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![Kees Cook](/assets/img/avatar_default.png)
Prior to v4.11, x86 used warn_slowpath_fmt() for handling WARN()s.
After WARN() was moved to using UD0 on x86, the warning text started
appearing _before_ the "cut here" line. This appears to have been a
long-standing bug on architectures that used __WARN_TAINT, but it didn't
get fixed.
v4.11 and earlier on x86:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 2956 at drivers/misc/lkdtm_bugs.c:65 lkdtm_WARNING+0x21/0x30
This is a warning message
Modules linked in:
v4.12 and later on x86:
This is a warning message
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2982 at drivers/misc/lkdtm_bugs.c:68 lkdtm_WARNING+0x15/0x20
Modules linked in:
With this fix:
------------[ cut here ]------------
This is a warning message
WARNING: CPU: 3 PID: 3009 at drivers/misc/lkdtm_bugs.c:67 lkdtm_WARNING+0x15/0x20
Since the __FILE__ reporting happens as part of the UD0 handler, it
isn't trivial to move the message to after the WARNING line, but at
least we can fix the position of the "cut here" line so all the various
logging tools will start including the actual runtime warning message
again, when they follow the instruction and "cut here".
Link: http://lkml.kernel.org/r/1510100869-73751-4-git-send-email-keescook@chromium.org
Fixes: 9a93848fe7
("x86/debug: Implement __WARN() using UD0")
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
241 lines
6.5 KiB
C
241 lines
6.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_GENERIC_BUG_H
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#define _ASM_GENERIC_BUG_H
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#include <linux/compiler.h>
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#define CUT_HERE "------------[ cut here ]------------\n"
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#ifdef CONFIG_GENERIC_BUG
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#define BUGFLAG_WARNING (1 << 0)
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#define BUGFLAG_ONCE (1 << 1)
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#define BUGFLAG_DONE (1 << 2)
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#define BUGFLAG_TAINT(taint) ((taint) << 8)
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#define BUG_GET_TAINT(bug) ((bug)->flags >> 8)
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#endif
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#ifndef __ASSEMBLY__
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#include <linux/kernel.h>
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#ifdef CONFIG_BUG
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#ifdef CONFIG_GENERIC_BUG
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struct bug_entry {
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#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
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unsigned long bug_addr;
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#else
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signed int bug_addr_disp;
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#endif
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
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const char *file;
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#else
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signed int file_disp;
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#endif
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unsigned short line;
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#endif
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unsigned short flags;
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};
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#endif /* CONFIG_GENERIC_BUG */
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/*
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* Don't use BUG() or BUG_ON() unless there's really no way out; one
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* example might be detecting data structure corruption in the middle
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* of an operation that can't be backed out of. If the (sub)system
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* can somehow continue operating, perhaps with reduced functionality,
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* it's probably not BUG-worthy.
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*
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* If you're tempted to BUG(), think again: is completely giving up
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* really the *only* solution? There are usually better options, where
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* users don't need to reboot ASAP and can mostly shut down cleanly.
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*/
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#ifndef HAVE_ARCH_BUG
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#define BUG() do { \
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printk("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
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panic("BUG!"); \
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} while (0)
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#endif
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#ifndef HAVE_ARCH_BUG_ON
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#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
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#endif
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#ifdef __WARN_FLAGS
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#define __WARN_TAINT(taint) __WARN_FLAGS(BUGFLAG_TAINT(taint))
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#define __WARN_ONCE_TAINT(taint) __WARN_FLAGS(BUGFLAG_ONCE|BUGFLAG_TAINT(taint))
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#define WARN_ON_ONCE(condition) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_ONCE_TAINT(TAINT_WARN); \
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unlikely(__ret_warn_on); \
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})
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#endif
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/*
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* WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
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* significant issues that need prompt attention if they should ever
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* appear at runtime. Use the versions with printk format strings
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* to provide better diagnostics.
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*/
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#ifndef __WARN_TAINT
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extern __printf(3, 4)
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void warn_slowpath_fmt(const char *file, const int line,
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const char *fmt, ...);
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extern __printf(4, 5)
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void warn_slowpath_fmt_taint(const char *file, const int line, unsigned taint,
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const char *fmt, ...);
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extern void warn_slowpath_null(const char *file, const int line);
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#define WANT_WARN_ON_SLOWPATH
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#define __WARN() warn_slowpath_null(__FILE__, __LINE__)
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#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg)
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#define __WARN_printf_taint(taint, arg...) \
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warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
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#else
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extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
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#define __WARN() __WARN_TAINT(TAINT_WARN)
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#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
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#define __WARN_printf_taint(taint, arg...) \
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do { __warn_printk(arg); __WARN_TAINT(taint); } while (0)
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#endif
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/* used internally by panic.c */
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struct warn_args;
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struct pt_regs;
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void __warn(const char *file, int line, void *caller, unsigned taint,
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struct pt_regs *regs, struct warn_args *args);
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#ifndef WARN_ON
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#define WARN_ON(condition) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN(); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#ifndef WARN
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#define WARN(condition, format...) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_printf(format); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#define WARN_TAINT(condition, taint, format...) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_printf_taint(taint, format); \
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unlikely(__ret_warn_on); \
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})
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#ifndef WARN_ON_ONCE
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#define WARN_ON_ONCE(condition) ({ \
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static bool __section(.data.once) __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once && !__warned)) { \
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__warned = true; \
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WARN_ON(1); \
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} \
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unlikely(__ret_warn_once); \
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})
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#endif
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#define WARN_ONCE(condition, format...) ({ \
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static bool __section(.data.once) __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once && !__warned)) { \
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__warned = true; \
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WARN(1, format); \
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} \
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unlikely(__ret_warn_once); \
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})
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#define WARN_TAINT_ONCE(condition, taint, format...) ({ \
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static bool __section(.data.once) __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once && !__warned)) { \
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__warned = true; \
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WARN_TAINT(1, taint, format); \
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} \
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unlikely(__ret_warn_once); \
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})
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#else /* !CONFIG_BUG */
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#ifndef HAVE_ARCH_BUG
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#define BUG() do {} while (1)
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#endif
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#ifndef HAVE_ARCH_BUG_ON
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#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
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#endif
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#ifndef HAVE_ARCH_WARN_ON
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#define WARN_ON(condition) ({ \
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int __ret_warn_on = !!(condition); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#ifndef WARN
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#define WARN(condition, format...) ({ \
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int __ret_warn_on = !!(condition); \
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no_printk(format); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#define WARN_ON_ONCE(condition) WARN_ON(condition)
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#define WARN_ONCE(condition, format...) WARN(condition, format)
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#define WARN_TAINT(condition, taint, format...) WARN(condition, format)
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#define WARN_TAINT_ONCE(condition, taint, format...) WARN(condition, format)
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#endif
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/*
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* WARN_ON_SMP() is for cases that the warning is either
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* meaningless for !SMP or may even cause failures.
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* This is usually used for cases that we have
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* WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked()
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* returns 0 for uniprocessor settings.
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* It can also be used with values that are only defined
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* on SMP:
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*
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* struct foo {
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* [...]
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* #ifdef CONFIG_SMP
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* int bar;
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* #endif
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* };
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*
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* void func(struct foo *zoot)
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* {
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* WARN_ON_SMP(!zoot->bar);
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*
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* For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(),
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* and should be a nop and return false for uniprocessor.
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*
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* if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set
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* and x is true.
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*/
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#ifdef CONFIG_SMP
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# define WARN_ON_SMP(x) WARN_ON(x)
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#else
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/*
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* Use of ({0;}) because WARN_ON_SMP(x) may be used either as
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* a stand alone line statement or as a condition in an if ()
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* statement.
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* A simple "0" would cause gcc to give a "statement has no effect"
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* warning.
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*/
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# define WARN_ON_SMP(x) ({0;})
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#endif
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#endif /* __ASSEMBLY__ */
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#endif
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