linux-toradex.git/include/linux/bug.h, branch v4.13-rc4

bug: split BUILD_BUG stuff out into

2017-07-10T23:32:34+00:00

Including  pulls in a lot of bloat from  and
 that is not needed to call the BUILD_BUG() family of
macros.  Split them out into their own header, .

Also correct some checkpatch.pl errors for the BUILD_BUG_ON_ZERO() and
BUILD_BUG_ON_NULL() macros by adding parentheses around the bitfield
widths that begin with a minus sign.

Link: http://lkml.kernel.org/r/20170525120316.24473-6-abbotti@mev.co.uk
Signed-off-by: Ian Abbott 
Acked-by: Michal Nazarewicz 
Acked-by: Kees Cook 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Jakub Kicinski 
Cc: Rasmus Villemoes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

linux/bug.h: correct "space required before that '-'"

2017-07-10T23:32:34+00:00

Correct these checkpatch.pl errors:

|ERROR: space required before that '-' (ctx:OxO)
|#37: FILE: include/linux/bug.h:37:
|+#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))

|ERROR: space required before that '-' (ctx:OxO)
|#38: FILE: include/linux/bug.h:38:
|+#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))

I decided to wrap the bitfield expressions that begin with minus signs
in parentheses rather than insert spaces before the minus signs.

Link: http://lkml.kernel.org/r/20170525120316.24473-5-abbotti@mev.co.uk
Signed-off-by: Ian Abbott 
Acked-by: Michal Nazarewicz 
Cc: Kees Cook 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Jakub Kicinski 
Cc: Rasmus Villemoes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

linux/bug.h: correct "(foo)" should be "(foo )"

2017-07-10T23:32:34+00:00

Correct this checkpatch.pl error:

|ERROR: "(foo*)" should be "(foo *)"
|#19: FILE: include/linux/bug.h:19:
|+#define BUILD_BUG_ON_NULL(e) ((void*)0)

Link: http://lkml.kernel.org/r/20170525120316.24473-4-abbotti@mev.co.uk
Signed-off-by: Ian Abbott 
Acked-by: Michal Nazarewicz 
Cc: Kees Cook 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Jakub Kicinski 
Cc: Rasmus Villemoes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

linux/bug.h: correct formatting of block comment

2017-07-10T23:32:34+00:00

Correct these checkpatch.pl warnings:

|WARNING: Block comments use * on subsequent lines
|#34: FILE: include/linux/bug.h:34:
|+/* Force a compilation error if condition is true, but also produce a
|+   result (of value 0 and type size_t), so the expression can be used

|WARNING: Block comments use a trailing */ on a separate line
|#36: FILE: include/linux/bug.h:36:
|+   aren't permitted). */

Link: http://lkml.kernel.org/r/20170525120316.24473-3-abbotti@mev.co.uk
Signed-off-by: Ian Abbott 
Acked-by: Michal Nazarewicz 
Cc: Kees Cook 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Jakub Kicinski 
Cc: Rasmus Villemoes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

debug: Add _ONCE() logic to report_bug()

2017-03-30T07:37:20+00:00

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 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar

bug: switch data corruption check to __must_check

2017-02-25T01:46:56+00:00

The CHECK_DATA_CORRUPTION() macro was designed to have callers do
something meaningful/protective on failure.  However, using "return
false" in the macro too strictly limits the design patterns of callers.
Instead, let callers handle the logic test directly, but make sure that
the result IS checked by forcing __must_check (which appears to not be
able to be used directly on macro expressions).

Link: http://lkml.kernel.org/r/20170206204547.GA125312@beast
Signed-off-by: Kees Cook 
Suggested-by: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bug: Provide toggle for BUG on data corruption

2016-10-31T20:01:58+00:00

The kernel checks for cases of data structure corruption under some
CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some
systems may want to BUG() immediately instead of letting the system run
with known corruption.  Usually these kinds of manipulation primitives can
be used by security flaws to gain arbitrary memory write control. This
provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding
macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even
if not BUGing, the kernel should not continue processing the corrupted
structure.

This is inspired by similar hardening by Syed Rameez Mustafa in MSM
kernels, and in PaX and Grsecurity, which is likely in response to earlier
removal of the BUG calls in commit 924d9addb9b1 ("list debugging: use
WARN() instead of BUG()").

Signed-off-by: Kees Cook 
Acked-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Acked-by: Rik van Riel

add basic register-field manipulation macros

2016-09-09T09:09:24+00:00

Common approach to accessing register fields is to define
structures or sets of macros containing mask and shift pair.
Operations on the register are then performed as follows:

 field = (reg >> shift) & mask;

 reg &= ~(mask << shift);
 reg |= (field & mask) << shift;

Defining shift and mask separately is tedious.  Ivo van Doorn
came up with an idea of computing them at compilation time
based on a single shifted mask (later refined by Felix) which
can be used like this:

 #define REG_FIELD 0x000ff000

 field = FIELD_GET(REG_FIELD, reg);

 reg &= ~REG_FIELD;
 reg |= FIELD_PREP(REG_FIELD, field);

FIELD_{GET,PREP} macros take care of finding out what the
appropriate shift is based on compilation time ffs operation.

GENMASK can be used to define registers (which is usually
less error-prone and easier to match with datasheets).

This approach is the most convenient I've seen so to limit code
multiplication let's move the macros to a global header file.
Attempts to use static inlines instead of macros failed due
to false positive triggering of BUILD_BUG_ON()s, especially with
GCC < 6.0.

Signed-off-by: Jakub Kicinski 
Reviewed-by: Dinan Gunawardena 
Signed-off-by: Kalle Valo

mm: Some arch may want to use HPAGE_PMD related values as variables

2016-03-03T10:18:29+00:00

With next generation power processor, we are having a new mmu model
[1] that require us to maintain a different linux page table format.

Inorder to support both current and future ppc64 systems with a single
kernel we need to make sure kernel can select between different page
table format at runtime. With the new MMU (radix MMU) added, we will
have two different pmd hugepage size 16MB for hash model and 2MB for
Radix model. Hence make HPAGE_PMD related values as a variable.

Actual conversion of HPAGE_PMD to a variable for ppc64 happens in a
followup patch.

[1] http://ibm.biz/power-isa3 (Needs registration).

Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG

2013-02-22T01:22:16+00:00

Introduce compiletime_assert to compiler.h, which moves the details of
how to break a build and emit an error message for a specific compiler
to the headers where these details should be.  Following in the
tradition of the POSIX assert macro, compiletime_assert creates a
build-time error when the supplied condition is *false*.

Next, we add BUILD_BUG_ON_MSG to bug.h which simply wraps
compiletime_assert, inverting the logic, so that it fails when the
condition is *true*, consistent with the language "build bug on." This
macro allows you to specify the error message you want emitted when the
supplied condition is true.

Finally, we remove all other code from bug.h that mucks with these
details (BUILD_BUG & BUILD_BUG_ON), and have them all call
BUILD_BUG_ON_MSG.  This not only reduces source code bloat, but also
prevents the possibility of code being changed for one macro and not for
the other (which was previously the case for BUILD_BUG and
BUILD_BUG_ON).

Since __compiletime_error_fallback is now only used in compiler.h, I'm
considering it a private macro and removing the double negation that's
now extraneous.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Daniel Santos 
Cc: Andi Kleen 
Cc: Borislav Petkov 
Cc: David Rientjes 
Cc: Joe Perches 
Cc: Josh Triplett 
Cc: Paul Gortmaker 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

linux-toradex.git/include/linux/bug.h, branch v4.13-rc4

bug: split BUILD_BUG stuff out into

linux/bug.h: correct "space required before that '-'"

linux/bug.h: correct "(foo*)" should be "(foo *)"

linux/bug.h: correct formatting of block comment

debug: Add _ONCE() logic to report_bug()

bug: switch data corruption check to __must_check

bug: Provide toggle for BUG on data corruption

add basic register-field manipulation macros

mm: Some arch may want to use HPAGE_PMD related values as variables

bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG

linux/bug.h: correct "(foo)" should be "(foo )"