s390/kprobes: remove KPROBE_SWAP_INST state

For an unknown reason the s390 kprobes instruction replacement
function modifies the kprobe_status of the current CPU to
KPROBE_SWAP_INST. This was supposed to catch traps that happened
during instruction patching. Such a fault is not supposed to happen,
and silently discarding such a fault is certainly also not what we
want. In fact s390 is the only architecture which has this odd piece
of code.

Just remove this and behave like all other architectures. This was
pointed out by Jens Remus.

Reported-by: Jens Remus <jremus@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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 28792ef82c837a2f2c11a5765098434018d02598..921391f2341eb8c4e886ee1bb4b67554f2d35d91 100644 (file)
--- a/arch/s390/include/asm/kprobes.h
+++ b/arch/s390/include/asm/kprobes.h
@@ -63,8 +63,6 @@ typedef u16 kprobe_opcode_t;
 
 #define kretprobe_blacklist_size 0
 
-#define KPROBE_SWAP_INST       0x10
-
 /* Architecture specific copy of original instruction */
 struct arch_specific_insn {
        /* copy of original instruction */

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 6842e4501e2e53a82f1da1de7b25860f3f96a034..1a6521af17514a722c02e1b032fe3514d6857a15 100644 (file)
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -161,8 +161,6 @@ struct swap_insn_args {
 
 static int swap_instruction(void *data)
 {
-       struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-       unsigned long status = kcb->kprobe_status;
        struct swap_insn_args *args = data;
        struct ftrace_insn new_insn, *insn;
        struct kprobe *p = args->p;
@@ -185,9 +183,7 @@ static int swap_instruction(void *data)
                        ftrace_generate_nop_insn(&new_insn);
        }
 skip_ftrace:
-       kcb->kprobe_status = KPROBE_SWAP_INST;
        s390_kernel_write(p->addr, &new_insn, len);
-       kcb->kprobe_status = status;
        return 0;
 }
 NOKPROBE_SYMBOL(swap_instruction);
@@ -574,9 +570,6 @@ static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
        const struct exception_table_entry *entry;
 
        switch(kcb->kprobe_status) {
-       case KPROBE_SWAP_INST:
-               /* We are here because the instruction replacement failed */
-               return 0;
        case KPROBE_HIT_SS:
        case KPROBE_REENTER:
                /*