kunmap_atomic() is currently at level -4 on Rusty's "Hard To Misuse"
list[1] ("Follow common convention and you'll get it wrong"), except in
some architectures when CONFIG_DEBUG_HIGHMEM is set[2][3].
kunmap() takes a pointer to a struct page; kunmap_atomic(), however, takes
takes a pointer to within the page itself. This seems to once in a while
trip people up (the convention they are following is the one from
kunmap()).
Make it much harder to misuse, by moving it to level 9 on Rusty's list[4]
("The compiler/linker won't let you get it wrong"). This is done by
refusing to build if the type of its first argument is a pointer to a
struct page.
The real kunmap_atomic() is renamed to kunmap_atomic_notypecheck()
(which is what you would call in case for some strange reason calling it
with a pointer to a struct page is not incorrect in your code).
The previous version of this patch was compile tested on x86-64.
[1] http://ozlabs.org/~rusty/index.cgi/tech/2008-04-01.html
[2] In these cases, it is at level 5, "Do it right or it will always
break at runtime."
[3] At least mips and powerpc look very similar, and sparc also seems to
share a common ancestor with both; there seems to be quite some
degree of copy-and-paste coding here. The include/asm/highmem.h file
for these three archs mention x86 CPUs at its top.
[4] http://ozlabs.org/~rusty/index.cgi/tech/2008-03-30.html
[5] As an aside, could someone tell me why mn10300 uses unsigned long as
the first parameter of kunmap_atomic() instead of void *?
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Russell King <linux@arm.linux.org.uk> (arch/arm)
Cc: Ralf Baechle <ralf@linux-mips.org> (arch/mips)
Cc: David Howells <dhowells@redhat.com> (arch/frv, arch/mn10300)
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> (arch/mn10300)
Cc: Kyle McMartin <kyle@mcmartin.ca> (arch/parisc)
Cc: Helge Deller <deller@gmx.de> (arch/parisc)
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> (arch/parisc)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> (arch/powerpc)
Cc: Paul Mackerras <paulus@samba.org> (arch/powerpc)
Cc: "David S. Miller" <davem@davemloft.net> (arch/sparc)
Cc: Thomas Gleixner <tglx@linutronix.de> (arch/x86)
Cc: Ingo Molnar <mingo@redhat.com> (arch/x86)
Cc: "H. Peter Anvin" <hpa@zytor.com> (arch/x86)
Cc: Arnd Bergmann <arnd@arndb.de> (include/asm-generic)
Cc: Rusty Russell <rusty@rustcorp.com.au> ("Hard To Misuse" list)
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On 64bit, local_t is of size long, and thus we make local64_t an alias.
On 32bit, we fall back to atomic64_t. (architecture can provide optimized
32-bit version)
(This new facility is to be used by perf events optimizations.)
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-arch@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'for-35' of git://repo.or.cz/linux-kbuild: (81 commits)
kbuild: Revert part of e8d400a to resolve a conflict
kbuild: Fix checking of scm-identifier variable
gconfig: add support to show hidden options that have prompts
menuconfig: add support to show hidden options which have prompts
gconfig: remove show_debug option
gconfig: remove dbg_print_ptype() and dbg_print_stype()
kconfig: fix zconfdump()
kconfig: some small fixes
add random binaries to .gitignore
kbuild: Include gen_initramfs_list.sh and the file list in the .d file
kconfig: recalc symbol value before showing search results
.gitignore: ignore *.lzo files
headerdep: perlcritic warning
scripts/Makefile.lib: Align the output of LZO
kbuild: Generate modules.builtin in make modules_install
Revert "kbuild: specify absolute paths for cscope"
kbuild: Do not unnecessarily regenerate modules.builtin
headers_install: use local file handles
headers_check: fix perl warnings
export_report: fix perl warnings
...
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
parisc: Call pagefault_disable/pagefault_enable in kmap_atomic/kunmap_atomic
parisc: Remove unnecessary macros from entry.S
parisc: LWS fixes for syscall.S
parisc: Delete unnecessary nop's in entry.S
parisc: Avoid interruption in critical region in entry.S
parisc: invoke oom-killer from page fault
parisc: clear floating point exception flag on SIGFPE signal
parisc: Use of align_frame provides stack frame.
Based on the generic implementation of kmap_atomic and kunmap_atomic,
we should call pagefault_disable and pagefault_enable in our PA8000
implementation.
The define for kmap_atomic_prot was also missing, and I updated
kmap_atomic_pfn to use the generic implementation because of the
change to kmap_atomic.
I believe that this change is needed to fix the fork copy-on-write
bug.
Signed-off-by: John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
* git://git.infradead.org/iommu-2.6:
intel-iommu: Set a more specific taint flag for invalid BIOS DMAR tables
intel-iommu: Combine the BIOS DMAR table warning messages
panic: Add taint flag TAINT_FIRMWARE_WORKAROUND ('I')
panic: Allow warnings to set different taint flags
intel-iommu: intel_iommu_map_range failed at very end of address space
intel-iommu: errors with smaller iommu widths
intel-iommu: Fix boot inside 64bit virtualbox with io-apic disabled
intel-iommu: use physfn to search drhd for VF
intel-iommu: Print out iommu seq_id
intel-iommu: Don't complain that ACPI_DMAR_SCOPE_TYPE_IOAPIC is not supported
intel-iommu: Avoid global flushes with caching mode.
intel-iommu: Use correct domain ID when caching mode is enabled
intel-iommu mistakenly uses offset_pfn when caching mode is enabled
intel-iommu: use for_each_set_bit()
intel-iommu: Fix section mismatch dmar_ir_support() uses dmar_tbl.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (44 commits)
vlynq: make whole Kconfig-menu dependant on architecture
add descriptive comment for TIF_MEMDIE task flag declaration.
EEPROM: max6875: Header file cleanup
EEPROM: 93cx6: Header file cleanup
EEPROM: Header file cleanup
agp: use NULL instead of 0 when pointer is needed
rtc-v3020: make bitfield unsigned
PCI: make bitfield unsigned
jbd2: use NULL instead of 0 when pointer is needed
cciss: fix shadows sparse warning
doc: inode uses a mutex instead of a semaphore.
uml: i386: Avoid redefinition of NR_syscalls
fix "seperate" typos in comments
cocbalt_lcdfb: correct sections
doc: Change urls for sparse
Powerpc: wii: Fix typo in comment
i2o: cleanup some exit paths
Documentation/: it's -> its where appropriate
UML: Fix compiler warning due to missing task_struct declaration
UML: add kernel.h include to signal.c
...
WARN() is used in some places to report firmware or hardware bugs that
are then worked-around. These bugs do not affect the stability of the
kernel and should not set the flag for TAINT_WARN. To allow for this,
add WARN_TAINT() and WARN_TAINT_ONCE() macros that take a taint number
as argument.
Architectures that implement warnings using trap instructions instead
of calls to warn_slowpath_*() now implement __WARN_TAINT(taint)
instead of __WARN().
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Helge Deller <deller@gmx.de>
Tested-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
In preparation for removing volatile from the atomic_t definition, this
patch adds a volatile cast to all the atomic read functions.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While in theory user_enable_single_step/user_disable_single_step/
user_enable_blockstep could also be provided as an inline or macro there's
no good reason to do so, and having the prototype in one places keeps code
size and confusion down.
Roland said:
The original thought there was that user_enable_single_step() et al
might well be only an instruction or three on a sane machine (as if we
have any of those!), and since there is only one call site inlining
would be beneficial. But I agree that there is no strong reason to care
about inlining it.
As to the arch changes, there is only one thought I'd add to the
record. It was always my thinking that for an arch where
PTRACE_SINGLESTEP does text-modifying breakpoint insertion,
user_enable_single_step() should not be provided. That is,
arch_has_single_step()=>true means that there is an arch facility with
"pure" semantics that does not have any unexpected side effects.
Inserting a breakpoint might do very unexpected strange things in
multi-threaded situations. Aside from that, it is a peculiar side
effect that user_{enable,disable}_single_step() should cause COW
de-sharing of text pages and so forth. For PTRACE_SINGLESTEP, all these
peculiarities are the status quo ante for that arch, so having
arch_ptrace() itself do those is one thing. But for building other
things in the future, it is nicer to have a uniform "pure" semantics
that arch-independent code can expect.
OTOH, all such arch issues are really up to the arch maintainer. As
of today, there is nothing but ptrace using user_enable_single_step() et
al so it's a distinction without a practical difference. If/when there
are other facilities that use user_enable_single_step() and might care,
the affected arch's can revisit the question when someone cares about
the quality of the arch support for said new facility.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__ldcw_align() can directly access the slock member of struct arch_spinlock_t
instead of using an ugly cast.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Add CONFIG_DEBUG_STRICT_USER_COPY_CHECKS, copied from the x86
implementation. Tested with 32 and 64bit kernel.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Cesar Eduardo Barros
FUJITA Tomonori
Ingo Molnar
Peter Zijlstra
Linus Torvalds
John David Anglin
Ben Hutchings
Anton Blanchard
Andreas Dilger
Christoph Hellwig
Robert P. J. Day
Helge Deller
Kyle McMartin
Denys Vlasenko