Commit 9fa881f7 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/ftrace: fix ftrace_caller/ftrace_regs_caller generation 



ftrace_caller was used for both ftrace_caller and ftrace_regs_caller,
which means that the target address of the hotpatch trampoline was
never updated.

With commit 89497968 ("s390/ftrace: provide separate
ftrace_caller/ftrace_regs_caller implementations") a separate
ftrace_regs_caller entry point was implemeted, however it was
forgotten to implement the necessary changes for ftrace_modify_call
and ftrace_make_call, where the branch target has to be modified
accordingly.

Therefore add the missing code now.

Fixes: 89497968 ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations")
Reviewed-by: default avatarSven Schnelle <svens@linux.ibm.com>
Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 6b4b54c7

arch/s390/kernel/ftrace.c

+35 −0
Original line number Diff line number Diff line
@@ -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;

}