[PATCH v5 16/15] ring-buffer: Use subbuf_order for buffer page masking

[Steven Rostedt]

From: "Steven Rostedt (Google)" <rost...@goodmis.org>

The comparisons to PAGE_SIZE were all converted to use the
buffer->subbuf_order, but the use of PAGE_MASK was missed.

Convert all the PAGE_MASK usages over to:

  (PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1

Fixes: TBD ("ring-buffer: Page size per ring buffer")
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 kernel/trace/ring_buffer.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7ee6779bf292..173d2595ce2d 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2269,11 +2269,13 @@ rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer)
 }
 
 static __always_inline unsigned
-rb_event_index(struct ring_buffer_event *event)
+rb_event_index(struct ring_buffer_per_cpu *cpu_buffer, struct 
ring_buffer_event *event)
 {
        unsigned long addr = (unsigned long)event;
 
-       return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE;
+       addr &= (PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1;
+
+       return addr - BUF_PAGE_HDR_SIZE;
 }
 
 static void rb_inc_iter(struct ring_buffer_iter *iter)
@@ -2646,7 +2648,8 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 
 /* Slow path */
 static struct ring_buffer_event *
-rb_add_time_stamp(struct ring_buffer_event *event, u64 delta, bool abs)
+rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
+                 struct ring_buffer_event *event, u64 delta, bool abs)
 {
        if (abs)
                event->type_len = RINGBUF_TYPE_TIME_STAMP;
@@ -2654,7 +2657,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 
delta, bool abs)
                event->type_len = RINGBUF_TYPE_TIME_EXTEND;
 
        /* Not the first event on the page, or not delta? */
-       if (abs || rb_event_index(event)) {
+       if (abs || rb_event_index(cpu_buffer, event)) {
                event->time_delta = delta & TS_MASK;
                event->array[0] = delta >> TS_SHIFT;
        } else {
@@ -2728,7 +2731,7 @@ static void rb_add_timestamp(struct ring_buffer_per_cpu 
*cpu_buffer,
                if (!abs)
                        info->delta = 0;
        }
-       *event = rb_add_time_stamp(*event, info->delta, abs);
+       *event = rb_add_time_stamp(cpu_buffer, *event, info->delta, abs);
        *length -= RB_LEN_TIME_EXTEND;
        *delta = 0;
 }
@@ -2812,10 +2815,10 @@ rb_try_to_discard(struct ring_buffer_per_cpu 
*cpu_buffer,
        struct buffer_page *bpage;
        unsigned long addr;
 
-       new_index = rb_event_index(event);
+       new_index = rb_event_index(cpu_buffer, event);
        old_index = new_index + rb_event_ts_length(event);
        addr = (unsigned long)event;
-       addr &= PAGE_MASK;
+       addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1);
 
        bpage = READ_ONCE(cpu_buffer->tail_page);
 
@@ -3726,7 +3729,7 @@ rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer,
        struct buffer_page *bpage = cpu_buffer->commit_page;
        struct buffer_page *start;
 
-       addr &= PAGE_MASK;
+       addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1);
 
        /* Do the likely case first */
        if (likely(bpage->page == (void *)addr)) {
-- 
2.42.0