[Crash-utility] [PATCH 5/5] ppc64: Enable live debug support for gdb stack unwinding

The live debug can be enabled for ppc64. For inactive tasks, it can show the stack unwinding results: crash> sys KERNEL: /usr/lib/debug/lib/modules/5.14.0-425.el9.ppc64le/vmlinux DUMPFILE: /proc/kcore ... crash> set 1 crash> bt PID: 1 TASK: c0000000035fc900 CPU: 1 COMMAND: "systemd" #0 [c00000000369fa60] __schedule at c000000000fc3c58 #1 [c00000000369fb20] schedule at c000000000fc411c #2 [c00000000369fb50] schedule_hrtimeout_range_clock at c000000000fcd2a4 #3 [c00000000369fc00] ep_poll at c00000000063640c #4 [c00000000369fcf0] do_epoll_wait at c000000000636584 #5 [c00000000369fd40] sys_epoll_wait at c000000000636608 #6 [c00000000369fdb0] system_call_exception at c00000000002e994 #7 [c00000000369fe10] system_call_vectored_common at c00000000000bfe8 crash> gdb bt #0 0xc000000000fc3c58 in context_switch ... #1 __schedule ... #2 0xc000000000fc411c in schedule_loop ... #3 schedule ... #4 0xc000000000fcd2a4 in schedule_hrtimeout_range_clock ... #5 0xc00000000063640c in ep_poll ... #6 0xc000000000636584 in do_epoll_wait ... #7 0xc000000000636608 in __do_sys_epoll_wait ... #8 __se_sys_epoll_wait ... #9 0xc00000000002e994 in system_call_exception ... #10 0xc00000000000bfe8 in system_call_vectored_common ... However for active tasks in live mode, stack unwind will fail. The behaviour is similar for "bt" and "gdb bt": crash> ps PID PPID CPU TASK ST %MEM VSZ RSS COMM 0 0 0 c000000002af6380 RU 0.0 0 0 [swapper/0] ... crash> set c0000000035f0180 crash> bt PID: 0 TASK: c0000000035f0180 CPU: 2 COMMAND: "swapper/2" (active) crash> gdb bt #0 0xc000000003847d50 in ?? () #1 0x0000000000000000 in ?? () Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- ppc64.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/ppc64.c b/ppc64.c index f86d951..a87e621 100644 --- a/ppc64.c +++ b/ppc64.c @@ -2516,11 +2516,6 @@ ppc64_get_cpu_reg(int cpu, int regno, const char *name, int size, ulong ip, sp; bool ret = FALSE; - if (LIVE()) { - /* doesn't support reading registers in live dump */ - return FALSE; - } - /* Currently only handling registers available in ppc64_pt_regs: * * 0-31: r0-r31 -- 2.40.1