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mirror_zfs/config/kernel-bdev-block-device-operations.m4

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Add build system Add autoconf style build infrastructure to the ZFS tree. This includes autogen.sh, configure.ac, m4 macros, some scripts/*, and makefiles for all the core ZFS components.
2010-08-26 22:22:58 +04:00
dnl #
dnl # 2.6.x API change
dnl #
AC_DEFUN([ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS], [
AC_MSG_CHECKING([block device operation prototypes])
Fix configure tests to play nice with GCC 4.6 As of GCC 4.6, specific kernel 2.6.32 header files do not compile cleanly without warnings. One specific example of this is the arch/x86/include/asm/percpu.h file. Thus, a few of the configure tests were getting hung up on this and the '-Wno-unsued-but-set-variables' compile option had to be introduced. Signed-off-by: Prakash Surya <surya1@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #459
2011-11-30 02:31:20 +04:00
tmp_flags="$EXTRA_KCFLAGS"
Only use gcc -Wunused-but-set-variable when available Certain versions of gcc generate an 'unrecognized command line option' error message when -Wunused-but-set-variable is used unconditionally. This in turn can cause several of the autoconf tests to misdetect an interface. Now, the use of -Wunused-but-set-variable in the autoconf tests was introduced by commit b9c59ec8 to address a gcc 4.6 compatibility problem. So we really only need to pass this option for version of gcc which are known to support it. Therefore, the tests have been updated to use the result of the existing ZFS_AC_CONFIG_ALWAYS_NO_UNUSED_BUT_SET_VARIABLE which determines if gcc supports this option. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #1004
2013-01-11 04:09:31 +04:00
EXTRA_KCFLAGS="${NO_UNUSED_BUT_SET_VARIABLE}"
Add build system Add autoconf style build infrastructure to the ZFS tree. This includes autogen.sh, configure.ac, m4 macros, some scripts/*, and makefiles for all the core ZFS components.
2010-08-26 22:22:58 +04:00
ZFS_LINUX_TRY_COMPILE([
#include <linux/blkdev.h>
Eliminate runtime function pointer mods in autotools checks PaX/GrSecurity patched kernels implement a dialect of C that relies on a GCC plugin for enforcement. A basic idea in this dialect is that function pointers in structures should not change during runtime. This causes code that modifies function pointers at runtime to fail to compile in many instances. The autotools checks rely on whether or not small test cases compile against a given kernel. Some autotools checks assume some default case if other cases fail. When one of these autotools checks tests a PaX/GrSecurity patched kernel by modifying a function pointer at runtime, the default case will be used. Early detection of such situations is possible by relying on compiler warnings, which are compiler errors when --enable-debug is used. Unfortunately, very few people build ZFS with --enable-debug. The more common situation is that these issues manifest themselves as runtime failures in the form of NULL pointer exceptions. Previous patches that addressed such issues with PaX/GrSecurity compatibility largely relied on rewriting autotools checks to avoid runtime function pointer modification or the addition of PaX/GrSecurity specific checks. This patch takes the previous work to its logical conclusion by eliminating the use of runtime function pointer modification. This permits the removal of PaX-specific autotools checks in favor of ones that work across all supported kernels. This should resolve issues that were reported to occur with PaX/GrSecurity-patched Linux 3.7.5 kernels on Gentoo Linux. https://bugs.gentoo.org/show_bug.cgi?id=457176 We should be able to prevent future regressions in PaX/GrSecurity compatibility by ensuring that all changes to ZFSOnLinux avoid runtime function pointer modification. At the same time, this does not solve the issue of silent failures triggering default cases in the autotools check, which is what permitted these regressions to become runtime failures in the first place. This will need to be addressed in a future patch. Reported-by: Marcin Mirosław <bug@mejor.pl> Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #1300
2013-02-15 03:54:04 +04:00
int blk_open(struct block_device *bdev, fmode_t mode)
{ return 0; }
int blk_release(struct gendisk *g, fmode_t mode) { return 0; }
int blk_ioctl(struct block_device *bdev, fmode_t mode,
unsigned x, unsigned long y) { return 0; }
int blk_compat_ioctl(struct block_device * bdev, fmode_t mode,
unsigned x, unsigned long y) { return 0; }
static const struct block_device_operations
bops __attribute__ ((unused)) = {
Add build system Add autoconf style build infrastructure to the ZFS tree. This includes autogen.sh, configure.ac, m4 macros, some scripts/*, and makefiles for all the core ZFS components.
2010-08-26 22:22:58 +04:00
.open = blk_open,
.release = blk_release,
.ioctl = blk_ioctl,
.compat_ioctl = blk_compat_ioctl,
};
Eliminate runtime function pointer mods in autotools checks PaX/GrSecurity patched kernels implement a dialect of C that relies on a GCC plugin for enforcement. A basic idea in this dialect is that function pointers in structures should not change during runtime. This causes code that modifies function pointers at runtime to fail to compile in many instances. The autotools checks rely on whether or not small test cases compile against a given kernel. Some autotools checks assume some default case if other cases fail. When one of these autotools checks tests a PaX/GrSecurity patched kernel by modifying a function pointer at runtime, the default case will be used. Early detection of such situations is possible by relying on compiler warnings, which are compiler errors when --enable-debug is used. Unfortunately, very few people build ZFS with --enable-debug. The more common situation is that these issues manifest themselves as runtime failures in the form of NULL pointer exceptions. Previous patches that addressed such issues with PaX/GrSecurity compatibility largely relied on rewriting autotools checks to avoid runtime function pointer modification or the addition of PaX/GrSecurity specific checks. This patch takes the previous work to its logical conclusion by eliminating the use of runtime function pointer modification. This permits the removal of PaX-specific autotools checks in favor of ones that work across all supported kernels. This should resolve issues that were reported to occur with PaX/GrSecurity-patched Linux 3.7.5 kernels on Gentoo Linux. https://bugs.gentoo.org/show_bug.cgi?id=457176 We should be able to prevent future regressions in PaX/GrSecurity compatibility by ensuring that all changes to ZFSOnLinux avoid runtime function pointer modification. At the same time, this does not solve the issue of silent failures triggering default cases in the autotools check, which is what permitted these regressions to become runtime failures in the first place. This will need to be addressed in a future patch. Reported-by: Marcin Mirosław <bug@mejor.pl> Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #1300
2013-02-15 03:54:04 +04:00
],[
Add build system Add autoconf style build infrastructure to the ZFS tree. This includes autogen.sh, configure.ac, m4 macros, some scripts/*, and makefiles for all the core ZFS components.
2010-08-26 22:22:58 +04:00
],[
AC_MSG_RESULT(struct block_device)
AC_DEFINE(HAVE_BDEV_BLOCK_DEVICE_OPERATIONS, 1,
[struct block_device_operations use bdevs])
],[
AC_MSG_RESULT(struct inode)
])
Fix configure tests to play nice with GCC 4.6 As of GCC 4.6, specific kernel 2.6.32 header files do not compile cleanly without warnings. One specific example of this is the arch/x86/include/asm/percpu.h file. Thus, a few of the configure tests were getting hung up on this and the '-Wno-unsued-but-set-variables' compile option had to be introduced. Signed-off-by: Prakash Surya <surya1@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #459
2011-11-30 02:31:20 +04:00
EXTRA_KCFLAGS="$tmp_flags"
Add build system Add autoconf style build infrastructure to the ZFS tree. This includes autogen.sh, configure.ac, m4 macros, some scripts/*, and makefiles for all the core ZFS components.
2010-08-26 22:22:58 +04:00
])
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