From 708b13763920ab3c191b31da555f2d90eef4c618 Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Sat, 5 Mar 2022 13:16:07 +0100 Subject: [PATCH] s390/unwind: avoid duplicated unwinding entries for kretprobes Currently when unwinding starts from pt_regs or encounters pt_regs along the way unwinder tries to yield 2 unwinding entries: 1. (reliable) ip1: pt_regs->psw.addr, sp1: regs->gprs[15] 2. (non-reliable) ip2: sp1->gprs[8] (r14), sp2: regs->gprs[15] In case of kretprobes those are identical and serves no other purpose than causing confusion over duplicated entries and cause kprobes tests to fail. So, skip a duplicate non-reliable entry in this case. With that kretprobes and unwinder implementation now comply with ARCH_CORRECT_STACKTRACE_ON_KRETPROBE. Reviewed-by: Tobias Huschle Signed-off-by: Vasily Gorbik --- arch/s390/Kconfig | 1 + arch/s390/kernel/unwind_bc.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 9b80e8b..77b5a03 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -58,6 +58,7 @@ config S390 select ALTERNATE_USER_ADDRESS_SPACE select ARCH_32BIT_USTAT_F_TINODE select ARCH_BINFMT_ELF_STATE + select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM select ARCH_ENABLE_MEMORY_HOTREMOVE select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2 diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c index 9849703..0ece156 100644 --- a/arch/s390/kernel/unwind_bc.c +++ b/arch/s390/kernel/unwind_bc.c @@ -64,8 +64,8 @@ bool unwind_next_frame(struct unwind_state *state) ip = READ_ONCE_NOCHECK(sf->gprs[8]); reliable = false; regs = NULL; - if (!__kernel_text_address(ip)) { - /* skip bogus %r14 */ + /* skip bogus %r14 or if is the same as regs->psw.addr */ + if (!__kernel_text_address(ip) || state->ip == unwind_recover_ret_addr(state, ip)) { state->regs = NULL; return unwind_next_frame(state); } -- 2.7.4