x86: kprobes code for x86 unification

This patch unifies kprobes code.

- Unify kprobes_*.h to kprobes.h
- Unify kprobes_*.c to kprobes.c
  (Differences are separated by ifdefs)
 - Most differences are related to REX prefix and rip relatives.
 - Two inline assembly code are different.
 - One difference in kprobe_handlre()
 - One fixup exception code is different, but it will be unified
   if mm/extable_*.c are unified.
- Merge history logs into arch/x86/kernel/kprobes.c.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/Makefile_32

@@ -35,7 +35,7 @@ obj-$(CONFIG_KEXEC)		+= machine_kexec_32.o relocate_kernel_32.o crash.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_32.o
 obj-$(CONFIG_X86_NUMAQ)		+= numaq_32.o
 obj-$(CONFIG_X86_SUMMIT_NUMA)	+= summit_32.o
-obj-$(CONFIG_KPROBES)		+= kprobes_32.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_MODULES)		+= module_32.o
 obj-$(CONFIG_ACPI_SRAT) 	+= srat_32.o
 obj-$(CONFIG_EFI) 		+= efi.o efi_32.o efi_stub_32.o

arch/x86/kernel/Makefile_64

@@ -34,7 +34,7 @@ obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_GART_IOMMU)	+= pci-gart_64.o aperture_64.o
 obj-$(CONFIG_CALGARY_IOMMU)	+= pci-calgary_64.o tce_64.o
 obj-$(CONFIG_SWIOTLB)		+= pci-swiotlb_64.o
-obj-$(CONFIG_KPROBES)		+= kprobes_64.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer_64.o
 obj-$(CONFIG_X86_VSMP)		+= vsmp_64.o
 obj-$(CONFIG_K8_NB)		+= k8.o

arch/x86/kernel/kprobes_64.c → arch/x86/kernel/kprobes.c

@@ -22,14 +22,22 @@
  *		Rusty Russell).
  * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  *		interface to access function arguments.
- * 2004-Oct	Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi
- *		<prasanna@in.ibm.com> adapted for x86_64
+ * 2004-Oct	Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ *		<prasanna@in.ibm.com> adapted for x86_64 from i386.
  * 2005-Mar	Roland McGrath <roland@redhat.com>
  *		Fixed to handle %rip-relative addressing mode correctly.
- * 2005-May     Rusty Lynch <rusty.lynch@intel.com>
- *              Added function return probes functionality
+ * 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.
+ * 2005-May	Rusty Lynch <rusty.lynch@intel.com>
+ * 		Added function return probes functionality
+ * 2006-Feb	Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
+ * 		kprobe-booster and kretprobe-booster for i386.
  * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
  * 		and kretprobe-booster for x86-64
+ * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
+ * 		<arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
+ * 		unified x86 kprobes code.
  */
 
 #include <linux/kprobes.h>
@@ -51,7 +59,19 @@ void jprobe_return_end(void);
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+#ifdef CONFIG_X86_64
 #define stack_addr(regs) ((unsigned long *)regs->sp)
+#else
+/*
+ * "&regs->sp" looks wrong, but it's correct for x86_32.  x86_32 CPUs
+ * don't save the ss and esp registers if the CPU is already in kernel
+ * mode when it traps.  So for kprobes, regs->sp and regs->ss are not
+ * the [nonexistent] saved stack pointer and ss register, but rather
+ * the top 8 bytes of the pre-int3 stack.  So &regs->sp happens to
+ * point to the top of the pre-int3 stack.
+ */
+#define stack_addr(regs) ((unsigned long *)&regs->sp)
+#endif
 
 #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
 	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
@@ -151,8 +171,8 @@ static __always_inline void set_jmp_op(void *from, void *to)
 }
 
 /*
- * returns non-zero if opcode is boostable.
- * RIP relative instructions are adjusted at copying time
+ * Returns non-zero if opcode is boostable.
+ * RIP relative instructions are adjusted at copying time in 64 bits mode
  */
 static __always_inline int can_boost(kprobe_opcode_t *opcodes)
 {
@@ -173,8 +193,10 @@ static __always_inline int can_boost(kprobe_opcode_t *opcodes)
 	}
 
 	switch (opcode & 0xf0) {
+#ifdef CONFIG_X86_64
 	case 0x40:
 		goto retry; /* REX prefix is boostable */
+#endif
 	case 0x60:
 		if (0x63 < opcode && opcode < 0x67)
 			goto retry; /* prefixes */
@@ -206,7 +228,7 @@ static __always_inline int can_boost(kprobe_opcode_t *opcodes)
 }
 
 /*
- * returns non-zero if opcode modifies the interrupt flag.
+ * Returns non-zero if opcode modifies the interrupt flag.
  */
 static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
 {
@@ -217,16 +239,18 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
 	case 0x9d:		/* popf/popfd */
 		return 1;
 	}
-
+#ifdef CONFIG_X86_64
 	/*
 	 * on 64 bit x86, 0x40-0x4f are prefixes so we need to look
 	 * at the next byte instead.. but of course not recurse infinitely
 	 */
 	if (*insn  >= 0x40 && *insn <= 0x4f)
 		return is_IF_modifier(++insn);
+#endif
 	return 0;
 }
 
+#ifdef CONFIG_X86_64
 /*
  * Adjust the displacement if the instruction uses the %rip-relative
  * addressing mode.
@@ -263,17 +287,20 @@ static void __kprobes fix_riprel(struct kprobe *p)
 	if ((*insn & 0xf0) == 0x40)
 		++insn;
 
-	if (*insn == 0x0f) {	/* Two-byte opcode.  */
+	if (*insn == 0x0f) {
+		/* Two-byte opcode.  */
 		++insn;
 		need_modrm = test_bit(*insn,
 				      (unsigned long *)twobyte_has_modrm);
-	} else			/* One-byte opcode.  */
+	} else
+		/* One-byte opcode.  */
 		need_modrm = test_bit(*insn,
 				      (unsigned long *)onebyte_has_modrm);
 
 	if (need_modrm) {
 		u8 modrm = *++insn;
-		if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */
+		if ((modrm & 0xc7) == 0x05) {
+			/* %rip+disp32 addressing mode */
 			/* Displacement follows ModRM byte.  */
 			++insn;
 			/*
@@ -296,11 +323,14 @@ static void __kprobes fix_riprel(struct kprobe *p)
 		}
 	}
 }
+#endif
 
 static void __kprobes arch_copy_kprobe(struct kprobe *p)
 {
 	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+#ifdef CONFIG_X86_64
 	fix_riprel(p);
+#endif
 	if (can_boost(p->addr))
 		p->ainsn.boostable = 0;
 	else
@@ -365,13 +395,13 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 static __always_inline void clear_btf(void)
 {
 	if (test_thread_flag(TIF_DEBUGCTLMSR))
-		wrmsrl(MSR_IA32_DEBUGCTLMSR, 0);
+		wrmsr(MSR_IA32_DEBUGCTLMSR, 0, 0);
 }
 
 static __always_inline void restore_btf(void)
 {
 	if (test_thread_flag(TIF_DEBUGCTLMSR))
-		wrmsrl(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr);
+		wrmsr(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr, 0);
 }
 
 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
@@ -427,6 +457,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 				regs->flags &= ~TF_MASK;
 				regs->flags |= kcb->kprobe_saved_flags;
 				goto no_kprobe;
+#ifdef CONFIG_X86_64
 			} else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) {
 				/* TODO: Provide re-entrancy from
 				 * post_kprobes_handler() and avoid exception
@@ -437,6 +468,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 				regs->ip = (unsigned long)p->addr;
 				reset_current_kprobe();
 				return 1;
+#endif
 			}
 			/* We have reentered the kprobe_handler(), since
 			 * another probe was hit while within the handler.
@@ -461,9 +493,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 				goto no_kprobe;
 			}
 			p = __get_cpu_var(current_kprobe);
-			if (p->break_handler && p->break_handler(p, regs)) {
+			if (p->break_handler && p->break_handler(p, regs))
 				goto ss_probe;
-			}
 		}
 		goto no_kprobe;
 	}
@@ -519,8 +550,10 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
  */
  void __kprobes kretprobe_trampoline_holder(void)
  {
- 	asm volatile (  ".global kretprobe_trampoline\n"
+	asm volatile (
+			".global kretprobe_trampoline\n"
 			"kretprobe_trampoline: \n"
+#ifdef CONFIG_X86_64
 			/* We don't bother saving the ss register */
 			"	pushq %rsp\n"
 			"	pushfq\n"
@@ -566,25 +599,64 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 			/* Skip orig_ax, ip, cs */
 			"	addq $24, %rsp\n"
 			"	popfq\n"
+#else
+			"	pushf\n"
+			/*
+			 * Skip cs, ip, orig_ax.
+			 * trampoline_handler() will plug in these values
+			 */
+			"	subl $12, %esp\n"
+			"	pushl %fs\n"
+			"	pushl %ds\n"
+			"	pushl %es\n"
+			"	pushl %eax\n"
+			"	pushl %ebp\n"
+			"	pushl %edi\n"
+			"	pushl %esi\n"
+			"	pushl %edx\n"
+			"	pushl %ecx\n"
+			"	pushl %ebx\n"
+			"	movl %esp, %eax\n"
+			"	call trampoline_handler\n"
+			/* Move flags to cs */
+			"	movl 52(%esp), %edx\n"
+			"	movl %edx, 48(%esp)\n"
+			/* Replace saved flags with true return address. */
+			"	movl %eax, 52(%esp)\n"
+			"	popl %ebx\n"
+			"	popl %ecx\n"
+			"	popl %edx\n"
+			"	popl %esi\n"
+			"	popl %edi\n"
+			"	popl %ebp\n"
+			"	popl %eax\n"
+			/* Skip ip, orig_ax, es, ds, fs */
+			"	addl $20, %esp\n"
+			"	popf\n"
+#endif
 			"	ret\n");
  }
 
 /*
  * Called from kretprobe_trampoline
  */
-fastcall void * __kprobes trampoline_handler(struct pt_regs *regs)
+void * __kprobes trampoline_handler(struct pt_regs *regs)
 {
 	struct kretprobe_instance *ri = NULL;
 	struct hlist_head *head, empty_rp;
 	struct hlist_node *node, *tmp;
 	unsigned long flags, orig_ret_address = 0;
-	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
+	unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 
 	INIT_HLIST_HEAD(&empty_rp);
 	spin_lock_irqsave(&kretprobe_lock, flags);
 	head = kretprobe_inst_table_head(current);
 	/* fixup registers */
+#ifdef CONFIG_X86_64
 	regs->cs = __KERNEL_CS;
+#else
+	regs->cs = __KERNEL_CS | get_kernel_rpl();
+#endif
 	regs->ip = trampoline_address;
 	regs->orig_ax = ~0UL;
 
@@ -671,9 +743,11 @@ static void __kprobes resume_execution(struct kprobe *p,
 	unsigned long orig_ip = (unsigned long)p->addr;
 	kprobe_opcode_t *insn = p->ainsn.insn;
 
+#ifdef CONFIG_X86_64
 	/*skip the REX prefix*/
 	if (*insn >= 0x40 && *insn <= 0x4f)
 		insn++;
+#endif
 
 	regs->flags &= ~TF_MASK;
 	switch (*insn) {
@@ -693,6 +767,11 @@ static void __kprobes resume_execution(struct kprobe *p,
 	case 0xe8:	/* call relative - Fix return addr */
 		*tos = orig_ip + (*tos - copy_ip);
 		break;
+#ifndef CONFIG_X86_64
+	case 0x9a:	/* call absolute -- same as call absolute, indirect */
+		*tos = orig_ip + (*tos - copy_ip);
+		goto no_change;
+#endif
 	case 0xff:
 		if ((insn[1] & 0x30) == 0x10) {
 			/*
@@ -783,9 +862,8 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-	const struct exception_table_entry *fixup;
 
-	switch(kcb->kprobe_status) {
+	switch (kcb->kprobe_status) {
 	case KPROBE_HIT_SS:
 	case KPROBE_REENTER:
 		/*
@@ -826,12 +904,19 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
-		fixup = search_exception_tables(regs->ip);
-		if (fixup) {
-			regs->ip = fixup->fixup;
-			return 1;
+#ifdef CONFIG_X86_64
+		{
+			const struct exception_table_entry *fixup;
+			fixup = search_exception_tables(regs->ip);
+			if (fixup) {
+				regs->ip = fixup->fixup;
+				return 1;
+			}
 		}
-
+#else
+		if (fixup_exception(regs))
+			return 1;
+#endif
 		/*
 		 * fixup routine could not handle it,
 		 * Let do_page_fault() fix it.
@@ -896,7 +981,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 	 * the argument area.
 	 */
 	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
-			MIN_STACK_SIZE(addr));
+	       MIN_STACK_SIZE(addr));
 	regs->flags &= ~IF_MASK;
 	trace_hardirqs_off();
 	regs->ip = (unsigned long)(jp->entry);
@@ -907,12 +992,17 @@ void __kprobes jprobe_return(void)
 {
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
-	asm volatile ("       xchg   %%rbx,%%rsp     \n"
-		      "       int3			\n"
-		      "       .globl jprobe_return_end	\n"
-		      "       jprobe_return_end:	\n"
-		      "       nop			\n"::"b"
-		      (kcb->jprobe_saved_sp):"memory");
+	asm volatile (
+#ifdef CONFIG_X86_64
+			"       xchg   %%rbx,%%rsp	\n"
+#else
+			"       xchgl   %%ebx,%%esp	\n"
+#endif
+			"       int3			\n"
+			"       .globl jprobe_return_end\n"
+			"       jprobe_return_end:	\n"
+			"       nop			\n"::"b"
+			(kcb->jprobe_saved_sp):"memory");
 }
 
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
@@ -921,14 +1011,16 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 	u8 *addr = (u8 *) (regs->ip - 1);
 	struct jprobe *jp = container_of(p, struct jprobe, kp);
 
-	if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
+	if ((addr > (u8 *) jprobe_return) &&
+	    (addr < (u8 *) jprobe_return_end)) {
 		if (stack_addr(regs) != kcb->jprobe_saved_sp) {
 			struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
-			printk("current sp %p does not match saved sp %p\n",
+			printk(KERN_ERR
+			       "current sp %p does not match saved sp %p\n",
 			       stack_addr(regs), kcb->jprobe_saved_sp);
-			printk("Saved registers for jprobe %p\n", jp);
+			printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
 			show_registers(saved_regs);
-			printk("Current registers\n");
+			printk(KERN_ERR "Current registers\n");
 			show_registers(regs);
 			BUG();
 		}