diff --git a/gdbutil b/gdbutil new file mode 100644 index 0000000000000000000000000000000000000000..e0c362fbdb7d5acd8b774e7256a2aec2aeba4e89 --- /dev/null +++ b/gdbutil @@ -0,0 +1,291 @@ +# -*- 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