[POWERPC] Generic BUG for powerpc

This makes powerpc use the generic BUG machinery.  The biggest reports the
function name, since it is redundant with kallsyms, and not needed in general.

There is an overall reduction of code, since module_32/64 duplicated several
functions.

Unfortunately there's no way to tell gcc that BUG won't return, so the BUG
macro includes a goto loop.  This will generate a real jmp instruction, which
is never used.

[akpm@osdl.org: build fix]
[paulus@samba.org: remove infinite loop in BUG_ON]
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/Kconfig

@@ -99,6 +99,11 @@ config AUDIT_ARCH
 	bool
 	default y
 
+config GENERIC_BUG
+	bool
+	default y
+	depends on BUG
+
 config DEFAULT_UIMAGE
 	bool
 	help

arch/powerpc/kernel/module_32.c

@@ -23,6 +23,7 @@
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/cache.h>
+#include <linux/bug.h>
 
 #include "setup.h"
 
@@ -290,23 +291,11 @@ int module_finalize(const Elf_Ehdr *hdr,
 		    struct module *me)
 {
 	const Elf_Shdr *sect;
+	int err;
 
-	me->arch.bug_table = NULL;
-	me->arch.num_bugs = 0;
-
-	/* Find the __bug_table section, if present */
-	sect = find_section(hdr, sechdrs, "__bug_table");
-	if (sect != NULL) {
-		me->arch.bug_table = (void *) sect->sh_addr;
-		me->arch.num_bugs = sect->sh_size / sizeof(struct bug_entry);
-	}
-
- 	/*
-	 * Strictly speaking this should have a spinlock to protect against
-	 * traversals, but since we only traverse on BUG()s, a spinlock
-	 * could potentially lead to deadlock and thus be counter-productive.
-	 */
-	list_add(&me->arch.bug_list, &module_bug_list);
+	err = module_bug_finalize(hdr, sechdrs, me);
+	if (err)		/* never true, currently */
+		return err;
 
 	/* Apply feature fixups */
 	sect = find_section(hdr, sechdrs, "__ftr_fixup");
@@ -320,7 +309,7 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 void module_arch_cleanup(struct module *mod)
 {
-	list_del(&mod->arch.bug_list);
+	module_bug_cleanup(mod);
 }
 
 struct bug_entry *module_find_bug(unsigned long bugaddr)

arch/powerpc/kernel/module_64.c

@@ -20,6 +20,7 @@
 #include <linux/moduleloader.h>
 #include <linux/err.h>
 #include <linux/vmalloc.h>
+#include <linux/bug.h>
 #include <asm/module.h>
 #include <asm/uaccess.h>
 #include <asm/firmware.h>
@@ -439,23 +440,11 @@ int module_finalize(const Elf_Ehdr *hdr,
 		const Elf_Shdr *sechdrs, struct module *me)
 {
 	const Elf_Shdr *sect;
+	int err;
 
-	me->arch.bug_table = NULL;
-	me->arch.num_bugs = 0;
-
-	/* Find the __bug_table section, if present */
-	sect = find_section(hdr, sechdrs, "__bug_table");
-	if (sect != NULL) {
-		me->arch.bug_table = (void *) sect->sh_addr;
-		me->arch.num_bugs = sect->sh_size / sizeof(struct bug_entry);
-	}
-
-	/*
-	 * Strictly speaking this should have a spinlock to protect against
-	 * traversals, but since we only traverse on BUG()s, a spinlock
-	 * could potentially lead to deadlock and thus be counter-productive.
-	 */
-	list_add(&me->arch.bug_list, &module_bug_list);
+	err = module_bug_finalize(hdr, sechdrs, me);
+	if (err)
+		return err;
 
 	/* Apply feature fixups */
 	sect = find_section(hdr, sechdrs, "__ftr_fixup");
@@ -475,7 +464,7 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 void module_arch_cleanup(struct module *mod)
 {
-	list_del(&mod->arch.bug_list);
+	module_bug_cleanup(mod);
 }
 
 struct bug_entry *module_find_bug(unsigned long bugaddr)

arch/powerpc/kernel/traps.c

@@ -32,6 +32,7 @@
 #include <linux/kprobes.h>
 #include <linux/kexec.h>
 #include <linux/backlight.h>
+#include <linux/bug.h>
 
 #include <asm/kdebug.h>
 #include <asm/pgtable.h>
@@ -727,54 +728,9 @@ static int emulate_instruction(struct pt_regs *regs)
 	return -EINVAL;
 }
 
-/*
- * Look through the list of trap instructions that are used for BUG(),
- * BUG_ON() and WARN_ON() and see if we hit one.  At this point we know
- * that the exception was caused by a trap instruction of some kind.
- * Returns 1 if we should continue (i.e. it was a WARN_ON) or 0
- * otherwise.
- */
-extern struct bug_entry __start___bug_table[], __stop___bug_table[];
-
-#ifndef CONFIG_MODULES
-#define module_find_bug(x)	NULL
-#endif
-
-struct bug_entry *find_bug(unsigned long bugaddr)
+int is_valid_bugaddr(unsigned long addr)
 {
-	struct bug_entry *bug;
-
-	for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
-		if (bugaddr == bug->bug_addr)
-			return bug;
-	return module_find_bug(bugaddr);
-}
-
-static int check_bug_trap(struct pt_regs *regs)
-{
-	struct bug_entry *bug;
-	unsigned long addr;
-
-	if (regs->msr & MSR_PR)
-		return 0;	/* not in kernel */
-	addr = regs->nip;	/* address of trap instruction */
-	if (addr < PAGE_OFFSET)
-		return 0;
-	bug = find_bug(regs->nip);
-	if (bug == NULL)
-		return 0;
-	if (bug->line & BUG_WARNING_TRAP) {
-		/* this is a WARN_ON rather than BUG/BUG_ON */
-		printk(KERN_ERR "Badness in %s at %s:%ld\n",
-		       bug->function, bug->file,
-		       bug->line & ~BUG_WARNING_TRAP);
-		dump_stack();
-		return 1;
-	}
-	printk(KERN_CRIT "kernel BUG in %s at %s:%ld!\n",
-	       bug->function, bug->file, bug->line);
-
-	return 0;
+	return is_kernel_addr(addr);
 }
 
 void __kprobes program_check_exception(struct pt_regs *regs)
@@ -810,7 +766,9 @@ void __kprobes program_check_exception(struct pt_regs *regs)
 			return;
 		if (debugger_bpt(regs))
 			return;
-		if (check_bug_trap(regs)) {
+
+		if (!(regs->msr & MSR_PR) &&  /* not user-mode */
+		    report_bug(regs->nip) == BUG_TRAP_TYPE_WARN) {
 			regs->nip += 4;
 			return;
 		}

arch/powerpc/kernel/vmlinux.lds.S

@@ -62,11 +62,7 @@ SECTIONS
 		__stop___ex_table = .;
 	}
 
-	__bug_table : {
-		__start___bug_table = .;
-		*(__bug_table)
-		__stop___bug_table = .;
-	}
+	BUG_TABLE
 
 /*
  * Init sections discarded at runtime

arch/powerpc/xmon/xmon.c

@@ -22,6 +22,7 @@
 #include <linux/sysrq.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/bug.h>
 
 #include <asm/ptrace.h>
 #include <asm/string.h>
@@ -35,7 +36,6 @@
 #include <asm/cputable.h>
 #include <asm/rtas.h>
 #include <asm/sstep.h>
-#include <asm/bug.h>
 #include <asm/irq_regs.h>
 #include <asm/spu.h>
 #include <asm/spu_priv1.h>
@@ -1346,7 +1346,7 @@ static void backtrace(struct pt_regs *excp)
 
 static void print_bug_trap(struct pt_regs *regs)
 {
-	struct bug_entry *bug;
+	const struct bug_entry *bug;
 	unsigned long addr;
 
 	if (regs->msr & MSR_PR)
@@ -1357,11 +1357,11 @@ static void print_bug_trap(struct pt_regs *regs)
 	bug = find_bug(regs->nip);
 	if (bug == NULL)
 		return;
-	if (bug->line & BUG_WARNING_TRAP)
+	if (is_warning_bug(bug))
 		return;
 
-	printf("kernel BUG in %s at %s:%d!\n",
-	       bug->function, bug->file, (unsigned int)bug->line);
+	printf("kernel BUG at %s:%u!\n",
+	       bug->file, bug->line);
 }
 
 void excprint(struct pt_regs *fp)

include/asm-powerpc/bug.h

@@ -13,23 +13,26 @@
 
 #ifndef __ASSEMBLY__
 
-struct bug_entry {
-	unsigned long	bug_addr;
-	long		line;
-	const char	*file;
-	const char	*function;
-};
-
-struct bug_entry *find_bug(unsigned long bugaddr);
-
-/*
- * If this bit is set in the line number it means that the trap
- * is for WARN_ON rather than BUG or BUG_ON.
- */
-#define BUG_WARNING_TRAP	0x1000000
-
 #ifdef CONFIG_BUG
 
+/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
+   sizeof(struct bug_entry), respectively */
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+#define _EMIT_BUG_ENTRY				\
+	".section __bug_table,\"a\"\n"		\
+	"2:\t" PPC_LONG "1b, %0\n"		\
+	"\t.short %1, %2\n"			\
+	".org 2b+%3\n"				\
+	".previous\n"
+#else
+#define _EMIT_BUG_ENTRY				\
+	".section __bug_table,\"a\"\n"		\
+	"2:\t" PPC_LONG "1b\n"			\
+	"\t.short %2\n"				\
+	".org 2b+%3\n"				\
+	".previous\n"
+#endif
+
 /*
  * BUG_ON() and WARN_ON() do their best to cooperate with compile-time
  * optimisations. However depending on the complexity of the condition
@@ -39,10 +42,10 @@ struct bug_entry *find_bug(unsigned long bugaddr);
 #define BUG() do {						\
 	__asm__ __volatile__(					\
 		"1:	twi 31,0,0\n"				\
-		".section __bug_table,\"a\"\n"				 \
-		"\t"PPC_LONG"	1b,%0,%1,%2\n"				 \
-		".previous"						 \
-		: : "i" (__LINE__), "i" (__FILE__), "i" (__FUNCTION__)); \
+		_EMIT_BUG_ENTRY					\
+		: : "i" (__FILE__), "i" (__LINE__),		\
+		    "i" (0), "i"  (sizeof(struct bug_entry)));	\
+	for(;;) ;						\
 } while (0)
 
 #define BUG_ON(x) do {						\
@@ -51,23 +54,21 @@ struct bug_entry *find_bug(unsigned long bugaddr);
 			BUG();					\
 	} else {						\
 		__asm__ __volatile__(				\
-		"1:	"PPC_TLNEI"	%0,0\n"			\
-		".section __bug_table,\"a\"\n"			\
-		"\t"PPC_LONG"	1b,%1,%2,%3\n"			\
-		".previous"					\
-		: : "r" ((long)(x)), "i" (__LINE__),		\
-		    "i" (__FILE__), "i" (__FUNCTION__));	\
+		"1:	"PPC_TLNEI"	%4,0\n"			\
+		_EMIT_BUG_ENTRY					\
+		: : "i" (__FILE__), "i" (__LINE__), "i" (0),	\
+		  "i" (sizeof(struct bug_entry)),		\
+		  "r" ((long)(x)));				\
 	}							\
 } while (0)
 
 #define __WARN() do {						\
 	__asm__ __volatile__(					\
 		"1:	twi 31,0,0\n"				\
-		".section __bug_table,\"a\"\n"			\
-		"\t"PPC_LONG"	1b,%0,%1,%2\n"			\
-		".previous"					\
-		: : "i" (__LINE__ + BUG_WARNING_TRAP),		\
-		    "i" (__FILE__), "i" (__FUNCTION__));	\
+		_EMIT_BUG_ENTRY					\
+		: : "i" (__FILE__), "i" (__LINE__),		\
+		  "i" (BUGFLAG_WARNING),			\
+		  "i" (sizeof(struct bug_entry)));		\
 } while (0)
 
 #define WARN_ON(x) ({						\
@@ -77,13 +78,12 @@ struct bug_entry *find_bug(unsigned long bugaddr);
 			__WARN();				\
 	} else {						\
 		__asm__ __volatile__(				\
-		"1:	"PPC_TLNEI"	%0,0\n"			\
-		".section __bug_table,\"a\"\n"			\
-		"\t"PPC_LONG"	1b,%1,%2,%3\n"			\
-		".previous"					\
-		: : "r" (__ret_warn_on),			\
-		    "i" (__LINE__ + BUG_WARNING_TRAP),		\
-		    "i" (__FILE__), "i" (__FUNCTION__));	\
+		"1:	"PPC_TLNEI"	%4,0\n"			\
+		_EMIT_BUG_ENTRY					\
+		: : "i" (__FILE__), "i" (__LINE__),		\
+		  "i" (BUGFLAG_WARNING),			\
+		  "i" (sizeof(struct bug_entry)),		\
+		  "r" (__ret_warn_on));				\
 	}							\
 	unlikely(__ret_warn_on);				\
 })

include/asm-powerpc/module.h

@@ -46,8 +46,6 @@ struct mod_arch_specific {
 	unsigned int num_bugs;
 };
 
-extern struct bug_entry *module_find_bug(unsigned long bugaddr);
-
 /*
  * Select ELF headers.
  * Make empty section for module_frob_arch_sections to expand.