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Diffstat (limited to '')
-rw-r--r-- | arch/powerpc/platforms/powernv/memtrace.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c new file mode 100644 index 000000000..0e42fe2d7 --- /dev/null +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -0,0 +1,342 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) IBM Corporation, 2014, 2017 + * Anton Blanchard, Rashmica Gupta. + */ + +#define pr_fmt(fmt) "memtrace: " fmt + +#include <linux/bitops.h> +#include <linux/string.h> +#include <linux/memblock.h> +#include <linux/init.h> +#include <linux/moduleparam.h> +#include <linux/fs.h> +#include <linux/debugfs.h> +#include <linux/slab.h> +#include <linux/memory.h> +#include <linux/memory_hotplug.h> +#include <linux/numa.h> +#include <asm/machdep.h> +#include <asm/debugfs.h> + +/* This enables us to keep track of the memory removed from each node. */ +struct memtrace_entry { + void *mem; + u64 start; + u64 size; + u32 nid; + struct dentry *dir; + char name[16]; +}; + +static DEFINE_MUTEX(memtrace_mutex); +static u64 memtrace_size; + +static struct memtrace_entry *memtrace_array; +static unsigned int memtrace_array_nr; + + +static ssize_t memtrace_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *ppos) +{ + struct memtrace_entry *ent = filp->private_data; + + return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size); +} + +static const struct file_operations memtrace_fops = { + .llseek = default_llseek, + .read = memtrace_read, + .open = simple_open, +}; + +static int check_memblock_online(struct memory_block *mem, void *arg) +{ + if (mem->state != MEM_ONLINE) + return -1; + + return 0; +} + +static int change_memblock_state(struct memory_block *mem, void *arg) +{ + unsigned long state = (unsigned long)arg; + + mem->state = state; + + return 0; +} + +static void memtrace_clear_range(unsigned long start_pfn, + unsigned long nr_pages) +{ + unsigned long pfn; + + /* + * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM + * does not apply, avoid passing around "struct page" and use + * clear_page() instead directly. + */ + for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) { + if (IS_ALIGNED(pfn, PAGES_PER_SECTION)) + cond_resched(); + clear_page(__va(PFN_PHYS(pfn))); + } +} + +/* called with device_hotplug_lock held */ +static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages) +{ + const unsigned long start = PFN_PHYS(start_pfn); + const unsigned long size = PFN_PHYS(nr_pages); + + if (walk_memory_blocks(start, size, NULL, check_memblock_online)) + return false; + + walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE, + change_memblock_state); + + if (offline_pages(start_pfn, nr_pages)) { + walk_memory_blocks(start, size, (void *)MEM_ONLINE, + change_memblock_state); + return false; + } + + walk_memory_blocks(start, size, (void *)MEM_OFFLINE, + change_memblock_state); + + + return true; +} + +static u64 memtrace_alloc_node(u32 nid, u64 size) +{ + u64 start_pfn, end_pfn, nr_pages, pfn; + u64 base_pfn; + u64 bytes = memory_block_size_bytes(); + + if (!node_spanned_pages(nid)) + return 0; + + start_pfn = node_start_pfn(nid); + end_pfn = node_end_pfn(nid); + nr_pages = size >> PAGE_SHIFT; + + /* Trace memory needs to be aligned to the size */ + end_pfn = round_down(end_pfn - nr_pages, nr_pages); + + lock_device_hotplug(); + for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) { + if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) { + /* + * Clear the range while we still have a linear + * mapping. + */ + memtrace_clear_range(base_pfn, nr_pages); + /* + * Remove memory in memory block size chunks so that + * iomem resources are always split to the same size and + * we never try to remove memory that spans two iomem + * resources. + */ + end_pfn = base_pfn + nr_pages; + for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) { + __remove_memory(nid, pfn << PAGE_SHIFT, bytes); + } + unlock_device_hotplug(); + return base_pfn << PAGE_SHIFT; + } + } + unlock_device_hotplug(); + + return 0; +} + +static int memtrace_init_regions_runtime(u64 size) +{ + u32 nid; + u64 m; + + memtrace_array = kcalloc(num_online_nodes(), + sizeof(struct memtrace_entry), GFP_KERNEL); + if (!memtrace_array) { + pr_err("Failed to allocate memtrace_array\n"); + return -EINVAL; + } + + for_each_online_node(nid) { + m = memtrace_alloc_node(nid, size); + + /* + * A node might not have any local memory, so warn but + * continue on. + */ + if (!m) { + pr_err("Failed to allocate trace memory on node %d\n", nid); + continue; + } + + pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m); + + memtrace_array[memtrace_array_nr].start = m; + memtrace_array[memtrace_array_nr].size = size; + memtrace_array[memtrace_array_nr].nid = nid; + memtrace_array_nr++; + } + + return 0; +} + +static struct dentry *memtrace_debugfs_dir; + +static int memtrace_init_debugfs(void) +{ + int ret = 0; + int i; + + for (i = 0; i < memtrace_array_nr; i++) { + struct dentry *dir; + struct memtrace_entry *ent = &memtrace_array[i]; + + ent->mem = ioremap(ent->start, ent->size); + /* Warn but continue on */ + if (!ent->mem) { + pr_err("Failed to map trace memory at 0x%llx\n", + ent->start); + ret = -1; + continue; + } + + snprintf(ent->name, 16, "%08x", ent->nid); + dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir); + + ent->dir = dir; + debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops); + debugfs_create_x64("start", 0400, dir, &ent->start); + debugfs_create_x64("size", 0400, dir, &ent->size); + } + + return ret; +} + +static int online_mem_block(struct memory_block *mem, void *arg) +{ + return device_online(&mem->dev); +} + +/* + * Iterate through the chunks of memory we have removed from the kernel + * and attempt to add them back to the kernel. + */ +static int memtrace_online(void) +{ + int i, ret = 0; + struct memtrace_entry *ent; + + for (i = memtrace_array_nr - 1; i >= 0; i--) { + ent = &memtrace_array[i]; + + /* We have onlined this chunk previously */ + if (ent->nid == NUMA_NO_NODE) + continue; + + /* Remove from io mappings */ + if (ent->mem) { + iounmap(ent->mem); + ent->mem = 0; + } + + if (add_memory(ent->nid, ent->start, ent->size, MHP_NONE)) { + pr_err("Failed to add trace memory to node %d\n", + ent->nid); + ret += 1; + continue; + } + + lock_device_hotplug(); + walk_memory_blocks(ent->start, ent->size, NULL, + online_mem_block); + unlock_device_hotplug(); + + /* + * Memory was added successfully so clean up references to it + * so on reentry we can tell that this chunk was added. + */ + debugfs_remove_recursive(ent->dir); + pr_info("Added trace memory back to node %d\n", ent->nid); + ent->size = ent->start = ent->nid = NUMA_NO_NODE; + } + if (ret) + return ret; + + /* If all chunks of memory were added successfully, reset globals */ + kfree(memtrace_array); + memtrace_array = NULL; + memtrace_size = 0; + memtrace_array_nr = 0; + return 0; +} + +static int memtrace_enable_set(void *data, u64 val) +{ + int rc = -EAGAIN; + u64 bytes; + + /* + * Don't attempt to do anything if size isn't aligned to a memory + * block or equal to zero. + */ + bytes = memory_block_size_bytes(); + if (val & (bytes - 1)) { + pr_err("Value must be aligned with 0x%llx\n", bytes); + return -EINVAL; + } + + mutex_lock(&memtrace_mutex); + + /* Re-add/online previously removed/offlined memory */ + if (memtrace_size) { + if (memtrace_online()) + goto out_unlock; + } + + if (!val) { + rc = 0; + goto out_unlock; + } + + /* Offline and remove memory */ + if (memtrace_init_regions_runtime(val)) + goto out_unlock; + + if (memtrace_init_debugfs()) + goto out_unlock; + + memtrace_size = val; + rc = 0; +out_unlock: + mutex_unlock(&memtrace_mutex); + return rc; +} + +static int memtrace_enable_get(void *data, u64 *val) +{ + *val = memtrace_size; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get, + memtrace_enable_set, "0x%016llx\n"); + +static int memtrace_init(void) +{ + memtrace_debugfs_dir = debugfs_create_dir("memtrace", + powerpc_debugfs_root); + + debugfs_create_file("enable", 0600, memtrace_debugfs_dir, + NULL, &memtrace_init_fops); + + return 0; +} +machine_device_initcall(powernv, memtrace_init); 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