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linux-next/include/asm-powerpc/bug.h
Linus Torvalds 8d4fbcfbe0 Fix WARN_ON() on bitfield ops
Alexey Dobriyan noticed that the new WARN_ON() semantics that were
introduced by commit 684f978347 (to also
return the value to be warned on) didn't compile when given a bitfield,
because the typeof doesn't work for bitfields.

So instead of the typeof trick, use an "int" variable together with a
"!!(x)" expression, as suggested by Al Viro.

To make matters more interesting, Paul Mackerras points out that that is
sub-optimal on Power, but the old asm-coded comparison seems to be buggy
anyway on 32-bit Power if the conditional was 64-bit, so I think there
are more problems there.

Regardless, the new WARN_ON() semantics may have been a bad idea.  But
this at least avoids the more serious complications.

Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2007-07-31 21:12:07 -07:00

122 lines
3.0 KiB
C

#ifndef _ASM_POWERPC_BUG_H
#define _ASM_POWERPC_BUG_H
#ifdef __KERNEL__
#include <asm/asm-compat.h>
/*
* Define an illegal instr to trap on the bug.
* We don't use 0 because that marks the end of a function
* in the ELF ABI. That's "Boo Boo" in case you wonder...
*/
#define BUG_OPCODE .long 0x00b00b00 /* For asm */
#define BUG_ILLEGAL_INSTR "0x00b00b00" /* For BUG macro */
#ifdef CONFIG_BUG
#ifdef __ASSEMBLY__
#ifdef CONFIG_DEBUG_BUGVERBOSE
.macro EMIT_BUG_ENTRY addr,file,line,flags
.section __bug_table,"a"
5001: PPC_LONG \addr, 5002f
.short \line, \flags
.org 5001b+BUG_ENTRY_SIZE
.previous
.section .rodata,"a"
5002: .asciz "\file"
.previous
.endm
#else
.macro EMIT_BUG_ENTRY addr,file,line,flags
.section __bug_table,"a"
5001: PPC_LONG \addr
.short \flags
.org 5001b+BUG_ENTRY_SIZE
.previous
.endm
#endif /* verbose */
#else /* !__ASSEMBLY__ */
/* _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
* some compiler versions may not produce optimal results.
*/
#define BUG() do { \
__asm__ __volatile__( \
"1: twi 31,0,0\n" \
_EMIT_BUG_ENTRY \
: : "i" (__FILE__), "i" (__LINE__), \
"i" (0), "i" (sizeof(struct bug_entry))); \
for(;;) ; \
} while (0)
#define BUG_ON(x) do { \
if (__builtin_constant_p(x)) { \
if (x) \
BUG(); \
} else { \
__asm__ __volatile__( \
"1: "PPC_TLNEI" %4,0\n" \
_EMIT_BUG_ENTRY \
: : "i" (__FILE__), "i" (__LINE__), "i" (0), \
"i" (sizeof(struct bug_entry)), \
"r" ((__force long)(x))); \
} \
} while (0)
#define __WARN() do { \
__asm__ __volatile__( \
"1: twi 31,0,0\n" \
_EMIT_BUG_ENTRY \
: : "i" (__FILE__), "i" (__LINE__), \
"i" (BUGFLAG_WARNING), \
"i" (sizeof(struct bug_entry))); \
} while (0)
#define WARN_ON(x) ({ \
int __ret_warn_on = !!(x); \
if (__builtin_constant_p(__ret_warn_on)) { \
if (__ret_warn_on) \
__WARN(); \
} else { \
__asm__ __volatile__( \
"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); \
})
#define HAVE_ARCH_BUG
#define HAVE_ARCH_BUG_ON
#define HAVE_ARCH_WARN_ON
#endif /* __ASSEMBLY __ */
#endif /* CONFIG_BUG */
#include <asm-generic/bug.h>
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_BUG_H */