Decode the caller address instead of the return address by default. This
also introduced -R option to provide return address decoding mode.
This changes the decode_stacktrace.sh to decode the line info 1byte before
the return address which will be the call(branch) instruction address. If
the return address is a symbol address (zero offset from it), it falls
back to decoding the return address.
This improves results especially when optimizations have changed the order
of the lines around the return address, or when the return address does
not have the actual line information.
With this change;
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
lockdep_rcu_suspicious (kernel/locking/lockdep.c:6876)
event_filter_pid_sched_process_fork (kernel/trace/trace_events.c:1057)
kernel_clone (include/trace/events/sched.h:396 include/trace/events/sched.h:396 kernel/fork.c:2664)
__x64_sys_clone (kernel/fork.c:2795 kernel/fork.c:2779 kernel/fork.c:2779)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
? trace_irq_disable (include/trace/events/preemptirq.h:36)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
Without this (or give -R option);
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:122)
lockdep_rcu_suspicious (kernel/locking/lockdep.c:6877)
event_filter_pid_sched_process_fork (kernel/trace/trace_events.c:?)
kernel_clone (include/trace/events/sched.h:? include/trace/events/sched.h:396 kernel/fork.c:2664)
__x64_sys_clone (kernel/fork.c:2779)
do_syscall_64 (arch/x86/entry/syscall_64.c:?)
? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
? trace_irq_disable (include/trace/events/preemptirq.h:36)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[akpm@linux-foundation.org: fix spello]
Link: https://lkml.kernel.org/r/177275821652.1557019.18367881408364381866.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> [arm64]
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Sasha Levin (Microsoft) <sashal@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ecfad17122