This is the same patch Rusty has been sending you for a while,
rediffed against 2.5.47-bk1.
This has incorporated all your feedback and DaveM's (who wanted
the arch-indep bits for sparc).
Please apply,
Vamsi.
--Name: Kprobes for i386 Author: Vamsi Krishna S Status: Tested on 2.5.47 SMP
D: This patch allows trapping at almost any kernel address, useful for D: various kernel-hacking tasks, and building on for more D: infrastructure. This patch is x86 only, but other archs can add D: support as required. -- diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/Kconfig 47-bk1-kprobes/arch/i386/Kconfig --- 47-bk1-pure/arch/i386/Kconfig 2002-11-13 15:06:52.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/Kconfig 2002-11-13 15:07:16.000000000 +0530 @@ -1551,6 +1551,15 @@ Say Y here if you are developing drivers or trying to debug and identify kernel problems. +config KPROBES + bool "Kprobes" + depends on DEBUG_KERNEL + help + Kprobes allows you to trap at almost any kernel address, using + register_kprobe(), and providing a callback function. This is useful + for kernel debugging, non-intrusive instrumentation and testing. If + in doubt, say "N". + config DEBUG_STACKOVERFLOW bool "Check for stack overflows" depends on DEBUG_KERNEL diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/kernel/entry.S 47-bk1-kprobes/arch/i386/kernel/entry.S --- 47-bk1-pure/arch/i386/kernel/entry.S 2002-11-13 15:06:52.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/kernel/entry.S 2002-11-13 15:07:16.000000000 +0530 @@ -404,9 +404,16 @@ jmp ret_from_exception ENTRY(debug) + pushl $-1 # mark this as an int + SAVE_ALL + movl %esp,%edx pushl $0 - pushl $do_debug - jmp error_code + pushl %edx + call do_debug + addl $8,%esp + testl %eax,%eax + jnz restore_all + jmp ret_from_exception ENTRY(nmi) pushl %eax @@ -419,9 +426,16 @@ RESTORE_ALL ENTRY(int3) + pushl $-1 # mark this as an int + SAVE_ALL + movl %esp,%edx pushl $0 - pushl $do_int3 - jmp error_code + pushl %edx + call do_int3 + addl $8,%esp + testl %eax,%eax + jnz restore_all + jmp ret_from_exception ENTRY(overflow) pushl $0 diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/kernel/kprobes.c 47-bk1-kprobes/arch/i386/kernel/kprobes.c --- 47-bk1-pure/arch/i386/kernel/kprobes.c 1970-01-01 05:30:00.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/kernel/kprobes.c 2002-11-13 15:07:16.000000000 +0530 @@ -0,0 +1,160 @@ +/* + * Support for kernel probes. + * (C) 2002 Vamsi Krishna S <vamsi_krishna@in.ibm.com>. + */ + +#include <linux/config.h> +#include <linux/kprobes.h> +#include <linux/ptrace.h> +#include <linux/spinlock.h> +#include <linux/preempt.h> + +/* kprobe_status settings */ +#define KPROBE_HIT_ACTIVE 0x00000001 +#define KPROBE_HIT_SS 0x00000002 + +static struct kprobe *current_kprobe; +static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags; + +/* + * returns non-zero if opcode modifies the interrupt flag. + */ +static inline int is_IF_modifier(u8 opcode) +{ + switch(opcode) { + case 0xfa: /* cli */ + case 0xfb: /* sti */ + case 0xcf: /* iret/iretd */ + case 0x9d: /* popf/popfd */ + return 1; + } + return 0; +} + +static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + *p->addr = p->opcode; + regs->eip = (unsigned long)p->addr; +} + +/* + * Interrupts are disabled on entry as trap3 is an interrupt gate and they + * remain disabled thorough out this function. + */ +int kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p; + int ret = 0; + u8 *addr = (u8 *)(regs->eip-1); + + /* We're in an interrupt, but this is clear and BUG()-safe. */ + preempt_disable(); + + /* Check we're not actually recursing */ + if (kprobe_running()) { + /* We *are* holding lock here, so this is safe. + Disarm the probe we just hit, and ignore it. */ + p = get_kprobe(addr); + if (p) { + disarm_kprobe(p, regs); + ret = 1; + } + /* If it's not ours, can't be delete race, (we hold lock). */ + goto no_kprobe; + } + + lock_kprobes(); + p = get_kprobe(addr); + if (!p) { + unlock_kprobes(); + /* Unregistered (on another cpu) after this hit? Ignore */ + if (*addr != BREAKPOINT_INSTRUCTION) + ret = 1; + /* Not one of ours: let kernel handle it */ + goto no_kprobe; + } + + kprobe_status = KPROBE_HIT_ACTIVE; + current_kprobe = p; + kprobe_saved_eflags = kprobe_old_eflags + = (regs->eflags & (TF_MASK|IF_MASK)); + if (is_IF_modifier(p->opcode)) + kprobe_saved_eflags &= ~IF_MASK; + + p->pre_handler(p, regs); + + regs->eflags |= TF_MASK; + regs->eflags &= ~IF_MASK; + + /* We hold lock, now we remove breakpoint and single step. */ + disarm_kprobe(p, regs); + kprobe_status = KPROBE_HIT_SS; + return 1; + +no_kprobe: + preempt_enable_no_resched(); + return ret; +} + +static void rearm_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + regs->eflags &= ~TF_MASK; + *p->addr = BREAKPOINT_INSTRUCTION; +} + +/* + * Interrupts are disabled on entry as trap1 is an interrupt gate and they + * remain disabled thorough out this function. And we hold kprobe lock. + */ +int post_kprobe_handler(struct pt_regs *regs) +{ + if (!kprobe_running()) + return 0; + + if (current_kprobe->post_handler) + current_kprobe->post_handler(current_kprobe, regs, 0); + + /* + * We singlestepped with interrupts disabled. So, the result on + * the stack would be incorrect for "pushfl" instruction. + * Note that regs->esp is actually the top of the stack when the + * trap occurs in kernel space. + */ + if (current_kprobe->opcode == 0x9c) { /* pushfl */ + regs->esp &= ~(TF_MASK | IF_MASK); + regs->esp |= kprobe_old_eflags; + } + + rearm_kprobe(current_kprobe, regs); + regs->eflags |= kprobe_saved_eflags; + + unlock_kprobes(); + preempt_enable_no_resched(); + + /* + * if somebody else is singlestepping across a probe point, eflags + * will have TF set, in which case, continue the remaining processing + * of do_debug, as if this is not a probe hit. + */ + if (regs->eflags & TF_MASK) + return 0; + + return 1; +} + +/* Interrupts disabled, kprobe_lock held. */ +int kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + if (current_kprobe->fault_handler + && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) + return 1; + + if (kprobe_status & KPROBE_HIT_SS) { + rearm_kprobe(current_kprobe, regs); + regs->eflags |= kprobe_old_eflags; + + unlock_kprobes(); + preempt_enable_no_resched(); + } + return 0; +} diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/kernel/Makefile 47-bk1-kprobes/arch/i386/kernel/Makefile --- 47-bk1-pure/arch/i386/kernel/Makefile 2002-11-13 15:06:52.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/kernel/Makefile 2002-11-13 15:07:42.000000000 +0530 @@ -29,6 +29,7 @@ obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_EDD) += edd.o obj-$(CONFIG_MODULES) += module.o +obj-$(CONFIG_KPROBES) += kprobes.o EXTRA_AFLAGS := -traditional diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/kernel/traps.c 47-bk1-kprobes/arch/i386/kernel/traps.c --- 47-bk1-pure/arch/i386/kernel/traps.c 2002-11-13 15:06:52.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/kernel/traps.c 2002-11-13 15:07:16.000000000 +0530 @@ -23,6 +23,7 @@ #include <linux/spinlock.h> #include <linux/interrupt.h> #include <linux/highmem.h> +#include <linux/kprobes.h> #ifdef CONFIG_EISA #include <linux/ioport.h> @@ -403,7 +404,6 @@ } DO_VM86_ERROR_INFO( 0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->eip) -DO_VM86_ERROR( 3, SIGTRAP, "int3", int3) DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow) DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds) DO_ERROR_INFO( 6, SIGILL, "invalid operand", invalid_op, ILL_ILLOPN, regs->eip) @@ -419,6 +419,9 @@ { if (regs->eflags & VM_MASK) goto gp_in_vm86; + + if (kprobe_running() && kprobe_fault_handler(regs, 13)) + return; if (!(regs->xcs & 3)) goto gp_in_kernel; @@ -550,6 +553,17 @@ nmi_callback = dummy_nmi_callback; } +asmlinkage int do_int3(struct pt_regs *regs, long error_code) +{ + if (kprobe_handler(regs)) + return 1; + /* This is an interrupt gate, because kprobes wants interrupts + disabled. Normal trap handlers don't. */ + restore_interrupts(regs); + do_trap(3, SIGTRAP, "int3", 1, regs, error_code, NULL); + return 0; +} + /* * Our handling of the processor debug registers is non-trivial. * We do not clear them on entry and exit from the kernel. Therefore @@ -572,7 +586,7 @@ * find every occurrence of the TF bit that could be saved away even * by user code) */ -asmlinkage void do_debug(struct pt_regs * regs, long error_code) +asmlinkage int do_debug(struct pt_regs * regs, long error_code) { unsigned int condition; struct task_struct *tsk = current; @@ -580,6 +594,12 @@ __asm__ __volatile__("movl %%db6,%0" : "=r" (condition)); + if (post_kprobe_handler(regs)) + return 1; + + /* Interrupts not disabled for normal trap handling. */ + restore_interrupts(regs); + /* Mask out spurious debug traps due to lazy DR7 setting */ if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) { if (!tsk->thread.debugreg[7]) @@ -630,15 +650,15 @@ __asm__("movl %0,%%db7" : /* no output */ : "r" (0)); - return; + return 0; debug_vm86: handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1); - return; + return 0; clear_TF: regs->eflags &= ~TF_MASK; - return; + return 0; } /* @@ -802,6 +822,8 @@ struct task_struct *tsk = current; clts(); /* Allow maths ops (or we recurse) */ + if (kprobe_running() && kprobe_fault_handler(®s, 7)) + return; if (!tsk->used_math) init_fpu(tsk); restore_fpu(tsk); @@ -895,9 +917,9 @@ #endif set_trap_gate(0,÷_error); - set_trap_gate(1,&debug); + _set_gate(idt_table+1,14,3,&debug); /* debug trap for kprobes */ set_intr_gate(2,&nmi); - set_system_gate(3,&int3); /* int3-5 can be called from all */ + _set_gate(idt_table+3,14,3,&int3); /* int3-5 can be called from all */ set_system_gate(4,&overflow); set_system_gate(5,&bounds); set_trap_gate(6,&invalid_op); diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/arch/i386/mm/fault.c 47-bk1-kprobes/arch/i386/mm/fault.c --- 47-bk1-pure/arch/i386/mm/fault.c 2002-11-05 04:00:03.000000000 +0530 +++ 47-bk1-kprobes/arch/i386/mm/fault.c 2002-11-13 15:07:16.000000000 +0530 @@ -19,6 +19,7 @@ #include <linux/init.h> #include <linux/tty.h> #include <linux/vt_kern.h> /* For unblank_screen() */ +#include <linux/kprobes.h> #include <asm/system.h> #include <asm/uaccess.h> @@ -163,6 +164,9 @@ /* get the address */ __asm__("movl %%cr2,%0":"=r" (address)); + if (kprobe_running() && kprobe_fault_handler(regs, 14)) + return; + /* It's safe to allow irq's after cr2 has been saved */ if (regs->eflags & X86_EFLAGS_IF) local_irq_enable(); diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/include/asm-i386/kprobes.h 47-bk1-kprobes/include/asm-i386/kprobes.h --- 47-bk1-pure/include/asm-i386/kprobes.h 1970-01-01 05:30:00.000000000 +0530 +++ 47-bk1-kprobes/include/asm-i386/kprobes.h 2002-11-13 15:07:16.000000000 +0530 @@ -0,0 +1,34 @@ +#ifndef _ASM_KPROBES_H +#define _ASM_KPROBES_H +/* + * Dynamic Probes (kprobes) support + * Vamsi Krishna S <vamsi_krishna@in.ibm.com>, July, 2002 + * Mailing list: dprobes@www-124.ibm.com + */ +#include <linux/types.h> +#include <linux/ptrace.h> + +struct pt_regs; + +typedef u8 kprobe_opcode_t; +#define BREAKPOINT_INSTRUCTION 0xcc + +/* trap3/1 are intr gates for kprobes. So, restore the status of IF, + * if necessary, before executing the original int3/1 (trap) handler. + */ +static inline void restore_interrupts(struct pt_regs *regs) +{ + if (regs->eflags & IF_MASK) + __asm__ __volatile__ ("sti"); +} + +#ifdef CONFIG_KPROBES +extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); +extern int post_kprobe_handler(struct pt_regs *regs); +extern int kprobe_handler(struct pt_regs *regs); +#else /* !CONFIG_KPROBES */ +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) { return 0; } +static inline int post_kprobe_handler(struct pt_regs *regs) { return 0; } +static inline int kprobe_handler(struct pt_regs *regs) { return 0; } +#endif +#endif /* _ASM_KPROBES_H */ diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/include/linux/kprobes.h 47-bk1-kprobes/include/linux/kprobes.h --- 47-bk1-pure/include/linux/kprobes.h 1970-01-01 05:30:00.000000000 +0530 +++ 47-bk1-kprobes/include/linux/kprobes.h 2002-11-13 15:07:16.000000000 +0530 @@ -0,0 +1,60 @@ +#ifndef _LINUX_KPROBES_H +#define _LINUX_KPROBES_H +#include <linux/config.h> +#include <linux/list.h> +#include <linux/notifier.h> +#include <linux/smp.h> +#include <asm/kprobes.h> + +struct kprobe; +struct pt_regs; + +typedef void (*kprobe_pre_handler_t)(struct kprobe *, struct pt_regs *); +typedef void (*kprobe_post_handler_t)(struct kprobe *, struct pt_regs *, + unsigned long flags); +typedef int (*kprobe_fault_handler_t)(struct kprobe *, struct pt_regs *, + int trapnr); + +struct kprobe { + struct list_head list; + + /* location of the probe point */ + kprobe_opcode_t *addr; + + /* Called before addr is executed. */ + kprobe_pre_handler_t pre_handler; + + /* Called after addr is executed, unless... */ + kprobe_post_handler_t post_handler; + + /* ... called if executing addr causes a fault (eg. page fault). + * Return 1 if it handled fault, otherwise kernel will see it. */ + kprobe_fault_handler_t fault_handler; + + /* Saved opcode (which has been replaced with breakpoint) */ + kprobe_opcode_t opcode; +}; + +#ifdef CONFIG_KPROBES +/* Locks kprobe: irq must be disabled */ +void lock_kprobes(void); +void unlock_kprobes(void); + +/* kprobe running now on this CPU? */ +static inline int kprobe_running(void) +{ + extern unsigned int kprobe_cpu; + return kprobe_cpu == smp_processor_id(); +} + +/* Get the kprobe at this addr (if any). Must have called lock_kprobes */ +struct kprobe *get_kprobe(void *addr); + +int register_kprobe(struct kprobe *p); +void unregister_kprobe(struct kprobe *p); +#else +static inline int kprobe_running(void) { return 0; } +static inline int register_kprobe(struct kprobe *p) { return -ENOSYS; } +static inline void unregister_kprobe(struct kprobe *p) { } +#endif +#endif /* _LINUX_KPROBES_H */ diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/kernel/kprobes.c 47-bk1-kprobes/kernel/kprobes.c --- 47-bk1-pure/kernel/kprobes.c 1970-01-01 05:30:00.000000000 +0530 +++ 47-bk1-kprobes/kernel/kprobes.c 2002-11-13 15:07:16.000000000 +0530 @@ -0,0 +1,89 @@ +/* Support for kernel probes. + (C) 2002 Vamsi Krishna S <vamsi_krishna@in.ibm.com>. +*/ +#include <linux/kprobes.h> +#include <linux/spinlock.h> +#include <linux/hash.h> +#include <linux/init.h> +#include <linux/module.h> +#include <asm/cacheflush.h> +#include <asm/errno.h> + +#define KPROBE_HASH_BITS 6 +#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) + +static struct list_head kprobe_table[KPROBE_TABLE_SIZE]; + +unsigned int kprobe_cpu = NR_CPUS; +static spinlock_t kprobe_lock = SPIN_LOCK_UNLOCKED; + +/* Locks kprobe: irqs must be disabled */ +void lock_kprobes(void) +{ + spin_lock(&kprobe_lock); + kprobe_cpu = smp_processor_id(); +} + +void unlock_kprobes(void) +{ + kprobe_cpu = NR_CPUS; + spin_unlock(&kprobe_lock); +} + +/* You have to be holding the kprobe_lock */ +struct kprobe *get_kprobe(void *addr) +{ + struct list_head *head, *tmp; + + head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; + list_for_each(tmp, head) { + struct kprobe *p = list_entry(tmp, struct kprobe, list); + if (p->addr == addr) + return p; + } + return NULL; +} + +int register_kprobe(struct kprobe *p) +{ + int ret = 0; + + spin_lock_irq(&kprobe_lock); + if (get_kprobe(p->addr)) { + ret = -EEXIST; + goto out; + } + list_add(&p->list, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); + + p->opcode = *p->addr; + *p->addr = BREAKPOINT_INSTRUCTION; + flush_icache_range(p->addr, p->addr + sizeof(kprobe_opcode_t)); + out: + spin_unlock_irq(&kprobe_lock); + return ret; +} + +void unregister_kprobe(struct kprobe *p) +{ + spin_lock_irq(&kprobe_lock); + *p->addr = p->opcode; + list_del(&p->list); + flush_icache_range(p->addr, p->addr + sizeof(kprobe_opcode_t)); + spin_unlock_irq(&kprobe_lock); +} + +static int __init init_kprobes(void) +{ + int i; + + /* FIXME allocate the probe table, currently defined statically */ + /* initialize all list heads */ + for (i = 0; i < KPROBE_TABLE_SIZE; i++) + INIT_LIST_HEAD(&kprobe_table[i]); + + return 0; +} +__initcall(init_kprobes); + +EXPORT_SYMBOL_GPL(register_kprobe); +EXPORT_SYMBOL_GPL(unregister_kprobe); diff -urN -X /home/vamsi/.dontdiff 47-bk1-pure/kernel/Makefile 47-bk1-kprobes/kernel/Makefile --- 47-bk1-pure/kernel/Makefile 2002-11-13 15:06:55.000000000 +0530 +++ 47-bk1-kprobes/kernel/Makefile 2002-11-13 15:08:14.000000000 +0530 @@ -4,7 +4,7 @@ export-objs = signal.o sys.o kmod.o workqueue.o ksyms.o pm.o exec_domain.o \ printk.o platform.o suspend.o dma.o module.o cpufreq.o \ - profile.o rcupdate.o intermodule.o + profile.o rcupdate.o intermodule.o kprobes.o obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \ exit.o itimer.o time.o softirq.o resource.o \ @@ -21,6 +21,7 @@ obj-$(CONFIG_CPU_FREQ) += cpufreq.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o +obj-$(CONFIG_KPROBES) += kprobes.o ifneq ($(CONFIG_IA64),y) # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Nov 15 2002 - 22:00:28 EST