tracing: Simplify stack trace retrieval

Replace the indirection through struct stack_trace by using the storage
array based interfaces.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094803.248604594@linutronix.de

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d8369d27c1afeadb050e9fac06f18a0d49dcde57..0ce8515dd47045086bae7f1f5edaaae7645db83a 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2774,22 +2774,18 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
 {
        struct trace_event_call *call = &event_kernel_stack;
        struct ring_buffer_event *event;
+       unsigned int size, nr_entries;
        struct ftrace_stack *fstack;
        struct stack_entry *entry;
-       struct stack_trace trace;
-       int size = FTRACE_KSTACK_ENTRIES;
        int stackidx;
 
-       trace.nr_entries        = 0;
-       trace.skip              = skip;
-
        /*
         * Add one, for this function and the call to save_stack_trace()
         * If regs is set, then these functions will not be in the way.
         */
 #ifndef CONFIG_UNWINDER_ORC
        if (!regs)
-               trace.skip++;
+               skip++;
 #endif
 
        /*
@@ -2816,28 +2812,24 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
        barrier();
 
        fstack = this_cpu_ptr(ftrace_stacks.stacks) + stackidx;
-       trace.entries           = fstack->calls;
-       trace.max_entries       = FTRACE_KSTACK_ENTRIES;
-
-       if (regs)
-               save_stack_trace_regs(regs, &trace);
-       else
-               save_stack_trace(&trace);
-
-       if (trace.nr_entries > size)
-               size = trace.nr_entries;
+       size = ARRAY_SIZE(fstack->calls);
 
-       size *= sizeof(unsigned long);
+       if (regs) {
+               nr_entries = stack_trace_save_regs(regs, fstack->calls,
+                                                  size, skip);
+       } else {
+               nr_entries = stack_trace_save(fstack->calls, size, skip);
+       }
 
+       size = nr_entries * sizeof(unsigned long);
        event = __trace_buffer_lock_reserve(buffer, TRACE_STACK,
                                            sizeof(*entry) + size, flags, pc);
        if (!event)
                goto out;
        entry = ring_buffer_event_data(event);
 
-       memcpy(&entry->caller, trace.entries, size);
-
-       entry->size = trace.nr_entries;
+       memcpy(&entry->caller, fstack->calls, size);
+       entry->size = nr_entries;
 
        if (!call_filter_check_discard(call, entry, buffer, event))
                __buffer_unlock_commit(buffer, event);
@@ -2916,7 +2908,6 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
        struct trace_event_call *call = &event_user_stack;
        struct ring_buffer_event *event;
        struct userstack_entry *entry;
-       struct stack_trace trace;
 
        if (!(global_trace.trace_flags & TRACE_ITER_USERSTACKTRACE))
                return;
@@ -2947,12 +2938,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
        entry->tgid             = current->tgid;
        memset(&entry->caller, 0, sizeof(entry->caller));
 
-       trace.nr_entries        = 0;
-       trace.max_entries       = FTRACE_STACK_ENTRIES;
-       trace.skip              = 0;
-       trace.entries           = entry->caller;
-
-       save_stack_trace_user(&trace);
+       stack_trace_save_user(entry->caller, FTRACE_STACK_ENTRIES);
        if (!call_filter_check_discard(call, entry, buffer, event))
                __buffer_unlock_commit(buffer, event);