x86: add far read test to testmmiotrace

Apparently pages far into an ioremapped region might not actually be
mapped during ioremap(). Add an optional read test to try to trigger a
multiply faulting MMIO access. Also add more messages to the kernel log
to help debugging.

This patch is based on a patch suggested by
Stuart Bennett <stuart@freedesktop.org>
who discovered bugs in mmiotrace related to normal kernel space faults.

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

1 files changed, 28 insertions, 7 deletions

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 4b29f3b0ee01..427fd1b56df5 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -9,7 +9,13 @@
 
 static unsigned long mmio_address;
 module_param(mmio_address, ulong, 0);
-MODULE_PARM_DESC(mmio_address, "Start address of the mapping of 16 kB.");
+MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
+                                "(or 8 MB if read_far is non-zero).");
+
+static unsigned long read_far = 0x400100;
+module_param(read_far, ulong, 0);
+MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
+                                "(default: 0x400100).");
 
 static unsigned v16(unsigned i)
 {
@@ -24,6 +30,7 @@ static unsigned v32(unsigned i)
 static void do_write_test(void __iomem *p)
 {
         unsigned int i;
+        pr_info(MODULE_NAME ": write test.\n");
         mmiotrace_printk("Write test.\n");
 
         for (i = 0; i < 256; i++)
@@ -40,6 +47,7 @@ static void do_read_test(void __iomem *p)
 {
         unsigned int i;
         unsigned errs[3] = { 0 };
+        pr_info(MODULE_NAME ": read test.\n");
         mmiotrace_printk("Read test.\n");
 
         for (i = 0; i < 256; i++)
@@ -58,9 +66,17 @@ static void do_read_test(void __iomem *p)
                                                 errs[0], errs[1], errs[2]);
 }
 
-static void do_test(void)
+static void do_read_far_test(void __iomem *p)
+{
+        pr_info(MODULE_NAME ": read far test.\n");
+        mmiotrace_printk("Read far test.\n");
+
+        ioread32(p + read_far);
+}
+
+static void do_test(unsigned long size)
 {
-        void __iomem *p = ioremap_nocache(mmio_address, 0x4000);
+        void __iomem *p = ioremap_nocache(mmio_address, size);
         if (!p) {
                 pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
                 return;
@@ -68,11 +84,15 @@ static void do_test(void)
         mmiotrace_printk("ioremap returned %p.\n", p);
         do_write_test(p);
         do_read_test(p);
+        if (read_far && read_far < size - 4)
+                do_read_far_test(p);
         iounmap(p);
 }
 
 static int __init init(void)
 {
+        unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
+
         if (mmio_address == 0) {
                 pr_err(MODULE_NAME ": you have to use the module argument "
                                                         "mmio_address.\n");
@@ -81,10 +101,11 @@ static int __init init(void)
                 return -ENXIO;
         }
 
-        pr_warning(MODULE_NAME ": WARNING: mapping 16 kB @ 0x%08lx "
-                                        "in PCI address space, and writing "
-                                        "rubbish in there.\n", mmio_address);
-        do_test();
+        pr_warning(MODULE_NAME ": WARNING: mapping %lu kB @ 0x%08lx in PCI "
+                "address space, and writing 16 kB of rubbish in there.\n",
+                 size >> 10, mmio_address);
+        do_test(size);
+        pr_info(MODULE_NAME ": All done.\n");
         return 0;
 }