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debug: Add _ONCE() logic to report_bug()

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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 <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2017-02-25 08:56:53 +01:00
committed by Ingo Molnar
parent 70579a86e3
commit 19d436268d
10 changed files with 52 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
include/asm-generic/bug.h
View File

@@ -5,6 +5,8 @@
#ifdef CONFIG_GENERIC_BUG
#define BUGFLAG_WARNING (1 << 0)
#define BUGFLAG_ONCE (1 << 1)
#define BUGFLAG_DONE (1 << 2)
#define BUGFLAG_TAINT(taint) (BUGFLAG_WARNING | ((taint) << 8))
#define BUG_GET_TAINT(bug) ((bug)->flags >> 8)
#endif
@@ -55,6 +57,18 @@ struct bug_entry {
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
#endif
#ifdef __WARN_FLAGS
#define __WARN_TAINT(taint) __WARN_FLAGS(BUGFLAG_TAINT(taint))
#define __WARN_ONCE_TAINT(taint) __WARN_FLAGS(BUGFLAG_ONCE|BUGFLAG_TAINT(taint))
#define WARN_ON_ONCE(condition) ({ \
int __ret_warn_on = !!(condition); \
if (unlikely(__ret_warn_on)) \
__WARN_ONCE_TAINT(TAINT_WARN); \
unlikely(__ret_warn_on); \
})
#endif
/*
* WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
* significant issues that need prompt attention if they should ever
@@ -97,7 +111,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
#endif
#ifndef WARN
#define WARN(condition, format...) ({ \
#define WARN(condition, format...) ({ \
int __ret_warn_on = !!(condition); \
if (unlikely(__ret_warn_on)) \
__WARN_printf(format); \
@@ -112,6 +126,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
unlikely(__ret_warn_on); \
})
#ifndef WARN_ON_ONCE
#define WARN_ON_ONCE(condition) ({ \
static bool __section(.data.unlikely) __warned; \
int __ret_warn_once = !!(condition); \
@@ -122,6 +137,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
} \
unlikely(__ret_warn_once); \
})
#endif
#define WARN_ONCE(condition, format...) ({ \
static bool __section(.data.unlikely) __warned; \

5
include/asm-generic/vmlinux.lds.h
View File

@@ -286,8 +286,6 @@
*(.rodata1) \
} \
\
BUG_TABLE \
\
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_pci_fixups_early) = .; \
@@ -855,7 +853,8 @@
READ_MOSTLY_DATA(cacheline) \
DATA_DATA \
CONSTRUCTORS \
}
} \
BUG_TABLE
#define INIT_TEXT_SECTION(inittext_align) \
. = ALIGN(inittext_align); \