From 65b2c8f0e53347583168423de0f32227d8baf01b Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 28 Oct 2012 16:55:36 +0100 Subject: uprobes/powerpc: Do not use arch_uprobe_*_step() helpers No functional changes. powerpc is the only user of arch_uprobe_enable/disable_step() helpers, but they should die. They can not be used correctly, every arch needs its own implementation (like x86 does). And they do not really help even as initial-and-almost-working code, arch_uprobe_*_xol() hooks can easily use user_enable/disable_single_step() directly. Change arch_uprobe_*_step() to do nothing, and convert powerpc to use ptrace helpers. This is equally wrong, powerpc needs the arch-specific fixes. Signed-off-by: Oleg Nesterov Acked-by: Ananth N Mavinakayanahalli Acked-by: Srikar Dronamraju --- kernel/events/uprobes.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 5cc4e7e42e68..abbfd8440a6d 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1432,12 +1432,10 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) void __weak arch_uprobe_enable_step(struct arch_uprobe *arch) { - user_enable_single_step(current); } void __weak arch_uprobe_disable_step(struct arch_uprobe *arch) { - user_disable_single_step(current); } /* -- cgit v1.2.3-55-g7522 From 19f5ee2716373519fda2129e9333f4c3847aa742 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 28 Oct 2012 18:14:14 +0100 Subject: uprobes: Kill arch_uprobe_enable/disable_step() hooks Kill arch_uprobe_enable/disable_step() hooks, they do nothing and nobody needs them. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- include/linux/uprobes.h | 2 -- kernel/events/uprobes.c | 10 ---------- 2 files changed, 12 deletions(-) (limited to 'kernel/events') diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 24594571c5a3..2615c4d7788d 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -101,8 +101,6 @@ extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm); extern void uprobe_free_utask(struct task_struct *t); extern void uprobe_copy_process(struct task_struct *t); extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs); -extern void __weak arch_uprobe_enable_step(struct arch_uprobe *arch); -extern void __weak arch_uprobe_disable_step(struct arch_uprobe *arch); extern int uprobe_post_sstep_notifier(struct pt_regs *regs); extern int uprobe_pre_sstep_notifier(struct pt_regs *regs); extern void uprobe_notify_resume(struct pt_regs *regs); diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index abbfd8440a6d..39c75cc51efc 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1430,14 +1430,6 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) return uprobe; } -void __weak arch_uprobe_enable_step(struct arch_uprobe *arch) -{ -} - -void __weak arch_uprobe_disable_step(struct arch_uprobe *arch) -{ -} - /* * Run handler and ask thread to singlestep. * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. @@ -1491,7 +1483,6 @@ static void handle_swbp(struct pt_regs *regs) goto out; if (!pre_ssout(uprobe, regs, bp_vaddr)) { - arch_uprobe_enable_step(&uprobe->arch); utask->active_uprobe = uprobe; utask->state = UTASK_SSTEP; return; @@ -1523,7 +1514,6 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) else WARN_ON_ONCE(1); - arch_uprobe_disable_step(&uprobe->arch); put_uprobe(uprobe); utask->active_uprobe = NULL; utask->state = UTASK_RUNNING; -- cgit v1.2.3-55-g7522 From 65b6ecc03838fd263cf7fafdfa6cf13012b91d56 Mon Sep 17 00:00:00 2001 From: Rabin Vincent Date: Wed, 14 Nov 2012 18:27:07 +0100 Subject: uprobes: Flush cache after xol write Flush the cache so that the instructions written to the XOL area are visible. Signed-off-by: Rabin Vincent Acked-by: Ananth N Mavinakayanahalli Signed-off-by: Oleg Nesterov --- kernel/events/uprobes.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/events') diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 39c75cc51efc..5ce99cfd2e6e 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1199,6 +1199,11 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot vaddr = kmap_atomic(area->page); memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); kunmap_atomic(vaddr); + /* + * We probably need flush_icache_user_range() but it needs vma. + * This should work on supported architectures too. + */ + flush_dcache_page(area->page); return current->utask->xol_vaddr; } -- cgit v1.2.3-55-g7522 From 32cdba1e05418909708a17e52505e8b2ba4381d1 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 14 Nov 2012 19:03:42 +0100 Subject: uprobes: Use percpu_rw_semaphore to fix register/unregister vs dup_mmap() race This was always racy, but 268720903f87e0b84b161626c4447b81671b5d18 "uprobes: Rework register_for_each_vma() to make it O(n)" should be blamed anyway, it made everything worse and I didn't notice. register/unregister call build_map_info() and then do install/remove breakpoint for every mm which mmaps inode/offset. This can obviously race with fork()->dup_mmap() in between and we can miss the child. uprobe_register() could be easily fixed but unregister is much worse, the new mm inherits "int3" from parent and there is no way to detect this if uprobe goes away. So this patch simply adds percpu_down_read/up_read around dup_mmap(), and percpu_down_write/up_write into register_for_each_vma(). This adds 2 new hooks into dup_mmap() but we can kill uprobe_dup_mmap() and fold it into uprobe_end_dup_mmap(). Reported-by: Srikar Dronamraju Acked-by: Srikar Dronamraju Signed-off-by: Oleg Nesterov --- include/linux/uprobes.h | 8 ++++++++ kernel/events/uprobes.c | 26 +++++++++++++++++++++++--- kernel/fork.c | 2 ++ 3 files changed, 33 insertions(+), 3 deletions(-) (limited to 'kernel/events') diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 2615c4d7788d..4f628a6fc5b4 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -97,6 +97,8 @@ extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_con extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); extern int uprobe_mmap(struct vm_area_struct *vma); extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end); +extern void uprobe_start_dup_mmap(void); +extern void uprobe_end_dup_mmap(void); extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm); extern void uprobe_free_utask(struct task_struct *t); extern void uprobe_copy_process(struct task_struct *t); @@ -127,6 +129,12 @@ static inline void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { } +static inline void uprobe_start_dup_mmap(void) +{ +} +static inline void uprobe_end_dup_mmap(void) +{ +} static inline void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) { diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 5ce99cfd2e6e..dea7acfbb071 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -33,6 +33,7 @@ #include /* user_enable_single_step */ #include /* notifier mechanism */ #include "../../mm/internal.h" /* munlock_vma_page */ +#include #include @@ -71,6 +72,8 @@ static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) +static struct percpu_rw_semaphore dup_mmap_sem; + /* * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe * events active at this time. Probably a fine grained per inode count is @@ -766,10 +769,13 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) struct map_info *info; int err = 0; + percpu_down_write(&dup_mmap_sem); info = build_map_info(uprobe->inode->i_mapping, uprobe->offset, is_register); - if (IS_ERR(info)) - return PTR_ERR(info); + if (IS_ERR(info)) { + err = PTR_ERR(info); + goto out; + } while (info) { struct mm_struct *mm = info->mm; @@ -799,7 +805,8 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) mmput(mm); info = free_map_info(info); } - + out: + percpu_up_write(&dup_mmap_sem); return err; } @@ -1131,6 +1138,16 @@ void uprobe_clear_state(struct mm_struct *mm) kfree(area); } +void uprobe_start_dup_mmap(void) +{ + percpu_down_read(&dup_mmap_sem); +} + +void uprobe_end_dup_mmap(void) +{ + percpu_up_read(&dup_mmap_sem); +} + void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) { newmm->uprobes_state.xol_area = NULL; @@ -1597,6 +1614,9 @@ static int __init init_uprobes(void) mutex_init(&uprobes_mmap_mutex[i]); } + if (percpu_init_rwsem(&dup_mmap_sem)) + return -ENOMEM; + return register_die_notifier(&uprobe_exception_nb); } module_init(init_uprobes); diff --git a/kernel/fork.c b/kernel/fork.c index 8b20ab7d3aa2..c497e57aa654 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -352,6 +352,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) unsigned long charge; struct mempolicy *pol; + uprobe_start_dup_mmap(); down_write(&oldmm->mmap_sem); flush_cache_dup_mm(oldmm); uprobe_dup_mmap(oldmm, mm); @@ -469,6 +470,7 @@ out: up_write(&mm->mmap_sem); flush_tlb_mm(oldmm); up_write(&oldmm->mmap_sem); + uprobe_end_dup_mmap(); return retval; fail_nomem_anon_vma_fork: mpol_put(pol); -- cgit v1.2.3-55-g7522