Hello, Test builds: f18: http://koji.fedoraproject.org/koji/taskinfo?taskID=4635065 f17: http://koji.fedoraproject.org/koji/taskinfo?taskID=4635062 The split-out series is available in the git repository at: http://fedorapeople.org/cgit/aarapov/public_git/kernel-uprobes.git Just <at> jistone's patch is not upstream that exports functions. Yes, I know it must go to upstream. :-) I will try to do what I can before the next uprobes update. --------------------------------------------------------------- Josh Stone (1): uprobes: add exports necessary for uprobes use by modules Oleg Nesterov (35): uprobes: Kill uprobes_state->count uprobes: Kill dup_mmap()->uprobe_mmap(), simplify uprobe_mmap/munmap uprobes: Change uprobe_mmap() to ignore the errors but check fatal_signal_pending() uprobes: Do not use -EEXIST in install_breakpoint() paths uprobes: Introduce MMF_HAS_UPROBES uprobes: Fold uprobe_reset_state() into uprobe_dup_mmap() uprobes: Remove "verify" argument from set_orig_insn() uprobes: uprobes_treelock should not disable irqs uprobes: Introduce MMF_RECALC_UPROBES uprobes: Teach find_active_uprobe() to clear MMF_HAS_UPROBES ptrace/x86: Introduce set_task_blockstep() helper ptrace/x86: Partly fix set_task_blockstep()->update_debugctlmsr() logic uprobes/x86: Do not (ab)use TIF_SINGLESTEP/user_*_single_step() for single-stepping uprobes/x86: Xol should send SIGTRAP if X86_EFLAGS_TF was set uprobes/x86: Fix arch_uprobe_disable_step() && UTASK_SSTEP_TRAPPED interaction uprobes: Make arch_uprobe_task->saved_trap_nr "unsigned int" uprobes: Do not leak UTASK_BP_HIT if find_active_uprobe() fails uprobes: Do not setup ->active_uprobe/state prematurely uprobes: Fix UPROBE_SKIP_SSTEP checks in handle_swbp() uprobes: Kill UTASK_BP_HIT state uprobes: Move clear_thread_flag(TIF_UPROBE) to uprobe_notify_resume() uprobes: Change write_opcode() to use FOLL_FORCE uprobes: Change valid_vma() to demand VM_MAYEXEC rather than VM_EXEC uprobes: Restrict valid_vma(false) to skip VM_SHARED vmas uprobes: Kill set_swbp()->is_swbp_at_addr() uprobes: Introduce copy_opcode(), kill read_opcode() uprobes: Kill set_orig_insn()->is_swbp_at_addr() uprobes: Simplify is_swbp_at_addr(), remove stale comments uprobes/x86: Only rep+nop can be emulated correctly uprobes: Don't return success if alloc_uprobe() fails uprobes: Do not delete uprobe if uprobe_unregister() fails uprobes: Fix handle_swbp() vs unregister() + register() race uprobes: Introduce prepare_uprobe() uprobes: Fix prepare_uprobe() race with itself uprobes: Fix the racy uprobe->flags manipulation Sebastian Andrzej Siewior (4): uprobes: Remove check for uprobe variable in handle_swbp() uprobes: Don't put NULL pointer in uprobe_register() uprobes: Introduce arch_uprobe_enable/disable_step() uprobes/x86: Implement x86 specific arch_uprobe_*_step Srikar Dronamraju (1): uprobes: Remove redundant lock_page/unlock_page arch/x86/include/asm/processor.h | 2 + arch/x86/include/asm/uprobes.h | 3 +- arch/x86/kernel/signal.c | 4 +- arch/x86/kernel/step.c | 53 ++-- arch/x86/kernel/uprobes.c | 64 ++++- include/linux/sched.h | 3 + include/linux/uprobes.h | 26 +- kernel/events/uprobes.c | 564 ++++++++++++++++++--------------------- kernel/fork.c | 6 +- kernel/ptrace.c | 6 + 10 files changed, 375 insertions(+), 356 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index d048cad..433d2e5 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -759,6 +759,8 @@ static inline void update_debugctlmsr(unsigned long debugctlmsr) wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctlmsr); } +extern void set_task_blockstep(struct task_struct *task, bool on); + /* * from system description table in BIOS. Mostly for MCA use, but * others may find it useful: diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index f3971bb..8ff8be7 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -42,10 +42,11 @@ struct arch_uprobe { }; struct arch_uprobe_task { - unsigned long saved_trap_nr; #ifdef CONFIG_X86_64 unsigned long saved_scratch_register; #endif + unsigned int saved_trap_nr; + unsigned int saved_tf; }; extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr); diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index b280908..0041e5a 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -785,10 +785,8 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) mce_notify_process(); #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ - if (thread_info_flags & _TIF_UPROBE) { - clear_thread_flag(TIF_UPROBE); + if (thread_info_flags & _TIF_UPROBE) uprobe_notify_resume(regs); - } /* deal with pending signal delivery */ if (thread_info_flags & _TIF_SIGPENDING) diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index c346d11..cd3b243 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -157,6 +157,33 @@ static int enable_single_step(struct task_struct *child) return 1; } +void set_task_blockstep(struct task_struct *task, bool on) +{ + unsigned long debugctl; + + /* + * Ensure irq/preemption can't change debugctl in between. + * Note also that both TIF_BLOCKSTEP and debugctl should + * be changed atomically wrt preemption. + * FIXME: this means that set/clear TIF_BLOCKSTEP is simply + * wrong if task != current, SIGKILL can wakeup the stopped + * tracee and set/clear can play with the running task, this + * can confuse the next __switch_to_xtra(). + */ + local_irq_disable(); + debugctl = get_debugctlmsr(); + if (on) { + debugctl |= DEBUGCTLMSR_BTF; + set_tsk_thread_flag(task, TIF_BLOCKSTEP); + } else { + debugctl &= ~DEBUGCTLMSR_BTF; + clear_tsk_thread_flag(task, TIF_BLOCKSTEP); + } + if (task == current) + update_debugctlmsr(debugctl); + local_irq_enable(); +} + /* * Enable single or block step. */ @@ -169,19 +196,10 @@ static void enable_step(struct task_struct *child, bool block) * So no one should try to use debugger block stepping in a program * that uses user-mode single stepping itself. */ - if (enable_single_step(child) && block) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl |= DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); - set_tsk_thread_flag(child, TIF_BLOCKSTEP); - } else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl &= ~DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); - clear_tsk_thread_flag(child, TIF_BLOCKSTEP); - } + if (enable_single_step(child) && block) + set_task_blockstep(child, true); + else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) + set_task_blockstep(child, false); } void user_enable_single_step(struct task_struct *child) @@ -199,13 +217,8 @@ void user_disable_single_step(struct task_struct *child) /* * Make sure block stepping (BTF) is disabled. */ - if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) { - unsigned long debugctl = get_debugctlmsr(); - - debugctl &= ~DEBUGCTLMSR_BTF; - update_debugctlmsr(debugctl); - clear_tsk_thread_flag(child, TIF_BLOCKSTEP); - } + if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) + set_task_blockstep(child, false); /* Always clear TIF_SINGLESTEP... */ clear_tsk_thread_flag(child, TIF_SINGLESTEP); diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 36fd420..aafa555 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -41,6 +41,9 @@ /* Adjust the return address of a call insn */ #define UPROBE_FIX_CALL 0x2 +/* Instruction will modify TF, don't change it */ +#define UPROBE_FIX_SETF 0x4 + #define UPROBE_FIX_RIP_AX 0x8000 #define UPROBE_FIX_RIP_CX 0x4000 @@ -239,6 +242,10 @@ static void prepare_fixups(struct arch_uprobe *auprobe, struct insn *insn) insn_get_opcode(insn); /* should be a nop */ switch (OPCODE1(insn)) { + case 0x9d: + /* popf */ + auprobe->fixups |= UPROBE_FIX_SETF; + break; case 0xc3: /* ret/lret */ case 0xcb: case 0xc2: @@ -644,32 +651,63 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) /* * Skip these instructions as per the currently known x86 ISA. - * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 } + * rep=0x66*; nop=0x90 */ -bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) { int i; for (i = 0; i < MAX_UINSN_BYTES; i++) { - if ((auprobe->insn[i] == 0x66)) + if (auprobe->insn[i] == 0x66) continue; if (auprobe->insn[i] == 0x90) return true; - if (i == (MAX_UINSN_BYTES - 1)) - break; + break; + } + return false; +} - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x1f)) - return true; +bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + bool ret = __skip_sstep(auprobe, regs); + if (ret && (regs->flags & X86_EFLAGS_TF)) + send_sig(SIGTRAP, current, 0); + return ret; +} - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x19)) - return true; +void arch_uprobe_enable_step(struct arch_uprobe *auprobe) +{ + struct task_struct *task = current; + struct arch_uprobe_task *autask = &task->utask->autask; + struct pt_regs *regs = task_pt_regs(task); - if ((auprobe->insn[i] == 0x87) && (auprobe->insn[i+1] == 0xc0)) - return true; + autask->saved_tf = !!(regs->flags & X86_EFLAGS_TF); - break; + regs->flags |= X86_EFLAGS_TF; + if (test_tsk_thread_flag(task, TIF_BLOCKSTEP)) + set_task_blockstep(task, false); +} + +void arch_uprobe_disable_step(struct arch_uprobe *auprobe) +{ + struct task_struct *task = current; + struct arch_uprobe_task *autask = &task->utask->autask; + bool trapped = (task->utask->state == UTASK_SSTEP_TRAPPED); + struct pt_regs *regs = task_pt_regs(task); + /* + * The state of TIF_BLOCKSTEP was not saved so we can get an extra + * SIGTRAP if we do not clear TF. We need to examine the opcode to + * make it right. + */ + if (unlikely(trapped)) { + if (!autask->saved_tf) + regs->flags &= ~X86_EFLAGS_TF; + } else { + if (autask->saved_tf) + send_sig(SIGTRAP, task, 0); + else if (!(auprobe->fixups & UPROBE_FIX_SETF)) + regs->flags &= ~X86_EFLAGS_TF; } - return false; } diff --git a/include/linux/sched.h b/include/linux/sched.h index 23bddac..ba300be 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -446,6 +446,9 @@ extern int get_dumpable(struct mm_struct *mm); #define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */ #define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */ +#define MMF_HAS_UPROBES 19 /* has uprobes */ +#define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */ + #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK) struct sighand_struct { diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index efe4b33..2459457 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -35,16 +35,6 @@ struct inode; # include <asm/uprobes.h> #endif -/* flags that denote/change uprobes behaviour */ - -/* Have a copy of original instruction */ -#define UPROBE_COPY_INSN 0x1 - -/* Dont run handlers when first register/ last unregister in progress*/ -#define UPROBE_RUN_HANDLER 0x2 -/* Can skip singlestep */ -#define UPROBE_SKIP_SSTEP 0x4 - struct uprobe_consumer { int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs); /* @@ -59,7 +49,6 @@ struct uprobe_consumer { #ifdef CONFIG_UPROBES enum uprobe_task_state { UTASK_RUNNING, - UTASK_BP_HIT, UTASK_SSTEP, UTASK_SSTEP_ACK, UTASK_SSTEP_TRAPPED, @@ -99,25 +88,27 @@ struct xol_area { struct uprobes_state { struct xol_area *xol_area; - atomic_t count; }; + extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr); -extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr, bool verify); +extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr); extern bool __weak is_swbp_insn(uprobe_opcode_t *insn); extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); 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_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); extern bool uprobe_deny_signal(void); extern bool __weak arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs); extern void uprobe_clear_state(struct mm_struct *mm); -extern void uprobe_reset_state(struct mm_struct *mm); #else /* !CONFIG_UPROBES */ struct uprobes_state { }; @@ -138,6 +129,10 @@ static inline void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { } +static inline void +uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) +{ +} static inline void uprobe_notify_resume(struct pt_regs *regs) { } @@ -158,8 +153,5 @@ static inline void uprobe_copy_process(struct task_struct *t) static inline void uprobe_clear_state(struct mm_struct *mm) { } -static inline void uprobe_reset_state(struct mm_struct *mm) -{ -} #endif /* !CONFIG_UPROBES */ #endif /* _LINUX_UPROBES_H */ diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index c08a22d..e933f65 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -27,6 +27,7 @@ #include <linux/pagemap.h> /* read_mapping_page */ #include <linux/slab.h> #include <linux/sched.h> +#include <linux/export.h> #include <linux/rmap.h> /* anon_vma_prepare */ #include <linux/mmu_notifier.h> /* set_pte_at_notify */ #include <linux/swap.h> /* try_to_free_swap */ @@ -78,15 +79,23 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; */ static atomic_t uprobe_events = ATOMIC_INIT(0); +/* Have a copy of original instruction */ +#define UPROBE_COPY_INSN 0 +/* Dont run handlers when first register/ last unregister in progress*/ +#define UPROBE_RUN_HANDLER 1 +/* Can skip singlestep */ +#define UPROBE_SKIP_SSTEP 2 + struct uprobe { struct rb_node rb_node; /* node in the rb tree */ atomic_t ref; struct rw_semaphore consumer_rwsem; + struct mutex copy_mutex; /* TODO: kill me and UPROBE_COPY_INSN */ struct list_head pending_list; struct uprobe_consumer *consumers; struct inode *inode; /* Also hold a ref to inode */ loff_t offset; - int flags; + unsigned long flags; struct arch_uprobe arch; }; @@ -100,17 +109,12 @@ struct uprobe { */ static bool valid_vma(struct vm_area_struct *vma, bool is_register) { - if (!vma->vm_file) - return false; + vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; - if (!is_register) - return true; + if (is_register) + flags |= VM_WRITE; - if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) - == (VM_READ|VM_EXEC)) - return true; - - return false; + return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; } static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) @@ -188,19 +192,44 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn) return *insn == UPROBE_SWBP_INSN; } +static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode) +{ + void *kaddr = kmap_atomic(page); + memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE); + kunmap_atomic(kaddr); +} + +static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) +{ + uprobe_opcode_t old_opcode; + bool is_swbp; + + copy_opcode(page, vaddr, &old_opcode); + is_swbp = is_swbp_insn(&old_opcode); + + if (is_swbp_insn(new_opcode)) { + if (is_swbp) /* register: already installed? */ + return 0; + } else { + if (!is_swbp) /* unregister: was it changed by us? */ + return 0; + } + + return 1; +} + /* * NOTE: * Expect the breakpoint instruction to be the smallest size instruction for * the architecture. If an arch has variable length instruction and the * breakpoint instruction is not of the smallest length instruction - * supported by that architecture then we need to modify read_opcode / + * supported by that architecture then we need to modify is_swbp_at_addr and * write_opcode accordingly. This would never be a problem for archs that * have fixed length instructions. */ /* * write_opcode - write the opcode at a given virtual address. - * @auprobe: arch breakpointing information. * @mm: the probed process address space. * @vaddr: the virtual address to store the opcode. * @opcode: opcode to be written at @vaddr. @@ -211,8 +240,8 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn) * For mm @mm, write the opcode at @vaddr. * Return 0 (success) or a negative errno. */ -static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, - unsigned long vaddr, uprobe_opcode_t opcode) +static int write_opcode(struct mm_struct *mm, unsigned long vaddr, + uprobe_opcode_t opcode) { struct page *old_page, *new_page; void *vaddr_old, *vaddr_new; @@ -221,10 +250,14 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, retry: /* Read the page with vaddr into memory */ - ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); + ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); if (ret <= 0) return ret; + ret = verify_opcode(old_page, vaddr, &opcode); + if (ret <= 0) + goto put_old; + ret = -ENOMEM; new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); if (!new_page) @@ -259,65 +292,6 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, } /** - * read_opcode - read the opcode at a given virtual address. - * @mm: the probed process address space. - * @vaddr: the virtual address to read the opcode. - * @opcode: location to store the read opcode. - * - * Called with mm->mmap_sem held (for read and with a reference to - * mm. - * - * For mm @mm, read the opcode at @vaddr and store it in @opcode. - * Return 0 (success) or a negative errno. - */ -static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) -{ - struct page *page; - void *vaddr_new; - int ret; - - ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); - if (ret <= 0) - return ret; - - lock_page(page); - vaddr_new = kmap_atomic(page); - vaddr &= ~PAGE_MASK; - memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); - kunmap_atomic(vaddr_new); - unlock_page(page); - - put_page(page); - - return 0; -} - -static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) -{ - uprobe_opcode_t opcode; - int result; - - if (current->mm == mm) { - pagefault_disable(); - result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, - sizeof(opcode)); - pagefault_enable(); - - if (likely(result == 0)) - goto out; - } - - result = read_opcode(mm, vaddr, &opcode); - if (result) - return result; -out: - if (is_swbp_insn(&opcode)) - return 1; - - return 0; -} - -/** * set_swbp - store breakpoint at a given address. * @auprobe: arch specific probepoint information. * @mm: the probed process address space. @@ -328,18 +302,7 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) */ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { - int result; - /* - * See the comment near uprobes_hash(). - */ - result = is_swbp_at_addr(mm, vaddr); - if (result == 1) - return -EEXIST; - - if (result) - return result; - - return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); + return write_opcode(mm, vaddr, UPROBE_SWBP_INSN); } /** @@ -347,25 +310,14 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned * @mm: the probed process address space. * @auprobe: arch specific probepoint information. * @vaddr: the virtual address to insert the opcode. - * @verify: if true, verify existance of breakpoint instruction. * * For mm @mm, restore the original opcode (opcode) at @vaddr. * Return 0 (success) or a negative errno. */ int __weak -set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify) +set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { - if (verify) { - int result; - - result = is_swbp_at_addr(mm, vaddr); - if (!result) - return -EINVAL; - - if (result != 1) - return result; - } - return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); + return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); } static int match_uprobe(struct uprobe *l, struct uprobe *r) @@ -415,11 +367,10 @@ static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) { struct uprobe *uprobe; - unsigned long flags; - spin_lock_irqsave(&uprobes_treelock, flags); + spin_lock(&uprobes_treelock); uprobe = __find_uprobe(inode, offset); - spin_unlock_irqrestore(&uprobes_treelock, flags); + spin_unlock(&uprobes_treelock); return uprobe; } @@ -466,15 +417,14 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe) */ static struct uprobe *insert_uprobe(struct uprobe *uprobe) { - unsigned long flags; struct uprobe *u; - spin_lock_irqsave(&uprobes_treelock, flags); + spin_lock(&uprobes_treelock); u = __insert_uprobe(uprobe); - spin_unlock_irqrestore(&uprobes_treelock, flags); + spin_unlock(&uprobes_treelock); /* For now assume that the instruction need not be single-stepped */ - uprobe->flags |= UPROBE_SKIP_SSTEP; + __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); return u; } @@ -496,6 +446,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) uprobe->inode = igrab(inode); uprobe->offset = offset; init_rwsem(&uprobe->consumer_rwsem); + mutex_init(&uprobe->copy_mutex); /* add to uprobes_tree, sorted on inode:offset */ cur_uprobe = insert_uprobe(uprobe); @@ -516,7 +467,7 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) { struct uprobe_consumer *uc; - if (!(uprobe->flags & UPROBE_RUN_HANDLER)) + if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags)) return; down_read(&uprobe->consumer_rwsem); @@ -622,33 +573,48 @@ static int copy_insn(struct uprobe *uprobe, struct file *filp) return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); } -/* - * How mm->uprobes_state.count gets updated - * uprobe_mmap() increments the count if - * - it successfully adds a breakpoint. - * - it cannot add a breakpoint, but sees that there is a underlying - * breakpoint (via a is_swbp_at_addr()). - * - * uprobe_munmap() decrements the count if - * - it sees a underlying breakpoint, (via is_swbp_at_addr) - * (Subsequent uprobe_unregister wouldnt find the breakpoint - * unless a uprobe_mmap kicks in, since the old vma would be - * dropped just after uprobe_munmap.) - * - * uprobe_register increments the count if: - * - it successfully adds a breakpoint. - * - * uprobe_unregister decrements the count if: - * - it sees a underlying breakpoint and removes successfully. - * (via is_swbp_at_addr) - * (Subsequent uprobe_munmap wouldnt find the breakpoint - * since there is no underlying breakpoint after the - * breakpoint removal.) - */ +static int prepare_uprobe(struct uprobe *uprobe, struct file *file, + struct mm_struct *mm, unsigned long vaddr) +{ + int ret = 0; + + if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) + return ret; + + mutex_lock(&uprobe->copy_mutex); + if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) + goto out; + + ret = copy_insn(uprobe, file); + if (ret) + goto out; + + ret = -ENOTSUPP; + if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) + goto out; + + ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); + if (ret) + goto out; + + /* write_opcode() assumes we don't cross page boundary */ + BUG_ON((uprobe->offset & ~PAGE_MASK) + + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); + + smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ + set_bit(UPROBE_COPY_INSN, &uprobe->flags); + + out: + mutex_unlock(&uprobe->copy_mutex); + + return ret; +} + static int install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, struct vm_area_struct *vma, unsigned long vaddr) { + bool first_uprobe; int ret; /* @@ -659,48 +625,38 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, * Hence behave as if probe already existed. */ if (!uprobe->consumers) - return -EEXIST; - - if (!(uprobe->flags & UPROBE_COPY_INSN)) { - ret = copy_insn(uprobe, vma->vm_file); - if (ret) - return ret; - - if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) - return -ENOTSUPP; - - ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); - if (ret) - return ret; - - /* write_opcode() assumes we don't cross page boundary */ - BUG_ON((uprobe->offset & ~PAGE_MASK) + - UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); + return 0; - uprobe->flags |= UPROBE_COPY_INSN; - } + ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); + if (ret) + return ret; /* - * Ideally, should be updating the probe count after the breakpoint - * has been successfully inserted. However a thread could hit the - * breakpoint we just inserted even before the probe count is - * incremented. If this is the first breakpoint placed, breakpoint - * notifier might ignore uprobes and pass the trap to the thread. - * Hence increment before and decrement on failure. + * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), + * the task can hit this breakpoint right after __replace_page(). */ - atomic_inc(&mm->uprobes_state.count); + first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); + if (first_uprobe) + set_bit(MMF_HAS_UPROBES, &mm->flags); + ret = set_swbp(&uprobe->arch, mm, vaddr); - if (ret) - atomic_dec(&mm->uprobes_state.count); + if (!ret) + clear_bit(MMF_RECALC_UPROBES, &mm->flags); + else if (first_uprobe) + clear_bit(MMF_HAS_UPROBES, &mm->flags); return ret; } -static void +static int remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) { - if (!set_orig_insn(&uprobe->arch, mm, vaddr, true)) - atomic_dec(&mm->uprobes_state.count); + /* can happen if uprobe_register() fails */ + if (!test_bit(MMF_HAS_UPROBES, &mm->flags)) + return 0; + + set_bit(MMF_RECALC_UPROBES, &mm->flags); + return set_orig_insn(&uprobe->arch, mm, vaddr); } /* @@ -710,11 +666,9 @@ remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vad */ static void delete_uprobe(struct uprobe *uprobe) { - unsigned long flags; - - spin_lock_irqsave(&uprobes_treelock, flags); + spin_lock(&uprobes_treelock); rb_erase(&uprobe->rb_node, &uprobes_tree); - spin_unlock_irqrestore(&uprobes_treelock, flags); + spin_unlock(&uprobes_treelock); iput(uprobe->inode); put_uprobe(uprobe); atomic_dec(&uprobe_events); @@ -818,7 +772,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) struct mm_struct *mm = info->mm; struct vm_area_struct *vma; - if (err) + if (err && is_register) goto free; down_write(&mm->mmap_sem); @@ -831,17 +785,11 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) vaddr_to_offset(vma, info->vaddr) != uprobe->offset) goto unlock; - if (is_register) { + if (is_register) err = install_breakpoint(uprobe, mm, vma, info->vaddr); - /* - * We can race against uprobe_mmap(), see the - * comment near uprobe_hash(). - */ - if (err == -EEXIST) - err = 0; - } else { - remove_breakpoint(uprobe, mm, info->vaddr); - } + else + err |= remove_breakpoint(uprobe, mm, info->vaddr); + unlock: up_write(&mm->mmap_sem); free: @@ -897,21 +845,25 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * mutex_lock(uprobes_hash(inode)); uprobe = alloc_uprobe(inode, offset); - if (uprobe && !consumer_add(uprobe, uc)) { + if (!uprobe) { + ret = -ENOMEM; + } else if (!consumer_add(uprobe, uc)) { ret = __uprobe_register(uprobe); if (ret) { uprobe->consumers = NULL; __uprobe_unregister(uprobe); } else { - uprobe->flags |= UPROBE_RUN_HANDLER; + set_bit(UPROBE_RUN_HANDLER, &uprobe->flags); } } mutex_unlock(uprobes_hash(inode)); - put_uprobe(uprobe); + if (uprobe) + put_uprobe(uprobe); return ret; } +EXPORT_SYMBOL_GPL(uprobe_register); /* * uprobe_unregister - unregister a already registered probe. @@ -935,7 +887,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume if (consumer_del(uprobe, uc)) { if (!uprobe->consumers) { __uprobe_unregister(uprobe); - uprobe->flags &= ~UPROBE_RUN_HANDLER; + clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags); } } @@ -943,6 +895,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume if (uprobe) put_uprobe(uprobe); } +EXPORT_SYMBOL_GPL(uprobe_unregister); static struct rb_node * find_node_in_range(struct inode *inode, loff_t min, loff_t max) @@ -978,7 +931,6 @@ static void build_probe_list(struct inode *inode, struct list_head *head) { loff_t min, max; - unsigned long flags; struct rb_node *n, *t; struct uprobe *u; @@ -986,7 +938,7 @@ static void build_probe_list(struct inode *inode, min = vaddr_to_offset(vma, start); max = min + (end - start) - 1; - spin_lock_irqsave(&uprobes_treelock, flags); + spin_lock(&uprobes_treelock); n = find_node_in_range(inode, min, max); if (n) { for (t = n; t; t = rb_prev(t)) { @@ -1004,27 +956,20 @@ static void build_probe_list(struct inode *inode, atomic_inc(&u->ref); } } - spin_unlock_irqrestore(&uprobes_treelock, flags); + spin_unlock(&uprobes_treelock); } /* - * Called from mmap_region. - * called with mm->mmap_sem acquired. - * - * Return -ve no if we fail to insert probes and we cannot - * bail-out. - * Return 0 otherwise. i.e: + * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. * - * - successful insertion of probes - * - (or) no possible probes to be inserted. - * - (or) insertion of probes failed but we can bail-out. + * Currently we ignore all errors and always return 0, the callers + * can't handle the failure anyway. */ int uprobe_mmap(struct vm_area_struct *vma) { struct list_head tmp_list; struct uprobe *uprobe, *u; struct inode *inode; - int ret, count; if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) return 0; @@ -1036,44 +981,35 @@ int uprobe_mmap(struct vm_area_struct *vma) mutex_lock(uprobes_mmap_hash(inode)); build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); - ret = 0; - count = 0; - list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { - if (!ret) { + if (!fatal_signal_pending(current)) { unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); - - ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); - /* - * We can race against uprobe_register(), see the - * comment near uprobe_hash(). - */ - if (ret == -EEXIST) { - ret = 0; - - if (!is_swbp_at_addr(vma->vm_mm, vaddr)) - continue; - - /* - * Unable to insert a breakpoint, but - * breakpoint lies underneath. Increment the - * probe count. - */ - atomic_inc(&vma->vm_mm->uprobes_state.count); - } - - if (!ret) - count++; + install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); } put_uprobe(uprobe); } - mutex_unlock(uprobes_mmap_hash(inode)); - if (ret) - atomic_sub(count, &vma->vm_mm->uprobes_state.count); + return 0; +} - return ret; +static bool +vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) +{ + loff_t min, max; + struct inode *inode; + struct rb_node *n; + + inode = vma->vm_file->f_mapping->host; + + min = vaddr_to_offset(vma, start); + max = min + (end - start) - 1; + + spin_lock(&uprobes_treelock); + n = find_node_in_range(inode, min, max); + spin_unlock(&uprobes_treelock); + + return !!n; } /* @@ -1081,37 +1017,18 @@ int uprobe_mmap(struct vm_area_struct *vma) */ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { - struct list_head tmp_list; - struct uprobe *uprobe, *u; - struct inode *inode; - if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) return; if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ return; - if (!atomic_read(&vma->vm_mm->uprobes_state.count)) - return; - - inode = vma->vm_file->f_mapping->host; - if (!inode) + if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || + test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) return; - mutex_lock(uprobes_mmap_hash(inode)); - build_probe_list(inode, vma, start, end, &tmp_list); - - list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { - unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); - /* - * An unregister could have removed the probe before - * unmap. So check before we decrement the count. - */ - if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1) - atomic_dec(&vma->vm_mm->uprobes_state.count); - put_uprobe(uprobe); - } - mutex_unlock(uprobes_mmap_hash(inode)); + if (vma_has_uprobes(vma, start, end)) + set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); } /* Slot allocation for XOL */ @@ -1213,13 +1130,15 @@ void uprobe_clear_state(struct mm_struct *mm) kfree(area); } -/* - * uprobe_reset_state - Free the area allocated for slots. - */ -void uprobe_reset_state(struct mm_struct *mm) +void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) { - mm->uprobes_state.xol_area = NULL; - atomic_set(&mm->uprobes_state.count, 0); + newmm->uprobes_state.xol_area = NULL; + + if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { + set_bit(MMF_HAS_UPROBES, &newmm->flags); + /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ + set_bit(MMF_RECALC_UPROBES, &newmm->flags); + } } /* @@ -1430,13 +1349,57 @@ bool uprobe_deny_signal(void) */ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) { - if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) - return true; - - uprobe->flags &= ~UPROBE_SKIP_SSTEP; + if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) { + if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) + return true; + clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); + } return false; } +static void mmf_recalc_uprobes(struct mm_struct *mm) +{ + struct vm_area_struct *vma; + + for (vma = mm->mmap; vma; vma = vma->vm_next) { + if (!valid_vma(vma, false)) + continue; + /* + * This is not strictly accurate, we can race with + * uprobe_unregister() and see the already removed + * uprobe if delete_uprobe() was not yet called. + */ + if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) + return; + } + + clear_bit(MMF_HAS_UPROBES, &mm->flags); +} + +static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) +{ + struct page *page; + uprobe_opcode_t opcode; + int result; + + pagefault_disable(); + result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, + sizeof(opcode)); + pagefault_enable(); + + if (likely(result == 0)) + goto out; + + result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); + if (result < 0) + return result; + + copy_opcode(page, vaddr, &opcode); + put_page(page); + out: + return is_swbp_insn(&opcode); +} + static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) { struct mm_struct *mm = current->mm; @@ -1458,11 +1421,24 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) } else { *is_swbp = -EFAULT; } + + if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) + mmf_recalc_uprobes(mm); up_read(&mm->mmap_sem); return uprobe; } +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); +} + /* * Run handler and ask thread to singlestep. * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. @@ -1494,41 +1470,42 @@ static void handle_swbp(struct pt_regs *regs) } return; } + /* + * TODO: move copy_insn/etc into _register and remove this hack. + * After we hit the bp, _unregister + _register can install the + * new and not-yet-analyzed uprobe at the same address, restart. + */ + smp_rmb(); /* pairs with wmb() in install_breakpoint() */ + if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) + goto restart; utask = current->utask; if (!utask) { utask = add_utask(); /* Cannot allocate; re-execute the instruction. */ if (!utask) - goto cleanup_ret; + goto restart; } - utask->active_uprobe = uprobe; + handler_chain(uprobe, regs); - if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) - goto cleanup_ret; + if (can_skip_sstep(uprobe, regs)) + goto out; - utask->state = UTASK_SSTEP; if (!pre_ssout(uprobe, regs, bp_vaddr)) { - user_enable_single_step(current); + arch_uprobe_enable_step(&uprobe->arch); + utask->active_uprobe = uprobe; + utask->state = UTASK_SSTEP; return; } -cleanup_ret: - if (utask) { - utask->active_uprobe = NULL; - utask->state = UTASK_RUNNING; - } - if (uprobe) { - if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) - - /* - * cannot singlestep; cannot skip instruction; - * re-execute the instruction. - */ - instruction_pointer_set(regs, bp_vaddr); - - put_uprobe(uprobe); - } +restart: + /* + * cannot singlestep; cannot skip instruction; + * re-execute the instruction. + */ + instruction_pointer_set(regs, bp_vaddr); +out: + put_uprobe(uprobe); } /* @@ -1547,10 +1524,10 @@ 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; - user_disable_single_step(current); xol_free_insn_slot(current); spin_lock_irq(&current->sighand->siglock); @@ -1559,13 +1536,12 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) } /* - * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on - * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and - * allows the thread to return from interrupt. + * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and + * allows the thread to return from interrupt. After that handle_swbp() + * sets utask->active_uprobe. * - * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and - * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from - * interrupt. + * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag + * and allows the thread to return from interrupt. * * While returning to userspace, thread notices the TIF_UPROBE flag and calls * uprobe_notify_resume(). @@ -1574,11 +1550,13 @@ void uprobe_notify_resume(struct pt_regs *regs) { struct uprobe_task *utask; + clear_thread_flag(TIF_UPROBE); + utask = current->utask; - if (!utask || utask->state == UTASK_BP_HIT) - handle_swbp(regs); - else + if (utask && utask->active_uprobe) handle_singlestep(utask, regs); + else + handle_swbp(regs); } /* @@ -1587,18 +1565,10 @@ void uprobe_notify_resume(struct pt_regs *regs) */ int uprobe_pre_sstep_notifier(struct pt_regs *regs) { - struct uprobe_task *utask; - - if (!current->mm || !atomic_read(&current->mm->uprobes_state.count)) - /* task is currently not uprobed */ + if (!current->mm || !test_bit(MMF_HAS_UPROBES, &current->mm->flags)) return 0; - utask = current->utask; - if (utask) - utask->state = UTASK_BP_HIT; - set_thread_flag(TIF_UPROBE); - return 1; } diff --git a/kernel/fork.c b/kernel/fork.c index 2c8857e..2343c9e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -353,6 +353,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) down_write(&oldmm->mmap_sem); flush_cache_dup_mm(oldmm); + uprobe_dup_mmap(oldmm, mm); /* * Not linked in yet - no deadlock potential: */ @@ -454,9 +455,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) if (retval) goto out; - - if (file) - uprobe_mmap(tmp); } /* a new mm has just been created */ arch_dup_mmap(oldmm, mm); @@ -839,8 +837,6 @@ struct mm_struct *dup_mm(struct task_struct *tsk) #ifdef CONFIG_TRANSPARENT_HUGEPAGE mm->pmd_huge_pte = NULL; #endif - uprobe_reset_state(mm); - if (!mm_init(mm, tsk)) goto fail_nomem; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index a232bb5..764fcd1 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -33,6 +33,12 @@ static int ptrace_trapping_sleep_fn(void *flags) } /* + * This is declared in linux/regset.h and defined in machine-dependent + * code. We put the export here to ensure no machine forgets it. + */ +EXPORT_SYMBOL_GPL(task_user_regset_view); + +/* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. *