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linux/arch/s390/kernel/asm-offsets.c
Martin Schwidefsky 20b40a794b [S390] signal race with restarting system calls 
For a ERESTARTNOHAND/ERESTARTSYS/ERESTARTNOINTR restarting system call
do_signal will prepare the restart of the system call with a rewind of
the PSW before calling get_signal_to_deliver (where the debugger might
take control). For A ERESTART_RESTARTBLOCK restarting system call
do_signal will set -EINTR as return code.
There are two issues with this approach:
1) strace never sees ERESTARTNOHAND, ERESTARTSYS, ERESTARTNOINTR or
   ERESTART_RESTARTBLOCK as the rewinding already took place or the
   return code has been changed to -EINTR
2) if get_signal_to_deliver does not return with a signal to deliver
   the restart via the repeat of the svc instruction is left in place.
   This opens a race if another signal is made pending before the
   system call instruction can be reexecuted. The original system call
   will be restarted even if the second signal would have ended the
   system call with -EINTR.

These two issues can be solved by dropping the early rewind of the
system call before get_signal_to_deliver has been called and by using
the TIF_RESTART_SVC magic to do the restart if no signal has to be
delivered. The only situation where the system call restart via the
repeat of the svc instruction is appropriate is when a SA_RESTART
signal is delivered to user space.

Unfortunately this breaks inferior calls by the debugger again. The
system call number and the length of the system call instruction is
lost over the inferior call and user space will see ERESTARTNOHAND/
ERESTARTSYS/ERESTARTNOINTR/ERESTART_RESTARTBLOCK. To correct this a
new ptrace interface is added to save/restore the system call number
and system call instruction length.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00

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/*
* Generate definitions needed by assembly language modules.
* This code generates raw asm output which is post-processed to extract
* and format the required data.
*/
#define ASM_OFFSETS_C
#include <linux/kbuild.h>
#include <linux/sched.h>
#include <asm/vdso.h>
#include <asm/sigp.h>
#include <asm/pgtable.h>
/*
* Make sure that the compiler is new enough. We want a compiler that
* is known to work with the "Q" assembler constraint.
*/
#if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 3)
#error Your compiler is too old; please use version 3.3.3 or newer
#endif
int main(void)
{
DEFINE(__THREAD_info, offsetof(struct task_struct, stack));
DEFINE(__THREAD_ksp, offsetof(struct task_struct, thread.ksp));
DEFINE(__THREAD_mm_segment, offsetof(struct task_struct, thread.mm_segment));
BLANK();
DEFINE(__TASK_pid, offsetof(struct task_struct, pid));
BLANK();
DEFINE(__THREAD_per_cause, offsetof(struct task_struct, thread.per_event.cause));
DEFINE(__THREAD_per_address, offsetof(struct task_struct, thread.per_event.address));
DEFINE(__THREAD_per_paid, offsetof(struct task_struct, thread.per_event.paid));
BLANK();
DEFINE(__TI_task, offsetof(struct thread_info, task));
DEFINE(__TI_domain, offsetof(struct thread_info, exec_domain));
DEFINE(__TI_flags, offsetof(struct thread_info, flags));
DEFINE(__TI_cpu, offsetof(struct thread_info, cpu));
DEFINE(__TI_precount, offsetof(struct thread_info, preempt_count));
DEFINE(__TI_user_timer, offsetof(struct thread_info, user_timer));
DEFINE(__TI_system_timer, offsetof(struct thread_info, system_timer));
DEFINE(__TI_last_break, offsetof(struct thread_info, last_break));
BLANK();
DEFINE(__PT_ARGS, offsetof(struct pt_regs, args));
DEFINE(__PT_PSW, offsetof(struct pt_regs, psw));
DEFINE(__PT_GPRS, offsetof(struct pt_regs, gprs));
DEFINE(__PT_ORIG_GPR2, offsetof(struct pt_regs, orig_gpr2));
DEFINE(__PT_SVC_CODE, offsetof(struct pt_regs, svc_code));
DEFINE(__PT_SIZE, sizeof(struct pt_regs));
BLANK();
DEFINE(__SF_BACKCHAIN, offsetof(struct stack_frame, back_chain));
DEFINE(__SF_GPRS, offsetof(struct stack_frame, gprs));
DEFINE(__SF_EMPTY, offsetof(struct stack_frame, empty1));
BLANK();
/* timeval/timezone offsets for use by vdso */
DEFINE(__VDSO_UPD_COUNT, offsetof(struct vdso_data, tb_update_count));
DEFINE(__VDSO_XTIME_STAMP, offsetof(struct vdso_data, xtime_tod_stamp));
DEFINE(__VDSO_XTIME_SEC, offsetof(struct vdso_data, xtime_clock_sec));
DEFINE(__VDSO_XTIME_NSEC, offsetof(struct vdso_data, xtime_clock_nsec));
DEFINE(__VDSO_WTOM_SEC, offsetof(struct vdso_data, wtom_clock_sec));
DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));
DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));
DEFINE(__VDSO_NTP_MULT, offsetof(struct vdso_data, ntp_mult));
DEFINE(__VDSO_ECTG_BASE, offsetof(struct vdso_per_cpu_data, ectg_timer_base));
DEFINE(__VDSO_ECTG_USER, offsetof(struct vdso_per_cpu_data, ectg_user_time));
/* constants used by the vdso */
DEFINE(__CLOCK_REALTIME, CLOCK_REALTIME);
DEFINE(__CLOCK_MONOTONIC, CLOCK_MONOTONIC);
DEFINE(__CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);
BLANK();
/* constants for SIGP */
DEFINE(__SIGP_STOP, sigp_stop);
DEFINE(__SIGP_RESTART, sigp_restart);
DEFINE(__SIGP_SENSE, sigp_sense);
DEFINE(__SIGP_INITIAL_CPU_RESET, sigp_initial_cpu_reset);
BLANK();
/* lowcore offsets */
DEFINE(__LC_EXT_PARAMS, offsetof(struct _lowcore, ext_params));
DEFINE(__LC_CPU_ADDRESS, offsetof(struct _lowcore, cpu_addr));
DEFINE(__LC_EXT_INT_CODE, offsetof(struct _lowcore, ext_int_code));
DEFINE(__LC_SVC_ILC, offsetof(struct _lowcore, svc_ilc));
DEFINE(__LC_SVC_INT_CODE, offsetof(struct _lowcore, svc_code));
DEFINE(__LC_PGM_ILC, offsetof(struct _lowcore, pgm_ilc));
DEFINE(__LC_PGM_INT_CODE, offsetof(struct _lowcore, pgm_code));
DEFINE(__LC_TRANS_EXC_CODE, offsetof(struct _lowcore, trans_exc_code));
DEFINE(__LC_PER_CAUSE, offsetof(struct _lowcore, per_perc_atmid));
DEFINE(__LC_PER_ADDRESS, offsetof(struct _lowcore, per_address));
DEFINE(__LC_PER_PAID, offsetof(struct _lowcore, per_access_id));
DEFINE(__LC_AR_MODE_ID, offsetof(struct _lowcore, ar_access_id));
DEFINE(__LC_SUBCHANNEL_ID, offsetof(struct _lowcore, subchannel_id));
DEFINE(__LC_SUBCHANNEL_NR, offsetof(struct _lowcore, subchannel_nr));
DEFINE(__LC_IO_INT_PARM, offsetof(struct _lowcore, io_int_parm));
DEFINE(__LC_IO_INT_WORD, offsetof(struct _lowcore, io_int_word));
DEFINE(__LC_STFL_FAC_LIST, offsetof(struct _lowcore, stfl_fac_list));
DEFINE(__LC_MCCK_CODE, offsetof(struct _lowcore, mcck_interruption_code));
DEFINE(__LC_DUMP_REIPL, offsetof(struct _lowcore, ipib));
BLANK();
DEFINE(__LC_RST_NEW_PSW, offsetof(struct _lowcore, restart_psw));
DEFINE(__LC_RST_OLD_PSW, offsetof(struct _lowcore, restart_old_psw));
DEFINE(__LC_EXT_OLD_PSW, offsetof(struct _lowcore, external_old_psw));
DEFINE(__LC_SVC_OLD_PSW, offsetof(struct _lowcore, svc_old_psw));
DEFINE(__LC_PGM_OLD_PSW, offsetof(struct _lowcore, program_old_psw));
DEFINE(__LC_MCK_OLD_PSW, offsetof(struct _lowcore, mcck_old_psw));
DEFINE(__LC_IO_OLD_PSW, offsetof(struct _lowcore, io_old_psw));
DEFINE(__LC_EXT_NEW_PSW, offsetof(struct _lowcore, external_new_psw));
DEFINE(__LC_SVC_NEW_PSW, offsetof(struct _lowcore, svc_new_psw));
DEFINE(__LC_PGM_NEW_PSW, offsetof(struct _lowcore, program_new_psw));
DEFINE(__LC_MCK_NEW_PSW, offsetof(struct _lowcore, mcck_new_psw));
DEFINE(__LC_IO_NEW_PSW, offsetof(struct _lowcore, io_new_psw));
DEFINE(__LC_SAVE_AREA, offsetof(struct _lowcore, save_area));
DEFINE(__LC_RETURN_PSW, offsetof(struct _lowcore, return_psw));
DEFINE(__LC_RETURN_MCCK_PSW, offsetof(struct _lowcore, return_mcck_psw));
DEFINE(__LC_SYNC_ENTER_TIMER, offsetof(struct _lowcore, sync_enter_timer));
DEFINE(__LC_ASYNC_ENTER_TIMER, offsetof(struct _lowcore, async_enter_timer));
DEFINE(__LC_MCCK_ENTER_TIMER, offsetof(struct _lowcore, mcck_enter_timer));
DEFINE(__LC_EXIT_TIMER, offsetof(struct _lowcore, exit_timer));
DEFINE(__LC_USER_TIMER, offsetof(struct _lowcore, user_timer));
DEFINE(__LC_SYSTEM_TIMER, offsetof(struct _lowcore, system_timer));
DEFINE(__LC_STEAL_TIMER, offsetof(struct _lowcore, steal_timer));
DEFINE(__LC_LAST_UPDATE_TIMER, offsetof(struct _lowcore, last_update_timer));
DEFINE(__LC_LAST_UPDATE_CLOCK, offsetof(struct _lowcore, last_update_clock));
DEFINE(__LC_CURRENT, offsetof(struct _lowcore, current_task));
DEFINE(__LC_CURRENT_PID, offsetof(struct _lowcore, current_pid));
DEFINE(__LC_THREAD_INFO, offsetof(struct _lowcore, thread_info));
DEFINE(__LC_KERNEL_STACK, offsetof(struct _lowcore, kernel_stack));
DEFINE(__LC_ASYNC_STACK, offsetof(struct _lowcore, async_stack));
DEFINE(__LC_PANIC_STACK, offsetof(struct _lowcore, panic_stack));
DEFINE(__LC_USER_ASCE, offsetof(struct _lowcore, user_asce));
DEFINE(__LC_INT_CLOCK, offsetof(struct _lowcore, int_clock));
DEFINE(__LC_MCCK_CLOCK, offsetof(struct _lowcore, mcck_clock));
DEFINE(__LC_MACHINE_FLAGS, offsetof(struct _lowcore, machine_flags));
DEFINE(__LC_FTRACE_FUNC, offsetof(struct _lowcore, ftrace_func));
DEFINE(__LC_IRB, offsetof(struct _lowcore, irb));
DEFINE(__LC_CPU_TIMER_SAVE_AREA, offsetof(struct _lowcore, cpu_timer_save_area));
DEFINE(__LC_CLOCK_COMP_SAVE_AREA, offsetof(struct _lowcore, clock_comp_save_area));
DEFINE(__LC_PSW_SAVE_AREA, offsetof(struct _lowcore, psw_save_area));
DEFINE(__LC_PREFIX_SAVE_AREA, offsetof(struct _lowcore, prefixreg_save_area));
DEFINE(__LC_AREGS_SAVE_AREA, offsetof(struct _lowcore, access_regs_save_area));
DEFINE(__LC_FPREGS_SAVE_AREA, offsetof(struct _lowcore, floating_pt_save_area));
DEFINE(__LC_GPREGS_SAVE_AREA, offsetof(struct _lowcore, gpregs_save_area));
DEFINE(__LC_CREGS_SAVE_AREA, offsetof(struct _lowcore, cregs_save_area));
#ifdef CONFIG_32BIT
DEFINE(SAVE_AREA_BASE, offsetof(struct _lowcore, extended_save_area_addr));
#else /* CONFIG_32BIT */
DEFINE(__LC_EXT_PARAMS2, offsetof(struct _lowcore, ext_params2));
DEFINE(SAVE_AREA_BASE, offsetof(struct _lowcore, floating_pt_save_area));
DEFINE(__LC_PASTE, offsetof(struct _lowcore, paste));
DEFINE(__LC_FP_CREG_SAVE_AREA, offsetof(struct _lowcore, fpt_creg_save_area));
DEFINE(__LC_LAST_BREAK, offsetof(struct _lowcore, breaking_event_addr));
DEFINE(__LC_VDSO_PER_CPU, offsetof(struct _lowcore, vdso_per_cpu_data));
DEFINE(__LC_GMAP, offsetof(struct _lowcore, gmap));
DEFINE(__LC_CMF_HPP, offsetof(struct _lowcore, cmf_hpp));
DEFINE(__GMAP_ASCE, offsetof(struct gmap, asce));
#endif /* CONFIG_32BIT */
return 0;
}
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