[Skiboot] [PATCH 05/15] core/trace: Change buffer alignment from 4K to 64K

[Jordan Niethe]

The trace buffers are currently aligned to 4K. Later when we will mmap
the buffers, they must be page aligned. Most Power systems have a 64K
page size. On systems with a 4K page size, 64K aligned will still be
page aligned so they would not be effected by this change. It is the
trace_info struct that is aligned, meaning the tracebuf within it will
not be. Change the physical address exposed to the kernel from the
tracebuf_struct to the trace_info struct that contains it. This way an
aligned address exposed however the lock within the trace_info struct is
now exposed too.
---
 core/trace.c    | 13 ++++++-------
 include/trace.h |  2 +-
 skiboot.lds.S   |  6 +++---
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/core/trace.c b/core/trace.c
index 64a64bd7c35c..8e231b32eaa4 100644
--- a/core/trace.c
+++ b/core/trace.c
@@ -191,7 +191,7 @@ static void trace_add_desc(struct trace_info *t, uint64_t size)
 	}
 	debug_descriptor.num_traces++;
 
-	debug_descriptor.trace_phys[i] = (uint64_t)&t->tb;
+	debug_descriptor.trace_phys[i] = (uint64_t)t;
 	debug_descriptor.trace_tce[i] = 0; /* populated later */
 	debug_descriptor.trace_size[i] = size;
 }
@@ -204,23 +204,22 @@ void init_trace_buffers(void)
 	uint64_t size;
 
 	/* Boot the boot trace in the debug descriptor */
-	trace_add_desc(any, sizeof(boot_tracebuf.buf));
+	trace_add_desc(any, sizeof(boot_tracebuf));
 
 	/* Allocate a trace buffer for each primary cpu. */
 	for_each_cpu(t) {
 		if (t->is_secondary)
 			continue;
 
-		/* Use a 4K alignment for TCE mapping */
-		size = ALIGN_UP(sizeof(*t->trace) + tracebuf_extra(), 0x1000);
-		t->trace = local_alloc(t->chip_id, size, 0x1000);
+		/* Use a 64K alignment for TCE mapping */
+		size = ALIGN_UP(sizeof(*t->trace) + tracebuf_extra(), 0x10000);
+		t->trace = local_alloc(t->chip_id, size, 0x10000);
 		if (t->trace) {
 			any = t->trace;
 			memset(t->trace, 0, size);
 			init_lock(&t->trace->lock);
 			t->trace->tb.max_size = cpu_to_be32(MAX_SIZE);
-			trace_add_desc(any, sizeof(t->trace->tb) +
-				       tracebuf_extra());
+			trace_add_desc(any, size);
 		} else
 			prerror("TRACE: cpu 0x%x allocation failed\n", t->pir);
 	}
diff --git a/include/trace.h b/include/trace.h
index da43572e2d06..2b65e9075591 100644
--- a/include/trace.h
+++ b/include/trace.h
@@ -29,7 +29,7 @@ struct cpu_thread;
 void init_boot_tracebuf(struct cpu_thread *boot_cpu);
 
 struct trace_info {
-	/* Lock for writers. */
+	/* Lock for writers. Exposed to kernel. */
 	struct lock lock;
 	/* Exposed to kernel. */
 	struct tracebuf tb;
diff --git a/skiboot.lds.S b/skiboot.lds.S
index 8d09b40e601c..596ee8d78abf 100644
--- a/skiboot.lds.S
+++ b/skiboot.lds.S
@@ -142,11 +142,11 @@ SECTIONS
 		 * to reside in their own pages for the sake of TCE
 		 * mappings
 		 */
-		. = ALIGN(0x1000);
+		. = ALIGN(0x10000);
 		*(.data.memcons);
-		. = ALIGN(0x1000);
+		. = ALIGN(0x10000);
 		*(.data.boot_trace);
-		. = ALIGN(0x1000);
+		. = ALIGN(0x10000);
 		*(.data*)
 		*(.force.data)
 		*(.toc1)
-- 
2.20.1