x86 mmiotrace: implement mmiotrace_printk()

Offer mmiotrace users a function to inject markers from inside the kernel.
This depends on the trace_vprintk() patch.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 42 insertions, 3 deletions

diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index 754bd1eaf4f6..5e2e2e72ee80 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -75,7 +75,7 @@ static LIST_HEAD(trace_list);		/* struct remap_trace */
  *   and trace_lock.
  * - Routines depending on is_enabled() must take trace_lock.
  * - trace_list users must hold trace_lock.
- * - is_enabled() guarantees that mmio_trace_record is allowed.
+ * - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed.
  * - pre/post callbacks assume the effect of is_enabled() being true.
  */
 
@@ -379,6 +379,23 @@ void mmiotrace_iounmap(volatile void __iomem *addr)
                 iounmap_trace_core(addr);
 }
 
+int mmiotrace_printk(const char *fmt, ...)
+{
+        int ret = 0;
+        va_list args;
+        unsigned long flags;
+        va_start(args, fmt);
+
+        spin_lock_irqsave(&trace_lock, flags);
+        if (is_enabled())
+                ret = mmio_trace_printk(fmt, args);
+        spin_unlock_irqrestore(&trace_lock, flags);
+
+        va_end(args);
+        return ret;
+}
+EXPORT_SYMBOL(mmiotrace_printk);
+
 static void clear_trace_list(void)
 {
         struct remap_trace *trace;
diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index d877c5b423ef..ab50a8d7402c 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -3,6 +3,7 @@
  */
 #include <linux/module.h>
 #include <linux/io.h>
+#include <linux/mmiotrace.h>
 
 #define MODULE_NAME "testmmiotrace"
 
@@ -13,6 +14,7 @@ MODULE_PARM_DESC(mmio_address, "Start address of the mapping of 16 kB.");
 static void do_write_test(void __iomem *p)
 {
         unsigned int i;
+        mmiotrace_printk("Write test.\n");
         for (i = 0; i < 256; i++)
                 iowrite8(i, p + i);
         for (i = 1024; i < (5 * 1024); i += 2)
@@ -24,6 +26,7 @@ static void do_write_test(void __iomem *p)
 static void do_read_test(void __iomem *p)
 {
         unsigned int i;
+        mmiotrace_printk("Read test.\n");
         for (i = 0; i < 256; i++)
                 ioread8(p + i);
         for (i = 1024; i < (5 * 1024); i += 2)
@@ -39,6 +42,7 @@ static void do_test(void)
                 pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
                 return;
         }
+        mmiotrace_printk("ioremap returned %p.\n", p);
         do_write_test(p);
         do_read_test(p);
         iounmap(p);
diff --git a/include/linux/mmiotrace.h b/include/linux/mmiotrace.h
index 61d19e1b7a0b..60cc3bf5c538 100644
--- a/include/linux/mmiotrace.h
+++ b/include/linux/mmiotrace.h
@@ -34,11 +34,15 @@ extern void unregister_kmmio_probe(struct kmmio_probe *p);
 /* Called from page fault handler. */
 extern int kmmio_handler(struct pt_regs *regs, unsigned long addr);
 
-/* Called from ioremap.c */
 #ifdef CONFIG_MMIOTRACE
+/* Called from ioremap.c */
 extern void mmiotrace_ioremap(resource_size_t offset, unsigned long size,
                                                         void __iomem *addr);
 extern void mmiotrace_iounmap(volatile void __iomem *addr);
+
+/* For anyone to insert markers. Remember trailing newline. */
+extern int mmiotrace_printk(const char *fmt, ...)
+                                __attribute__ ((format (printf, 1, 2)));
 #else
 static inline void mmiotrace_ioremap(resource_size_t offset,
                                         unsigned long size, void __iomem *addr)
@@ -48,7 +52,15 @@ static inline void mmiotrace_ioremap(resource_size_t offset,
 static inline void mmiotrace_iounmap(volatile void __iomem *addr)
 {
 }
-#endif /* CONFIG_MMIOTRACE_HOOKS */
+
+static inline int mmiotrace_printk(const char *fmt, ...)
+                                __attribute__ ((format (printf, 1, 0)));
+
+static inline int mmiotrace_printk(const char *fmt, ...)
+{
+        return 0;
+}
+#endif /* CONFIG_MMIOTRACE */
 
 enum mm_io_opcode {
         MMIO_READ = 0x1,     /* struct mmiotrace_rw */
@@ -81,5 +93,6 @@ extern void enable_mmiotrace(void);
 extern void disable_mmiotrace(void);
 extern void mmio_trace_rw(struct mmiotrace_rw *rw);
 extern void mmio_trace_mapping(struct mmiotrace_map *map);
+extern int mmio_trace_printk(const char *fmt, va_list args);
 
 #endif /* MMIOTRACE_H */
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index ef02747b26d9..767d1faf56e5 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -335,3 +335,8 @@ void mmio_trace_mapping(struct mmiotrace_map *map)
         __trace_mmiotrace_map(tr, data, map);
         preempt_enable();
 }
+
+int mmio_trace_printk(const char *fmt, va_list args)
+{
+        return trace_vprintk(0, fmt, args);
+}