linux-toradex.git/include/asm-generic/bug.h, branch v5.9-rc6

compiler.h: Move instrumentation_begin()/end() to new header

2020-07-24T11:56:23+00:00

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:

  655389666643: ("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: , 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 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/r/20200604071921.GA1361070@gmail.com
Cc: Thomas Gleixner 
Cc: Borislav Petkov 
Cc: Peter Zijlstra

bug: Annotate WARN/BUG/stackfail as noinstr safe

2020-06-11T13:14:36+00:00

Warnings, bugs and stack protection fails from noinstr sections, e.g. low
level and early entry code, are likely to be fatal.

Mark them as "safe" to be invoked from noinstr protected code to avoid
annotating all usage sites. Getting the information out is important.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexandre Chartre 
Acked-by: Peter Zijlstra 
Link: https://lkml.kernel.org/r/20200505134100.376598577@linutronix.de

bug: move WARN_ON() "cut here" into exception handler

2019-09-26T00:51:41+00:00

The original clean up of "cut here" missed the WARN_ON() case (that does
not have a printk message), which was fixed recently by adding an explicit
printk of "cut here".  This had the downside of adding a printk() to every
WARN_ON() caller, which reduces the utility of using an instruction
exception to streamline the resulting code.  By making this a new BUGFLAG,
all of these can be removed and "cut here" can be handled by the exception
handler.

This was very pronounced on PowerPC, but the effect can be seen on x86 as
well.  The resulting text size of a defconfig build shows some small
savings from this patch:

   text    data     bss     dec     hex filename
19691167        5134320 1646664 26472151        193eed7 vmlinux.before
19676362        5134260 1663048 26473670        193f4c6 vmlinux.after

This change also opens the door for creating something like BUG_MSG(),
where a custom printk() before issuing BUG(), without confusing the "cut
here" line.

Link: http://lkml.kernel.org/r/201908200943.601DD59DCE@keescook
Fixes: 6b15f678fb7d ("include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures")
Signed-off-by: Kees Cook 
Reported-by: Christophe Leroy 
Cc: Peter Zijlstra 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Arnd Bergmann 
Cc: "Steven Rostedt (VMware)" 
Cc: Feng Tang 
Cc: Petr Mladek 
Cc: Mauro Carvalho Chehab 
Cc: Borislav Petkov 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: consolidate __WARN_FLAGS usage

2019-09-26T00:51:41+00:00

Instead of having separate tests for __WARN_FLAGS, merge the two #ifdef
blocks and replace the synonym WANT_WARN_ON_SLOWPATH macro.

Link: http://lkml.kernel.org/r/20190819234111.9019-7-keescook@chromium.org
Signed-off-by: Kees Cook 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Feng Tang 
Cc: Mauro Carvalho Chehab 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: "Steven Rostedt (VMware)" 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: clean up helper macros to remove __WARN_TAINT()

2019-09-26T00:51:40+00:00

In preparation for cleaning up "cut here" even more, this removes the
__WARN_*TAINT() helpers, as they limit the ability to add new BUGFLAG_*
flags to call sites.  They are removed by expanding them into full
__WARN_FLAGS() calls.

Link: http://lkml.kernel.org/r/20190819234111.9019-6-keescook@chromium.org
Signed-off-by: Kees Cook 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Feng Tang 
Cc: Mauro Carvalho Chehab 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: "Steven Rostedt (VMware)" 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: consolidate warn_slowpath_fmt() usage

2019-09-26T00:51:40+00:00

Instead of having a separate helper for no printk output, just consolidate
the logic into warn_slowpath_fmt().

Link: http://lkml.kernel.org/r/20190819234111.9019-4-keescook@chromium.org
Signed-off-by: Kees Cook 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Feng Tang 
Cc: Mauro Carvalho Chehab 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: "Steven Rostedt (VMware)" 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: rename __WARN_printf_taint() to __WARN_printf()

2019-09-26T00:51:40+00:00

This just renames the helper to improve readability.

Link: http://lkml.kernel.org/r/20190819234111.9019-3-keescook@chromium.org
Signed-off-by: Kees Cook 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Feng Tang 
Cc: Mauro Carvalho Chehab 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: "Steven Rostedt (VMware)" 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: refactor away warn_slowpath_fmt_taint()

2019-09-26T00:51:40+00:00

Patch series "Clean up WARN() "cut here" handling", v2.

Christophe Leroy noticed that the fix for missing "cut here" in the WARN()
case was adding explicit printk() calls instead of teaching the exception
handler to add it.  This refactors the bug/warn infrastructure to pass
this information as a new BUGFLAG.

Longer details repeated from the last patch in the series:

bug: move WARN_ON() "cut here" into exception handler

The original cleanup of "cut here" missed the WARN_ON() case (that does
not have a printk message), which was fixed recently by adding an explicit
printk of "cut here".  This had the downside of adding a printk() to every
WARN_ON() caller, which reduces the utility of using an instruction
exception to streamline the resulting code.  By making this a new BUGFLAG,
all of these can be removed and "cut here" can be handled by the exception
handler.

This was very pronounced on PowerPC, but the effect can be seen on x86 as
well.  The resulting text size of a defconfig build shows some small
savings from this patch:

   text    data     bss     dec     hex filename
19691167        5134320 1646664 26472151        193eed7 vmlinux.before
19676362        5134260 1663048 26473670        193f4c6 vmlinux.after

This change also opens the door for creating something like BUG_MSG(),
where a custom printk() before issuing BUG(), without confusing the "cut
here" line.

This patch (of 7):

There's no reason to have specialized helpers for passing the warn taint
down to __warn().  Consolidate and refactor helper macros, removing
__WARN_printf() and warn_slowpath_fmt_taint().

Link: http://lkml.kernel.org/r/20190819234111.9019-2-keescook@chromium.org
Signed-off-by: Kees Cook 
Cc: Christophe Leroy 
Cc: Peter Zijlstra 
Cc: Christophe Leroy 
Cc: Drew Davenport 
Cc: Arnd Bergmann 
Cc: "Steven Rostedt (VMware)" 
Cc: Feng Tang 
Cc: Petr Mladek 
Cc: Mauro Carvalho Chehab 
Cc: Borislav Petkov 
Cc: YueHaibing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

asm-generic: add unlikely to default BUG_ON(x)

2019-09-01T21:53:39+00:00

Add unlikely to default BUG_ON(x) in !CONFIG_BUG. It makes
the define consistent with BUG_ON(x) in CONFIG_BUG.

Signed-off-by: Denis Efremov 
Cc: Arnd Bergmann 
Cc: 
Signed-off-by: Arnd Bergmann

include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures

2019-07-17T02:23:24+00:00

For architectures using __WARN_TAINT, the WARN_ON macro did not print
out the "cut here" string.  The other WARN_XXX macros would print "cut
here" inside __warn_printk, which is not called for WARN_ON since it
doesn't have a message to print.

Link: http://lkml.kernel.org/r/20190624154831.163888-1-ddavenport@chromium.org
Fixes: a7bed27af194 ("bug: fix "cut here" location for __WARN_TAINT architectures")
Signed-off-by: Drew Davenport 
Acked-by: Kees Cook 
Tested-by: Kees Cook 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds