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minix/lib/libsys/sef.c
Ben Gras 50e2064049 No more intel/minix segments. 
This commit removes all traces of Minix segments (the text/data/stack
memory map abstraction in the kernel) and significance of Intel segments
(hardware segments like CS, DS that add offsets to all addressing before
page table translation). This ultimately simplifies the memory layout
and addressing and makes the same layout possible on non-Intel
architectures.

There are only two types of addresses in the world now: virtual
and physical; even the kernel and processes have the same virtual
address space. Kernel and user processes can be distinguished at a
glance as processes won't use 0xF0000000 and above.

No static pre-allocated memory sizes exist any more.

Changes to booting:
        . The pre_init.c leaves the kernel and modules exactly as
          they were left by the bootloader in physical memory
        . The kernel starts running using physical addressing,
          loaded at a fixed location given in its linker script by the
          bootloader.  All code and data in this phase are linked to
          this fixed low location.
        . It makes a bootstrap pagetable to map itself to a
          fixed high location (also in linker script) and jumps to
          the high address. All code and data then use this high addressing.
        . All code/data symbols linked at the low addresses is prefixed by
          an objcopy step with __k_unpaged_*, so that that code cannot
          reference highly-linked symbols (which aren't valid yet) or vice
          versa (symbols that aren't valid any more).
        . The two addressing modes are separated in the linker script by
          collecting the unpaged_*.o objects and linking them with low
          addresses, and linking the rest high. Some objects are linked
          twice, once low and once high.
        . The bootstrap phase passes a lot of information (e.g. free memory
          list, physical location of the modules, etc.) using the kinfo
          struct.
        . After this bootstrap the low-linked part is freed.
        . The kernel maps in VM into the bootstrap page table so that VM can
          begin executing. Its first job is to make page tables for all other
          boot processes. So VM runs before RS, and RS gets a fully dynamic,
          VM-managed address space. VM gets its privilege info from RS as usual
          but that happens after RS starts running.
        . Both the kernel loading VM and VM organizing boot processes happen
	  using the libexec logic. This removes the last reason for VM to
	  still know much about exec() and vm/exec.c is gone.

Further Implementation:
        . All segments are based at 0 and have a 4 GB limit.
        . The kernel is mapped in at the top of the virtual address
          space so as not to constrain the user processes.
        . Processes do not use segments from the LDT at all; there are
          no segments in the LDT any more, so no LLDT is needed.
        . The Minix segments T/D/S are gone and so none of the
          user-space or in-kernel copy functions use them. The copy
          functions use a process endpoint of NONE to realize it's
          a physical address, virtual otherwise.
        . The umap call only makes sense to translate a virtual address
          to a physical address now.
        . Segments-related calls like newmap and alloc_segments are gone.
        . All segments-related translation in VM is gone (vir2map etc).
        . Initialization in VM is simpler as no moving around is necessary.
        . VM and all other boot processes can be linked wherever they wish
          and will be mapped in at the right location by the kernel and VM
          respectively.

Other changes:
        . The multiboot code is less special: it does not use mb_print
          for its diagnostics any more but uses printf() as normal, saving
          the output into the diagnostics buffer, only printing to the
          screen using the direct print functions if a panic() occurs.
        . The multiboot code uses the flexible 'free memory map list'
          style to receive the list of free memory if available.
        . The kernel determines the memory layout of the processes to
          a degree: it tells VM where the kernel starts and ends and
          where the kernel wants the top of the process to be. VM then
          uses this entire range, i.e. the stack is right at the top,
          and mmap()ped bits of memory are placed below that downwards,
          and the break grows upwards.

Other Consequences:
        . Every process gets its own page table as address spaces
          can't be separated any more by segments.
        . As all segments are 0-based, there is no distinction between
          virtual and linear addresses, nor between userspace and
          kernel addresses.
        . Less work is done when context switching, leading to a net
          performance increase. (8% faster on my machine for 'make servers'.)
	. The layout and configuration of the GDT makes sysenter and syscall
	  possible.
2012-07-15 22:30:15 +02:00

311 lines
9.5 KiB
C
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#include "syslib.h"
#include <assert.h>
#include <minix/sysutil.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
/* Self variables. */
#define SEF_SELF_NAME_MAXLEN 20
char sef_self_name[SEF_SELF_NAME_MAXLEN];
endpoint_t sef_self_endpoint;
int sef_self_priv_flags;
int sef_self_first_receive_done;
int sef_self_receiving;
/* Debug. */
#if SEF_INIT_DEBUG || SEF_LU_DEBUG || SEF_PING_DEBUG || SEF_SIGNAL_DEBUG
#define SEF_DEBUG_HEADER_MAXLEN 32
static time_t sef_debug_boottime = 0;
static u32_t sef_debug_system_hz = 0;
static time_t sef_debug_time_sec = 0;
static time_t sef_debug_time_us = 0;
static char sef_debug_header_buff[SEF_DEBUG_HEADER_MAXLEN];
static void sef_debug_refresh_params(void);
char* sef_debug_header(void);
#endif
/* SEF Init prototypes. */
#ifdef USE_COVERAGE
EXTERN int do_sef_gcov_request(message *m_ptr);
#endif
EXTERN int do_sef_rs_init(endpoint_t old_endpoint);
EXTERN int do_sef_init_request(message *m_ptr);
/* SEF Ping prototypes. */
EXTERN int do_sef_ping_request(message *m_ptr);
/* SEF Live update prototypes. */
EXTERN void do_sef_lu_before_receive(void);
EXTERN int do_sef_lu_request(message *m_ptr);
/* SEF Signal prototypes. */
EXTERN int do_sef_signal_request(message *m_ptr);
/*===========================================================================*
* sef_startup *
*===========================================================================*/
void sef_startup()
{
/* SEF startup interface for system services. */
int r, status;
endpoint_t old_endpoint;
int priv_flags;
/* Get information about self. */
r = sys_whoami(&sef_self_endpoint, sef_self_name, SEF_SELF_NAME_MAXLEN,
&priv_flags);
if ( r != OK) {
sef_self_endpoint = SELF;
sprintf(sef_self_name, "%s", "Unknown");
}
sef_self_priv_flags = priv_flags;
old_endpoint = NONE;
#if USE_LIVEUPDATE
/* RS may wake up with the wrong endpoint, perfom the update in that case. */
if((sef_self_priv_flags & ROOT_SYS_PROC) && sef_self_endpoint != RS_PROC_NR) {
r = vm_update(RS_PROC_NR, sef_self_endpoint);
if(r != OK) {
panic("unable to update RS from instance %d to %d",
RS_PROC_NR, sef_self_endpoint);
}
old_endpoint = sef_self_endpoint;
sef_self_endpoint = RS_PROC_NR;
}
#endif /* USE_LIVEUPDATE */
#if INTERCEPT_SEF_INIT_REQUESTS
/* Intercept SEF Init requests. */
if(sef_self_priv_flags & ROOT_SYS_PROC) {
/* RS initialization is special. */
if((r = do_sef_rs_init(old_endpoint)) != OK) {
panic("RS unable to complete init: %d", r);
}
}
else if(sef_self_endpoint == VM_PROC_NR) {
/* VM handles initialization by RS later */
} else {
message m;
/* Wait for an initialization message from RS. We need this to learn the
* initialization type and parameters. When restarting after a crash, we
* may get some spurious IPC messages from RS (e.g. update request) that
* were originally meant to be delivered to the old instance. We discard
* these messages and block till a proper initialization request arrives.
*/
do {
r = receive(RS_PROC_NR, &m, &status);
if(r != OK) {
panic("unable to receive from RS: %d", r);
}
} while(!IS_SEF_INIT_REQUEST(&m));
/* Process initialization request for this system service. */
if((r = do_sef_init_request(&m)) != OK) {
panic("unable to process init request: %d", r);
}
}
#endif
/* (Re)initialize SEF variables. */
sef_self_first_receive_done = FALSE;
sef_self_priv_flags = priv_flags;
}
/*===========================================================================*
* sef_receive_status *
*===========================================================================*/
int sef_receive_status(endpoint_t src, message *m_ptr, int *status_ptr)
{
/* SEF receive() interface for system services. */
int r, status;
sef_self_receiving = TRUE;
while(TRUE) {
/* If the caller indicated that it no longer wants to receive a message,
* return now.
*/
if (!sef_self_receiving)
return EINTR;
#if INTERCEPT_SEF_LU_REQUESTS
/* Handle SEF Live update before receive events. */
do_sef_lu_before_receive();
#endif
/* Receive and return in case of error. */
r = receive(src, m_ptr, &status);
if(status_ptr) *status_ptr = status;
if(!sef_self_first_receive_done) sef_self_first_receive_done = TRUE;
if(r != OK) {
return r;
}
#if INTERCEPT_SEF_PING_REQUESTS
/* Intercept SEF Ping requests. */
if(IS_SEF_PING_REQUEST(m_ptr, status)) {
if(do_sef_ping_request(m_ptr) == OK) {
continue;
}
}
#endif
#if INTERCEPT_SEF_LU_REQUESTS
/* Intercept SEF Live update requests. */
if(IS_SEF_LU_REQUEST(m_ptr, status)) {
if(do_sef_lu_request(m_ptr) == OK) {
continue;
}
}
#endif
#if INTERCEPT_SEF_SIGNAL_REQUESTS
/* Intercept SEF Signal requests. */
if(IS_SEF_SIGNAL_REQUEST(m_ptr, status)) {
if(do_sef_signal_request(m_ptr) == OK) {
continue;
}
}
#endif
#ifdef USE_COVERAGE
/* Intercept GCOV data requests (sent by VFS in vfs/gcov.c). */
if(m_ptr->m_type == COMMON_REQ_GCOV_DATA &&
m_ptr->m_source == VFS_PROC_NR) {
if(do_sef_gcov_request(m_ptr) == OK) {
continue;
}
}
#endif
/* If we get this far, this is not a valid SEF request, return and
* let the caller deal with that.
*/
break;
}
return r;
}
/*===========================================================================*
* sef_cancel *
*===========================================================================*/
void sef_cancel(void)
{
/* Cancel receiving a message. This function be called from a callback invoked
* from within sef_receive_status(), which will then return an EINTR error
* code. In particular, this function can be used to exit from the main receive
* loop when a signal handler causes the process to want to shut down.
*/
sef_self_receiving = FALSE;
}
/*===========================================================================*
* sef_exit *
*===========================================================================*/
void sef_exit(int status)
{
/* System services use a special version of exit() that generates a
* self-termination signal.
*/
message m;
/* Ask the kernel to exit. */
sys_exit();
/* If sys_exit() fails, this is not a system service. Exit through PM. */
m.m1_i1 = status;
_syscall(PM_PROC_NR, EXIT, &m);
/* If everything else fails, hang. */
printf("Warning: system service %d couldn't exit\n", sef_self_endpoint);
for(;;) { }
}
/*===========================================================================*
* _exit *
*===========================================================================*/
void _exit(int status)
{
/* Make exit() an alias for sef_exit() for system services. */
sef_exit(status);
panic("sef_exit failed");
}
/*===========================================================================*
* __exit *
*===========================================================================*/
void __exit(int status)
{
/* Make exit() an alias for sef_exit() for system services. */
sef_exit(status);
panic("sef_exit failed");
}
#if SEF_INIT_DEBUG || SEF_LU_DEBUG || SEF_PING_DEBUG || SEF_SIGNAL_DEBUG
/*===========================================================================*
* sef_debug_refresh_params *
*===========================================================================*/
static void sef_debug_refresh_params(void)
{
/* Refresh SEF debug params. */
clock_t uptime;
int r;
/* Get boottime the first time. */
if(!sef_debug_boottime) {
r = sys_times(NONE, NULL, NULL, NULL, &sef_debug_boottime);
if ( r != OK) {
sef_debug_boottime = -1;
}
}
/* Get system hz the first time. */
if(!sef_debug_system_hz) {
r = sys_getinfo(GET_HZ, &sef_debug_system_hz,
sizeof(sef_debug_system_hz), 0, 0);
if ( r != OK) {
sef_debug_system_hz = -1;
}
}
/* Get uptime. */
uptime = -1;
if(sef_debug_boottime!=-1 && sef_debug_system_hz!=-1) {
r = sys_times(NONE, NULL, NULL, &uptime, NULL);
if ( r != OK) {
uptime = -1;
}
}
/* Compute current time. */
if(sef_debug_boottime==-1 || sef_debug_system_hz==-1 || uptime==-1) {
sef_debug_time_sec = 0;
sef_debug_time_us = 0;
}
else {
sef_debug_time_sec = (time_t) (sef_debug_boottime
+ (uptime/sef_debug_system_hz));
sef_debug_time_us = (uptime%sef_debug_system_hz)
* 1000000/sef_debug_system_hz;
}
}
/*===========================================================================*
* sef_debug_header *
*===========================================================================*/
char* sef_debug_header(void)
{
/* Build and return a SEF debug header. */
sef_debug_refresh_params();
sprintf(sef_debug_header_buff, "%s: time = %ds %06dus",
sef_self_name, (int) sef_debug_time_sec, (int) sef_debug_time_us);
return sef_debug_header_buff;
}
#endif /*SEF_INIT_DEBUG || SEF_LU_DEBUG || SEF_PING_DEBUG || SEF_SIGNAL_DEBUG*/
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