android_kernel_xiaomi_sm8350/arch/um/os-Linux/main.c
Jeff Dike 1d7173baf2 [PATCH] uml: implement soft interrupts
This patch implements soft interrupts.  Interrupt enabling and disabling no
longer map to sigprocmask.  Rather, a flag is set indicating whether
interrupts may be handled.  If a signal comes in and interrupts are marked as
OK, then it is handled normally.  If interrupts are marked as off, then the
signal handler simply returns after noting that a signal needs handling.  When
interrupts are enabled later on, this pending signals flag is checked, and the
IRQ handlers are called at that point.

The point of this is to reduce the cost of local_irq_save et al, since they
are very much more common than the signals that they are enabling and
disabling.  Soft interrupts produce a speed-up of ~25% on a kernel build.

Subtleties -

    UML uses sigsetjmp/siglongjmp to switch contexts.  sigsetjmp has been
    wrapped in a save_flags-like macro which remembers the interrupt state at
    setjmp time, and restores it when it is longjmp-ed back to.

    The enable_signals function has to loop because the IRQ handler
    disables interrupts before returning.  enable_signals has to return with
    signals enabled, and signals may come in between the disabling and the
    return to enable_signals.  So, it loops for as long as there are pending
    signals, ensuring that signals are enabled when it finally returns, and
    that there are no pending signals that need to be dealt with.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-18 19:20:20 -08:00

246 lines
5.5 KiB
C

/*
* Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <asm/page.h>
#include "user_util.h"
#include "kern_util.h"
#include "mem_user.h"
#include "irq_user.h"
#include "user.h"
#include "init.h"
#include "mode.h"
#include "choose-mode.h"
#include "uml-config.h"
#include "os.h"
/* Set in set_stklim, which is called from main and __wrap_malloc.
* __wrap_malloc only calls it if main hasn't started.
*/
unsigned long stacksizelim;
/* Set in main */
char *linux_prog;
#define PGD_BOUND (4 * 1024 * 1024)
#define STACKSIZE (8 * 1024 * 1024)
#define THREAD_NAME_LEN (256)
static void set_stklim(void)
{
struct rlimit lim;
if(getrlimit(RLIMIT_STACK, &lim) < 0){
perror("getrlimit");
exit(1);
}
if((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)){
lim.rlim_cur = STACKSIZE;
if(setrlimit(RLIMIT_STACK, &lim) < 0){
perror("setrlimit");
exit(1);
}
}
stacksizelim = (lim.rlim_cur + PGD_BOUND - 1) & ~(PGD_BOUND - 1);
}
static __init void do_uml_initcalls(void)
{
initcall_t *call;
call = &__uml_initcall_start;
while (call < &__uml_initcall_end){;
(*call)();
call++;
}
}
static void last_ditch_exit(int sig)
{
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
signal(SIGHUP, SIG_DFL);
uml_cleanup();
exit(1);
}
extern int uml_exitcode;
extern void scan_elf_aux( char **envp);
int main(int argc, char **argv, char **envp)
{
char **new_argv;
int ret, i, err;
#ifdef UML_CONFIG_CMDLINE_ON_HOST
/* Allocate memory for thread command lines */
if(argc < 2 || strlen(argv[1]) < THREAD_NAME_LEN - 1){
char padding[THREAD_NAME_LEN] = {
[ 0 ... THREAD_NAME_LEN - 2] = ' ', '\0'
};
new_argv = malloc((argc + 2) * sizeof(char*));
if(!new_argv) {
perror("Allocating extended argv");
exit(1);
}
new_argv[0] = argv[0];
new_argv[1] = padding;
for(i = 2; i <= argc; i++)
new_argv[i] = argv[i - 1];
new_argv[argc + 1] = NULL;
execvp(new_argv[0], new_argv);
perror("execing with extended args");
exit(1);
}
#endif
linux_prog = argv[0];
set_stklim();
new_argv = malloc((argc + 1) * sizeof(char *));
if(new_argv == NULL){
perror("Mallocing argv");
exit(1);
}
for(i=0;i<argc;i++){
new_argv[i] = strdup(argv[i]);
if(new_argv[i] == NULL){
perror("Mallocing an arg");
exit(1);
}
}
new_argv[argc] = NULL;
set_handler(SIGINT, last_ditch_exit, SA_ONESHOT | SA_NODEFER, -1);
set_handler(SIGTERM, last_ditch_exit, SA_ONESHOT | SA_NODEFER, -1);
set_handler(SIGHUP, last_ditch_exit, SA_ONESHOT | SA_NODEFER, -1);
scan_elf_aux( envp);
do_uml_initcalls();
ret = linux_main(argc, argv);
/* Disable SIGPROF - I have no idea why libc doesn't do this or turn
* off the profiling time, but UML dies with a SIGPROF just before
* exiting when profiling is active.
*/
change_sig(SIGPROF, 0);
/* This signal stuff used to be in the reboot case. However,
* sometimes a SIGVTALRM can come in when we're halting (reproducably
* when writing out gcov information, presumably because that takes
* some time) and cause a segfault.
*/
/* stop timers and set SIG*ALRM to be ignored */
disable_timer();
/* disable SIGIO for the fds and set SIGIO to be ignored */
err = deactivate_all_fds();
if(err)
printf("deactivate_all_fds failed, errno = %d\n", -err);
/* Let any pending signals fire now. This ensures
* that they won't be delivered after the exec, when
* they are definitely not expected.
*/
unblock_signals();
/* Reboot */
if(ret){
printf("\n");
execvp(new_argv[0], new_argv);
perror("Failed to exec kernel");
ret = 1;
}
printf("\n");
return(uml_exitcode);
}
#define CAN_KMALLOC() \
(kmalloc_ok && CHOOSE_MODE((os_getpid() != tracing_pid), 1))
extern void *__real_malloc(int);
void *__wrap_malloc(int size)
{
void *ret;
if(!CAN_KMALLOC())
return(__real_malloc(size));
else if(size <= PAGE_SIZE) /* finding contiguos pages can be hard*/
ret = um_kmalloc(size);
else ret = um_vmalloc(size);
/* glibc people insist that if malloc fails, errno should be
* set by malloc as well. So we do.
*/
if(ret == NULL)
errno = ENOMEM;
return(ret);
}
void *__wrap_calloc(int n, int size)
{
void *ptr = __wrap_malloc(n * size);
if(ptr == NULL) return(NULL);
memset(ptr, 0, n * size);
return(ptr);
}
extern void __real_free(void *);
extern unsigned long high_physmem;
void __wrap_free(void *ptr)
{
unsigned long addr = (unsigned long) ptr;
/* We need to know how the allocation happened, so it can be correctly
* freed. This is done by seeing what region of memory the pointer is
* in -
* physical memory - kmalloc/kfree
* kernel virtual memory - vmalloc/vfree
* anywhere else - malloc/free
* If kmalloc is not yet possible, then either high_physmem and/or
* end_vm are still 0 (as at startup), in which case we call free, or
* we have set them, but anyway addr has not been allocated from those
* areas. So, in both cases __real_free is called.
*
* CAN_KMALLOC is checked because it would be bad to free a buffer
* with kmalloc/vmalloc after they have been turned off during
* shutdown.
* XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
* there is a possibility for memory leaks.
*/
if((addr >= uml_physmem) && (addr < high_physmem)){
if(CAN_KMALLOC())
kfree(ptr);
}
else if((addr >= start_vm) && (addr < end_vm)){
if(CAN_KMALLOC())
vfree(ptr);
}
else __real_free(ptr);
}