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Commit 6312e0ee authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[MIPS] Add some debugfs files to debug unaligned accesses 



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: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 2db30150

arch/mips/kernel/setup.c

+16 −0
Original line number Diff line number Diff line
@@ -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

arch/mips/kernel/unaligned.c

+38 −3
Original line number Diff line number Diff line
@@ -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