d19e789f06
Linus pointed out that compiler.h - which is a key header that gets included in every
single one of the 28,000+ kernel files during a kernel build - was bloated in:
6553896666: ("vmlinux.lds.h: Create section for protection against instrumentation")
Linus noted:
> I have pulled this, but do we really want to add this to a header file
> that is _so_ core that it gets included for basically every single
> file built?
>
> I don't even see those instrumentation_begin/end() things used
> anywhere right now.
>
> It seems excessive. That 53 lines is maybe not a lot, but it pushed
> that header file to over 12kB, and while it's mostly comments, it's
> extra IO and parsing basically for _every_ single file compiled in the
> kernel.
>
> For what appears to be absolutely zero upside right now, and I really
> don't see why this should be in such a core header file!
Move these primitives into a new header: <linux/instrumentation.h>, and include that
header in the headers that make use of it.
Unfortunately one of these headers is asm-generic/bug.h, which does get included
in a lot of places, similarly to compiler.h. So the de-bloating effect isn't as
good as we'd like it to be - but at least the interfaces are defined separately.
No change to functionality intended.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200604071921.GA1361070@gmail.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
247 lines
6.8 KiB
C
247 lines
6.8 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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#include <linux/instrumentation.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_NO_CUT_HERE (1 << 3) /* CUT_HERE already sent */
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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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barrier_before_unreachable(); \
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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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/*
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* WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
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* significant kernel issues that need prompt attention if they should ever
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* appear at runtime.
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*
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* Do not use these macros when checking for invalid external inputs
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* (e.g. invalid system call arguments, or invalid data coming from
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* network/devices), and on transient conditions like ENOMEM or EAGAIN.
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* These macros should be used for recoverable kernel issues only.
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* For invalid external inputs, transient conditions, etc use
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* pr_err[_once/_ratelimited]() followed by dump_stack(), if necessary.
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* Do not include "BUG"/"WARNING" in format strings manually to make these
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* conditions distinguishable from kernel issues.
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*
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* Use the versions with printk format strings to provide better diagnostics.
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*/
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#ifndef __WARN_FLAGS
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extern __printf(4, 5)
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void warn_slowpath_fmt(const char *file, const int line, unsigned taint,
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const char *fmt, ...);
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#define __WARN() __WARN_printf(TAINT_WARN, NULL)
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#define __WARN_printf(taint, arg...) do { \
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instrumentation_begin(); \
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warn_slowpath_fmt(__FILE__, __LINE__, taint, arg); \
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instrumentation_end(); \
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} while (0)
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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_FLAGS(BUGFLAG_TAINT(TAINT_WARN))
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#define __WARN_printf(taint, arg...) do { \
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instrumentation_begin(); \
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__warn_printk(arg); \
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__WARN_FLAGS(BUGFLAG_NO_CUT_HERE | BUGFLAG_TAINT(taint));\
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instrumentation_end(); \
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} while (0)
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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_FLAGS(BUGFLAG_ONCE | \
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BUGFLAG_TAINT(TAINT_WARN)); \
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unlikely(__ret_warn_on); \
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})
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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(TAINT_WARN, 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, 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 (unlikely(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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* 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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