2 files changed, 24 insertions, 6 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 854ed5ca7e3f..f7735a125f4b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1848,6 +1848,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         arch_perfmon: [X86] Force use of architectural
                                 perfmon on Intel CPUs instead of the
                                 CPU specific event set.
+                        timer: [X86] Force use of architectural NMI
+                                timer mode (see also oprofile.timer
+                                for generic hr timer mode)
 
         oops=panic      Always panic on oopses. Default is to just kill the
                         process, but there is a small probability of
diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index 68894fdc034b..7ca4d43e8988 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -613,24 +613,36 @@ static int __init p4_init(char **cpu_type)
         return 0;
 }
 
-static int force_arch_perfmon;
-static int force_cpu_type(const char *str, struct kernel_param *kp)
+enum __force_cpu_type {
+        reserved = 0,           /* do not force */
+        timer,
+        arch_perfmon,
+};
+
+static int force_cpu_type;
+
+static int set_cpu_type(const char *str, struct kernel_param *kp)
 {
-        if (!strcmp(str, "arch_perfmon")) {
-                force_arch_perfmon = 1;
+        if (!strcmp(str, "timer")) {
+                force_cpu_type = timer;
+                printk(KERN_INFO "oprofile: forcing NMI timer mode\n");
+        } else if (!strcmp(str, "arch_perfmon")) {
+                force_cpu_type = arch_perfmon;
                 printk(KERN_INFO "oprofile: forcing architectural perfmon\n");
+        } else {
+                force_cpu_type = 0;
         }
 
         return 0;
 }
-module_param_call(cpu_type, force_cpu_type, NULL, NULL, 0);
+module_param_call(cpu_type, set_cpu_type, NULL, NULL, 0);
 
 static int __init ppro_init(char **cpu_type)
 {
         __u8 cpu_model = boot_cpu_data.x86_model;
         struct op_x86_model_spec *spec = &op_ppro_spec; /* default */
 
-        if (force_arch_perfmon && cpu_has_arch_perfmon)
+        if (force_cpu_type == arch_perfmon && cpu_has_arch_perfmon)
                 return 0;
 
         /*
@@ -697,6 +709,9 @@ int __init op_nmi_init(struct oprofile_operations *ops)
         if (!cpu_has_apic)
                 return -ENODEV;
 
+        if (force_cpu_type == timer)
+                return -ENODEV;
+
         switch (vendor) {
         case X86_VENDOR_AMD:
                 /* Needs to be at least an Athlon (or hammer in 32bit mode) */