Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | Copyright 2004 Linus Torvalds |
| 2 | Copyright 2004 Pavel Machek <pavel@suse.cz> |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 3 | Copyright 2006 Bob Copeland <me@bobcopeland.com> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4 | |
| 5 | Using sparse for typechecking |
| 6 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 7 | |
| 8 | "__bitwise" is a type attribute, so you have to do something like this: |
| 9 | |
| 10 | typedef int __bitwise pm_request_t; |
| 11 | |
| 12 | enum pm_request { |
| 13 | PM_SUSPEND = (__force pm_request_t) 1, |
| 14 | PM_RESUME = (__force pm_request_t) 2 |
| 15 | }; |
| 16 | |
| 17 | which makes PM_SUSPEND and PM_RESUME "bitwise" integers (the "__force" is |
| 18 | there because sparse will complain about casting to/from a bitwise type, |
| 19 | but in this case we really _do_ want to force the conversion). And because |
| 20 | the enum values are all the same type, now "enum pm_request" will be that |
| 21 | type too. |
| 22 | |
| 23 | And with gcc, all the __bitwise/__force stuff goes away, and it all ends |
| 24 | up looking just like integers to gcc. |
| 25 | |
| 26 | Quite frankly, you don't need the enum there. The above all really just |
| 27 | boils down to one special "int __bitwise" type. |
| 28 | |
| 29 | So the simpler way is to just do |
| 30 | |
| 31 | typedef int __bitwise pm_request_t; |
| 32 | |
| 33 | #define PM_SUSPEND ((__force pm_request_t) 1) |
| 34 | #define PM_RESUME ((__force pm_request_t) 2) |
| 35 | |
| 36 | and you now have all the infrastructure needed for strict typechecking. |
| 37 | |
| 38 | One small note: the constant integer "0" is special. You can use a |
| 39 | constant zero as a bitwise integer type without sparse ever complaining. |
| 40 | This is because "bitwise" (as the name implies) was designed for making |
| 41 | sure that bitwise types don't get mixed up (little-endian vs big-endian |
| 42 | vs cpu-endian vs whatever), and there the constant "0" really _is_ |
| 43 | special. |
| 44 | |
Sam Ravnborg | 20375bf | 2009-04-10 13:18:08 +0200 | [diff] [blame] | 45 | __bitwise__ - to be used for relatively compact stuff (gfp_t, etc.) that |
| 46 | is mostly warning-free and is supposed to stay that way. Warnings will |
| 47 | be generated without __CHECK_ENDIAN__. |
| 48 | |
| 49 | __bitwise - noisy stuff; in particular, __le*/__be* are that. We really |
| 50 | don't want to drown in noise unless we'd explicitly asked for it. |
| 51 | |
| 52 | |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 53 | Getting sparse |
| 54 | ~~~~~~~~~~~~~~ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | |
Dave Jones | a55028f | 2007-03-08 19:45:26 -0500 | [diff] [blame] | 56 | You can get latest released versions from the Sparse homepage at |
Bill Pemberton | 05be7a8 | 2010-04-27 16:20:15 -0400 | [diff] [blame] | 57 | https://sparse.wiki.kernel.org/index.php/Main_Page |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
Dave Jones | a55028f | 2007-03-08 19:45:26 -0500 | [diff] [blame] | 59 | Alternatively, you can get snapshots of the latest development version |
| 60 | of sparse using git to clone.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | |
Bill Pemberton | 05be7a8 | 2010-04-27 16:20:15 -0400 | [diff] [blame] | 62 | git://git.kernel.org/pub/scm/devel/sparse/sparse.git |
Dave Jones | a55028f | 2007-03-08 19:45:26 -0500 | [diff] [blame] | 63 | |
| 64 | DaveJ has hourly generated tarballs of the git tree available at.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 66 | http://www.codemonkey.org.uk/projects/git-snapshots/sparse/ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | |
| 68 | |
| 69 | Once you have it, just do |
| 70 | |
| 71 | make |
| 72 | make install |
| 73 | |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 74 | as a regular user, and it will install sparse in your ~/bin directory. |
| 75 | |
| 76 | Using sparse |
| 77 | ~~~~~~~~~~~~ |
| 78 | |
| 79 | Do a kernel make with "make C=1" to run sparse on all the C files that get |
| 80 | recompiled, or use "make C=2" to run sparse on the files whether they need to |
| 81 | be recompiled or not. The latter is a fast way to check the whole tree if you |
| 82 | have already built it. |
| 83 | |
Geert Uytterhoeven | a887a07 | 2008-06-20 15:45:12 +0200 | [diff] [blame] | 84 | The optional make variable CF can be used to pass arguments to sparse. The |
| 85 | build system passes -Wbitwise to sparse automatically. To perform endianness |
| 86 | checks, you may define __CHECK_ENDIAN__: |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 87 | |
Geert Uytterhoeven | a887a07 | 2008-06-20 15:45:12 +0200 | [diff] [blame] | 88 | make C=2 CF="-D__CHECK_ENDIAN__" |
Bob Copeland | e833195 | 2006-06-23 02:06:09 -0700 | [diff] [blame] | 89 | |
| 90 | These checks are disabled by default as they generate a host of warnings. |