user/sven/linux.git/include/linux/bug.h, branch v4.12.4

debug: Add _ONCE() logic to report_bug()

2017-03-30T07:37:20Z

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

2017-02-25T01:46:56Z

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

2016-10-31T20:01:58Z

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

2016-09-09T09:09:24Z

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

2016-03-03T10:18:29Z

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

2013-02-22T01:22:16Z

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

compiler.h, bug.h: prevent double error messages with BUILD_BUG{,_ON}

2013-02-22T01:22:16Z

Prior to the introduction of __attribute__((error("msg"))) in gcc 4.3, creating compile-time errors required a little trickery. BUILD_BUG{,_ON} uses this attribute when available to generate compile-time errors, but also uses the negative-sized array trick for older compilers, resulting in two error messages in some cases. The reason it's "some" cases is that as of gcc 4.4, the negative-sized array will not create an error in some situations, like inline functions. This patch replaces the negative-sized array code with the new __compiletime_error_fallback() macro which expands to the same thing unless the the error attribute is available, in which case it expands to do{}while(0), resulting in exactly one compile-time error on all versions of gcc. Note that we are not changing the negative-sized array code for the unoptimized version of BUILD_BUG_ON, since it has the potential to catch problems that would be disabled in later versions of gcc were __compiletime_error_fallback used. The reason is that that an unoptimized build can't always remove calls to an error-attributed function call (like we are using) that should effectively become dead code if it were optimized. However, using a negative-sized array with a similar value will not result in an false-positive (error). The only caveat being that it will also fail to catch valid conditions, which we should be expecting in an unoptimized build anyway. 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

bug.h: make BUILD_BUG_ON generate compile-time error

2013-02-22T01:22:16Z

Negative sized arrays wont create a compile-time error in some cases starting with gcc 4.4 (e.g., inlined functions), but gcc 4.3 introduced the error function attribute that will. This patch modifies BUILD_BUG_ON to behave like BUILD_BUG already does, using the error function attribute so that you don't have to build the entire kernel to discover that you have a problem, and then enjoy trying to track it down from a link-time error. Also, we are only including asm/bug.h and then expecting that linux/compiler.h will eventually be included to define __linktime_error (used in BUILD_BUG_ON). This patch includes it directly for clarity and to avoid the possibility of changes in /*/include/asm/bug.h being changed or not including linux/compiler.h for some reason. Signed-off-by: Daniel Santos Acked-by: Borislav Petkov Cc: Andi Kleen Cc: David Rientjes Cc: Joe Perches Cc: Josh Triplett Cc: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bug.h: prevent double evaulation of `condition' in BUILD_BUG_ON

2013-02-22T01:22:16Z

When calling BUILD_BUG_ON in an optimized build using gcc 4.3 and later, the condition will be evaulated twice, possibily with side-effects. This patch eliminates that error. [akpm@linux-foundation.org: tweak code layout] 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

bug.h: fix BUILD_BUG_ON macro in CHECKER

2013-02-22T01:22:15Z

When __CHECKER__ is defined, we disable all of the BUILD_BUG.* macros. However, both BUILD_BUG_ON_NOT_POWER_OF_2 and BUILD_BUG_ON was evaluating to nothing in this case, and we want (0) since this is a function-like macro that will be followed by a semicolon. Signed-off-by: Daniel Santos Acked-by: Borislav Petkov Cc: Andi Kleen Cc: David Rientjes Cc: Joe Perches Cc: Josh Triplett Cc: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

user/sven/linux.git/include/linux/bug.h, branch v4.12.4

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

compiler.h, bug.h: prevent double error messages with BUILD_BUG{,_ON}

bug.h: make BUILD_BUG_ON generate compile-time error

bug.h: prevent double evaulation of `condition' in BUILD_BUG_ON

bug.h: fix BUILD_BUG_ON macro in __CHECKER__

bug.h: fix BUILD_BUG_ON macro in CHECKER