litmus-rt.git - The LITMUS^RT kernel.

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author	Matt Helsley <matthltc@us.ibm.com>	2010-09-13 16:01:20 -0400
committer	Ingo Molnar <mingo@elte.hu>	2010-09-15 04:44:00 -0400
commit	38a81da2205f94e8a2a834b51a6b99c91fc7c2e8 (patch)
tree	5227c665f37d1c472608a44aaad0a04be68befb2 /include/linux/usb/musb.h
parent	2ebd4ffb6d0cb877787b1e42be8485820158857e (diff)

perf events: Clean up pid passing

The kernel perf event creation path shouldn't use find_task_by_vpid() because a vpid exists in a specific namespace. find_task_by_vpid() uses current's pid namespace which isn't always the correct namespace to use for the vpid in all the places perf_event_create_kernel_counter() (and thus find_get_context()) is called. The goal is to clean up pid namespace handling and prevent bugs like: https://bugzilla.kernel.org/show_bug.cgi?id=17281 Instead of using pids switch find_get_context() to use task struct pointers directly. The syscall is responsible for resolving the pid to a task struct. This moves the pid namespace resolution into the syscall much like every other syscall that takes pid parameters. Signed-off-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robin Green <greenrd@greenrd.org> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> LKML-Reference: <a134e5e392ab0204961fd1a62c84a222bf5874a9.1284407763.git.matthltc@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Diffstat (limited to 'include/linux/usb/musb.h')

0 files changed, 0 insertions, 0 deletions

/* * Kernel Probes (KProbes) * kernel/kprobes.c * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * 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. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright (C) IBM Corporation, 2002, 2004 * * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel * Probes initial implementation (includes suggestions from * Rusty Russell). * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with * hlists and exceptions notifier as suggested by Andi Kleen. * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes * interface to access function arguments. * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes * exceptions notifier to be first on the priority list. * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi * <prasanna@in.ibm.com> added function-return probes. */ #include <linux/kprobes.h> #include <linux/hash.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/module.h> #include <linux/moduleloader.h> #include <linux/kallsyms.h> #include <asm-generic/sections.h> #include <asm/cacheflush.h> #include <asm/errno.h> #include <asm/kdebug.h> #define KPROBE_HASH_BITS 6 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) /* * Some oddball architectures like 64bit powerpc have function descriptors * so this must be overridable. */ #ifndef kprobe_lookup_name #define kprobe_lookup_name(name, addr) \ addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) #endif static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; static atomic_t kprobe_count; DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; static struct notifier_block kprobe_page_fault_nb = { .notifier_call = kprobe_exceptions_notify, .priority = 0x7fffffff /* we need to notified first */ }; #ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* * kprobe->ainsn.insn points to the copy of the instruction to be * single-stepped. x86_64, POWER4 and above have no-exec support and * stepping on the instruction on a vmalloced/kmalloced/data page * is a recipe for disaster */ #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) struct kprobe_insn_page { struct hlist_node hlist; kprobe_opcode_t *insns; /* Page of instruction slots */ char slot_used[INSNS_PER_PAGE]; int nused; }; static struct hlist_head kprobe_insn_pages; /** * get_insn_slot() - Find a slot on an executable page for an instruction. * We allocate an executable page if there's no room on existing ones. */ kprobe_opcode_t __kprobes *get_insn_slot(void) { struct kprobe_insn_page *kip; struct hlist_node *pos; hlist_for_each(pos, &kprobe_insn_pages) { kip = hlist_entry(pos, struct kprobe_insn_page, hlist); if (kip->nused < INSNS_PER_PAGE) { int i; for (i = 0; i < INSNS_PER_PAGE; i++) { if (!kip->slot_used[i]) { kip->slot_used[i] = 1; kip->nused++; return kip->insns + (i * MAX_INSN_SIZE); } } /* Surprise! No unused slots. Fix kip->nused. */ kip->nused = INSNS_PER_PAGE; } } /* All out of space. Need to allocate a new page. Use slot 0.*/ kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); if (!kip) { return NULL; } /* * Use module_alloc so this page is within +/- 2GB of where the * kernel image and loaded module images reside. This is required * so x86_64 can correctly handle the %rip-relative fixups. */ kip->insns = module_alloc(PAGE_SIZE); if (!kip->insns) { kfree(kip); return NULL; } INIT_HLIST_NODE(&kip->hlist); hlist_add_head(&kip->hlist, &kprobe_insn_pages); memset(kip->slot_used, 0, INSNS_PER_PAGE); kip->slot_used[0] = 1; kip->nused = 1; return kip->insns; } void __kprobes free_insn_slot(kprobe_opcode_t *slot) { struct kprobe_insn_page *kip; struct hlist_node *pos; hlist_for_each(pos, &kprobe_insn_pages) { kip = hlist_entry(pos, struct kprobe_insn_page, hlist); if (kip->insns <= slot && slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { int i = (slot - kip->insns) / MAX_INSN_SIZE; kip->slot_used[i] = 0; kip->nused--; if (kip->nused == 0) { /* * Page is no longer in use. Free it unless * it's the last one. We keep the last one * so as not to have to set it up again the * next time somebody inserts a probe. */ hlist_del(&kip->hlist); if (hlist_empty(&kprobe_insn_pages)) { INIT_HLIST_NODE(&kip->hlist); hlist_add_head(&kip->hlist, &kprobe_insn_pages); } else { module_free(NULL, kip->insns); kfree(kip); } } return; } } } #endif /* We have preemption disabled.. so it is safe to use __ versions */ static inline void set_kprobe_instance(struct kprobe *kp) { __get_cpu_var(kprobe_instance) = kp; } static inline void reset_kprobe_instance(void) { __get_cpu_var(kprobe_instance) = NULL; } /* * This routine is called either: * - under the kprobe_mutex - during kprobe_[un]register() * OR * - with preemption disabled - from arch/xxx/kernel/kprobes.c */ struct kprobe __kprobes *get_kprobe(void *addr) { struct hlist_head *head; struct hlist_node *node; struct kprobe *p; head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; hlist_for_each_entry_rcu(p, node, head, hlist) { if (p->addr == addr) return p; } return NULL; } /* * Aggregate handlers for multiple kprobes support - these handlers * take care of invoking the individual kprobe handlers on p->list */ static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe *kp; list_for_each_entry_rcu(kp, &p->list, list) { if (kp->pre_handler) { set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) return 1; } reset_kprobe_instance(); } return 0; } static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, unsigned long flags) { struct kprobe *kp; list_for_each_entry_rcu(kp, &p->list, list) { if (kp->post_handler) { set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); reset_kprobe_instance(); } } return; } static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr) { struct kprobe *cur = __get_cpu_var(kprobe_instance); /* * if we faulted "during" the execution of a user specified * probe handler, invoke just that probe's fault handler */ if (cur && cur->fault_handler) { if (cur->fault_handler(cur, regs, trapnr)) return 1; } return 0; } static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe *cur = __get_cpu_var(kprobe_instance); int ret = 0; if (cur && cur->break_handler) { if (cur->break_handler(cur, regs)) ret = 1; } reset_kprobe_instance(); return ret; } /* Walks the list and increments nmissed count for multiprobe case */ void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) { struct kprobe *kp; if (p->pre_handler != aggr_pre_handler) { p->nmissed++; } else { list_for_each_entry_rcu(kp, &p->list, list) kp->nmissed++; } return; } /* Called with kretprobe_lock held */ struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp) { struct hlist_node *node; struct kretprobe_instance *ri; hlist_for_each_entry(ri, node, &rp->free_instances, uflist) return ri; return NULL; } /* Called with kretprobe_lock held */ static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe *rp) { struct hlist_node *node; struct kretprobe_instance *ri; hlist_for_each_entry(ri, node, &rp->used_instances, uflist) return ri; return NULL; } /* Called with kretprobe_lock held */ void __kprobes add_rp_inst(struct kretprobe_instance *ri) { /* * Remove rp inst off the free list - * Add it back when probed function returns */ hlist_del(&ri->uflist); /* Add rp inst onto table */ INIT_HLIST_NODE(&ri->hlist); hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]); /* Also add this rp inst to the used list. */ INIT_HLIST_NODE(&ri->uflist); hlist_add_head(&ri->uflist, &ri->rp->used_instances); } /* Called with kretprobe_lock held */ void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head) { /* remove rp inst off the rprobe_inst_table */ hlist_del(&ri->hlist); if (ri->rp) { /* remove rp inst off the used list */ hlist_del(&ri->uflist); /* put rp inst back onto the free list */ INIT_HLIST_NODE(&ri->uflist); hlist_add_head(&ri->uflist, &ri->rp->free_instances); } else /* Unregistering */ hlist_add_head(&ri->hlist, head); } struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk) { return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; } /* * This function is called from finish_task_switch when task tk becomes dead, * so that we can recycle any function-return probe instances associated * with this task. These left over instances represent probed functions * that have been called but will never return. */ void __kprobes kprobe_flush_task(struct task_struct *tk) { struct kretprobe_instance *ri; struct hlist_head *head, empty_rp; struct hlist_node *node, *tmp; unsigned long flags = 0; INIT_HLIST_HEAD(&empty_rp); spin_lock_irqsave(&kretprobe_lock, flags); head = kretprobe_inst_table_head(tk); hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { if (ri->task == tk) recycle_rp_inst(ri, &empty_rp); } spin_unlock_irqrestore(&kretprobe_lock, flags); hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri); } } static inline void free_rp_inst(struct kretprobe *rp) { struct kretprobe_instance *ri; while ((ri = get_free_rp_inst(rp)) != NULL) { hlist_del(&ri->uflist); kfree(ri); } } /* * Keep all fields in the kprobe consistent */ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) { memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); } /* * Add the new probe to old_p->list. Fail if this is the * second jprobe at the address - two jprobes can't coexist */ static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p) { if (p->break_handler) { if (old_p->break_handler) return -EEXIST; list_add_tail_rcu(&p->list, &old_p->list); old_p->break_handler = aggr_break_handler; } else list_add_rcu(&p->list, &old_p->list); if (p->post_handler && !old_p->post_handler) old_p->post_handler = aggr_post_handler; return 0; } /* * Fill in the required fields of the "manager kprobe". Replace the * earlier kprobe in the hlist with the manager kprobe */ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) {


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