/*
* This routine returns the a pointer to the data for the named segment
* if it exist in the mach header passed to it. Also it returns
* the size of the segment data indirectly through the pointer size.
* Otherwise it returns zero for the pointer and the size.
*/
void *
getsegdatafromheader(
kernel_mach_header_t *mhp,
const char *segname,
unsigned long *size)
{
const kernel_segment_command_t *sc;
void *result;
sc = getsegbynamefromheader(mhp, segname);
if(sc == (kernel_segment_command_t *)0){
*size = 0;
return((char *)0);
}
*size = sc->vmsize;
result = (void *)sc->vmaddr;
return result;
}
/*
* Return the address of the named Mach-O segment from the currently
* executing kernel kernel, or NULL.
*/
kernel_segment_command_t *
getsegbyname(const char *seg_name)
{
return(getsegbynamefromheader(&_mh_execute_header, seg_name));
}
void
fbt_init( void )
{
PE_parse_boot_argn("DisableFBT", &gDisableFBT, sizeof (gDisableFBT));
if (0 == gDisableFBT)
{
int majdevno = cdevsw_add(FBT_MAJOR, &fbt_cdevsw);
unsigned long size = 0, header_size, round_size;
kern_return_t ret;
void *p, *q;
if (majdevno < 0) {
printf("fbt_init: failed to allocate a major number!\n");
return;
}
/*
* Capture the kernel's mach_header in its entirety and the contents of
* its LINKEDIT segment (and only that segment). This is sufficient to
* build all the fbt probes lazily the first time a client looks to
* the fbt provider. Remeber these on the global struct modctl g_fbt_kernctl.
*/
header_size = sizeof(kernel_mach_header_t) + _mh_execute_header.sizeofcmds;
p = getsegdatafromheader(&_mh_execute_header, SEG_LINKEDIT, &size);
round_size = round_page(header_size + size);
/* "q" will accomodate copied kernel_mach_header_t, its load commands, and LINKEIT segment. */
ret = kmem_alloc_pageable(kernel_map, (vm_offset_t *)&q, round_size);
if (p && (ret == KERN_SUCCESS)) {
kernel_segment_command_t *sgp;
bcopy( (void *)&_mh_execute_header, q, header_size);
bcopy( p, (char *)q + header_size, size);
sgp = getsegbynamefromheader(q, SEG_LINKEDIT);
if (sgp) {
sgp->vmaddr = (uintptr_t)((char *)q + header_size);
g_fbt_kernctl.address = (vm_address_t)q;
g_fbt_kernctl.size = header_size + size;
} else {
kmem_free(kernel_map, (vm_offset_t)q, round_size);
g_fbt_kernctl.address = (vm_address_t)NULL;
g_fbt_kernctl.size = 0;
}
} else {
if (ret == KERN_SUCCESS)
kmem_free(kernel_map, (vm_offset_t)q, round_size);
g_fbt_kernctl.address = (vm_address_t)NULL;
g_fbt_kernctl.size = 0;
}
strncpy((char *)&(g_fbt_kernctl.mod_modname), "mach_kernel", KMOD_MAX_NAME);
((char *)&(g_fbt_kernctl.mod_modname))[KMOD_MAX_NAME -1] = '\0';
fbt_attach( (dev_info_t *)(uintptr_t)majdevno, DDI_ATTACH );
gDisableFBT = 1; /* Ensure this initialization occurs just one time. */
}
else
printf("fbt_init: DisableFBT non-zero, no FBT probes will be provided.\n");
}
