A __naked function is defined in C but with a body completely implemented
by asm(), including any prologue and epilogue. These asm() bodies expect
standard calling conventions for parameter passing. Older GCCs implement
that correctly, but 4.[56] currently do not, see GCC PR44290. In the
Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c
modules to get miscompiled, resulting in kernel crashes during bootup.
Part of the kernel fix is to augment the __naked function attribute to
also imply noinline and noclone. This patch implements that, and has been
verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1
kernels. The patch is a no-op with older GCCs.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I wrote some code which is used as compile-time checker, and the
code should be elided after compile.
So I need to annotate the code as "always unused", compared to
"maybe unused".
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <4AEE2CEC.8040206@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is a fix for the following crash observed in 2.6.29-rc3:
http://lkml.org/lkml/2009/1/29/150
On ARM it doesn't make sense to trace a naked function because then
mcount is called without stack and frame pointer being set up and there
is no chance to restore the lr register to the value before mcount was
called.
Reported-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Tested-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Cc: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Steven Rostedt <rostedt@home.goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
- include the gcc version-dependent header files from the generic gcc
header file, rather than the other way around (iow: don't make the
non-gcc header file have to know about gcc versions)
- don't include compiler-gcc4.h for gcc 5 (for whenever it gets
released). That's just confusing and made us do odd things in the
gcc4 header file (testing that we really had version 4!)
- generate the name from the __GNUC__ version directly, rather than
having a mess of #if conditionals.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fix the condition to match intention: always use the old inlining
behavior on all gcc versions below 4.
this should solve the UML build problem.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stephen Rothwell reported that linux-next did not build on powerpc64.
make optimized inlining dependent on architecture opt-in.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
add CONFIG_OPTIMIZE_INLINING=y.
allow gcc to optimize the kernel image's size by uninlining
functions that have been marked 'inline'. Previously gcc was
forced by Linux to always-inline these functions via a gcc
attribute:
#define inline inline __attribute__((always_inline))
Especially when the user has already selected
CONFIG_OPTIMIZE_FOR_SIZE=y this can make a huge difference in
kernel image size (using a standard Fedora .config):
text data bss dec hex filename
5613924 562708 3854336 10030968 990f78 vmlinux.before
5486689 562708 3854336 9903733 971e75 vmlinux.after
that's a 2.3% text size reduction (!).
Signed-off-by: Ingo Molnar <mingo@elte.hu>
To be consistent with the use of attributes in the rest of the kernel
replace all use of __attribute_pure__ with __pure and delete the definition
of __attribute_pure__.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Acked-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace worthless comments with actual preprocessor errors when including
the wrong versions of the compiler.h files.
[akpm@linux-foundation.org: make it work]
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__used is defined to be __attribute__((unused)) for all pre-3.3 gcc
compilers to suppress warnings for unused functions because perhaps they
are referenced only in inline assembly. It is defined to be
__attribute__((used)) for gcc 3.3 and later so that the code is still
emitted for such functions.
__maybe_unused is defined to be __attribute__((unused)) for both function
and variable use if it could possibly be unreferenced due to the evaluation
of preprocessor macros. Function prototypes shall be marked with
__maybe_unused if the actual definition of the function is dependant on
preprocessor macros.
No update to compiler-intel.h is necessary because ICC supports both
__attribute__((used)) and __attribute__((unused)) as specified by the gcc
manual.
__attribute_used__ is deprecated and will be removed once all current
code is converted to using __used.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can use a gcc extension to ensure that ARRAY_SIZE() is handed an array,
not a pointer. This is especially important when code is changed from a
fixed array to a pointer. I assume the Intel compiler doesn't support
__builtin_types_compatible_p.
[jdike@addtoit.com: uml: update UML definition of ARRAY_SIZE]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extend the set of "__attribute__" shortcut macros, and remove identical
(and now superfluous) definitions from a couple of source files.
based on a page at robert love's blog:
http://rlove.org/log/2005102601
extend the set of shortcut macros defined in compiler-gcc.h with the
following:
#define __packed __attribute__((packed))
#define __weak __attribute__((weak))
#define __naked __attribute__((naked))
#define __noreturn __attribute__((noreturn))
#define __pure __attribute__((pure))
#define __aligned(x) __attribute__((aligned(x)))
#define __printf(a,b) __attribute__((format(printf,a,b)))
Once these are in place, it's up to subsystem maintainers to decide if they
want to take advantage of them. there is already a strong precedent for
using shortcuts like this in the source tree.
The ones that might give people pause are "__aligned" and "__printf", but
shortcuts for both of those are already in use, and in some ways very
confusingly. note the two very different definitions for a macro named
"ALIGNED":
drivers/net/sgiseeq.c:#define ALIGNED(x) ((((unsigned long)(x)) + 0xf) & ~(0xf))
drivers/scsi/ultrastor.c:#define ALIGNED(x) __attribute__((aligned(x)))
also:
include/acpi/platform/acgcc.h:
#define ACPI_PRINTF_LIKE(c) __attribute__ ((__format__ (__printf__, c, c+1)))
Given the precedent, then, it seems logical to at least standardize on a
consistent set of these macros.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the process of optimising our per cpu data code, I found a ppc64
compiler bug that has been around forever. Basically the current
RELOC_HIDE can end up trashing r30. Details of the bug can be found at
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572
This bug is present in all compilers before 4.1. It is masked by the
fact that our current per cpu data code is inefficient and causes
other loads that end up marking r30 as used.
A workaround identified by Alan Modra is to use the =r asm constraint
instead of =g.
Signed-off-by: Anton Blanchard <anton@samba.org>
[ Verified that this makes no real difference on x86[-64] */
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove various things which were checking for gcc-1.x and gcc-2.x compilers.
From: Adrian Bunk <bunk@stusta.de>
Some documentation updates and removes some code paths for gcc < 3.2.
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
