Messages in this thread | | | Date | Thu, 24 Apr 2003 21:20:10 -0400 | From | Chuck Ebbert <> | Subject | [ANNOUNCE] desc.c v0.60 -- print i386 CPU descriptor tables |
| |
desc version 0.60, a program to dump i386 descriptor tables, is enclosed. Changes include:
o bug fixes o dumps some TSS fields o prints LDTs
Partial output on Linux 2.5.68-ce2 (note that you can now find the doublefault handler and lcall entry points): ================================================================================ desc v0.60 -- dump i386 CPU descriptor tables
GDT at c0306280, 32 entries:
GDT#012: base=00000000 limit=ffffffff flags=c09b <P=1 DPL=0 32-bit Code> GDT#013: base=00000000 limit=ffffffff flags=c093 <P=1 DPL=0 RW Data> GDT#014: base=00000000 limit=ffffffff flags=c0fb <P=1 DPL=3 32-bit Code> GDT#015: base=00000000 limit=ffffffff flags=c0f3 <P=1 DPL=3 RW Data> GDT#016: base=c0353800 limit=000eb flags=008b <P=1 DPL=0 Busy TSS>
TSS at c0353800, 236 bytes:
CS:0000 <GDT#00,RPL0> EIP:00000000 EFLAGS:00000000
GDT#017: base=c0307c70 limit=00027 flags=0082 <P=1 DPL=0 LDT>
LDT at c0307c70, 5 entries:
LDT#000 [0x00]: flags=ec <P,DPL3,call> sel=60 <GDT#12,RPL0> off=c0108b60 LDT#004 [0x04]: flags=ec <P,DPL3,call> sel=60 <GDT#12,RPL0> off=c0108ba4
GDT#018: base=00000000 limit=00000fff flags=c09a <P=1 DPL=0 32-bit Code> GDT#019: base=00000000 limit=00000fff flags=809a <P=1 DPL=0 16-bit Code> GDT#020: base=00000000 limit=00000fff flags=8092 <P=1 DPL=0 RW Data> GDT#021: base=00000000 limit=00000fff flags=8092 <P=1 DPL=0 RW Data> GDT#022: base=00000000 limit=00000fff flags=8092 <P=1 DPL=0 RW Data> GDT#023: base=00000000 limit=00000 flags=409a <P=1 DPL=0 32-bit Code> GDT#024: base=00000000 limit=00000 flags=009a <P=1 DPL=0 16-bit Code> GDT#025: base=00000000 limit=00000 flags=4092 <P=1 DPL=0 RW Data> GDT#031: base=c0355600 limit=000eb flags=0089 <P=1 DPL=0 Available TSS>
TSS at c0355600, 236 bytes:
CS:0060 <GDT#12,RPL0> EIP:c010f700 EFLAGS:00000082 ================================================================================ #define PROG_NAME "desc" #define PROG_TITLE "dump i386 CPU descriptor tables" #define VERSION "0.60" #define AUTHOR "Chuck Ebbert <76306.1226ompuserve.com>" #define LICENSE "Released under the GPL"
#include <stdio.h> #include <fcntl.h> #include <sys/types.h>
typedef struct { /* taken from Linux source */ unsigned short back_link,__blh; unsigned long esp0; unsigned short ss0,__ss0h; unsigned long esp1; unsigned short ss1,__ss1h; unsigned long esp2; unsigned short ss2,__ss2h; unsigned long __cr3; unsigned long eip; unsigned long eflags; unsigned long eax,ecx,edx,ebx; unsigned long esp; unsigned long ebp; unsigned long esi; unsigned long edi; unsigned short es, __esh; unsigned short cs, __csh; unsigned short ss, __ssh; unsigned short ds, __dsh; unsigned short fs, __fsh; unsigned short gs, __gsh; unsigned short ldt, __ldth; unsigned short trace, bitmap; } __attribute__ ((packed)) tss_t;
typedef struct { unsigned short limit; unsigned int base; } __attribute__ ((packed)) dtr_t;
typedef struct { unsigned short off1; unsigned short sel; unsigned char none,flags; unsigned short off2; } __attribute__ ((packed)) idt_entry_t;
typedef struct { unsigned a,b; } __attribute__ ((packed)) gdt_ldt_entry_t;
/* read/write from kmem */ #define BUILD_IO_FN(fn_name, fn_fn) \ static int fn_name(int fd, int offset, void *buf, int size) { \ if (lseek(fd, offset, 0) != offset) return 0; \ if (fn_fn(fd, buf, size) != size) return 0; \ return size; \ } BUILD_IO_FN(rkm, read) BUILD_IO_FN(wkm, write)
int kmem;
void perr(char *err) { /* exit with err msg */ perror(err), exit(1); } /* read/write wrapper with err handling */ #define xkm(f, p1, p2, p3, p4, msg) { \ int _p4 = (p4); if ((f)((p1), (p2), (p3), _p4) != _p4) perr(msg); } #define TEST_BIT(v,b) ( !!(v & (1 << b)) )
void dump_sys_desc(char *name, unsigned base, unsigned i) { unsigned sel, flags; idt_entry_t desc;
xkm(rkm, kmem, base + 8*i, &desc, sizeof(desc), "rkm sys"); sel = desc.sel, flags = desc.flags; printf("%s#%03d [0x%02x]: flags=%02x <%s,DPL%d,%s>" " sel=%02x <%s#%02d,RPL%d> off=%08x\n", name, i, i, flags, flags & 0x80 ? "P" : "NP", (flags & 0x60) >> 5, (flags & 0x1f) == 0x0e ? "intr" : (flags & 0x1f) == 0x0f ? "trap" : (flags & 0x1f) == 0x05 ? "task" : (flags & 0x1f) == 0x0c ? "call" : "????", sel, sel & 4 ? "LDT" : "GDT", sel >> 3, sel & 3, (unsigned)((desc.off2 << 16) | desc.off1)); } void dump_gdt_ldt (char * name, unsigned base, unsigned num) { unsigned dbase, dlimit, a, b, t, i, f; gdt_ldt_entry_t desc; tss_t tss;
printf("\n %s at %08x, %d entries:\n\n", name, base, num); for (i = 0; i < num; i++) { xkm(rkm, kmem, base + 8*i, &desc, sizeof(desc), "rkm gdtldt"); a = desc.a, b = desc.b, f = (b & 0xf0ff00) >> 8, t = f & 0x1f; if (!a & !b) continue; if (t == 0x0c) { /* call gate */ dump_sys_desc(name, base, i); continue; } dbase = (b & 0xff000000) | ((b & 0xff) << 16) | (a >> 16); dlimit = (a & 0xffff) | (b & 0x0f0000); printf("%s#%03d: base=%08x limit=%05x%s" "\tflags=%04x <P=%d DPL=%d %s>\n", name, i, dbase, dlimit, TEST_BIT(b,23) ? "fff" : "", f, TEST_BIT(b,15), (b & 0x6000) >> 13, t == 0x0b ? "Busy TSS" : t == 0x09 ? "Available TSS" : t == 0x02 ? "LDT" : (f & 0x401c) == 0x4018 ? "32-bit Code" : (f & 0x401c) == 0x18 ? "16-bit Code" : (t & 0x1c) == 0x1c ? "Conforming code" : (t & 0x1e) == 0x10 ? "RO Data" : (t & 0x1e) == 0x12 ? "RW Data" : (t & 0x1c) == 0x14 ? "Exp-down data" : "Unknown"); if (t == 0x02) dump_gdt_ldt(" LDT", dbase, dlimit + 1 >> 3); if ((t == 0x09) | (t == 0x0b)) { xkm(rkm, kmem, dbase, &tss, sizeof(tss), "rkm tss"); printf("\n TSS at %08x, %d bytes:\n\n", dbase, dlimit + 1); printf(" CS:%04x <%s#%02d,RPL%d>" " EIP:%08x EFLAGS:%08x\n\n", tss.cs, tss.cs & 4 ? "LDT" : "GDT", tss.cs >> 3, tss.cs & 3, tss.eip, tss.eflags); } } printf("\n"); } void dump_idt (unsigned base, unsigned num) { int i; printf(" IDT at %08x, %d entries:\n\n", base, num); for (i = 0; i < num; i++) { dump_sys_desc("IDT", base, i); } } main() { dtr_t gdtr, idtr;
printf(PROG_NAME " v" VERSION " -- " PROG_TITLE "\n");
kmem = open("/dev/kmem", O_RDONLY); if (kmem < 0) perr("open kmem");
asm("sgdt %0" : "=m" (gdtr)); dump_gdt_ldt("GDT", gdtr.base, gdtr.limit + 1 >> 3); asm("sidt %0" : "=m" (idtr)); dump_idt(idtr.base, idtr.limit + 1 >> 3);
close(kmem); }
------ Chuck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |