user/sven/linux.git/arch/powerpc/kernel/sysfs.c, branch v4.4.27

powerpc/dscr: Add some in-code documentation

2015-06-07T09:29:15Z

This patch adds some in-code documentation to the DSCR related code to make it more readable without having any functional change to it. Signed-off-by: Anshuman Khandual Signed-off-by: Michael Ellerman

powerpc: Replace __get_cpu_var uses

2014-11-03T01:12:32Z

This still has not been merged and now powerpc is the only arch that does not have this change. Sorry about missing linuxppc-dev before. V2->V2 - Fix up to work against 3.18-rc1 __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 : __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: Benjamin Herrenschmidt CC: Paul Mackerras Signed-off-by: Christoph Lameter [mpe: Fix build errors caused by set/or_softirq_pending(), and rework assignment in __set_breakpoint() to use memcpy().] Signed-off-by: Michael Ellerman

powerpc: Fix regression of per-CPU DSCR setting

2014-05-28T03:35:40Z

Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)" it is no longer possible to set the DSCR on a per-CPU basis. The old behaviour was to minipulate the DSCR SPR directly but this is no longer sufficient: the value is quickly overwritten by context switching. This patch stores the per-CPU DSCR value in a kernel variable rather than directly in the SPR and it is used whenever a process has not set the DSCR itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged. Writes to the old global default (/sys/devices/system/cpu/dscr_default) now set all of the per-CPU values and reads return the last written value. The new per-CPU default is added to the paca_struct and is used everywhere outside of sysfs.c instead of the old global default. Signed-off-by: Sam Bobroff Signed-off-by: Benjamin Herrenschmidt

powerpc: Split __SYSFS_SPRSETUP macro

2014-05-28T03:35:39Z

Split the __SYSFS_SPRSETUP macro into two parts so that registers requiring custom read and write functions can use common code for their show and store functions. Signed-off-by: Sam Bobroff Signed-off-by: Benjamin Herrenschmidt

powerpc, sysfs: Fix CPU hotplug callback registration

2014-03-20T12:43:42Z

Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the sysfs code in powerpc by using this latter form of callback registration. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Olof Johansson Cc: Wang Dongsheng Cc: Ingo Molnar Acked-by: Madhavan Srinivasan Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

powerpc/pseries/cpuidle: smt-snooze-delay cleanup.

2014-01-29T06:02:24Z

smt-snooze-delay was designed to disable NAP state or delay the entry to the NAP state prior to adoption of cpuidle framework. This is per-cpu variable. With the coming of CPUIDLE framework, states can be disabled on per-cpu basis using the cpuidle/enable sysfs entry. Also, with the coming of cpuidle driver each state's target residency is per-driver unlike earlier which was per-device. Therefore, the per-cpu sysfs smt-snooze-delay which decides the target residency of the idle state on a particular cpu causes more confusion to the user as we cannot have different smt-snooze-delay (target residency) values for each cpu. In the current code, smt-snooze-delay functionality is completely broken. It makes sense to remove smt-snooze-delay from idle driver with the coming of cpuidle framework. However, sysfs files are retained as ppc64_util currently utilises it. Once we fix ppc64_util, propose to clean up the kernel code. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt

powerpc/85xx: add sysfs for pw20 state and altivec idle

2014-01-09T23:51:38Z

Add a sys interface to enable/diable pw20 state or altivec idle, and control the wait entry time. Enable/Disable interface: 0, disable. 1, enable. /sys/devices/system/cpu/cpuX/pw20_state /sys/devices/system/cpu/cpuX/altivec_idle Set wait time interface:(Nanosecond) /sys/devices/system/cpu/cpuX/pw20_wait_time /sys/devices/system/cpu/cpuX/altivec_idle_wait_time Example: Base on TBfreq is 41MHZ. 1~48(ns): TB[63] 49~97(ns): TB[62] 98~195(ns): TB[61] 196~390(ns): TB[60] 391~780(ns): TB[59] 781~1560(ns): TB[58] ... Signed-off-by: Wang Dongsheng [scottwood@freescale.com: change ifdef] Signed-off-by: Scott Wood

powerpc/kernel/sysfs: Cleanup set up macros for PMC/non-PMC SPRs

2013-12-02T03:16:04Z

Currently PMC (Performance Monitor Counter) setup macros are used for other SPRs. Since not all SPRs are PMC related, this patch modifies the exisiting macro and uses it to setup both PMC and non PMC SPRs accordingly. Signed-off-by: Madhavan Srinivasan Acked-by: Olof Johansson Acked-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt

powerpc/sysfs: Disable writing to PURR in guest mode

2013-10-03T07:22:53Z

arch/powerpc/kernel/sysfs.c exports PURR with write permission. This may be valid for kernel in phyp mode. But writing to the file in guest mode causes crash due to a priviledge violation Signed-off-by: Madhavan Srinivasan Signed-off-by: Benjamin Herrenschmidt CC:

powerpc: Delete __cpuinit usage from all users

2013-07-01T01:10:36Z

The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the powerpc uses of the __cpuinit macros. There are no __CPUINIT users in assembly files in powerpc. [1] https://lkml.org/lkml/2013/5/20/589 Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Josh Boyer Cc: Matt Porter Cc: Kumar Gala Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Paul Gortmaker Signed-off-by: Benjamin Herrenschmidt