| #include <sys/types.h> |
| #include <sys/ioctl.h> |
| #include "qemu-common.h" |
| |
| #ifdef CONFIG_KVM_GS_RESTORE |
| |
| #define INVALID_GS_REG 0xffff |
| #define KVM_GS_RESTORE_NODETECTED 0x1 |
| #define KVM_GS_RESTORE_NO 0x2 |
| #define KVM_GS_RESTORE_YES 0x3 |
| int initial_gs = INVALID_GS_REG; |
| int gs_need_restore = KVM_GS_RESTORE_NODETECTED; |
| |
| static void restoregs(int gs) |
| { |
| asm("movl %0, %%gs"::"r"(gs)); |
| } |
| |
| static unsigned int _getgs() |
| { |
| unsigned int gs = 0; |
| asm("movl %%gs,%0" :"=r"(gs):); |
| return gs; |
| } |
| |
| /* No fprintf or any system call before the gs is restored successfully */ |
| static void check_and_restore_gs(void) |
| { |
| if (gs_need_restore == KVM_GS_RESTORE_NO) |
| return; |
| |
| restoregs(initial_gs); |
| } |
| |
| static struct sigaction old_alarm_act, old_gio_act, old_pipe_act,old_usr1_act, old_chld_act; |
| static void temp_sig_handler(int host_signum) |
| { |
| /* !!! must restore gs firstly */ |
| check_and_restore_gs(); |
| switch (host_signum) |
| { |
| case SIGALRM: |
| old_alarm_act.sa_handler(host_signum); |
| break; |
| |
| case SIGIO: |
| old_gio_act.sa_handler(host_signum); |
| break; |
| |
| case SIGUSR1: |
| old_usr1_act.sa_handler(host_signum); |
| break; |
| |
| case SIGPIPE: |
| old_pipe_act.sa_handler(host_signum); |
| break; |
| |
| case SIGCHLD: |
| old_chld_act.sa_handler(host_signum); |
| break; |
| |
| default: |
| fprintf(stderr, "Not take signal %x!!\n", host_signum); |
| break; |
| } |
| } |
| |
| static int sig_taken = 0; |
| static int take_signal_handler(void) |
| { |
| struct sigaction act; |
| int ret; |
| |
| if (gs_need_restore == KVM_GS_RESTORE_NO) |
| return 0; |
| if (sig_taken) |
| return 0; |
| |
| sig_taken = 1; |
| sigfillset(&act.sa_mask); |
| act.sa_flags = 0; |
| act.sa_handler = temp_sig_handler; |
| /* Did we missed any other signal ? */ |
| sigaction(SIGALRM, &act, &old_alarm_act); |
| sigaction(SIGIO, &act, &old_gio_act); |
| sigaction(SIGUSR1, &act, &old_usr1_act); |
| sigaction(SIGPIPE, &act, &old_pipe_act); |
| act.sa_flags = SA_NOCLDSTOP; |
| sigaction(SIGCHLD, &act, &old_chld_act); |
| return 1; |
| } |
| |
| int gs_base_pre_run(void) |
| { |
| if (unlikely(initial_gs == INVALID_GS_REG) ) |
| { |
| initial_gs = _getgs(); |
| /* |
| * As 2.6.35-28 lucid will get correct gs but clobbered GS_BASE |
| * we have to always re-write the gs base |
| */ |
| if (initial_gs == 0x0) |
| gs_need_restore = KVM_GS_RESTORE_NO; |
| else |
| gs_need_restore = KVM_GS_RESTORE_YES; |
| } |
| |
| take_signal_handler(); |
| return 0; |
| } |
| |
| int gs_base_post_run(void) |
| { |
| check_and_restore_gs(); |
| return 0; |
| } |
| |
| /* |
| * ioctl may update errno, which is in thread local storage and |
| * requires gs register, we have to provide our own ioctl |
| * XXX should "call %%gs:$0x10" be replaced with call to vsyscall |
| * page, which is more generic and clean? |
| */ |
| int no_gs_ioctl(int fd, int type, void *arg) |
| { |
| int ret=0; |
| |
| asm( |
| "movl %3, %%edx;\n" |
| "movl %2, %%ecx;\n" |
| "movl %1, %%ebx;\n" |
| "movl $0x36, %%eax;\n" |
| "call *%%gs:0x10;\n" |
| "movl %%eax, %0\n" |
| : "=m"(ret) |
| :"m"(fd),"m"(type),"m"(arg) |
| :"%edx","%ecx","%eax","%ebx" |
| ); |
| |
| return ret; |
| } |
| |
| #endif |
| |