sh: generic BUG() support.

Wire up GENERIC_BUG for SH. This moves off of the special bug
frame and on to the generic struct bug_entry. Roughly the same
semantics are retained, and we can kill off some of the verbose
BUG() reporting code.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -22,6 +22,10 @@ config RWSEM_GENERIC_SPINLOCK
 config RWSEM_XCHGADD_ALGORITHM
 	bool
 
+config GENERIC_BUG
+	def_bool y
+	depends on BUG
+
 config GENERIC_FIND_NEXT_BIT
 	bool
 	default y

arch/sh/kernel/traps.c

@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/kallsyms.h>
 #include <linux/io.h>
+#include <linux/bug.h>
 #include <linux/debug_locks.h>
 #include <linux/limits.h>
 #include <asm/system.h>
@@ -130,40 +131,6 @@ static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
 	return -EFAULT;
 }
 
-#ifdef CONFIG_BUG
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-static inline void do_bug_verbose(struct pt_regs *regs)
-{
-	struct bug_frame f;
-	long len;
-
-	if (__copy_from_user(&f, (const void __user *)regs->pc,
-			     sizeof(struct bug_frame)))
-		return;
-
-	len = __strnlen_user(f.file, PATH_MAX) - 1;
-	if (unlikely(len < 0 || len >= PATH_MAX))
-		f.file = "<bad filename>";
-	len = __strnlen_user(f.func, PATH_MAX) - 1;
-	if (unlikely(len < 0 || len >= PATH_MAX))
-		f.func = "<bad function>";
-
-	printk(KERN_ALERT "kernel BUG in %s() at %s:%d!\n",
-	       f.func, f.file, f.line);
-}
-#else
-static inline void do_bug_verbose(struct pt_regs *regs)
-{
-}
-#endif /* CONFIG_DEBUG_BUGVERBOSE */
-
-void handle_BUG(struct pt_regs *regs)
-{
-	do_bug_verbose(regs);
-	die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
-}
-#endif /* CONFIG_BUG */
-
 /*
  * handle an instruction that does an unaligned memory access by emulating the
  * desired behaviour
@@ -888,6 +855,25 @@ void __init trap_init(void)
 	per_cpu_trap_init();
 }
 
+#ifdef CONFIG_BUG
+void handle_BUG(struct pt_regs *regs)
+{
+	enum bug_trap_type tt;
+	tt = report_bug(regs->pc);
+	if (tt == BUG_TRAP_TYPE_WARN) {
+		regs->pc += 2;
+		return;
+	}
+
+	die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
+}
+
+int is_valid_bugaddr(unsigned long addr)
+{
+	return addr >= PAGE_OFFSET;
+}
+#endif
+
 void show_trace(struct task_struct *tsk, unsigned long *sp,
 		struct pt_regs *regs)
 {

arch/sh/kernel/vmlinux.lds.S

@@ -34,9 +34,11 @@ SECTIONS
   __ex_table : { *(__ex_table) }
   __stop___ex_table = .;
 
+  _etext = .;			/* End of text section */
+
   RODATA
 
-  _etext = .;			/* End of text section */
+  BUG_TABLE
 
   .data : {			/* Data */
 	*(.data)
@@ -53,6 +55,10 @@ SECTIONS
 
   . = ALIGN(PAGE_SIZE);
   .data.page_aligned : { *(.data.page_aligned) }
+  __nosave_begin = .;
+  .data_nosave : { *(.data.nosave) }
+  . = ALIGN(PAGE_SIZE);
+  __nosave_end = .;
 
   . = ALIGN(PAGE_SIZE);
   __per_cpu_start = .;
@@ -110,43 +116,10 @@ SECTIONS
    * it's a module.
    */
   /DISCARD/ : {
-	*(.exit.text)
-	*(.exit.data)
 	*(.exitcall.exit)
 	}
 
-  /* Stabs debugging sections.  */
-  .stab 0 : { *(.stab) }
-  .stabstr 0 : { *(.stabstr) }
-  .stab.excl 0 : { *(.stab.excl) }
-  .stab.exclstr 0 : { *(.stab.exclstr) }
-  .stab.index 0 : { *(.stab.index) }
-  .stab.indexstr 0 : { *(.stab.indexstr) }
-  .comment 0 : { *(.comment) }
-  /* DWARF debug sections.
-     Symbols in the DWARF debugging section are relative to the beginning
-     of the section so we begin .debug at 0.  */
-  /* DWARF 1 */
-  .debug          0 : { *(.debug) }
-  .line           0 : { *(.line) }
-  /* GNU DWARF 1 extensions */
-  .debug_srcinfo  0 : { *(.debug_srcinfo) }
-  .debug_sfnames  0 : { *(.debug_sfnames) }
-  /* DWARF 1.1 and DWARF 2 */
-  .debug_aranges  0 : { *(.debug_aranges) }
-  .debug_pubnames 0 : { *(.debug_pubnames) }
-  /* DWARF 2 */
-  .debug_info     0 : { *(.debug_info) }
-  .debug_abbrev   0 : { *(.debug_abbrev) }
-  .debug_line     0 : { *(.debug_line) }
-  .debug_frame    0 : { *(.debug_frame) }
-  .debug_str      0 : { *(.debug_str) }
-  .debug_loc      0 : { *(.debug_loc) }
-  .debug_macinfo  0 : { *(.debug_macinfo) }
-  /* SGI/MIPS DWARF 2 extensions */
-  .debug_weaknames 0 : { *(.debug_weaknames) }
-  .debug_funcnames 0 : { *(.debug_funcnames) }
-  .debug_typenames 0 : { *(.debug_typenames) }
-  .debug_varnames  0 : { *(.debug_varnames) }
-  /* These must appear regardless of  .  */
+  STABS_DEBUG
+
+  DWARF_DEBUG
 }

include/asm-sh/bug.h

@@ -2,50 +2,80 @@
 #define __ASM_SH_BUG_H
 
 #ifdef CONFIG_BUG
-
-struct bug_frame {
-	unsigned short	opcode;
-	unsigned short	line;
-	const char	*file;
-	const char	*func;
-};
-
-struct pt_regs;
-
-extern void handle_BUG(struct pt_regs *);
+#define HAVE_ARCH_BUG
+#define HAVE_ARCH_WARN_ON
 
 #define TRAPA_BUG_OPCODE	0xc33e	/* trapa #0x3e */
 
+/**
+ * _EMIT_BUG_ENTRY
+ * %1 - __FILE__
+ * %2 - __LINE__
+ * %3 - trap type
+ * %4 - sizeof(struct bug_entry)
+ *
+ * The trapa opcode itself sits in %0.
+ * The %O notation is used to avoid # generation.
+ *
+ * The offending file and line are encoded in the __bug_table section.
+ */
 #ifdef CONFIG_DEBUG_BUGVERBOSE
+#define _EMIT_BUG_ENTRY				\
+	"\t.pushsection __bug_table,\"a\"\n"	\
+	"2:\t.long 1b, %O1\n"			\
+	"\t.short %O2, %O3\n"			\
+	"\t.org 2b+%O4\n"			\
+	"\t.popsection\n"
+#else
+#define _EMIT_BUG_ENTRY				\
+	"\t.pushsection __bug_table,\"a\"\n"	\
+	"2:\t.long 1b\n"			\
+	"\t.short %O3\n"			\
+	"\t.org 2b+%O4\n"			\
+	"\t.popsection\n"
+#endif
 
 #define BUG()						\
 do {							\
 	__asm__ __volatile__ (				\
-		".align	2\n\t"				\
-		".short	%O0\n\t"			\
-		".short	%O1\n\t"			\
-		".long	%O2\n\t"			\
-		".long	%O3\n\t"			\
+		"1:\t.short %O0\n"			\
+		_EMIT_BUG_ENTRY				\
 		 :					\
 		 : "n" (TRAPA_BUG_OPCODE),		\
-		  "i" (__LINE__), "X" (__FILE__),	\
-		  "X" (__FUNCTION__));			\
+		   "i" (__FILE__),			\
+		   "i" (__LINE__), "i" (0),		\
+		   "i" (sizeof(struct bug_entry)));	\
 } while (0)
 
-#else
-
-#define BUG()					\
+#define __WARN()					\
 do {							\
 	__asm__ __volatile__ (				\
-		".align	2\n\t"			\
-		".short	%O0\n\t"		\
+		"1:\t.short %O0\n"			\
+		 _EMIT_BUG_ENTRY			\
 		 :					\
-		: "n" (TRAPA_BUG_OPCODE));	\
+		 : "n" (TRAPA_BUG_OPCODE),		\
+		   "i" (__FILE__),			\
+		   "i" (__LINE__),			\
+		   "i" (BUGFLAG_WARNING),		\
+		   "i" (sizeof(struct bug_entry)));	\
 } while (0)
 
-#endif /* CONFIG_DEBUG_BUGVERBOSE */
+#define WARN_ON(x) ({						\
+	typeof(x) __ret_warn_on = (x);				\
+	if (__builtin_constant_p(__ret_warn_on)) {		\
+		if (__ret_warn_on)				\
+			__WARN();				\
+	} else {						\
+		if (unlikely(__ret_warn_on))			\
+			__WARN();				\
+	}							\
+	unlikely(__ret_warn_on);				\
+})
 
-#define HAVE_ARCH_BUG
+struct pt_regs;
+
+/* arch/sh/kernel/traps.c */
+void handle_BUG(struct pt_regs *);
 
 #endif /* CONFIG_BUG */