__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
CC: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch introduces Blackfin-specific bits to support the current
tip of the interrupt pipeline development, mainly:
- 2/3-level interrupt maps (sparse IRQs)
- generic virq handling
- sysinfo v2 format for ipipe_get_sysinfo()
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Rename h/w IRQ flags handling functions to be in line with what is expected for
the irq renaming patch. This renames local_*_hw() to hard_local_*() using the
following perl command:
perl -pi -e 's/local_irq_(restore|enable|disable)_hw/hard_local_irq_\1/ or s/local_irq_save_hw([_a-z]*)[(]flags[)]/flags = hard_local_irq_save\1()/' `find arch/blackfin/ -name "*.[ch]"`
and then fixing up asm/irqflags.h manually.
Additionally, arch/hard_local_save_flags() and arch/hard_local_irq_save() both
return the flags rather than passing it through the argument list.
Signed-off-by: David Howells <dhowells@redhat.com>
__ipipe_{stall, unstall}_root_raw() identifiers may leave the reader
under the impression that only the virtual state is affected by these
operations, which is wrong. Pick names following the convention used
throughout the interrupt pipeline code.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
ipipe-2.6.28.9-blackfin-git95aafe6.patch
Singed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
[Mike Frysinger <vapier.adi@gmail.com>:
- handle bf531/bf532/bf534/bf536 variants in ipipe.h
- cleanup IPIPE logic for bfin_set_irq_handler()
- cleanup ipipe asm code a bit and add missing ENDPROC()
- simplify IPIPE code in trap_c
- unify some of the IPIPE code and fix style
- simplify DO_IRQ_L1 handling with ipipe code
- revert IRQ_SW_INT# addition from ipipe merge
- remove duplicate get_{c,s}clk() prototypes
]
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
