debug: Add _ONCE() logic to report_bug()

Josh suggested moving the _ONCE logic inside the trap handler, using a
bit in the bug_entry::flags field, avoiding the need for the extra
variable.

Sadly this only works for WARN_ON_ONCE(), since the others have
printk() statements prior to triggering the trap.

Still, this saves a fair amount of text and some data:

  text         data       filename
  10682460     4530992    defconfig-build/vmlinux.orig
  10665111     4530096    defconfig-build/vmlinux.patched

Suggested-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Peter Zijlstra 2017-02-25 08:56:53 +01:00 • committed by Ingo Molnar
commit 19d436268d
10 changed files with 52 additions and 25 deletions

View file

@ -50,7 +50,7 @@ do { \
"i" (sizeof(struct bug_entry))); \
} while (0)
#define __WARN_TAINT(taint) \
#define __WARN_FLAGS(flags) \
do { \
__asm__ __volatile__ ( \
"1:\t.short %O0\n" \
@ -59,7 +59,7 @@ do { \
: "n" (TRAPA_BUG_OPCODE), \
"i" (__FILE__), \
"i" (__LINE__), \
"i" (BUGFLAG_TAINT(taint)), \
"i" (BUGFLAG_WARNING|(flags)), \
"i" (sizeof(struct bug_entry))); \
} while (0)