Merge branch 'tracing-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (131 commits)
  tracing/fastboot: improve help text
  tracing/stacktrace: improve help text
  tracing/fastboot: fix initcalls disposition in bootgraph.pl
  tracing/fastboot: fix bootgraph.pl initcall name regexp
  tracing/fastboot: fix issues and improve output of bootgraph.pl
  tracepoints: synchronize unregister static inline
  tracepoints: tracepoint_synchronize_unregister()
  ftrace: make ftrace_test_p6nop disassembler-friendly
  markers: fix synchronize marker unregister static inline
  tracing/fastboot: add better resolution to initcall debug/tracing
  trace: add build-time check to avoid overrunning hex buffer
  ftrace: fix hex output mode of ftrace
  tracing/fastboot: fix initcalls disposition in bootgraph.pl
  tracing/fastboot: fix printk format typo in boot tracer
  ftrace: return an error when setting a nonexistent tracer
  ftrace: make some tracers reentrant
  ring-buffer: make reentrant
  ring-buffer: move page indexes into page headers
  tracing/fastboot: only trace non-module initcalls
  ftrace: move pc counter in irqtrace
  ...

Manually fix conflicts:
 - init/main.c: initcall tracing
 - kernel/module.c: verbose level vs tracepoints
 - scripts/bootgraph.pl: fallout from cherry-picking commits.

9 files changed, 197 insertions, 192 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/sputrace.c b/arch/powerpc/platforms/cell/spufs/sputrace.c
index 92d20e993ede..2ece399f2862 100644
--- a/arch/powerpc/platforms/cell/spufs/sputrace.c
+++ b/arch/powerpc/platforms/cell/spufs/sputrace.c
@@ -232,6 +232,7 @@ static void __exit sputrace_exit(void)
 
         remove_proc_entry("sputrace", NULL);
         kfree(sputrace_log);
+        marker_synchronize_unregister();
 }
 
 module_init(sputrace_init);
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 739668968390..5b9b12321ad1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -26,6 +26,7 @@ config X86
         select HAVE_KPROBES
         select ARCH_WANT_OPTIONAL_GPIOLIB
         select HAVE_KRETPROBES
+        select HAVE_FTRACE_MCOUNT_RECORD
         select HAVE_DYNAMIC_FTRACE
         select HAVE_FTRACE
         select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
diff --git a/arch/x86/kernel/cpu/perfctr-watchdog.c b/arch/x86/kernel/cpu/perfctr-watchdog.c
index 6bff382094f5..9abd48b22674 100644
--- a/arch/x86/kernel/cpu/perfctr-watchdog.c
+++ b/arch/x86/kernel/cpu/perfctr-watchdog.c
@@ -17,6 +17,8 @@
 #include <linux/bitops.h>
 #include <linux/smp.h>
 #include <linux/nmi.h>
+#include <linux/kprobes.h>
+
 #include <asm/apic.h>
 #include <asm/intel_arch_perfmon.h>
 
@@ -336,7 +338,8 @@ static void single_msr_unreserve(void)
         release_perfctr_nmi(wd_ops->perfctr);
 }
 
-static void single_msr_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes
+single_msr_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
 {
         /* start the cycle over again */
         write_watchdog_counter(wd->perfctr_msr, NULL, nmi_hz);
@@ -401,7 +404,7 @@ static int setup_p6_watchdog(unsigned nmi_hz)
         return 1;
 }
 
-static void p6_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes p6_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
 {
         /*
          * P6 based Pentium M need to re-unmask
@@ -605,7 +608,7 @@ static void p4_unreserve(void)
         release_perfctr_nmi(MSR_P4_IQ_PERFCTR0);
 }
 
-static void p4_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes p4_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
 {
         unsigned dummy;
         /*
@@ -784,7 +787,7 @@ unsigned lapic_adjust_nmi_hz(unsigned hz)
         return hz;
 }
 
-int lapic_wd_event(unsigned nmi_hz)
+int __kprobes lapic_wd_event(unsigned nmi_hz)
 {
         struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
         u64 ctr;
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 4d82171d0f9c..c356423a6026 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1153,20 +1153,6 @@ ENDPROC(xen_failsafe_callback)
 #ifdef CONFIG_DYNAMIC_FTRACE
 
 ENTRY(mcount)
-        pushl %eax
-        pushl %ecx
-        pushl %edx
-        movl 0xc(%esp), %eax
-        subl $MCOUNT_INSN_SIZE, %eax
-
-.globl mcount_call
-mcount_call:
-        call ftrace_stub
-
-        popl %edx
-        popl %ecx
-        popl %eax
-
         ret
 END(mcount)
 
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1db6ce4314e1..09e7145484c5 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -64,32 +64,6 @@
 #ifdef CONFIG_FTRACE
 #ifdef CONFIG_DYNAMIC_FTRACE
 ENTRY(mcount)
-
-        subq $0x38, %rsp
-        movq %rax, (%rsp)
-        movq %rcx, 8(%rsp)
-        movq %rdx, 16(%rsp)
-        movq %rsi, 24(%rsp)
-        movq %rdi, 32(%rsp)
-        movq %r8, 40(%rsp)
-        movq %r9, 48(%rsp)
-
-        movq 0x38(%rsp), %rdi
-        subq $MCOUNT_INSN_SIZE, %rdi
-
-.globl mcount_call
-mcount_call:
-        call ftrace_stub
-
-        movq 48(%rsp), %r9
-        movq 40(%rsp), %r8
-        movq 32(%rsp), %rdi
-        movq 24(%rsp), %rsi
-        movq 16(%rsp), %rdx
-        movq 8(%rsp), %rcx
-        movq (%rsp), %rax
-        addq $0x38, %rsp
-
         retq
 END(mcount)
 
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ab115cd15fdf..d073d981a730 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -11,17 +11,18 @@
 
 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
+#include <linux/uaccess.h>
 #include <linux/ftrace.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
 #include <linux/list.h>
 
-#include <asm/alternative.h>
 #include <asm/ftrace.h>
+#include <asm/nops.h>
 
 
 /* Long is fine, even if it is only 4 bytes ;-) */
-static long *ftrace_nop;
+static unsigned long *ftrace_nop;
 
 union ftrace_code_union {
         char code[MCOUNT_INSN_SIZE];
@@ -60,11 +61,7 @@ notrace int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
                    unsigned char *new_code)
 {
-        unsigned replaced;
-        unsigned old = *(unsigned *)old_code; /* 4 bytes */
-        unsigned new = *(unsigned *)new_code; /* 4 bytes */
-        unsigned char newch = new_code[4];
-        int faulted = 0;
+        unsigned char replaced[MCOUNT_INSN_SIZE];
 
         /*
          * Note: Due to modules and __init, code can
@@ -72,29 +69,20 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
          *  as well as code changing.
          *
          * No real locking needed, this code is run through
-         * kstop_machine.
+         * kstop_machine, or before SMP starts.
          */
-        asm volatile (
-                "1: lock\n"
-                "   cmpxchg %3, (%2)\n"
-                "   jnz 2f\n"
-                "   movb %b4, 4(%2)\n"
-                "2:\n"
-                ".section .fixup, \"ax\"\n"
-                "3:     movl $1, %0\n"
-                "       jmp 2b\n"
-                ".previous\n"
-                _ASM_EXTABLE(1b, 3b)
-                : "=r"(faulted), "=a"(replaced)
-                : "r"(ip), "r"(new), "c"(newch),
-                  "0"(faulted), "a"(old)
-                : "memory");
-        sync_core();
+        if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE))
+                return 1;
+
+        if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+                return 2;
 
-        if (replaced != old && replaced != new)
-                faulted = 2;
+        WARN_ON_ONCE(__copy_to_user_inatomic((char __user *)ip, new_code,
+                                    MCOUNT_INSN_SIZE));
 
-        return faulted;
+        sync_core();
+
+        return 0;
 }
 
 notrace int ftrace_update_ftrace_func(ftrace_func_t func)
@@ -112,30 +100,76 @@ notrace int ftrace_update_ftrace_func(ftrace_func_t func)
 
 notrace int ftrace_mcount_set(unsigned long *data)
 {
-        unsigned long ip = (long)(&mcount_call);
-        unsigned long *addr = data;
-        unsigned char old[MCOUNT_INSN_SIZE], *new;
-
-        /*
-         * Replace the mcount stub with a pointer to the
-         * ip recorder function.
-         */
-        memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
-        new = ftrace_call_replace(ip, *addr);
-        *addr = ftrace_modify_code(ip, old, new);
-
+        /* mcount is initialized as a nop */
+        *data = 0;
         return 0;
 }
 
 int __init ftrace_dyn_arch_init(void *data)
 {
-        const unsigned char *const *noptable = find_nop_table();
-
-        /* This is running in kstop_machine */
-
-        ftrace_mcount_set(data);
+        extern const unsigned char ftrace_test_p6nop[];
+        extern const unsigned char ftrace_test_nop5[];
+        extern const unsigned char ftrace_test_jmp[];
+        int faulted = 0;
 
-        ftrace_nop = (unsigned long *)noptable[MCOUNT_INSN_SIZE];
+        /*
+         * There is no good nop for all x86 archs.
+         * We will default to using the P6_NOP5, but first we
+         * will test to make sure that the nop will actually
+         * work on this CPU. If it faults, we will then
+         * go to a lesser efficient 5 byte nop. If that fails
+         * we then just use a jmp as our nop. This isn't the most
+         * efficient nop, but we can not use a multi part nop
+         * since we would then risk being preempted in the middle
+         * of that nop, and if we enabled tracing then, it might
+         * cause a system crash.
+         *
+         * TODO: check the cpuid to determine the best nop.
+         */
+        asm volatile (
+                "jmp ftrace_test_jmp\n"
+                /* This code needs to stay around */
+                ".section .text, \"ax\"\n"
+                "ftrace_test_jmp:"
+                "jmp ftrace_test_p6nop\n"
+                "nop\n"
+                "nop\n"
+                "nop\n"  /* 2 byte jmp + 3 bytes */
+                "ftrace_test_p6nop:"
+                P6_NOP5
+                "jmp 1f\n"
+                "ftrace_test_nop5:"
+                ".byte 0x66,0x66,0x66,0x66,0x90\n"
+                "jmp 1f\n"
+                ".previous\n"
+                "1:"
+                ".section .fixup, \"ax\"\n"
+                "2:     movl $1, %0\n"
+                "       jmp ftrace_test_nop5\n"
+                "3:     movl $2, %0\n"
+                "       jmp 1b\n"
+                ".previous\n"
+                _ASM_EXTABLE(ftrace_test_p6nop, 2b)
+                _ASM_EXTABLE(ftrace_test_nop5, 3b)
+                : "=r"(faulted) : "0" (faulted));
+
+        switch (faulted) {
+        case 0:
+                pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
+                ftrace_nop = (unsigned long *)ftrace_test_p6nop;
+                break;
+        case 1:
+                pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
+                ftrace_nop = (unsigned long *)ftrace_test_nop5;
+                break;
+        case 2:
+                pr_info("ftrace: converting mcount calls to jmp . + 5\n");
+                ftrace_nop = (unsigned long *)ftrace_test_jmp;
+                break;
+        }
+
+        /* The return code is retured via data */
+        *(unsigned long *)data = 0;
 
         return 0;
 }
diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index 635b50e85581..2c4baa88f2cb 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -56,13 +56,6 @@ struct remap_trace {
 static DEFINE_PER_CPU(struct trap_reason, pf_reason);
 static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);
 
-#if 0 /* XXX: no way gather this info anymore */
-/* Access to this is not per-cpu. */
-static DEFINE_PER_CPU(atomic_t, dropped);
-#endif
-
-static struct dentry *marker_file;
-
 static DEFINE_MUTEX(mmiotrace_mutex);
 static DEFINE_SPINLOCK(trace_lock);
 static atomic_t mmiotrace_enabled;
@@ -75,7 +68,7 @@ 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.
  */
 
@@ -97,44 +90,6 @@ static bool is_enabled(void)
         return atomic_read(&mmiotrace_enabled);
 }
 
-#if 0 /* XXX: needs rewrite */
-/*
- * Write callback for the debugfs entry:
- * Read a marker and write it to the mmio trace log
- */
-static ssize_t write_marker(struct file *file, const char __user *buffer,
-                                                size_t count, loff_t *ppos)
-{
-        char *event = NULL;
-        struct mm_io_header *headp;
-        ssize_t len = (count > 65535) ? 65535 : count;
-
-        event = kzalloc(sizeof(*headp) + len, GFP_KERNEL);
-        if (!event)
-                return -ENOMEM;
-
-        headp = (struct mm_io_header *)event;
-        headp->type = MMIO_MAGIC | (MMIO_MARKER << MMIO_OPCODE_SHIFT);
-        headp->data_len = len;
-
-        if (copy_from_user(event + sizeof(*headp), buffer, len)) {
-                kfree(event);
-                return -EFAULT;
-        }
-
-        spin_lock_irq(&trace_lock);
-#if 0 /* XXX: convert this to use tracing */
-        if (is_enabled())
-                relay_write(chan, event, sizeof(*headp) + len);
-        else
-#endif
-                len = -EINVAL;
-        spin_unlock_irq(&trace_lock);
-        kfree(event);
-        return len;
-}
-#endif
-
 static void print_pte(unsigned long address)
 {
         unsigned int level;
@@ -307,8 +262,10 @@ static void ioremap_trace_core(resource_size_t offset, unsigned long size,
         map.map_id = trace->id;
 
         spin_lock_irq(&trace_lock);
-        if (!is_enabled())
+        if (!is_enabled()) {
+                kfree(trace);
                 goto not_enabled;
+        }
 
         mmio_trace_mapping(&map);
         list_add_tail(&trace->list, &trace_list);
@@ -377,6 +334,23 @@ 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;
@@ -462,26 +436,12 @@ static void leave_uniprocessor(void)
 }
 #endif
 
-#if 0 /* XXX: out of order */
-static struct file_operations fops_marker = {
-        .owner =        THIS_MODULE,
-        .write =        write_marker
-};
-#endif
-
 void enable_mmiotrace(void)
 {
         mutex_lock(&mmiotrace_mutex);
         if (is_enabled())
                 goto out;
 
-#if 0 /* XXX: tracing does not support text entries */
-        marker_file = debugfs_create_file("marker", 0660, dir, NULL,
-                                                                &fops_marker);
-        if (!marker_file)
-                pr_err(NAME "marker file creation failed.\n");
-#endif
-
         if (nommiotrace)
                 pr_info(NAME "MMIO tracing disabled.\n");
         enter_uniprocessor();
@@ -506,11 +466,6 @@ void disable_mmiotrace(void)
 
         clear_trace_list(); /* guarantees: no more kmmio callbacks */
         leave_uniprocessor();
-        if (marker_file) {
-                debugfs_remove(marker_file);
-                marker_file = NULL;
-        }
-
         pr_info(NAME "disabled.\n");
 out:
         mutex_unlock(&mmiotrace_mutex);
diff --git a/arch/x86/mm/pf_in.c b/arch/x86/mm/pf_in.c
index efa1911e20ca..df3d5c861cda 100644
--- a/arch/x86/mm/pf_in.c
+++ b/arch/x86/mm/pf_in.c
@@ -79,25 +79,34 @@ static unsigned int mw32[] = { 0xC7 };
 static unsigned int mw64[] = { 0x89, 0x8B };
 #endif /* not __i386__ */
 
-static int skip_prefix(unsigned char *addr, int *shorted, int *enlarged,
-                                                                int *rexr)
+struct prefix_bits {
+        unsigned shorted:1;
+        unsigned enlarged:1;
+        unsigned rexr:1;
+        unsigned rex:1;
+};
+
+static int skip_prefix(unsigned char *addr, struct prefix_bits *prf)
 {
         int i;
         unsigned char *p = addr;
-        *shorted = 0;
-        *enlarged = 0;
-        *rexr = 0;
+        prf->shorted = 0;
+        prf->enlarged = 0;
+        prf->rexr = 0;
+        prf->rex = 0;
 
 restart:
         for (i = 0; i < ARRAY_SIZE(prefix_codes); i++) {
                 if (*p == prefix_codes[i]) {
                         if (*p == 0x66)
-                                *shorted = 1;
+                                prf->shorted = 1;
 #ifdef __amd64__
                         if ((*p & 0xf8) == 0x48)
-                                *enlarged = 1;
+                                prf->enlarged = 1;
                         if ((*p & 0xf4) == 0x44)
-                                *rexr = 1;
+                                prf->rexr = 1;
+                        if ((*p & 0xf0) == 0x40)
+                                prf->rex = 1;
 #endif
                         p++;
                         goto restart;
@@ -135,12 +144,12 @@ enum reason_type get_ins_type(unsigned long ins_addr)
 {
         unsigned int opcode;
         unsigned char *p;
-        int shorted, enlarged, rexr;
+        struct prefix_bits prf;
         int i;
         enum reason_type rv = OTHERS;
 
         p = (unsigned char *)ins_addr;
-        p += skip_prefix(p, &shorted, &enlarged, &rexr);
+        p += skip_prefix(p, &prf);
         p += get_opcode(p, &opcode);
 
         CHECK_OP_TYPE(opcode, reg_rop, REG_READ);
@@ -156,10 +165,11 @@ static unsigned int get_ins_reg_width(unsigned long ins_addr)
 {
         unsigned int opcode;
         unsigned char *p;
-        int i, shorted, enlarged, rexr;
+        struct prefix_bits prf;
+        int i;
 
         p = (unsigned char *)ins_addr;
-        p += skip_prefix(p, &shorted, &enlarged, &rexr);
+        p += skip_prefix(p, &prf);
         p += get_opcode(p, &opcode);
 
         for (i = 0; i < ARRAY_SIZE(rw8); i++)
@@ -168,7 +178,7 @@ static unsigned int get_ins_reg_width(unsigned long ins_addr)
 
         for (i = 0; i < ARRAY_SIZE(rw32); i++)
                 if (rw32[i] == opcode)
-                        return (shorted ? 2 : (enlarged ? 8 : 4));
+                        return prf.shorted ? 2 : (prf.enlarged ? 8 : 4);
 
         printk(KERN_ERR "mmiotrace: Unknown opcode 0x%02x\n", opcode);
         return 0;
@@ -178,10 +188,11 @@ unsigned int get_ins_mem_width(unsigned long ins_addr)
 {
         unsigned int opcode;
         unsigned char *p;
-        int i, shorted, enlarged, rexr;
+        struct prefix_bits prf;
+        int i;
 
         p = (unsigned char *)ins_addr;
-        p += skip_prefix(p, &shorted, &enlarged, &rexr);
+        p += skip_prefix(p, &prf);
         p += get_opcode(p, &opcode);
 
         for (i = 0; i < ARRAY_SIZE(mw8); i++)
@@ -194,11 +205,11 @@ unsigned int get_ins_mem_width(unsigned long ins_addr)
 
         for (i = 0; i < ARRAY_SIZE(mw32); i++)
                 if (mw32[i] == opcode)
-                        return shorted ? 2 : 4;
+                        return prf.shorted ? 2 : 4;
 
         for (i = 0; i < ARRAY_SIZE(mw64); i++)
                 if (mw64[i] == opcode)
-                        return shorted ? 2 : (enlarged ? 8 : 4);
+                        return prf.shorted ? 2 : (prf.enlarged ? 8 : 4);
 
         printk(KERN_ERR "mmiotrace: Unknown opcode 0x%02x\n", opcode);
         return 0;
@@ -238,7 +249,7 @@ enum {
 #endif
 };
 
-static unsigned char *get_reg_w8(int no, struct pt_regs *regs)
+static unsigned char *get_reg_w8(int no, int rex, struct pt_regs *regs)
 {
         unsigned char *rv = NULL;
 
@@ -255,18 +266,6 @@ static unsigned char *get_reg_w8(int no, struct pt_regs *regs)
         case arg_DL:
                 rv = (unsigned char *)&regs->dx;
                 break;
-        case arg_AH:
-                rv = 1 + (unsigned char *)&regs->ax;
-                break;
-        case arg_BH:
-                rv = 1 + (unsigned char *)&regs->bx;
-                break;
-        case arg_CH:
-                rv = 1 + (unsigned char *)&regs->cx;
-                break;
-        case arg_DH:
-                rv = 1 + (unsigned char *)&regs->dx;
-                break;
 #ifdef __amd64__
         case arg_R8:
                 rv = (unsigned char *)&regs->r8;
@@ -294,9 +293,55 @@ static unsigned char *get_reg_w8(int no, struct pt_regs *regs)
                 break;
 #endif
         default:
-                printk(KERN_ERR "mmiotrace: Error reg no# %d\n", no);
                 break;
         }
+
+        if (rv)
+                return rv;
+
+        if (rex) {
+                /*
+                 * If REX prefix exists, access low bytes of SI etc.
+                 * instead of AH etc.
+                 */
+                switch (no) {
+                case arg_SI:
+                        rv = (unsigned char *)&regs->si;
+                        break;
+                case arg_DI:
+                        rv = (unsigned char *)&regs->di;
+                        break;
+                case arg_BP:
+                        rv = (unsigned char *)&regs->bp;
+                        break;
+                case arg_SP:
+                        rv = (unsigned char *)&regs->sp;
+                        break;
+                default:
+                        break;
+                }
+        } else {
+                switch (no) {
+                case arg_AH:
+                        rv = 1 + (unsigned char *)&regs->ax;
+                        break;
+                case arg_BH:
+                        rv = 1 + (unsigned char *)&regs->bx;
+                        break;
+                case arg_CH:
+                        rv = 1 + (unsigned char *)&regs->cx;
+                        break;
+                case arg_DH:
+                        rv = 1 + (unsigned char *)&regs->dx;
+                        break;
+                default:
+                        break;
+                }
+        }
+
+        if (!rv)
+                printk(KERN_ERR "mmiotrace: Error reg no# %d\n", no);
+
         return rv;
 }
 
@@ -368,11 +413,12 @@ unsigned long get_ins_reg_val(unsigned long ins_addr, struct pt_regs *regs)
         unsigned char mod_rm;
         int reg;
         unsigned char *p;
-        int i, shorted, enlarged, rexr;
+        struct prefix_bits prf;
+        int i;
         unsigned long rv;
 
         p = (unsigned char *)ins_addr;
-        p += skip_prefix(p, &shorted, &enlarged, &rexr);
+        p += skip_prefix(p, &prf);
         p += get_opcode(p, &opcode);
         for (i = 0; i < ARRAY_SIZE(reg_rop); i++)
                 if (reg_rop[i] == opcode) {
@@ -392,10 +438,10 @@ unsigned long get_ins_reg_val(unsigned long ins_addr, struct pt_regs *regs)
 
 do_work:
         mod_rm = *p;
-        reg = ((mod_rm >> 3) & 0x7) | (rexr << 3);
+        reg = ((mod_rm >> 3) & 0x7) | (prf.rexr << 3);
         switch (get_ins_reg_width(ins_addr)) {
         case 1:
-                return *get_reg_w8(reg, regs);
+                return *get_reg_w8(reg, prf.rex, regs);
 
         case 2:
                 return *(unsigned short *)get_reg_w32(reg, regs);
@@ -422,11 +468,12 @@ unsigned long get_ins_imm_val(unsigned long ins_addr)
         unsigned char mod_rm;
         unsigned char mod;
         unsigned char *p;
-        int i, shorted, enlarged, rexr;
+        struct prefix_bits prf;
+        int i;
         unsigned long rv;
 
         p = (unsigned char *)ins_addr;
-        p += skip_prefix(p, &shorted, &enlarged, &rexr);
+        p += skip_prefix(p, &prf);
         p += get_opcode(p, &opcode);
         for (i = 0; i < ARRAY_SIZE(imm_wop); i++)
                 if (imm_wop[i] == opcode) {
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);