From: Prasanna S Panchamukhi - Kprobes structure has been modified to support copying of original instruction as required by the architecture. On x86_64 normal pages we get from kmalloc or vmalloc are not executable. Single-stepping an instruction on such a page yields an oops. So instead of storing the instruction copies in their respective kprobe objects, we allocate a page, map it executable, and store all the instruction copies there and store the pointer of the copied instruction in the specific kprobes object. - jprobe_return_end is moved into inline assembly to avoid compiler optimization. - arch_prepare_kprobe() now returns an integer,since arch_prepare_kprobe() might fail on other architectures. - added arch_remove_kprobe() routine, since other architectures requires it. Signed-off-by: Prasanna S Panchamukhi Signed-off-by: Andrew Morton --- 25-akpm/arch/i386/kernel/kprobes.c | 32 +++++++++++++++++++------------- 25-akpm/include/asm-i386/kprobes.h | 7 +++++++ 25-akpm/include/linux/kprobes.h | 5 +++-- 25-akpm/kernel/kprobes.c | 6 +++++- 4 files changed, 34 insertions(+), 16 deletions(-) diff -puN arch/i386/kernel/kprobes.c~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 arch/i386/kernel/kprobes.c --- 25/arch/i386/kernel/kprobes.c~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 Mon Nov 1 15:36:58 2004 +++ 25-akpm/arch/i386/kernel/kprobes.c Mon Nov 1 15:36:58 2004 @@ -42,6 +42,7 @@ static struct pt_regs jprobe_saved_regs; static long *jprobe_saved_esp; /* copy of the kernel stack at the probe fire time */ static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE]; +void jprobe_return_end(void); /* * returns non-zero if opcode modifies the interrupt flag. @@ -58,9 +59,14 @@ static inline int is_IF_modifier(kprobe_ return 0; } -void arch_prepare_kprobe(struct kprobe *p) +int arch_prepare_kprobe(struct kprobe *p) +{ + memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + return 0; +} + +void arch_remove_kprobe(struct kprobe *p) { - memcpy(p->insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); } static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs) @@ -73,7 +79,7 @@ static inline void prepare_singlestep(st { regs->eflags |= TF_MASK; regs->eflags &= ~IF_MASK; - regs->eip = (unsigned long)&p->insn; + regs->eip = (unsigned long)&p->ainsn.insn; } /* @@ -153,7 +159,7 @@ static inline int kprobe_handler(struct * instruction. To avoid the SMP problems that can occur when we * temporarily put back the original opcode to single-step, we * single-stepped a copy of the instruction. The address of this - * copy is p->insn. + * copy is p->ainsn.insn. * * This function prepares to return from the post-single-step * interrupt. We have to fix up the stack as follows: @@ -173,10 +179,10 @@ static void resume_execution(struct kpro { unsigned long *tos = (unsigned long *)®s->esp; unsigned long next_eip = 0; - unsigned long copy_eip = (unsigned long)&p->insn; + unsigned long copy_eip = (unsigned long)&p->ainsn.insn; unsigned long orig_eip = (unsigned long)p->addr; - switch (p->insn[0]) { + switch (p->ainsn.insn[0]) { case 0x9c: /* pushfl */ *tos &= ~(TF_MASK | IF_MASK); *tos |= kprobe_old_eflags; @@ -185,13 +191,13 @@ static void resume_execution(struct kpro *tos = orig_eip + (*tos - copy_eip); break; case 0xff: - if ((p->insn[1] & 0x30) == 0x10) { + if ((p->ainsn.insn[1] & 0x30) == 0x10) { /* call absolute, indirect */ /* Fix return addr; eip is correct. */ next_eip = regs->eip; *tos = orig_eip + (*tos - copy_eip); - } else if (((p->insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ - ((p->insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ + } else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ + ((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ /* eip is correct. */ next_eip = regs->eip; } @@ -315,12 +321,12 @@ void jprobe_return(void) { preempt_enable_no_resched(); asm volatile (" xchgl %%ebx,%%esp \n" - " int3 \n"::"b" + " int3 \n" + " .globl jprobe_return_end \n" + " jprobe_return_end: \n" + " nop \n"::"b" (jprobe_saved_esp):"memory"); } -void jprobe_return_end(void) -{ -}; int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { diff -puN include/asm-i386/kprobes.h~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 include/asm-i386/kprobes.h --- 25/include/asm-i386/kprobes.h~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 Mon Nov 1 15:36:58 2004 +++ 25-akpm/include/asm-i386/kprobes.h Mon Nov 1 15:36:58 2004 @@ -38,6 +38,13 @@ typedef u8 kprobe_opcode_t; ? (MAX_STACK_SIZE) \ : (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR))) +/* Architecture specific copy of original instruction*/ +struct arch_specific_insn { + /* copy of the original instruction */ + kprobe_opcode_t insn[MAX_INSN_SIZE]; +}; + + /* trap3/1 are intr gates for kprobes. So, restore the status of IF, * if necessary, before executing the original int3/1 (trap) handler. */ diff -puN include/linux/kprobes.h~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 include/linux/kprobes.h --- 25/include/linux/kprobes.h~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 Mon Nov 1 15:36:58 2004 +++ 25-akpm/include/linux/kprobes.h Mon Nov 1 15:36:58 2004 @@ -64,7 +64,7 @@ struct kprobe { kprobe_opcode_t opcode; /* copy of the original instruction */ - kprobe_opcode_t insn[MAX_INSN_SIZE]; + struct arch_specific_insn ainsn; }; /* @@ -94,7 +94,8 @@ static inline int kprobe_running(void) return kprobe_cpu == smp_processor_id(); } -extern void arch_prepare_kprobe(struct kprobe *p); +extern int arch_prepare_kprobe(struct kprobe *p); +extern void arch_remove_kprobe(struct kprobe *p); extern void show_registers(struct pt_regs *regs); /* Get the kprobe at this addr (if any). Must have called lock_kprobes */ diff -puN kernel/kprobes.c~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 kernel/kprobes.c --- 25/kernel/kprobes.c~kprobes-minor-i386-changes-required-for-porting-kprobes-to-x86_64 Mon Nov 1 15:36:58 2004 +++ 25-akpm/kernel/kprobes.c Mon Nov 1 15:36:58 2004 @@ -84,10 +84,13 @@ int register_kprobe(struct kprobe *p) ret = -EEXIST; goto out; } + + if ((ret = arch_prepare_kprobe(p)) != 0) { + goto out; + } hlist_add_head(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); - arch_prepare_kprobe(p); p->opcode = *p->addr; *p->addr = BREAKPOINT_INSTRUCTION; flush_icache_range((unsigned long) p->addr, @@ -101,6 +104,7 @@ void unregister_kprobe(struct kprobe *p) { unsigned long flags; spin_lock_irqsave(&kprobe_lock, flags); + arch_remove_kprobe(p); *p->addr = p->opcode; hlist_del(&p->hlist); flush_icache_range((unsigned long) p->addr, _