diff options
Diffstat (limited to 'kernel/events/callchain.c')
| -rw-r--r-- | kernel/events/callchain.c | 152 |
1 files changed, 111 insertions, 41 deletions
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 24a77c34e9ad..b9c7e00725d6 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * Performance events callchain code, extracted from core.c: * @@ -5,23 +6,23 @@ * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> - * - * For licensing details see kernel-base/COPYING */ #include <linux/perf_event.h> #include <linux/slab.h> #include <linux/sched/task_stack.h> +#include <linux/uprobes.h> #include "internal.h" struct callchain_cpus_entries { struct rcu_head rcu_head; - struct perf_callchain_entry *cpu_entries[0]; + struct perf_callchain_entry *cpu_entries[]; }; int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH; int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK; +static const int six_hundred_forty_kb = 640 * 1024; static inline size_t perf_callchain_entry__sizeof(void) { @@ -30,7 +31,7 @@ static inline size_t perf_callchain_entry__sizeof(void) sysctl_perf_event_max_contexts_per_stack)); } -static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]); +static DEFINE_PER_CPU(u8, callchain_recursion[PERF_NR_CONTEXTS]); static atomic_t nr_callchain_events; static DEFINE_MUTEX(callchain_mutex); static struct callchain_cpus_entries *callchain_cpus_entries; @@ -150,7 +151,7 @@ void put_callchain_buffers(void) } } -static struct perf_callchain_entry *get_callchain_entry(int *rctx) +struct perf_callchain_entry *get_callchain_entry(int *rctx) { int cpu; struct callchain_cpus_entries *entries; @@ -160,8 +161,10 @@ static struct perf_callchain_entry *get_callchain_entry(int *rctx) return NULL; entries = rcu_dereference(callchain_cpus_entries); - if (!entries) + if (!entries) { + put_recursion_context(this_cpu_ptr(callchain_recursion), *rctx); return NULL; + } cpu = smp_processor_id(); @@ -169,32 +172,71 @@ static struct perf_callchain_entry *get_callchain_entry(int *rctx) (*rctx * perf_callchain_entry__sizeof())); } -static void +void put_callchain_entry(int rctx) { put_recursion_context(this_cpu_ptr(callchain_recursion), rctx); } +static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entry, + int start_entry_idx) +{ +#ifdef CONFIG_UPROBES + struct uprobe_task *utask = current->utask; + struct return_instance *ri; + __u64 *cur_ip, *last_ip, tramp_addr; + + if (likely(!utask || !utask->return_instances)) + return; + + cur_ip = &entry->ip[start_entry_idx]; + last_ip = &entry->ip[entry->nr - 1]; + ri = utask->return_instances; + tramp_addr = uprobe_get_trampoline_vaddr(); + + /* + * If there are pending uretprobes for the current thread, they are + * recorded in a list inside utask->return_instances; each such + * pending uretprobe replaces traced user function's return address on + * the stack, so when stack trace is captured, instead of seeing + * actual function's return address, we'll have one or many uretprobe + * trampoline addresses in the stack trace, which are not helpful and + * misleading to users. + * So here we go over the pending list of uretprobes, and each + * encountered trampoline address is replaced with actual return + * address. + */ + while (ri && cur_ip <= last_ip) { + if (*cur_ip == tramp_addr) { + *cur_ip = ri->orig_ret_vaddr; + ri = ri->next; + } + cur_ip++; + } +#endif +} + struct perf_callchain_entry * -get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user, - u32 max_stack, bool crosstask, bool add_mark) +get_perf_callchain(struct pt_regs *regs, bool kernel, bool user, + u32 max_stack, bool crosstask, bool add_mark, u64 defer_cookie) { struct perf_callchain_entry *entry; struct perf_callchain_entry_ctx ctx; - int rctx; + int rctx, start_entry_idx; - entry = get_callchain_entry(&rctx); - if (rctx == -1) + /* crosstask is not supported for user stacks */ + if (crosstask && user && !kernel) return NULL; + entry = get_callchain_entry(&rctx); if (!entry) - goto exit_put; + return NULL; - ctx.entry = entry; - ctx.max_stack = max_stack; - ctx.nr = entry->nr = init_nr; - ctx.contexts = 0; - ctx.contexts_maxed = false; + ctx.entry = entry; + ctx.max_stack = max_stack; + ctx.nr = entry->nr = 0; + ctx.contexts = 0; + ctx.contexts_maxed = false; if (kernel && !user_mode(regs)) { if (add_mark) @@ -202,28 +244,31 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user, perf_callchain_kernel(&ctx, regs); } - if (user) { + if (user && !crosstask) { if (!user_mode(regs)) { - if (current->mm) - regs = task_pt_regs(current); - else - regs = NULL; + if (current->flags & (PF_KTHREAD | PF_USER_WORKER)) + goto exit_put; + regs = task_pt_regs(current); } - if (regs) { - mm_segment_t fs; - - if (crosstask) - goto exit_put; + if (defer_cookie) { + /* + * Foretell the coming of PERF_RECORD_CALLCHAIN_DEFERRED + * which can be stitched to this one, and add + * the cookie after it (it will be cut off when the + * user stack is copied to the callchain). + */ + perf_callchain_store_context(&ctx, PERF_CONTEXT_USER_DEFERRED); + perf_callchain_store_context(&ctx, defer_cookie); + goto exit_put; + } - if (add_mark) - perf_callchain_store_context(&ctx, PERF_CONTEXT_USER); + if (add_mark) + perf_callchain_store_context(&ctx, PERF_CONTEXT_USER); - fs = get_fs(); - set_fs(USER_DS); - perf_callchain_user(&ctx, regs); - set_fs(fs); - } + start_entry_idx = entry->nr; + perf_callchain_user(&ctx, regs); + fixup_uretprobe_trampoline_entries(entry, start_entry_idx); } exit_put: @@ -232,12 +277,8 @@ exit_put: return entry; } -/* - * Used for sysctl_perf_event_max_stack and - * sysctl_perf_event_max_contexts_per_stack. - */ -int perf_event_max_stack_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, loff_t *ppos) +static int perf_event_max_stack_handler(const struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { int *value = table->data; int new_value = *value, ret; @@ -258,3 +299,32 @@ int perf_event_max_stack_handler(struct ctl_table *table, int write, return ret; } + +static const struct ctl_table callchain_sysctl_table[] = { + { + .procname = "perf_event_max_stack", + .data = &sysctl_perf_event_max_stack, + .maxlen = sizeof(sysctl_perf_event_max_stack), + .mode = 0644, + .proc_handler = perf_event_max_stack_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = (void *)&six_hundred_forty_kb, + }, + { + .procname = "perf_event_max_contexts_per_stack", + .data = &sysctl_perf_event_max_contexts_per_stack, + .maxlen = sizeof(sysctl_perf_event_max_contexts_per_stack), + .mode = 0644, + .proc_handler = perf_event_max_stack_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE_THOUSAND, + }, +}; + +static int __init init_callchain_sysctls(void) +{ + register_sysctl_init("kernel", callchain_sysctl_table); + return 0; +} +core_initcall(init_callchain_sysctls); + |