kernel/linux.git/arch/mips/include/asm/smp.h, branch linux-4.16.y

MIPS: Allow __cpu_number_map to be larger than NR_CPUS

2017-11-07T18:32:10+00:00

In systems where the CPU id space is sparse, this allows a smaller NR_CPUS to be chosen, thus keeping internal data structures smaller. Signed-off-by: David Daney Signed-off-by: Carlos Munoz Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17388/ [jhogan@kernel.org: Add depends on SMP to fix "warning: symbol value '' invalid for MIPS_NR_CPU_NR_MAP"] Signed-off-by: James Hogan

MIPS: SMP: Constify smp ops

2017-08-29T13:21:50+00:00

smp_ops providers do not modify their ops structures, so they should be made const for robustness. Since currently the MIPS kernel is not mapped with memory protection, this does not in itself provide any security benefit, but it still makes sense to make this change. There are also slight code size efficincies from the structure being made read-only, saving 128 bytes of kernel text on a pistachio_defconfig. Before: text data bss dec hex filename 7187239 1772752 470224 9430215 8fe4c7 vmlinux After: text data bss dec hex filename 7187111 1772752 470224 9430087 8fe447 vmlinux Signed-off-by: Matt Redfearn Cc: Sebastian Andrzej Siewior Cc: Arnd Bergmann Cc: Marcin Nowakowski Cc: Bart Van Assche Cc: Masahiro Yamada Cc: Huacai Chen Cc: Paul Gortmaker Cc: Kevin Cernekee Cc: Thomas Gleixner Cc: Doug Ledford Cc: James Hogan Cc: Joe Perches Cc: Florian Fainelli Cc: Ingo Molnar Cc: Paul Burton Cc: Andrew Morton Cc: Steven J. Hill Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/16784/ Signed-off-by: Ralf Baechle

MIPS: SMP: move asmlinkage before return type

2017-07-12T23:26:04+00:00

Make the code like the rest of the kernel. Link: http://lkml.kernel.org/r/756d3fb543e981b9284e756fa27616725a354b28.1499284835.git.joe@perches.com Signed-off-by: Joe Perches Cc: Ralf Baechle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

MIPS: kexec: remove SMP_DUMP

2017-01-03T15:34:44+00:00

SMP_DUMP has been added as a new IPI signal when kexec support was added for Cavium Octeon CPUs ('commit 7aa1c8f47e7e ("MIPS: kdump: Add support")'. However, the new signal doesn't appear to ever have a proper handler added (octeon_message_functions[] array has an empty handler for it), and generic IPI handlers now trigger a BUG() on unhandled signal. As the method is unused remove it completely and replace its only invocation with a smp_call_function(). [ralf@linux-mips.org: Renumber SMP_ASK_C0COUNT to avoid numbering gaps.] Signed-off-by: Marcin Nowakowski Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/14630/ Signed-off-by: Ralf Baechle

MIPS: SMP: Remove cpu_callin_map

2017-01-03T15:34:38+00:00

The previous commit made cpu_callin_map redundant, since it is no longer used to signal secondary CPUs starting, or going offline. Remove it now. Signed-off-by: Matt Redfearn Cc: Sebastian Andrzej Siewior Cc: Qais Yousef Cc: Masahiro Yamada Cc: Huacai Chen Cc: Kevin Cernekee Cc: Thomas Gleixner Cc: Andrew Morton Cc: James Hogan Cc: Paul Burton Cc: Florian Fainelli Cc: Anna-Maria Gleixner Cc: Adam Buchbinder Cc: Yang Shi Cc: David Daney Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/14503/ Signed-off-by: Ralf Baechle

MIPS: smp.c: Introduce mechanism for freeing and allocating IPIs

2016-10-04T23:31:20+00:00

For the MIPS remote processor implementation, we need additional IPIs to talk to the remote processor. Since MIPS GIC reserves exactly the right number of IPI IRQs required by Linux for the number of VPs in the system, this is not possible without releasing some recources. This commit introduces mips_smp_ipi_allocate() which allocates IPIs to a given cpumask. It is called as normal with the cpu_possible_mask at bootup to initialise IPIs to all CPUs. mips_smp_ipi_free() may then be used to free IPIs to a subset of those CPUs so that their hardware resources can be reused. Signed-off-by: Matt Redfearn Cc: Bjorn Andersson Cc: Ohad Ben-Cohen Cc: Thomas Gleixner Cc: Lisa Parratt Cc: James Hogan Cc: Qais Yousef Cc: Paul Burton Cc: linux-mips@linux-mips.org Cc: linux-remoteproc@vger.kernel.org Cc: lisa.parratt@imgtec.com Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/14285/ Signed-off-by: Ralf Baechle

MIPS: c-r4k: Exclude sibling CPUs in SMP calls

2016-07-29T08:19:29+00:00

When performing SMP calls to foreign cores, exclude sibling CPUs from the provided map, as we already handle the local core on the current CPU. This prevents an SMP call from for example core 0, VPE 1 to VPE 0 on the same core. In the process the cpu_foreign_map cpumask is turned into an array of cpumasks, so that each CPU has its own version of it which excludes sibling CPUs. r4k_op_needs_ipi() is also updated to reflect that cache management SMP calls are not needed when all CPUs are siblings (i.e. there are no foreign CPUs according to the new cpu_foreign_map[] semantics which exclude siblings). Signed-off-by: James Hogan Cc: Paul Burton Cc: Leonid Yegoshin Cc: Felix Fietkau Cc: Jayachandran C. Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/13801/ Signed-off-by: Ralf Baechle

MIPS: SMP: Update cpu_foreign_map on CPU disable

2016-07-29T08:19:28+00:00

When a CPU is disabled via CPU hotplug, cpu_foreign_map is not updated. This could result in cache management SMP calls being sent to offline CPUs instead of online siblings in the same core. Add a call to calculate_cpu_foreign_map() in the various MIPS cpu disable callbacks after set_cpu_online(). All cases are updated for consistency and to keep cpu_foreign_map strictly up to date, not just those which may support hardware multithreading. Fixes: cccf34e9411c ("MIPS: c-r4k: Fix cache flushing for MT cores") Signed-off-by: James Hogan Cc: Paul Burton Cc: David Daney Cc: Kevin Cernekee Cc: Florian Fainelli Cc: Huacai Chen Cc: Hongliang Tao Cc: Hua Yan Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/13799/ Signed-off-by: Ralf Baechle

MIPS: SMP: Don't increment irq_count multiple times for call function IPIs

2015-08-03T07:25:12+00:00

The majority of SMP platforms handle their IPIs through do_IRQ() which calls irq_{enter/exit}(). When a call function IPI is received, smp_call_function_interrupt() is called which also calls irq_{enter,exit}(), meaning irq_count is raised twice. When tick broadcasting is used (which is implemented via a call function IPI), this incorrectly causes all CPU idle time on the core receiving broadcast ticks to be accounted as time spent servicing IRQs, as account_process_tick() will account as such if irq_count is greater than 1. This results in 100% CPU usage being reported on a core which receives its ticks via broadcast. This patch removes the SMP smp_call_function_interrupt() wrapper which calls irq_{enter,exit}(). Platforms which handle their IPIs through do_IRQ() now call generic_smp_call_function_interrupt() directly to avoid incrementing irq_count a second time. Platforms which don't (loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt() wrapped in irq_{enter,exit}(). Signed-off-by: Alex Smith Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10770/ Signed-off-by: Ralf Baechle

MIPS: c-r4k: Fix cache flushing for MT cores

2015-07-10T08:59:16+00:00

MT_SMP is not the only SMP option for MT cores. The MT_SMP option allows more than one VPE per core to appear as a secondary CPU in the system. Because of how CM works, it propagates the address-based cache ops to the secondary cores but not the index-based ones. Because of that, the code does not use IPIs to flush the L1 caches on secondary cores because the CM would have done that already. However, the CM functionality is independent of the type of SMP kernel so even in non-MT kernels, IPIs are not necessary. As a result of which, we change the conditional to depend on the CM presence. Moreover, since VPEs on the same core share the same L1 caches, there is no need to send an IPI on all of them so we calculate a suitable cpumask with only one VPE per core. Signed-off-by: Markos Chandras Cc: # 3.15+ Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10654/ Signed-off-by: Ralf Baechle