static struct seg_desc
usd_to_seg_desc(struct user_segment_descriptor *usd)
{
struct seg_desc seg_desc;
seg_desc.base = (u_int)USD_GETBASE(usd);
if (usd->sd_gran)
seg_desc.limit = (u_int)(USD_GETLIMIT(usd) << 12) | 0xfff;
else
seg_desc.limit = (u_int)USD_GETLIMIT(usd);
seg_desc.access = usd->sd_type | usd->sd_dpl << 5 | usd->sd_p << 7;
seg_desc.access |= usd->sd_xx << 12;
seg_desc.access |= usd->sd_def32 << 14;
seg_desc.access |= usd->sd_gran << 15;
return (seg_desc);
}
static int
fasttrap_do_seg(fasttrap_tracepoint_t *tp, struct reg *rp, uintptr_t *addr)
{
proc_t *p = curproc;
#ifdef __i386__
struct segment_descriptor *desc;
#else
struct user_segment_descriptor *desc;
#endif
uint16_t sel = 0, ndx, type;
uintptr_t limit;
switch (tp->ftt_segment) {
case FASTTRAP_SEG_CS:
sel = rp->r_cs;
break;
case FASTTRAP_SEG_DS:
sel = rp->r_ds;
break;
case FASTTRAP_SEG_ES:
sel = rp->r_es;
break;
case FASTTRAP_SEG_FS:
sel = rp->r_fs;
break;
case FASTTRAP_SEG_GS:
sel = rp->r_gs;
break;
case FASTTRAP_SEG_SS:
sel = rp->r_ss;
break;
}
/*
* Make sure the given segment register specifies a user priority
* selector rather than a kernel selector.
*/
if (ISPL(sel) != SEL_UPL)
return (-1);
ndx = IDXSEL(sel);
/*
* Check the bounds and grab the descriptor out of the specified
* descriptor table.
*/
if (ISLDT(sel)) {
#ifdef __i386__
if (ndx > p->p_md.md_ldt->ldt_len)
return (-1);
desc = (struct segment_descriptor *)
p->p_md.md_ldt[ndx].ldt_base;
#else
if (ndx > max_ldt_segment)
return (-1);
desc = (struct user_segment_descriptor *)
p->p_md.md_ldt[ndx].ldt_base;
#endif
} else {
if (ndx >= NGDT)
return (-1);
#ifdef __i386__
desc = &gdt[ndx].sd;
#else
desc = &gdt[ndx];
#endif
}
/*
* The descriptor must have user privilege level and it must be
* present in memory.
*/
if (desc->sd_dpl != SEL_UPL || desc->sd_p != 1)
return (-1);
type = desc->sd_type;
/*
* If the S bit in the type field is not set, this descriptor can
* only be used in system context.
*/
if ((type & 0x10) != 0x10)
return (-1);
limit = USD_GETLIMIT(desc) * (desc->sd_gran ? PAGESIZE : 1);
if (tp->ftt_segment == FASTTRAP_SEG_CS) {
/*
* The code/data bit and readable bit must both be set.
*/
if ((type & 0xa) != 0xa)
return (-1);
if (*addr > limit)
return (-1);
} else {
/*
* The code/data bit must be clear.
*/
if ((type & 0x8) != 0)
return (-1);
/*
* If the expand-down bit is clear, we just check the limit as
* it would naturally be applied. Otherwise, we need to check
* that the address is the range [limit + 1 .. 0xffff] or
* [limit + 1 ... 0xffffffff] depending on if the default
* operand size bit is set.
*/
if ((type & 0x4) == 0) {
if (*addr > limit)
return (-1);
} else if (desc->sd_def32) {
if (*addr < limit + 1 || 0xffff < *addr)
return (-1);
} else {
if (*addr < limit + 1 || 0xffffffff < *addr)
return (-1);
}
}
*addr += USD_GETBASE(desc);
return (0);
}