diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 4 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 1 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/cmdline.c | 6 | ||||
| -rw-r--r-- | lib/stackdepot.c | 284 | ||||
| -rw-r--r-- | lib/swiotlb.c | 6 |
6 files changed, 297 insertions, 6 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index 7f6feb7a4687..4bb61d2e6746 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -547,4 +547,8 @@ config QMI_ENCDEC_DEBUG library. This will log the information regarding the element and message being encoded & decoded. +config STACKDEPOT + bool + select STACKTRACE + endmenu diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 20b74735508d..6da96c4f98a5 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -244,6 +244,7 @@ config PAGE_OWNER depends on DEBUG_KERNEL && STACKTRACE_SUPPORT select DEBUG_FS select STACKTRACE + select STACKDEPOT select PAGE_EXTENSION help This keeps track of what call chain is the owner of a page, may diff --git a/lib/Makefile b/lib/Makefile index 03a447a234cc..3ea641eb91bc 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -167,6 +167,8 @@ obj-$(CONFIG_GENERIC_NET_UTILS) += net_utils.o obj-$(CONFIG_SG_SPLIT) += sg_split.o obj-$(CONFIG_STMP_DEVICE) += stmp_device.o +obj-$(CONFIG_STACKDEPOT) += stackdepot.o + libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \ fdt_empty_tree.o $(foreach file, $(libfdt_files), \ diff --git a/lib/cmdline.c b/lib/cmdline.c index 8f13cf73c2ec..79069d7938ea 100644 --- a/lib/cmdline.c +++ b/lib/cmdline.c @@ -22,14 +22,14 @@ * the values[M, M+1, ..., N] into the ints array in get_options. */ -static int get_range(char **str, int *pint) +static int get_range(char **str, int *pint, int n) { int x, inc_counter, upper_range; (*str)++; upper_range = simple_strtol((*str), NULL, 0); inc_counter = upper_range - *pint; - for (x = *pint; x < upper_range; x++) + for (x = *pint; n && x < upper_range; x++, n--) *pint++ = x; return inc_counter; } @@ -96,7 +96,7 @@ char *get_options(const char *str, int nints, int *ints) break; if (res == 3) { int range_nums; - range_nums = get_range((char **)&str, ints + i); + range_nums = get_range((char **)&str, ints + i, nints - i); if (range_nums < 0) break; /* diff --git a/lib/stackdepot.c b/lib/stackdepot.c new file mode 100644 index 000000000000..192134b225ca --- /dev/null +++ b/lib/stackdepot.c @@ -0,0 +1,284 @@ +/* + * Generic stack depot for storing stack traces. + * + * Some debugging tools need to save stack traces of certain events which can + * be later presented to the user. For example, KASAN needs to safe alloc and + * free stacks for each object, but storing two stack traces per object + * requires too much memory (e.g. SLUB_DEBUG needs 256 bytes per object for + * that). + * + * Instead, stack depot maintains a hashtable of unique stacktraces. Since alloc + * and free stacks repeat a lot, we save about 100x space. + * Stacks are never removed from depot, so we store them contiguously one after + * another in a contiguos memory allocation. + * + * Author: Alexander Potapenko <glider@google.com> + * Copyright (C) 2016 Google, Inc. + * + * Based on code by Dmitry Chernenkov. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + */ + +#include <linux/gfp.h> +#include <linux/jhash.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/percpu.h> +#include <linux/printk.h> +#include <linux/slab.h> +#include <linux/stacktrace.h> +#include <linux/stackdepot.h> +#include <linux/string.h> +#include <linux/types.h> + +#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8) + +#define STACK_ALLOC_NULL_PROTECTION_BITS 1 +#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */ +#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER)) +#define STACK_ALLOC_ALIGN 4 +#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \ + STACK_ALLOC_ALIGN) +#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \ + STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS) +#define STACK_ALLOC_SLABS_CAP 1024 +#define STACK_ALLOC_MAX_SLABS \ + (((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \ + (1LL << (STACK_ALLOC_INDEX_BITS)) : STACK_ALLOC_SLABS_CAP) + +/* The compact structure to store the reference to stacks. */ +union handle_parts { + depot_stack_handle_t handle; + struct { + u32 slabindex : STACK_ALLOC_INDEX_BITS; + u32 offset : STACK_ALLOC_OFFSET_BITS; + u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS; + }; +}; + +struct stack_record { + struct stack_record *next; /* Link in the hashtable */ + u32 hash; /* Hash in the hastable */ + u32 size; /* Number of frames in the stack */ + union handle_parts handle; + unsigned long entries[1]; /* Variable-sized array of entries. */ +}; + +static void *stack_slabs[STACK_ALLOC_MAX_SLABS]; + +static int depot_index; +static int next_slab_inited; +static size_t depot_offset; +static DEFINE_SPINLOCK(depot_lock); + +static bool init_stack_slab(void **prealloc) +{ + if (!*prealloc) + return false; + /* + * This smp_load_acquire() pairs with smp_store_release() to + * |next_slab_inited| below and in depot_alloc_stack(). + */ + if (smp_load_acquire(&next_slab_inited)) + return true; + if (stack_slabs[depot_index] == NULL) { + stack_slabs[depot_index] = *prealloc; + } else { + stack_slabs[depot_index + 1] = *prealloc; + /* + * This smp_store_release pairs with smp_load_acquire() from + * |next_slab_inited| above and in depot_save_stack(). + */ + smp_store_release(&next_slab_inited, 1); + } + *prealloc = NULL; + return true; +} + +/* Allocation of a new stack in raw storage */ +static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, + u32 hash, void **prealloc, gfp_t alloc_flags) +{ + int required_size = offsetof(struct stack_record, entries) + + sizeof(unsigned long) * size; + struct stack_record *stack; + + required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN); + + if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) { + if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) { + WARN_ONCE(1, "Stack depot reached limit capacity"); + return NULL; + } + depot_index++; + depot_offset = 0; + /* + * smp_store_release() here pairs with smp_load_acquire() from + * |next_slab_inited| in depot_save_stack() and + * init_stack_slab(). + */ + if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) + smp_store_release(&next_slab_inited, 0); + } + init_stack_slab(prealloc); + if (stack_slabs[depot_index] == NULL) + return NULL; + + stack = stack_slabs[depot_index] + depot_offset; + + stack->hash = hash; + stack->size = size; + stack->handle.slabindex = depot_index; + stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN; + stack->handle.valid = 1; + memcpy(stack->entries, entries, size * sizeof(unsigned long)); + depot_offset += required_size; + + return stack; +} + +#define STACK_HASH_ORDER 18 +#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER) +#define STACK_HASH_MASK (STACK_HASH_SIZE - 1) +#define STACK_HASH_SEED 0x9747b28c + +static struct stack_record *stack_table[STACK_HASH_SIZE] = { + [0 ... STACK_HASH_SIZE - 1] = NULL +}; + +/* Calculate hash for a stack */ +static inline u32 hash_stack(unsigned long *entries, unsigned int size) +{ + return jhash2((u32 *)entries, + size * sizeof(unsigned long) / sizeof(u32), + STACK_HASH_SEED); +} + +/* Find a stack that is equal to the one stored in entries in the hash */ +static inline struct stack_record *find_stack(struct stack_record *bucket, + unsigned long *entries, int size, + u32 hash) +{ + struct stack_record *found; + + for (found = bucket; found; found = found->next) { + if (found->hash == hash && + found->size == size && + !memcmp(entries, found->entries, + size * sizeof(unsigned long))) { + return found; + } + } + return NULL; +} + +void depot_fetch_stack(depot_stack_handle_t handle, struct stack_trace *trace) +{ + union handle_parts parts = { .handle = handle }; + void *slab = stack_slabs[parts.slabindex]; + size_t offset = parts.offset << STACK_ALLOC_ALIGN; + struct stack_record *stack = slab + offset; + + trace->nr_entries = trace->max_entries = stack->size; + trace->entries = stack->entries; + trace->skip = 0; +} + +/** + * depot_save_stack - save stack in a stack depot. + * @trace - the stacktrace to save. + * @alloc_flags - flags for allocating additional memory if required. + * + * Returns the handle of the stack struct stored in depot. + */ +depot_stack_handle_t depot_save_stack(struct stack_trace *trace, + gfp_t alloc_flags) +{ + u32 hash; + depot_stack_handle_t retval = 0; + struct stack_record *found = NULL, **bucket; + unsigned long flags; + struct page *page = NULL; + void *prealloc = NULL; + + if (unlikely(trace->nr_entries == 0)) + goto fast_exit; + + hash = hash_stack(trace->entries, trace->nr_entries); + bucket = &stack_table[hash & STACK_HASH_MASK]; + + /* + * Fast path: look the stack trace up without locking. + * The smp_load_acquire() here pairs with smp_store_release() to + * |bucket| below. + */ + found = find_stack(smp_load_acquire(bucket), trace->entries, + trace->nr_entries, hash); + if (found) + goto exit; + + /* + * Check if the current or the next stack slab need to be initialized. + * If so, allocate the memory - we won't be able to do that under the + * lock. + * + * The smp_load_acquire() here pairs with smp_store_release() to + * |next_slab_inited| in depot_alloc_stack() and init_stack_slab(). + */ + if (unlikely(!smp_load_acquire(&next_slab_inited))) { + /* + * Zero out zone modifiers, as we don't have specific zone + * requirements. Keep the flags related to allocation in atomic + * contexts and I/O. + */ + alloc_flags &= ~GFP_ZONEMASK; + alloc_flags &= (GFP_ATOMIC | GFP_KERNEL); + page = alloc_pages(alloc_flags, STACK_ALLOC_ORDER); + if (page) + prealloc = page_address(page); + } + + spin_lock_irqsave(&depot_lock, flags); + + found = find_stack(*bucket, trace->entries, trace->nr_entries, hash); + if (!found) { + struct stack_record *new = + depot_alloc_stack(trace->entries, trace->nr_entries, + hash, &prealloc, alloc_flags); + if (new) { + new->next = *bucket; + /* + * This smp_store_release() pairs with + * smp_load_acquire() from |bucket| above. + */ + smp_store_release(bucket, new); + found = new; + } + } else if (prealloc) { + /* + * We didn't need to store this stack trace, but let's keep + * the preallocated memory for the future. + */ + WARN_ON(!init_stack_slab(&prealloc)); + } + + spin_unlock_irqrestore(&depot_lock, flags); +exit: + if (prealloc) { + /* Nobody used this memory, ok to free it. */ + free_pages((unsigned long)prealloc, STACK_ALLOC_ORDER); + } + if (found) + retval = found->handle.handle; +fast_exit: + return retval; +} diff --git a/lib/swiotlb.c b/lib/swiotlb.c index 76f29ecba8f4..771234d050c7 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -452,11 +452,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); /* - * For mappings greater than a page, we limit the stride (and - * hence alignment) to a page size. + * For mappings greater than or equal to a page, we limit the stride + * (and hence alignment) to a page size. */ nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT; - if (size > PAGE_SIZE) + if (size >= PAGE_SIZE) stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT)); else stride = 1; |