Currently a number of unaligned instructions is counted but not used.
Add /debug/mips/unaligned_instructions file to show the value.
And add /debug/mips/unaligned_action to control behavior upon an
unaligned access. Possible actions are:
0: silently fixup the unaligned access.
1: send SIGBUS.
2: dump registers, process name, etc. and fixup.
Signed-off-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
---
This is a replacement of a patch titled:
"[PATCH] Add some sysfs files to debug unaligned accesses"
arch/mips/kernel/setup.c | 16 ++++++++++++++++
arch/mips/kernel/unaligned.c | 41 ++++++++++++++++++++++++++++++++++++++---
2 files changed, 54 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 4975da0..316685f 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -20,6 +20,7 @@
#include <linux/highmem.h>
#include <linux/console.h>
#include <linux/pfn.h>
+#include <linux/debugfs.h>
#include <asm/addrspace.h>
#include <asm/bootinfo.h>
@@ -574,3 +575,18 @@ __setup("nodsp", dsp_disable);
unsigned long kernelsp[NR_CPUS];
unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
+
+#ifdef CONFIG_DEBUG_FS
+struct dentry *mips_debugfs_dir;
+static int __init debugfs_mips(void)
+{
+ struct dentry *d;
+
+ d = debugfs_create_dir("mips", NULL);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+ mips_debugfs_dir = d;
+ return 0;
+}
+arch_initcall(debugfs_mips);
+#endif
diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index 18c4a3c..8b9c34f 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/arch/mips/kernel/unaligned.c
@@ -77,6 +77,7 @@
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/sched.h>
+#include <linux/debugfs.h>
#include <asm/asm.h>
#include <asm/branch.h>
#include <asm/byteorder.h>
@@ -87,9 +88,18 @@
#define STR(x) __STR(x)
#define __STR(x) #x
-#ifdef CONFIG_PROC_FS
-unsigned long unaligned_instructions;
+enum {
+ UNALIGNED_ACTION_QUIET,
+ UNALIGNED_ACTION_SIGNAL,
+ UNALIGNED_ACTION_SHOW,
+};
+#ifdef CONFIG_DEBUG_FS
+static u32 unaligned_instructions;
+static u32 unaligned_action;
+#else
+#define unaligned_action UNALIGNED_ACTION_QUIET
#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 +469,7 @@ static inline int emulate_load_store_insn(struct pt_regs *regs,
goto sigill;
}
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_DEBUG_FS
unaligned_instructions++;
#endif
@@ -516,6 +526,10 @@ 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 == UNALIGNED_ACTION_SIGNAL)
+ goto sigbus;
+ else if (unaligned_action == UNALIGNED_ACTION_SHOW)
+ show_registers(regs);
/*
* Do branch emulation only if we didn't forward the exception.
@@ -546,3 +560,24 @@ sigbus:
* XXX On return from the signal handler we should advance the epc
*/
}
+
+#ifdef CONFIG_DEBUG_FS
+extern struct dentry *mips_debugfs_dir;
+static int __init debugfs_unaligned(void)
+{
+ struct dentry *d;
+
+ if (!mips_debugfs_dir)
+ return -ENODEV;
+ d = debugfs_create_u32("unaligned_instructions", S_IRUGO,
+ mips_debugfs_dir, &unaligned_instructions);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+ d = debugfs_create_u32("unaligned_action", S_IRUGO | S_IWUSR,
+ mips_debugfs_dir, &unaligned_action);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+ return 0;
+}
+__initcall(debugfs_unaligned);
+#endif
