diff options
Diffstat (limited to 'arch/powerpc/mm/mmu_context_nohash.c')
| -rw-r--r-- | arch/powerpc/mm/mmu_context_nohash.c | 161 |
1 files changed, 111 insertions, 50 deletions
diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c index 8b5de52de0a..52a0cfc38b6 100644 --- a/arch/powerpc/mm/mmu_context_nohash.c +++ b/arch/powerpc/mm/mmu_context_nohash.c @@ -28,54 +28,30 @@ #undef DEBUG #define DEBUG_STEAL_ONLY #undef DEBUG_MAP_CONSISTENCY +/*#define DEBUG_CLAMP_LAST_CONTEXT 15 */ #include <linux/kernel.h> #include <linux/mm.h> #include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/bootmem.h> +#include <linux/notifier.h> +#include <linux/cpu.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> -#include <linux/spinlock.h> - -/* - * The MPC8xx has only 16 contexts. We rotate through them on each - * task switch. A better way would be to keep track of tasks that - * own contexts, and implement an LRU usage. That way very active - * tasks don't always have to pay the TLB reload overhead. The - * kernel pages are mapped shared, so the kernel can run on behalf - * of any task that makes a kernel entry. Shared does not mean they - * are not protected, just that the ASID comparison is not performed. - * -- Dan - * - * The IBM4xx has 256 contexts, so we can just rotate through these - * as a way of "switching" contexts. If the TID of the TLB is zero, - * the PID/TID comparison is disabled, so we can use a TID of zero - * to represent all kernel pages as shared among all contexts. - * -- Dan - */ - -#ifdef CONFIG_8xx -#define LAST_CONTEXT 15 -#define FIRST_CONTEXT 0 - -#elif defined(CONFIG_4xx) -#define LAST_CONTEXT 255 -#define FIRST_CONTEXT 1 - -#elif defined(CONFIG_E200) || defined(CONFIG_E500) -#define LAST_CONTEXT 255 -#define FIRST_CONTEXT 1 - -#else -#error Unsupported processor type -#endif +static unsigned int first_context, last_context; static unsigned int next_context, nr_free_contexts; -static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; -static unsigned long stale_map[NR_CPUS][LAST_CONTEXT / BITS_PER_LONG + 1]; -static struct mm_struct *context_mm[LAST_CONTEXT+1]; +static unsigned long *context_map; +static unsigned long *stale_map[NR_CPUS]; +static struct mm_struct **context_mm; static spinlock_t context_lock = SPIN_LOCK_UNLOCKED; +#define CTX_MAP_SIZE \ + (sizeof(unsigned long) * (last_context / BITS_PER_LONG + 1)) + + /* Steal a context from a task that has one at the moment. * * This is used when we are running out of available PID numbers @@ -98,7 +74,7 @@ static unsigned int steal_context_smp(unsigned int id) unsigned int cpu, max; again: - max = LAST_CONTEXT - FIRST_CONTEXT; + max = last_context - first_context; /* Attempt to free next_context first and then loop until we manage */ while (max--) { @@ -110,8 +86,8 @@ static unsigned int steal_context_smp(unsigned int id) */ if (mm->context.active) { id++; - if (id > LAST_CONTEXT) - id = FIRST_CONTEXT; + if (id > last_context) + id = first_context; continue; } pr_debug("[%d] steal context %d from mm @%p\n", @@ -169,7 +145,7 @@ static void context_check_map(void) unsigned int id, nrf, nact; nrf = nact = 0; - for (id = FIRST_CONTEXT; id <= LAST_CONTEXT; id++) { + for (id = first_context; id <= last_context; id++) { int used = test_bit(id, context_map); if (!used) nrf++; @@ -187,6 +163,8 @@ static void context_check_map(void) if (nact > num_online_cpus()) pr_err("MMU: More active contexts than CPUs ! (%d vs %d)\n", nact, num_online_cpus()); + if (first_context > 0 && !test_bit(0, context_map)) + pr_err("MMU: Context 0 has been freed !!!\n"); } #else static void context_check_map(void) { } @@ -209,6 +187,10 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) /* Mark us active and the previous one not anymore */ next->context.active++; if (prev) { +#ifndef DEBUG_STEAL_ONLY + pr_debug(" old context %p active was: %d\n", + prev, prev->context.active); +#endif WARN_ON(prev->context.active < 1); prev->context.active--; } @@ -221,8 +203,8 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) /* We really don't have a context, let's try to acquire one */ id = next_context; - if (id > LAST_CONTEXT) - id = FIRST_CONTEXT; + if (id > last_context) + id = first_context; map = context_map; /* No more free contexts, let's try to steal one */ @@ -240,9 +222,9 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) /* We know there's at least one free context, try to find it */ while (__test_and_set_bit(id, map)) { - id = find_next_zero_bit(map, LAST_CONTEXT+1, id); - if (id > LAST_CONTEXT) - id = FIRST_CONTEXT; + id = find_next_zero_bit(map, last_context+1, id); + if (id > last_context) + id = first_context; } stolen: next_context = id + 1; @@ -311,6 +293,42 @@ void destroy_context(struct mm_struct *mm) spin_unlock(&context_lock); } +#ifdef CONFIG_SMP + +static int __cpuinit mmu_context_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + unsigned int cpu = (unsigned int)(long)hcpu; + + /* We don't touch CPU 0 map, it's allocated at aboot and kept + * around forever + */ + if (cpu == 0) + return NOTIFY_OK; + + switch (action) { + case CPU_ONLINE: + case CPU_ONLINE_FROZEN: + pr_debug("MMU: Allocating stale context map for CPU %d\n", cpu); + stale_map[cpu] = kzalloc(CTX_MAP_SIZE, GFP_KERNEL); + break; +#ifdef CONFIG_HOTPLUG_CPU + case CPU_DEAD: + case CPU_DEAD_FROZEN: + pr_debug("MMU: Freeing stale context map for CPU %d\n", cpu); + kfree(stale_map[cpu]); + stale_map[cpu] = NULL; + break; +#endif + } + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata mmu_context_cpu_nb = { + .notifier_call = mmu_context_cpu_notify, +}; + +#endif /* CONFIG_SMP */ /* * Initialize the context management stuff. @@ -324,13 +342,56 @@ void __init mmu_context_init(void) init_mm.context.active = NR_CPUS; /* + * The MPC8xx has only 16 contexts. We rotate through them on each + * task switch. A better way would be to keep track of tasks that + * own contexts, and implement an LRU usage. That way very active + * tasks don't always have to pay the TLB reload overhead. The + * kernel pages are mapped shared, so the kernel can run on behalf + * of any task that makes a kernel entry. Shared does not mean they + * are not protected, just that the ASID comparison is not performed. + * -- Dan + * + * The IBM4xx has 256 contexts, so we can just rotate through these + * as a way of "switching" contexts. If the TID of the TLB is zero, + * the PID/TID comparison is disabled, so we can use a TID of zero + * to represent all kernel pages as shared among all contexts. + * -- Dan + */ + if (mmu_has_feature(MMU_FTR_TYPE_8xx)) { + first_context = 0; + last_context = 15; + } else { + first_context = 1; + last_context = 255; + } + +#ifdef DEBUG_CLAMP_LAST_CONTEXT + last_context = DEBUG_CLAMP_LAST_CONTEXT; +#endif + /* + * Allocate the maps used by context management + */ + context_map = alloc_bootmem(CTX_MAP_SIZE); + context_mm = alloc_bootmem(sizeof(void *) * (last_context + 1)); + stale_map[0] = alloc_bootmem(CTX_MAP_SIZE); + +#ifdef CONFIG_SMP + register_cpu_notifier(&mmu_context_cpu_nb); +#endif + + printk(KERN_INFO + "MMU: Allocated %d bytes of context maps for %d contexts\n", + 2 * CTX_MAP_SIZE + (sizeof(void *) * (last_context + 1)), + last_context - first_context + 1); + + /* * Some processors have too few contexts to reserve one for * init_mm, and require using context 0 for a normal task. * Other processors reserve the use of context zero for the kernel. - * This code assumes FIRST_CONTEXT < 32. + * This code assumes first_context < 32. */ - context_map[0] = (1 << FIRST_CONTEXT) - 1; - next_context = FIRST_CONTEXT; - nr_free_contexts = LAST_CONTEXT - FIRST_CONTEXT + 1; + context_map[0] = (1 << first_context) - 1; + next_context = first_context; + nr_free_contexts = last_context - first_context + 1; } |