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    Subject[RFC PATCH v8 2/9] tracing: instrument restartable sequences
    Date
    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    CC: Thomas Gleixner <tglx@linutronix.de>
    CC: Paul Turner <pjt@google.com>
    CC: Andrew Hunter <ahh@google.com>
    CC: Peter Zijlstra <peterz@infradead.org>
    CC: Andy Lutomirski <luto@amacapital.net>
    CC: Andi Kleen <andi@firstfloor.org>
    CC: Dave Watson <davejwatson@fb.com>
    CC: Chris Lameter <cl@linux.com>
    CC: Ingo Molnar <mingo@redhat.com>
    CC: "H. Peter Anvin" <hpa@zytor.com>
    CC: Ben Maurer <bmaurer@fb.com>
    CC: Steven Rostedt <rostedt@goodmis.org>
    CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    CC: Josh Triplett <josh@joshtriplett.org>
    CC: Linus Torvalds <torvalds@linux-foundation.org>
    CC: Andrew Morton <akpm@linux-foundation.org>
    CC: Russell King <linux@arm.linux.org.uk>
    CC: Catalin Marinas <catalin.marinas@arm.com>
    CC: Will Deacon <will.deacon@arm.com>
    CC: Michael Kerrisk <mtk.manpages@gmail.com>
    CC: Boqun Feng <boqun.feng@gmail.com>
    CC: linux-api@vger.kernel.org
    ---
    include/trace/events/rseq.h | 64 +++++++++++++++++++++++++++++++++++++++++++++
    kernel/rseq.c | 11 +++++++-
    2 files changed, 74 insertions(+), 1 deletion(-)
    create mode 100644 include/trace/events/rseq.h

    diff --git a/include/trace/events/rseq.h b/include/trace/events/rseq.h
    new file mode 100644
    index 0000000..63a8eb7
    --- /dev/null
    +++ b/include/trace/events/rseq.h
    @@ -0,0 +1,64 @@
    +#undef TRACE_SYSTEM
    +#define TRACE_SYSTEM rseq
    +
    +#if !defined(_TRACE_RSEQ_H) || defined(TRACE_HEADER_MULTI_READ)
    +#define _TRACE_RSEQ_H
    +
    +#include <linux/tracepoint.h>
    +#include <linux/types.h>
    +
    +TRACE_EVENT(rseq_update,
    +
    + TP_PROTO(struct task_struct *t),
    +
    + TP_ARGS(t),
    +
    + TP_STRUCT__entry(
    + __field(s32, cpu_id)
    + __field(u32, event_counter)
    + ),
    +
    + TP_fast_assign(
    + __entry->cpu_id = raw_smp_processor_id();
    + __entry->event_counter = t->rseq_event_counter;
    + ),
    +
    + TP_printk("cpu_id=%d event_counter=%u",
    + __entry->cpu_id, __entry->event_counter)
    +);
    +
    +TRACE_EVENT(rseq_ip_fixup,
    +
    + TP_PROTO(void __user *regs_ip, void __user *start_ip,
    + void __user *post_commit_ip, void __user *abort_ip,
    + u32 kevcount, int ret),
    +
    + TP_ARGS(regs_ip, start_ip, post_commit_ip, abort_ip, kevcount, ret),
    +
    + TP_STRUCT__entry(
    + __field(void __user *, regs_ip)
    + __field(void __user *, start_ip)
    + __field(void __user *, post_commit_ip)
    + __field(void __user *, abort_ip)
    + __field(u32, kevcount)
    + __field(int, ret)
    + ),
    +
    + TP_fast_assign(
    + __entry->regs_ip = regs_ip;
    + __entry->start_ip = start_ip;
    + __entry->post_commit_ip = post_commit_ip;
    + __entry->abort_ip = abort_ip;
    + __entry->kevcount = kevcount;
    + __entry->ret = ret;
    + ),
    +
    + TP_printk("regs_ip=%p start_ip=%p post_commit_ip=%p abort_ip=%p kevcount=%u ret=%d",
    + __entry->regs_ip, __entry->start_ip, __entry->post_commit_ip,
    + __entry->abort_ip, __entry->kevcount, __entry->ret)
    +);
    +
    +#endif /* _TRACE_SOCK_H */
    +
    +/* This part must be outside protection */
    +#include <trace/define_trace.h>
    diff --git a/kernel/rseq.c b/kernel/rseq.c
    index 32bc1d2..a102fcc 100644
    --- a/kernel/rseq.c
    +++ b/kernel/rseq.c
    @@ -32,6 +32,9 @@
    #include <linux/types.h>
    #include <asm/ptrace.h>

    +#define CREATE_TRACE_POINTS
    +#include <trace/events/rseq.h>
    +
    /*
    * The restartable sequences mechanism is the overlap of two distinct
    * restart mechanisms: a sequence counter tracking preemption and signal
    @@ -137,6 +140,7 @@ static bool rseq_update_cpu_id_event_counter(struct task_struct *t)
    u.e.event_counter = ++t->rseq_event_counter;
    if (__put_user(u.v, &t->rseq->u.v))
    return false;
    + trace_rseq_update(t);
    return true;
    }

    @@ -168,8 +172,13 @@ static bool rseq_ip_fixup(struct pt_regs *regs)
    void __user *start_ip = NULL;
    void __user *post_commit_ip = NULL;
    void __user *abort_ip = NULL;
    + bool ret;

    - if (!rseq_get_rseq_cs(t, &start_ip, &post_commit_ip, &abort_ip))
    + ret = rseq_get_rseq_cs(t, &start_ip, &post_commit_ip, &abort_ip);
    + trace_rseq_ip_fixup((void __user *)instruction_pointer(regs),
    + start_ip, post_commit_ip, abort_ip, t->rseq_event_counter,
    + ret);
    + if (!ret)
    return false;

    /* Handle potentially not being within a critical section. */
    --
    2.1.4
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