From 7ddc6a2199f1da405a2fb68c40db8899b1a8cd87 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 24 Nov 2014 17:39:06 -0800 Subject: [PATCH 1/2] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs These functions can be executed on the int3 stack, so kprobes are dangerous. Tracing is probably a bad idea, too. Fixes: b645af2d5905 ("x86_64, traps: Rework bad_iret") Signed-off-by: Andy Lutomirski Cc: # Backport as far back as it would apply Cc: Linus Torvalds Cc: Steven Rostedt Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.net Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index de801f22128a..07ab8e9733c5 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -387,7 +387,7 @@ NOKPROBE_SYMBOL(do_int3); * for scheduling or signal handling. The actual stack switch is done in * entry.S */ -asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs) +asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs) { struct pt_regs *regs = eregs; /* Did already sync */ @@ -413,7 +413,7 @@ struct bad_iret_stack { struct pt_regs regs; }; -asmlinkage __visible +asmlinkage __visible notrace struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) { /* @@ -436,6 +436,7 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) BUG_ON(!user_mode_vm(&new_stack->regs)); return new_stack; } +NOKPROBE_SYMBOL(fixup_bad_iret); #endif /* From f61ff6c06dc8f32c7036013ad802c899ec590607 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 26 Nov 2014 16:39:31 +0100 Subject: [PATCH 2/2] perf session: Do not fail on processing out of order event Linus reported perf report command being interrupted due to processing of 'out of order' event, with following error: Timestamp below last timeslice flush 0x5733a8 [0x28]: failed to process type: 3 I could reproduce the issue and in my case it was caused by one CPU (mmap) being behind during record and userspace mmap reader seeing the data after other CPUs data were already stored. This is expected under some circumstances because we need to limit the number of events that we queue for reordering when we receive a PERF_RECORD_FINISHED_ROUND or when we force flush due to memory pressure. Reported-by: Linus Torvalds Signed-off-by: Jiri Olsa Acked-by: Ingo Molnar Cc: Andi Kleen Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Linus Torvalds Cc: Matt Fleming Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1417016371-30249-1-git-send-email-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/event.h | 1 + tools/perf/util/session.c | 11 +++++------ 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h index 5699e7e2a790..50a7b115698c 100644 --- a/tools/perf/util/event.h +++ b/tools/perf/util/event.h @@ -214,6 +214,7 @@ struct events_stats { u32 nr_invalid_chains; u32 nr_unknown_id; u32 nr_unprocessable_samples; + u32 nr_unordered_events; }; struct attr_event { diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 6702ac28754b..80dbba095f30 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -521,15 +521,11 @@ int perf_session_queue_event(struct perf_session *s, union perf_event *event, return -ETIME; if (timestamp < oe->last_flush) { - WARN_ONCE(1, "Timestamp below last timeslice flush\n"); - - pr_oe_time(timestamp, "out of order event"); + pr_oe_time(timestamp, "out of order event\n"); pr_oe_time(oe->last_flush, "last flush, last_flush_type %d\n", oe->last_flush_type); - /* We could get out of order messages after forced flush. */ - if (oe->last_flush_type != OE_FLUSH__HALF) - return -EINVAL; + s->stats.nr_unordered_events++; } new = ordered_events__new(oe, timestamp, event); @@ -1057,6 +1053,9 @@ static void perf_session__warn_about_errors(const struct perf_session *session, "Do you have a KVM guest running and not using 'perf kvm'?\n", session->stats.nr_unprocessable_samples); } + + if (session->stats.nr_unordered_events != 0) + ui__warning("%u out of order events recorded.\n", session->stats.nr_unordered_events); } volatile int session_done;