summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/suspend.c
AgeCommit message (Collapse)Author
2013-07-30ARM: suspend: use hash of cpu_logical_map value to index into save arrayNicolas Pitre
Currently we hash the MPIDR of the CPU being suspended to determine which entry in the sleep_save_sp array to use. In some situations, such as when we want to resume on another physical CPU, the MPIDR of another CPU should be used instead. So let's use the value of cpu_logical_map(smp_processor_id()) in place of the MPIDR in the suspend path. This will result in the same index being used as with the previous code unless the caller has modified cpu_logical_map() beforehand with the MPIDR of the physical CPU the suspending logical CPU will resume on. Consequently, if doing a physical CPU migration, cpu_logical_map() must be updated appropriately somewhere between cpu_pm_enter() and cpu_suspend(). The register allocation in __cpu_suspend is reworked in order to better accommodate the additional argument. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
2013-06-20ARM: kernel: implement stack pointer save array through MPIDR hashingLorenzo Pieralisi
Current implementation of cpu_{suspend}/cpu_{resume} relies on the MPIDR to index the array of pointers where the context is saved and restored. The current approach works as long as the MPIDR can be considered a linear index, so that the pointers array can simply be dereferenced by using the MPIDR[7:0] value. On ARM multi-cluster systems, where the MPIDR may not be a linear index, to properly dereference the stack pointer array, a mapping function should be applied to it so that it can be used for arrays look-ups. This patch adds code in the cpu_{suspend}/cpu_{resume} implementation that relies on shifting and ORing hashing method to map a MPIDR value to a set of buckets precomputed at boot to have a collision free mapping from MPIDR to context pointers. The hashing algorithm must be simple, fast, and implementable with few instructions since in the cpu_resume path the mapping is carried out with the MMU off and the I-cache off, hence code and data are fetched from DRAM with no-caching available. Simplicity is counterbalanced with a little increase of memory (allocated dynamically) for stack pointers buckets, that should be anyway fairly limited on most systems. Memory for context pointers is allocated in a early_initcall with size precomputed and stashed previously in kernel data structures. Memory for context pointers is allocated through kmalloc; this guarantees contiguous physical addresses for the allocated memory which is fundamental to the correct functioning of the resume mechanism that relies on the context pointer array to be a chunk of contiguous physical memory. Virtual to physical address conversion for the context pointer array base is carried out at boot to avoid fiddling with virt_to_phys conversions in the cpu_resume path which is quite fragile and should be optimized to execute as few instructions as possible. Virtual and physical context pointer base array addresses are stashed in a struct that is accessible from assembly using values generated through the asm-offsets.c mechanism. Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Colin Cross <ccross@android.com> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Amit Kucheria <amit.kucheria@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Nicolas Pitre <nico@linaro.org> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Kevin Hilman <khilman@linaro.org> Tested-by: Stephen Warren <swarren@wwwdotorg.org>
2013-06-07ARM: suspend: fix CPU suspend code for !CONFIG_MMU configurationsWill Deacon
The ARM CPU suspend code can be selected even for a !CONFIG_MMU configuration. The resulting kernel will not compile and, even if it did, would access undefined co-processor registers when executing. This patch fixes the v6 and v7 CPU suspend code for the nommu case. Signed-off-by: Will Deacon <will.deacon@arm.com> Tested-by: Jonathan Austin <jonathan.austin@arm.com> CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> (commit_signer:1/3=33%) CC: Santosh Shilimkar <santosh.shilimkar@ti.com> (commit_signer:1/3=33%) CC: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-03-03ARM: 7661/1: mm: perform explicit branch predictor maintenance when requiredWill Deacon
The ARM ARM requires branch predictor maintenance if, for a given ASID, the instructions at a specific virtual address appear to change. From the kernel's point of view, that means: - Changing the kernel's view of memory (e.g. switching to the identity map) - ASID rollover (since ASIDs will be re-allocated to new tasks) This patch adds explicit branch predictor maintenance when either of the two conditions above are met. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-09-25ARM: kernel: update cpu_suspend code to use cache LoUIS operationsLorenzo Pieralisi
In processors like A15/A7 L2 cache is unified and integrated within the processor cache hierarchy, so that it is not considered an outer cache anymore. For processors like A15/A7 flush_cache_all() ends up cleaning all cache levels up to Level of Coherency (LoC) that includes the L2 unified cache. When a single CPU is suspended (CPU idle) a complete L2 clean is not required, so generic cpu_suspend code must clean the data cache using the newly introduced cache LoUIS function. The context and stack pointer (context pointer) are cleaned to main memory using cache area functions that operate on MVA and guarantee that the data is written back to main memory (perform cache cleaning up to the Point of Coherency - PoC) so that the processor can fetch the context when the MMU is off in the cpu_resume code path. outer_cache management remains unchanged. Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Tested-by: Shawn Guo <shawn.guo@linaro.org>
2011-12-06ARM: suspend: use idmap_pgd instead of suspend_pgdWill Deacon
The ARM CPU suspend code requires cpu_resume_mmu to be identity mapped in order to re-enable the MMU when coming out of suspend. Currently, this is accomplished by maintaining a suspend_pgd with the relevant mapping put in place at init time. This patch replaces the use of suspend_pgd with the new idmap_pgd. cpu_resume_mmu is placed in the .idmap.text section so that it is included in the identity map. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Dave Martin <dave.martin@linaro.org> Tested-by: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-09-20ARM: pm: add L2 cache cleaning for suspendRussell King
We need to ensure that state is pushed out from the L2 cache when suspending so that the resume paths can access their data before the MMU and caches have been re-initialized. Add the necessary calls to __cpu_suspend_save(). Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: convert some assembly to CRussell King
Convert some of the sleep.S guts to C code, which makes it easier to use our macros and to add L2 cache handling. We provide a helper function, __cpu_suspend_save(), which deals with saving the common state, setting up for resume, and flushing caches. The remainder left as assembly code is the saving of the CPU general purpose registers, and allocating space on the stack to save the CPU specific registers and resume state. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: get rid of cpu_resume_turn_mmu_onRussell King
We don't require cpu_resume_turn_mmu_on as we can combine the ldr instruction with the following code provided we ensure that cpu_resume_mmu is aligned for older CPUs. Note that we also align to a 32-byte boundary to ensure that the code can't cross a section boundary. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: only use preallocated page table during resumeRussell King
Only use the preallocated page table during the resume, not while suspending. This avoids the overhead of having to switch unnecessarily to the resume page table in the suspend path. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: preallocate a page table for suspend/resumeRussell King
Preallocate a page table and setup an identity mapping for the MMU enable code. This means we don't have to "borrow" a page table to do this, avoiding complexities with L2 cache coherency. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>