On Tue, 06 Mar 2007 00:51:43 +0900 (JST), Atsushi Nemoto <anemo@xxxxxxxxxxxxx> wrote:
> Currently a number of unaligned instructions is counted but not used.
> Add /sys/kernel/mips/unaligned_instructions file to show the value.
Updated against current git tree.
Subject: [PATCH] Add some sysfs files to debug unaligned accesses
Currently a number of unaligned instructions is counted but not used.
Add /sys/kernel/mips/unaligned_instructions file to show the value.
And add /sys/kernel/mips/unaligned_action to control behavior upon an
unaligned access. Possible actions are:
quiet: silently fixup the unaligned access.
signal: send SIGBUS.
show: dump registers, process name, etc. and fixup.
Signed-off-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
---
arch/mips/kernel/setup.c | 14 ++++++++
arch/mips/kernel/unaligned.c | 70 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 81 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 4975da0..1c8629c 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -574,3 +574,17 @@ __setup("nodsp", dsp_disable);
unsigned long kernelsp[NR_CPUS];
unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
+
+static struct attribute *mips_attrs[] = {
+ NULL
+};
+static struct attribute_group mips_attr_group = {
+ .name = "mips",
+ .attrs = mips_attrs,
+};
+
+static int __init sysfs_mips(void)
+{
+ return sysfs_create_group(&kernel_subsys.kobj, &mips_attr_group);
+}
+arch_initcall(sysfs_mips);
diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index a7d49ae..bdead88 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/arch/mips/kernel/unaligned.c
@@ -87,9 +87,14 @@
#define STR(x) __STR(x)
#define __STR(x) #x
-#ifdef CONFIG_PROC_FS
-unsigned long unaligned_instructions;
+#ifdef CONFIG_SYSFS
+static unsigned long unaligned_instructions;
+static int unaligned_action;
+static const char *unaligned_actions[] = {"quiet", "signal", "show"};
+#else
+#define unaligned_action 0
#endif
+extern void show_registers(struct pt_regs *regs);
static inline int emulate_load_store_insn(struct pt_regs *regs,
void __user *addr, unsigned int __user *pc,
@@ -459,7 +464,7 @@ static inline int emulate_load_store_insn(struct pt_regs *regs,
goto sigill;
}
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_SYSFS
unaligned_instructions++;
#endif
@@ -516,6 +521,10 @@ asmlinkage void do_ade(struct pt_regs *regs)
pc = (unsigned int __user *) exception_epc(regs);
if (user_mode(regs) && (current->thread.mflags & MF_FIXADE) == 0)
goto sigbus;
+ if (unaligned_action == 1)
+ goto sigbus;
+ else if (unaligned_action == 2)
+ show_registers(regs);
/*
* Do branch emulation only if we didn't forward the exception.
@@ -546,3 +555,58 @@ sigbus:
* XXX On return from the signal handler we should advance the epc
*/
}
+
+#ifdef CONFIG_SYSFS
+static ssize_t unaligned_instructions_show(struct kset *kset, char *buf)
+{
+ return sprintf(buf, "%lu\n", unaligned_instructions);
+}
+
+static ssize_t unaligned_action_show(struct kset *kset, char *buf)
+{
+ int i;
+ char *s = buf;
+
+ for (i = 0; i < ARRAY_SIZE(unaligned_actions); i++) {
+ if (i == unaligned_action)
+ s += sprintf(s, "[%s] ", unaligned_actions[i]);
+ else
+ s += sprintf(s, "%s ", unaligned_actions[i]);
+ }
+ s += sprintf(s, "\n");
+ return s - buf;
+}
+
+static ssize_t unaligned_action_store(struct kset *kset,
+ const char *buf, size_t count)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(unaligned_actions); i++) {
+ if (!strncmp(buf, unaligned_actions[i],
+ min(count, strlen(unaligned_actions[i])))) {
+ unaligned_action = i;
+ return count;
+ }
+ }
+ return -EINVAL;
+}
+
+#define __ATTR_RW(_name) __ATTR(_name, 0644, _name##_show, _name##_store)
+static struct subsys_attribute unaligned_attrs[] = {
+ __ATTR_RO(unaligned_instructions),
+ __ATTR_RW(unaligned_action),
+};
+
+static int __init sysfs_unaligned(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(unaligned_attrs); i++)
+ sysfs_add_file_to_group(&kernel_subsys.kobj,
+ &unaligned_attrs[i].attr,
+ "mips");
+ return 0;
+}
+__initcall(sysfs_unaligned);
+#endif
