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/*
* This file contains the main routine for retrieval of the kernel information
* page, as well as abstraction routines for retrieval of specific values from
* this kernel-mapped user information structure. These routines may be used
* from both userland and system services, and their accesses are considered to
* establish part of the userland ABI. Do not add routines here that are not
* for retrieval of userland ABI fields (e.g., clock information)! Also, since
* these functions are MINIX3 specific, their names should contain - preferably
* be prefixed with - "minix_".
*/
#define _MINIX_SYSTEM
#include <sys/cdefs.h>
#include "namespace.h"
#include <lib.h>
#include <minix/param.h>
#include <assert.h>
extern struct minix_kerninfo *_minix_kerninfo;
/*
* Get a pointer to the kernel information page.
*/
struct minix_kerninfo *
get_minix_kerninfo(void)
{
assert(_minix_kerninfo != NULL);
return _minix_kerninfo;
}
/*
* Obtain the initial stack pointer for a new userland process. This value
* is used by routines that set up the stack when executing a new program.
* It is used for userland exec(2) and in various system services.
*/
vir_bytes
minix_get_user_sp(void)
{
struct minix_kerninfo *ki;
/* All information is obtained from the kernel information page. */
ki = get_minix_kerninfo();
/*
* Check whether we can retrieve the user stack pointer value from the
* kuserinfo structure. In general, this test is the correct one to
* see whether the kuserinfo structure has a certain field.
*/
if ((ki->ki_flags & MINIX_KIF_USERINFO) &&
KUSERINFO_HAS_FIELD(ki->kuserinfo, kui_user_sp)) {
return ki->kuserinfo->kui_user_sp;
}
/*
* Otherwise, fall back to legacy support: retrieve the value from the
* kinfo structure. This field will eventually be removed.
*/
return ki->kinfo->user_sp;
}
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