From ce34bd6bca2ad114e0e4e1dfcf9fd47e03d70a51 Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Thu, 5 Oct 2006 15:30:51 +0000 Subject: [PATCH] - Fix a couple of improper uses of leal in the previous space saving commits. For some reason I thought the scale factor was a shift count rather than the multiplicand (that is, I thought leal (%eax,%edx,4) was going to generate %eax + %edx << 4 rather than %eax + %edx * 4). What I need is to multiply by 16 to convert a real-mode (seg, offset) tuple into a flat address. However, the max multiplicand for scaled/index addressing on i386 is 8, so go back to using a shl and an add. - Convert two more inter-register mov instructions where we don't need to preserve the source register to xchg instructions to keep our space savings. Tested by: Ian FREISLICH if at hetzner.co.za MFC after: 1 week --- sys/boot/i386/btx/btx/btx.S | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/sys/boot/i386/btx/btx/btx.S b/sys/boot/i386/btx/btx/btx.S index c8955a5ceb52..ce9962269cf8 100644 --- a/sys/boot/i386/btx/btx/btx.S +++ b/sys/boot/i386/btx/btx/btx.S @@ -443,12 +443,12 @@ intrtn.1: leal 0x10(%esi),%ebx # Saved exception frame movb $0x4,%cl # Update seg regs rep # in INT_V86 movsl # args -intrtn.2: movl %edx,%esi # Segment registers +intrtn.2: xchgl %edx,%esi # Segment registers leal 0x28(%ebp),%edi # Set up seg movb $0x4,%cl # regs for rep # later movsl # pop - movl %ebx,%esi # Restore exception + xchgl %ebx,%esi # Restore exception movb $0x5,%cl # frame to rep # supervisor movsl # stack @@ -620,9 +620,10 @@ v86popf.1: movl (%ebx),%eax # Load flags */ int15_87: pushl %esi # Save pushl %edi # registers - movzwl 0x4(%ebp),%eax # Load user's SI movl 0x3C(%ebp),%edi # Load ES - leal (%eax,%edi,4),%edi # EDI = (ES << 4) + SI + movzwl 0x4(%ebp),%eax # Load user's SI + shll $0x4,%edi # EDI = (ES << 4) + + addl %eax,%edi # SI movl 0x11(%edi),%eax # Read base of movb 0x17(%edi),%al # GDT entry ror $8,%eax # for source @@ -898,7 +899,8 @@ dump.2: testb $DMP_MEM,%ch # Dump memory? dump.3: lodsl # Set offset xchgl %eax,%edx # Save lodsl # Get segment - leal (%edx,%eax,4),%eax # * 0x10 + offset + shll $0x4,%eax # * 0x10 + addl %edx,%eax # + offset xchgl %eax,%esi # Set pointer dump.4: movb $2,%dl # Num lines dump.4a: movb $0x10,%cl # Bytes to dump