Sparse
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Sparse is a tool to do compile-time checks on C code. Sparse can create a parse tree of C code, similar to a GCC frontend. Using this parse tree, it is possible to create additional compile-time checks of source code, in addition to what regular C provides. | Sparse is a tool to do compile-time checks on C code. Sparse can create a parse tree of C code, similar to a GCC frontend. Using this parse tree, it is possible to create additional compile-time checks of source code, in addition to what regular C provides. | ||
− | For example, a system call can be passed a userspace pointer. In regular C, this will simply be a | + | For example, a system call can be passed a userspace pointer. In regular C, this will simply be a <tt>void *</tt>. However, the kernel cannot directly dereference this pointer. There is no syntax to denote this restriction in regular C, and if a kernel developer makes a mistake, s/he will only discover it at runtime, probably in the form of a kernel crash. Sparse allows a developer to encode this restriction by annotating the pointer as <tt>void __user *</tt>, where <tt>__user</tt> denotes a separate address space. |
There are currently three address spaces recognized by the kernel: | There are currently three address spaces recognized by the kernel: | ||
− | * User address space, annotated with | + | * User address space, annotated with <tt>__user</tt> |
* Kernel address space, no annotation | * Kernel address space, no annotation | ||
− | * I/O memory address space, annotated with | + | * I/O memory address space, annotated with <tt>__iomem</tt> |
− | These are defined in | + | These are defined in <tt>include/linux/compiler.h</tt> |
More information about sparse can be found at http://www.linuxjournal.com/article.php?sid=7272 and http://kerneltrap.org/node/view/3848. The sparse mailing list is at http://vger.kernel.org/vger-lists.html#linux-sparse | More information about sparse can be found at http://www.linuxjournal.com/article.php?sid=7272 and http://kerneltrap.org/node/view/3848. The sparse mailing list is at http://vger.kernel.org/vger-lists.html#linux-sparse | ||
− | The sparse source code is kept in | + | The sparse source code is kept in [http://www.bkbits.net/ BitKeeper] at bk://kernel.bkbits.net/torvalds/sparse, snapshots can be found at http://www.codemonkey.org.uk/projects/bitkeeper/sparse/ |
Revision as of 20:59, 30 May 2014
Sparse
Sparse is a tool to do compile-time checks on C code. Sparse can create a parse tree of C code, similar to a GCC frontend. Using this parse tree, it is possible to create additional compile-time checks of source code, in addition to what regular C provides.
For example, a system call can be passed a userspace pointer. In regular C, this will simply be a void *. However, the kernel cannot directly dereference this pointer. There is no syntax to denote this restriction in regular C, and if a kernel developer makes a mistake, s/he will only discover it at runtime, probably in the form of a kernel crash. Sparse allows a developer to encode this restriction by annotating the pointer as void __user *, where __user denotes a separate address space.
There are currently three address spaces recognized by the kernel:
- User address space, annotated with __user
- Kernel address space, no annotation
- I/O memory address space, annotated with __iomem
These are defined in include/linux/compiler.h
More information about sparse can be found at http://www.linuxjournal.com/article.php?sid=7272 and http://kerneltrap.org/node/view/3848. The sparse mailing list is at http://vger.kernel.org/vger-lists.html#linux-sparse
The sparse source code is kept in BitKeeper at bk://kernel.bkbits.net/torvalds/sparse, snapshots can be found at http://www.codemonkey.org.uk/projects/bitkeeper/sparse/