tracing/kprobes: Use global event perf buffers in kprobe tracer

Use new percpu global event buffer instead of stack in kprobe
tracer while tracing through perf.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090925182011.10157.60140.stgit@omoto>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 73 insertions, 42 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 09cba270392d..97309d4714f7 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1149,35 +1149,49 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
         struct ftrace_event_call *call = &tp->call;
         struct kprobe_trace_entry *entry;
-        int size, __size, i, pc;
+        struct trace_entry *ent;
+        int size, __size, i, pc, __cpu;
         unsigned long irq_flags;
+        char *raw_data;
 
-        local_save_flags(irq_flags);
         pc = preempt_count();
-
         __size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
+        if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+                     "profile buffer not large enough"))
+                return 0;
 
-        do {
-                char raw_data[size];
-                struct trace_entry *ent;
-                /*
-                 * Zero dead bytes from alignment to avoid stack leak
-                 * to userspace
-                 */
-                *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
-                entry = (struct kprobe_trace_entry *)raw_data;
-                ent = &entry->ent;
-
-                tracing_generic_entry_update(ent, irq_flags, pc);
-                ent->type = call->id;
-                entry->nargs = tp->nr_args;
-                entry->ip = (unsigned long)kp->addr;
-                for (i = 0; i < tp->nr_args; i++)
-                        entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
-                perf_tp_event(call->id, entry->ip, 1, entry, size);
-        } while (0);
+        /*
+         * Protect the non nmi buffer
+         * This also protects the rcu read side
+         */
+        local_irq_save(irq_flags);
+        __cpu = smp_processor_id();
+
+        if (in_nmi())
+                raw_data = rcu_dereference(trace_profile_buf_nmi);
+        else
+                raw_data = rcu_dereference(trace_profile_buf);
+
+        if (!raw_data)
+                goto end;
+
+        raw_data = per_cpu_ptr(raw_data, __cpu);
+        /* Zero dead bytes from alignment to avoid buffer leak to userspace */
+        *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+        entry = (struct kprobe_trace_entry *)raw_data;
+        ent = &entry->ent;
+
+        tracing_generic_entry_update(ent, irq_flags, pc);
+        ent->type = call->id;
+        entry->nargs = tp->nr_args;
+        entry->ip = (unsigned long)kp->addr;
+        for (i = 0; i < tp->nr_args; i++)
+                entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
+        perf_tp_event(call->id, entry->ip, 1, entry, size);
+end:
+        local_irq_restore(irq_flags);
         return 0;
 }
 
@@ -1188,33 +1202,50 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
         struct ftrace_event_call *call = &tp->call;
         struct kretprobe_trace_entry *entry;
-        int size, __size, i, pc;
+        struct trace_entry *ent;
+        int size, __size, i, pc, __cpu;
         unsigned long irq_flags;
+        char *raw_data;
 
-        local_save_flags(irq_flags);
         pc = preempt_count();
-
         __size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
+        if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+                     "profile buffer not large enough"))
+                return 0;
+
+        /*
+         * Protect the non nmi buffer
+         * This also protects the rcu read side
+         */
+        local_irq_save(irq_flags);
+        __cpu = smp_processor_id();
+
+        if (in_nmi())
+                raw_data = rcu_dereference(trace_profile_buf_nmi);
+        else
+                raw_data = rcu_dereference(trace_profile_buf);
+
+        if (!raw_data)
+                goto end;
+
+        raw_data = per_cpu_ptr(raw_data, __cpu);
+        /* Zero dead bytes from alignment to avoid buffer leak to userspace */
+        *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+        entry = (struct kretprobe_trace_entry *)raw_data;
+        ent = &entry->ent;
 
-        do {
-                char raw_data[size];
-                struct trace_entry *ent;
-
-                *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
-                entry = (struct kretprobe_trace_entry *)raw_data;
-                ent = &entry->ent;
-
-                tracing_generic_entry_update(ent, irq_flags, pc);
-                ent->type = call->id;
-                entry->nargs = tp->nr_args;
-                entry->func = (unsigned long)tp->rp.kp.addr;
-                entry->ret_ip = (unsigned long)ri->ret_addr;
-                for (i = 0; i < tp->nr_args; i++)
-                        entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
-                perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
-        } while (0);
+        tracing_generic_entry_update(ent, irq_flags, pc);
+        ent->type = call->id;
+        entry->nargs = tp->nr_args;
+        entry->func = (unsigned long)tp->rp.kp.addr;
+        entry->ret_ip = (unsigned long)ri->ret_addr;
+        for (i = 0; i < tp->nr_args; i++)
+                entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
+        perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
+end:
+        local_irq_restore(irq_flags);
         return 0;
 }