -EINVAL;
+ s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
return 0;
}
@@ -188,6 +217,12 @@ static void brcl_enable(void *brcl)
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
+ struct ftrace_hotpatch_trampoline *trampoline;
+
+ trampoline = ftrace_get_trampoline(rec);
+ if (IS_ERR(trampoline))
+ return PTR_ERR(trampoline);
+ s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
brcl_enable((void *)rec->ip);
return 0;
}
@@ -291,7 +326,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
regs = ftrace_get_regs(fregs);
p = get_kprobe((kprobe_opcode_t *)ip);
- if (unlikely(!p) || kprobe_disabled(p))
+ if (!regs || unlikely(!p) || kprobe_disabled(p))
goto out;
if (kprobe_running()) {