From: Heiko Carstens <hca@xxxxxxxxxxxxx> commit 9fa881f7e3c74ce6626d166bca9397e5d925937f upstream. 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 894979689d3a ("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: 894979689d3a ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations") Reviewed-by: Sven Schnelle <svens@xxxxxxxxxxxxx> Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/kernel/ftrace.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -159,9 +159,38 @@ int ftrace_init_nop(struct module *mod, 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; } Patches currently in stable-queue which might be from hca@xxxxxxxxxxxxx are queue-5.16/s390-extable-fix-exception-table-sorting.patch queue-5.16/s390-ftrace-fix-arch_ftrace_get_regs-implementation.patch queue-5.16/s390-ftrace-fix-ftrace_caller-ftrace_regs_caller-generation.patch