Update Linux to v5.4.148
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz
Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 66358d6..5e1b9f6 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -11,6 +11,7 @@
#include <linux/trace_seq.h>
#include <linux/spinlock.h>
#include <linux/irq_work.h>
+#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kthread.h> /* for self test */
@@ -128,7 +129,16 @@
#define RB_ALIGNMENT 4U
#define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
#define RB_EVNT_MIN_SIZE 8U /* two 32bit words */
-#define RB_ALIGN_DATA __aligned(RB_ALIGNMENT)
+
+#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS
+# define RB_FORCE_8BYTE_ALIGNMENT 0
+# define RB_ARCH_ALIGNMENT RB_ALIGNMENT
+#else
+# define RB_FORCE_8BYTE_ALIGNMENT 1
+# define RB_ARCH_ALIGNMENT 8U
+#endif
+
+#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT)
/* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */
#define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX
@@ -421,14 +431,16 @@
/*
* Used for which event context the event is in.
- * NMI = 0
- * IRQ = 1
- * SOFTIRQ = 2
- * NORMAL = 3
+ * TRANSITION = 0
+ * NMI = 1
+ * IRQ = 2
+ * SOFTIRQ = 3
+ * NORMAL = 4
*
* See trace_recursive_lock() comment below for more details.
*/
enum {
+ RB_CTX_TRANSITION,
RB_CTX_NMI,
RB_CTX_IRQ,
RB_CTX_SOFTIRQ,
@@ -1716,18 +1728,18 @@
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long nr_pages;
- int cpu, err = 0;
+ int cpu, err;
/*
* Always succeed at resizing a non-existent buffer:
*/
if (!buffer)
- return size;
+ return 0;
/* Make sure the requested buffer exists */
if (cpu_id != RING_BUFFER_ALL_CPUS &&
!cpumask_test_cpu(cpu_id, buffer->cpumask))
- return size;
+ return 0;
nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
@@ -1867,7 +1879,7 @@
}
mutex_unlock(&buffer->mutex);
- return size;
+ return 0;
out_err:
for_each_buffer_cpu(buffer, cpu) {
@@ -2357,14 +2369,14 @@
if (unlikely(info->add_timestamp)) {
bool abs = ring_buffer_time_stamp_abs(cpu_buffer->buffer);
- event = rb_add_time_stamp(event, info->delta, abs);
+ event = rb_add_time_stamp(event, abs ? info->delta : delta, abs);
length -= RB_LEN_TIME_EXTEND;
delta = 0;
}
event->time_delta = delta;
length -= RB_EVNT_HDR_SIZE;
- if (length > RB_MAX_SMALL_DATA) {
+ if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) {
event->type_len = 0;
event->array[0] = length;
} else
@@ -2379,11 +2391,11 @@
if (!length)
length++;
- if (length > RB_MAX_SMALL_DATA)
+ if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT)
length += sizeof(event.array[0]);
length += RB_EVNT_HDR_SIZE;
- length = ALIGN(length, RB_ALIGNMENT);
+ length = ALIGN(length, RB_ARCH_ALIGNMENT);
/*
* In case the time delta is larger than the 27 bits for it
@@ -2659,10 +2671,10 @@
* a bit of overhead in something as critical as function tracing,
* we use a bitmask trick.
*
- * bit 0 = NMI context
- * bit 1 = IRQ context
- * bit 2 = SoftIRQ context
- * bit 3 = normal context.
+ * bit 1 = NMI context
+ * bit 2 = IRQ context
+ * bit 3 = SoftIRQ context
+ * bit 4 = normal context.
*
* This works because this is the order of contexts that can
* preempt other contexts. A SoftIRQ never preempts an IRQ
@@ -2685,6 +2697,30 @@
* The least significant bit can be cleared this way, and it
* just so happens that it is the same bit corresponding to
* the current context.
+ *
+ * Now the TRANSITION bit breaks the above slightly. The TRANSITION bit
+ * is set when a recursion is detected at the current context, and if
+ * the TRANSITION bit is already set, it will fail the recursion.
+ * This is needed because there's a lag between the changing of
+ * interrupt context and updating the preempt count. In this case,
+ * a false positive will be found. To handle this, one extra recursion
+ * is allowed, and this is done by the TRANSITION bit. If the TRANSITION
+ * bit is already set, then it is considered a recursion and the function
+ * ends. Otherwise, the TRANSITION bit is set, and that bit is returned.
+ *
+ * On the trace_recursive_unlock(), the TRANSITION bit will be the first
+ * to be cleared. Even if it wasn't the context that set it. That is,
+ * if an interrupt comes in while NORMAL bit is set and the ring buffer
+ * is called before preempt_count() is updated, since the check will
+ * be on the NORMAL bit, the TRANSITION bit will then be set. If an
+ * NMI then comes in, it will set the NMI bit, but when the NMI code
+ * does the trace_recursive_unlock() it will clear the TRANSTION bit
+ * and leave the NMI bit set. But this is fine, because the interrupt
+ * code that set the TRANSITION bit will then clear the NMI bit when it
+ * calls trace_recursive_unlock(). If another NMI comes in, it will
+ * set the TRANSITION bit and continue.
+ *
+ * Note: The TRANSITION bit only handles a single transition between context.
*/
static __always_inline int
@@ -2700,8 +2736,16 @@
bit = pc & NMI_MASK ? RB_CTX_NMI :
pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ;
- if (unlikely(val & (1 << (bit + cpu_buffer->nest))))
- return 1;
+ if (unlikely(val & (1 << (bit + cpu_buffer->nest)))) {
+ /*
+ * It is possible that this was called by transitioning
+ * between interrupt context, and preempt_count() has not
+ * been updated yet. In this case, use the TRANSITION bit.
+ */
+ bit = RB_CTX_TRANSITION;
+ if (val & (1 << (bit + cpu_buffer->nest)))
+ return 1;
+ }
val |= (1 << (bit + cpu_buffer->nest));
cpu_buffer->current_context = val;
@@ -2716,8 +2760,8 @@
cpu_buffer->current_context - (1 << cpu_buffer->nest);
}
-/* The recursive locking above uses 4 bits */
-#define NESTED_BITS 4
+/* The recursive locking above uses 5 bits */
+#define NESTED_BITS 5
/**
* ring_buffer_nest_start - Allow to trace while nested
@@ -3177,10 +3221,30 @@
if (unlikely(!head))
return true;
- return reader->read == rb_page_commit(reader) &&
- (commit == reader ||
- (commit == head &&
- head->read == rb_page_commit(commit)));
+ /* Reader should exhaust content in reader page */
+ if (reader->read != rb_page_commit(reader))
+ return false;
+
+ /*
+ * If writers are committing on the reader page, knowing all
+ * committed content has been read, the ring buffer is empty.
+ */
+ if (commit == reader)
+ return true;
+
+ /*
+ * If writers are committing on a page other than reader page
+ * and head page, there should always be content to read.
+ */
+ if (commit != head)
+ return false;
+
+ /*
+ * Writers are committing on the head page, we just need
+ * to care about there're committed data, and the reader will
+ * swap reader page with head page when it is to read data.
+ */
+ return rb_page_commit(commit) == 0;
}
/**
@@ -4404,6 +4468,8 @@
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return;
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
atomic_inc(&buffer->resize_disabled);
atomic_inc(&cpu_buffer->record_disabled);
@@ -4427,6 +4493,8 @@
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&buffer->resize_disabled);
+
+ mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
@@ -5068,6 +5136,11 @@
int cpu;
int ret = 0;
+ if (security_locked_down(LOCKDOWN_TRACEFS)) {
+ pr_warning("Lockdown is enabled, skipping ring buffer tests\n");
+ return 0;
+ }
+
pr_info("Running ring buffer tests...\n");
buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE);