Sparse

Some of the checks performed by Sparse require annotating the source code using the __attribute__ GCC extension, or the Sparse-specific __context__ specifier.{{cite web

| url = https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html

| title = Attribute Syntax — Using the GNU Compiler Collection (GCC)

| publisher = Free Software Foundation

| accessdate = 2010-11-13

}} Sparse defines the following list of attributes:

• address_space(num)
• bitwise
• force
• context(expression,in_context,out_context)

When an API is defined with a macro, the specifier __attribute__((context(...))) can be replaced by __context__(...).

The Linux kernel defines the following short forms as pre-processor macros in files [http://lxr.linux.no/linux+*/include/linux/compiler.h linux/compiler.h] and [http://lxr.linux.no/linux+*/include/linux/types.h linux/types.h] (when building without the __CHECKER__ flag, all these annotations are removed from the code):

1. ifdef __CHECKER__
2. define __user __attribute__((noderef, address_space(1)))
3. define __kernel __attribute__((address_space(0)))
4. define __safe __attribute__((safe))
5. define __force __attribute__((force))
6. define __nocast __attribute__((nocast))
7. define __iomem __attribute__((noderef, address_space(2)))
8. define __must_hold(x) __attribute__((context(x,1,1)))
9. define __acquires(x) __attribute__((context(x,0,1)))
10. define __releases(x) __attribute__((context(x,1,0)))
11. define __acquire(x) __context__(x,1)
12. define __release(x) __context__(x,-1)
13. define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
14. define __percpu __attribute__((noderef, address_space(3)))
15. ifdef CONFIG_SPARSE_RCU_POINTER
16. define __rcu __attribute__((noderef, address_space(4)))
17. else
18. define __rcu
19. endif

extern void __chk_user_ptr(const volatile void __user *);

extern void __chk_io_ptr(const volatile void __iomem *);

1. else
2. define __user
3. define __kernel
4. define __safe
5. define __force
6. define __nocast
7. define __iomem
8. define __chk_user_ptr(x) (void)0
9. define __chk_io_ptr(x) (void)0
10. define __builtin_warning(x, y...) (1)
11. define __must_hold(x)
12. define __acquires(x)
13. define __releases(x)
14. define __acquire(x) (void)0
15. define __release(x) (void)0
16. define __cond_lock(x,c) (c)
17. define __percpu
18. define __rcu
19. endif

1. ifdef __CHECKER__
2. define __bitwise __attribute__((bitwise))
3. else
4. define __bitwise
5. endif

The types __le32 and __be32 represent 32-bit integer types with different endianness. However, the C language does not allow to specify that variables of these types should not be mixed. The bitwise attribute is used to mark these types as restricted, so Sparse will give a warning if variables of these types or other integer variables are mixed:

typedef __u32 __bitwise __le32;

typedef __u32 __bitwise __be32;

To mark valid conversions between restricted types, a casting with the force attribute is used to avoid Sparse giving a warning.

{{Portal|Free and open-source software}}

• List of tools for static code analysis

{{reflist}}

• {{cite web

| title = Sparse: a look under the hood

| author = Neil Brown

| date = 2016-06-08

| work = LWN.net

| url = https://lwn.net/Articles/689907/

| accessdate = 2021-11-26

}}

• {{cite web

| title = Finding kernel problems automatically

| author = Jonathan Corbet

| date = 2004-06-01

| work = LWN.net

| url = https://lwn.net/Articles/87538/

| accessdate = 2021-11-26

}}

• {{cite web

| title = Linus & the Lunatics, Part I

| author = Doc Searls

| date = 2003-11-24

| work = Linux Journal

| url = http://www.linuxjournal.com/article/7272

| accessdate = 2021-11-26

}}

• {{cite conference

| title = Putting LTP to test—Validating both the Linux kernel and Test-cases

|author1=Subrata Modak |author2=Balbir Singh |author3=Yamato Masatake | year = 2009

| conference = Ottawa Linux Symposium 2009

| conference-url = https://www.kernel.org/doc/ols/2009/

| pages = 209–220

| url = https://www.kernel.org/doc/ols/2009/ols2009-pages-209-220.pdf

| accessdate = 2021-11-26

}}

• {{cite thesis

| degree = M.Sc.

| title = Detection of Static Flaws in Changesets

| author = Daniel De Graaf

| year = 2010

| publisher = Iowa State University

| location = Ames, Iowa

| accessdate = 2010-11-07

| url = http://archives.ece.iastate.edu/archive/00000566/01/thesis.pdf

| oclc = 665146513

}}

• [https://sparse.docs.kernel.org Official documentation]
• [https://www.kernel.org/doc/html/latest/dev-tools/sparse.html Using sparse for typechecking], Linux Kernel Documentation
• {{man|1|sparse|Linux|Semantic Parser for C}}
• {{man|1|cgcc|Linux|Compiler wrapper to run Sparse after compiling}}

Category:Static program analysis tools

Category:Free software testing tools

Category:Software using the MIT license