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[PATCH] Fix BUG(), BUG_ON() handling

To: linux-mips@linux-mips.org
Subject: [PATCH] Fix BUG(), BUG_ON() handling
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Thu, 12 Apr 2007 20:02:54 +0900 (JST)
Cc: ralf@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
With commit 63dc68a8cf60cb110b147dab1704d990808b39e2, kernel can not
handle BUG() and BUG_ON() properly since get_user() returns false for
kernel code.  Use __get_user() to skip unnecessary access_ok().  This
patch also make BRK_BUG code encoded in the TNE instruction.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
---
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7d76a85..56a770c 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -650,7 +650,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
        unsigned int opcode, bcode;
        siginfo_t info;
 
-       if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
+       if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                goto out_sigsegv;
 
        /*
@@ -700,7 +700,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
        unsigned int opcode, tcode = 0;
        siginfo_t info;
 
-       if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
+       if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                goto out_sigsegv;
 
        /* Immediate versions don't provide a code.  */
diff --git a/include/asm-mips/bug.h b/include/asm-mips/bug.h
index 4d560a5..7eb63de 100644
--- a/include/asm-mips/bug.h
+++ b/include/asm-mips/bug.h
@@ -18,7 +18,8 @@ do {                                                          
        \
 
 #define BUG_ON(condition)                                              \
 do {                                                                   \
-       __asm__ __volatile__("tne $0, %0" : : "r" (condition));         \
+       __asm__ __volatile__("tne $0, %0, %1"                           \
+                            : : "r" (condition), "i" (BRK_BUG));       \
 } while (0)
 
 #define HAVE_ARCH_BUG_ON

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