(Re-xmit) kprobes for i386

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diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .4156-linux-2.5.31/arch/i386/kernel/traps.c .4156-linux-2.5.31.updated/arch/i386/kernel/traps.c
@@ -24,6 +24,7 @@
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
 #include <linux/highmem.h>
+#include <linux/kprobes.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>

@@ -326,6 +327,8 @@ static void inline do_trap(int trapnr, i
 		panic("do_trap: can't hit this");
 	}
 #endif	
+	if (kprobe_running() && kprobe_fault_handler(regs, trapnr))
+		return;
 
 	if (!(regs->xcs & 3))
 		goto kernel_trap;

@@ -392,7 +395,6 @@ asmlinkage void do_##name(struct pt_regs
 }
 
 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)

@@ -408,6 +410,9 @@ asmlinkage void do_general_protection(st
 {
 	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;

@@ -508,6 +513,17 @@ asmlinkage void do_nmi(struct pt_regs * 
 	inb(0x71);		/* dummy */
 }
 
+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

@@ -530,7 +546,7 @@ asmlinkage void do_nmi(struct pt_regs * 
  * 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;

@@ -538,6 +554,12 @@ asmlinkage void do_debug(struct pt_regs 
 
 	__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])

@@ -588,15 +610,15 @@ clear_dr7:
 	__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;
 }
 
 /*

@@ -760,6 +782,8 @@ asmlinkage void math_state_restore(struc
 	struct task_struct *tsk = current;
 	clts();		/* Allow maths ops (or we recurse) */
 
+	if (kprobe_running() && kprobe_fault_handler(&regs, 7))
+		return;
 	if (!tsk->used_math)
 		init_fpu(tsk);
 	restore_fpu(tsk);

@@ -943,9 +967,9 @@ void __init trap_init(void)
 #endif
 
 	set_trap_gate(0,&divide_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 -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .4156-linux-2.5.31/arch/i386/mm/fault.c .4156-linux-2.5.31.updated/arch/i386/mm/fault.c
@@ -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>

@@ -155,6 +156,9 @@ asmlinkage void do_page_fault(struct pt_
 	/* 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 -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .4156-linux-2.5.31/include/asm-i386/kprobes.h .4156-linux-2.5.31.updated/include/asm-i386/kprobes.h
@@ -0,0 +1,34 @@
+#ifndef _ASM_KPROBES_H
+#define _ASM_KPROBES_H
+/*
+ *  Dynamic Probes (kprobes) support
+ *  	Vamsi Krishna S <[email protected]>, July, 2002
+ *	Mailing list: [email protected]
+ */
+#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 */

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