xv6-cs450/gdbutil

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# -*- gdb-script -*-
# Utility functions to pretty-print x86 segment/interrupt descriptors.
# To load this file, run "source gdbutil" in gdb.
# printdesc and printdescs are the main entry points.
# IA32 2007, Volume 3A, Table 3-2
set $STS_T16A = 0x1
set $STS_LDT = 0x2
set $STS_T16B = 0x3
set $STS_CG16 = 0x4
set $STS_TG = 0x5
set $STS_IG16 = 0x6
set $STS_TG16 = 0x7
set $STS_T32A = 0x9
set $STS_T32B = 0xB
set $STS_CG32 = 0xC
set $STS_IG32 = 0xE
set $STS_TG32 = 0xF
define outputsts
while 1
if $arg0 == $STS_T16A
echo STS_T16A
loop_break
end
if $arg0 == $STS_LDT
echo STS_LDT\
loop_break
end
if $arg0 == $STS_T16B
echo STS_T16B
loop_break
end
if $arg0 == $STS_CG16
echo STS_CG16
loop_break
end
if $arg0 == $STS_TG
echo STS_TG\ \
loop_break
end
if $arg0 == $STS_IG16
echo STS_IG16
loop_break
end
if $arg0 == $STS_TG16
echo STS_TG16
loop_break
end
if $arg0 == $STS_T32A
echo STS_T32A
loop_break
end
if $arg0 == $STS_T32B
echo STS_T32B
loop_break
end
if $arg0 == $STS_CG32
echo STS_CG32
loop_break
end
if $arg0 == $STS_IG32
echo STS_IG32
loop_break
end
if $arg0 == $STS_TG32
echo STS_TG32
loop_break
end
echo Reserved
loop_break
end
end
# IA32 2007, Volume 3A, Table 3-1
set $STA_X = 0x8
set $STA_E = 0x4
set $STA_C = 0x4
set $STA_W = 0x2
set $STA_R = 0x2
set $STA_A = 0x1
define outputsta
if $arg0 & $STA_X
# Code segment
echo code
if $arg0 & $STA_C
echo |STA_C
end
if $arg0 & $STA_R
echo |STA_R
end
else
# Data segment
echo data
if $arg0 & $STA_E
echo |STA_E
end
if $arg0 & $STA_W
echo |STA_W
end
end
if $arg0 & $STA_A
echo |STA_A
else
printf " "
end
end
# xv6-specific
set $SEG_KCODE = 1
set $SEG_KDATA = 2
set $SEG_KCPU = 3
set $SEG_UCODE = 4
set $SEG_UDATA = 5
set $SEG_TSS = 6
define outputcs
if ($arg0 & 4) == 0
if $arg0 >> 3 == $SEG_KCODE
printf "SEG_KCODE<<3"
end
if $arg0 >> 3 == $SEG_KDATA
printf "SEG_KDATA<<3"
end
if $arg0 >> 3 == $SEG_KCPU
printf "SEG_KCPU<<3"
end
if $arg0 >> 3 == $SEG_UCODE
printf "SEG_UCODE<<3"
end
if $arg0 >> 3 == $SEG_UDATA
printf "SEG_UDATA<<3"
end
if $arg0 >> 3 == $SEG_TSS
printf "SEG_TSS<<3"
end
if ($arg0 >> 3 < 1) + ($arg0 >> 3 > 6)
printf "GDT[%d]", $arg0 >> 3
end
else
printf "LDT[%d]", $arg0 >> 3
end
if ($arg0 & 3) > 0
printf "|"
outputdpl ($arg0&3)
end
end
define outputdpl
if $arg0 == 0
printf "DPL_KERN"
else
if $arg0 == 3
printf "DPL_USER"
else
printf "DPL%d", $arg0
end
end
end
define printdesc
if $argc != 1
echo Usage: printdesc expr
else
_printdesc ((uint*)&($arg0))[0] ((uint*)&($arg0))[1]
printf "\n"
end
end
document printdesc
Print an x86 segment or gate descriptor.
printdesc EXPR
EXPR must evaluate to a descriptor value. It can be of any C type.
end
define _printdesc
_printdesc1 $arg0 $arg1 ($arg1>>15&1) ($arg1>>13&3) ($arg1>>12&1) ($arg1>>8&15)
end
define _printdesc1
# 2:P 3:DPL 4:S 5:Type
if $arg2 == 0
printf "P = 0 (Not present)"
else
printf "type = "
if $arg4 == 0
# System segment
outputsts $arg5
printf " (0x%x) ", $arg5
_printsysdesc $arg0 $arg1 $arg5
else
# Code/data segment
outputsta $arg5
printf " "
_printsegdesc $arg0 $arg1
end
printf " DPL = "
outputdpl $arg3
printf " (%d)", $arg3
end
end
define _printsysdesc
# 2:Type
# GDB's || is buggy
if ($arg2 == $STS_TG) + (($arg2&7) == $STS_IG16) + (($arg2&7) == $STS_TG16)
# Gate descriptor
_printgate $arg2 ($arg0>>16) ($arg0&0xFFFF) ($arg1>>16)
else
# System segment descriptor
_printsegdesc $arg0 $arg1
end
end
define _printgate
# IA32 2007, Voume 3A, Figure 5-2
# 0:Type 1:CS 2:Offset 15..0 3:Offset 31..16
printf "CS = "
outputcs $arg1
printf " (%d)", $arg1
if (($arg0&7) == $STS_IG16) + (($arg0&7) == $STS_TG16)
printf " Offset = "
output/a $arg3 << 16 | $arg2
end
end
define _printsegdesc
# IA32 20007, Volume 3A, Figure 3-8 and Figure 4-1
_printsegdesc1 ($arg0>>16) ($arg1&0xFF) ($arg1>>24) ($arg0&0xFFFF) ($arg1>>16&15) ($arg1>>23&1)
if ($arg1>>12&1) == 1
printf " AVL = %d", $arg1>>20&1
if ($arg1>>11&1) == 0
# Data segment
if ($arg1>>22&1) == 0
printf " B = small (0) "
else
printf " B = big (1) "
end
else
# Code segment
printf " D = "
if ($arg1>>22&1) == 0
printf "16-bit (0)"
else
printf "32-bit (1)"
end
end
end
end
define _printsegdesc1
# 0:Base 0..15 1:Base 16..23 2:Base 24..32 3:Limit 0..15 4:Limit 16..19 5:G
printf "base = 0x%08x", $arg0 | ($arg1<<16) | ($arg2<<24)
printf " limit = 0x"
if $arg5 == 0
printf "%08x", $arg3 | ($arg4<<16)
else
printf "%08x", (($arg3 | ($arg4<<16)) << 12) | 0xFFF
end
end
define printdescs
if $argc < 1 || $argc > 2
echo Usage: printdescs expr [count]
else
if $argc == 1
_printdescs ($arg0) (sizeof($arg0)/sizeof(($arg0)[0]))
else
_printdescs ($arg0) ($arg1)
end
end
end
document printdescs
Print an array of x86 segment or gate descriptors.
printdescs EXPR [COUNT]
EXPR must evaluate to an array of descriptors.
end
define _printdescs
set $i = 0
while $i < $arg1
printf "[%d] ", $i
printdesc $arg0[$i]
set $i = $i + 1
end
end