commit a10d9a71bafd3a283da240d2868e71346d2aef6f
Author: Peter Zijlstra <peterz@infradead.org>
Date:   Wed Jul 18 20:59:22 2007 +0200

    i386: fixup TRACE_IRQ breakage
    
    The TRACE_IRQS_ON function in iret_exc: calls a C function without
    ensuring that the segments are set properly. Move the trace function and
    the enabling of interrupt into the C stub.
    
    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Index: pardus-2.6/arch/i386/kernel/entry.S
===================================================================
--- pardus-2.6.orig/arch/i386/kernel/entry.S
+++ pardus-2.6/arch/i386/kernel/entry.S
@@ -384,8 +384,6 @@ restore_nocheck_notrace:
 1:	iret
 .section .fixup,"ax"
 iret_exc:
-	TRACE_IRQS_ON
-	sti
 	pushl $0			# no error code
 	pushl $do_iret_error
 	jmp error_code
Index: pardus-2.6/arch/i386/kernel/traps.c
===================================================================
--- pardus-2.6.orig/arch/i386/kernel/traps.c
+++ pardus-2.6/arch/i386/kernel/traps.c
@@ -516,10 +516,12 @@ fastcall void do_##name(struct pt_regs *
 	do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
 }
 
-#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
+#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr, irq) \
 fastcall void do_##name(struct pt_regs * regs, long error_code) \
 { \
 	siginfo_t info; \
+	if (irq) \
+		local_irq_enable(); \
 	info.si_signo = signr; \
 	info.si_errno = 0; \
 	info.si_code = sicode; \
@@ -559,13 +561,13 @@ DO_VM86_ERROR( 3, SIGTRAP, "int3", int3)
 #endif
 DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow)
 DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds)
-DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip)
+DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip, 0)
 DO_ERROR( 9, SIGFPE,  "coprocessor segment overrun", coprocessor_segment_overrun)
 DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)
 DO_ERROR(12, SIGBUS,  "stack segment", stack_segment)
-DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
-DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0)
+DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0, 0)
+DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0, 1)
 
 fastcall void __kprobes do_general_protection(struct pt_regs * regs,
 					      long error_code)
Index: pardus-2.6/arch/i386/kernel/ptrace.c
===================================================================
--- pardus-2.6.orig/arch/i386/kernel/ptrace.c
+++ pardus-2.6/arch/i386/kernel/ptrace.c
@@ -172,14 +172,22 @@ static unsigned long convert_eip_to_line
 		u32 *desc;
 		unsigned long base;
 
-		down(&child->mm->context.sem);
-		desc = child->mm->context.ldt + (seg & ~7);
-		base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);
+		seg &= ~7UL;
 
-		/* 16-bit code segment? */
-		if (!((desc[1] >> 22) & 1))
-			addr &= 0xffff;
-		addr += base;
+		down(&child->mm->context.sem);
+		if (unlikely((seg >> 3) >= child->mm->context.size))
+			addr = -1L; /* bogus selector, access would fault */
+		else {
+			desc = child->mm->context.ldt + seg;
+			base = ((desc[0] >> 16) |
+				((desc[1] & 0xff) << 16) |
+				(desc[1] & 0xff000000));
+
+			/* 16-bit code segment? */
+			if (!((desc[1] >> 22) & 1))
+				addr &= 0xffff;
+			addr += base;
+		}
 		up(&child->mm->context.sem);
 	}
 	return addr;