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linux/arch/s390/kernel/asm-offsets.c
Sven Schnelle b61b159512 s390: add stack for machine check handler 
The previous code used the normal kernel stack for machine checks.
This is problematic when a machine check interrupts a system call
or interrupt handler right at the beginning where registers are set up.

Assume system_call is interrupted at the first instruction and a machine
check is triggered. The machine check handler is called, checks the PSW
to see whether it is coming from user space, notices that it is already
in kernel mode but %r15 still contains the user space stack. This would
lead to a kernel crash.

There are basically two ways of fixing that: Either using the 'critical
cleanup' approach which compares the address in the PSW to see whether
it is already at a point where the stack has been set up, or use an extra
stack for the machine check handler.

For simplicity, we will go with the second approach and allocate an extra
stack. This adds some memory overhead for large systems, but usually large
system have plenty of memory so this isn't really a concern. But it keeps
the mchk stack setup simple and less error prone.

Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: <stable@kernel.org> # v5.8+
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2021-02-13 17:17:53 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* 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/kvm_host.h>
#include <linux/sched.h>
#include <linux/purgatory.h>
#include <linux/pgtable.h>
#include <asm/idle.h>
#include <asm/gmap.h>
#include <asm/nmi.h>
#include <asm/stacktrace.h>
int main(void)
{
/* task struct offsets */
OFFSET(__TASK_stack, task_struct, stack);
OFFSET(__TASK_thread, task_struct, thread);
OFFSET(__TASK_pid, task_struct, pid);
BLANK();
/* thread struct offsets */
OFFSET(__THREAD_ksp, thread_struct, ksp);
BLANK();
/* thread info offsets */
OFFSET(__TI_flags, task_struct, thread_info.flags);
BLANK();
/* pt_regs offsets */
OFFSET(__PT_PSW, pt_regs, psw);
OFFSET(__PT_GPRS, pt_regs, gprs);
OFFSET(__PT_ORIG_GPR2, pt_regs, orig_gpr2);
OFFSET(__PT_FLAGS, pt_regs, flags);
OFFSET(__PT_CR1, pt_regs, cr1);
DEFINE(__PT_SIZE, sizeof(struct pt_regs));
BLANK();
/* stack_frame offsets */
OFFSET(__SF_BACKCHAIN, stack_frame, back_chain);
OFFSET(__SF_GPRS, stack_frame, gprs);
OFFSET(__SF_EMPTY, stack_frame, empty1[0]);
OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[1]);
OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[2]);
OFFSET(__SF_SIE_REASON, stack_frame, empty1[3]);
OFFSET(__SF_SIE_FLAGS, stack_frame, empty1[4]);
BLANK();
/* idle data offsets */
OFFSET(__CLOCK_IDLE_ENTER, s390_idle_data, clock_idle_enter);
OFFSET(__CLOCK_IDLE_EXIT, s390_idle_data, clock_idle_exit);
OFFSET(__TIMER_IDLE_ENTER, s390_idle_data, timer_idle_enter);
OFFSET(__TIMER_IDLE_EXIT, s390_idle_data, timer_idle_exit);
OFFSET(__MT_CYCLES_ENTER, s390_idle_data, mt_cycles_enter);
BLANK();
/* hardware defined lowcore locations 0x000 - 0x1ff */
OFFSET(__LC_EXT_PARAMS, lowcore, ext_params);
OFFSET(__LC_EXT_CPU_ADDR, lowcore, ext_cpu_addr);
OFFSET(__LC_EXT_INT_CODE, lowcore, ext_int_code);
OFFSET(__LC_SVC_ILC, lowcore, svc_ilc);
OFFSET(__LC_SVC_INT_CODE, lowcore, svc_code);
OFFSET(__LC_PGM_ILC, lowcore, pgm_ilc);
OFFSET(__LC_PGM_INT_CODE, lowcore, pgm_code);
OFFSET(__LC_DATA_EXC_CODE, lowcore, data_exc_code);
OFFSET(__LC_MON_CLASS_NR, lowcore, mon_class_num);
OFFSET(__LC_PER_CODE, lowcore, per_code);
OFFSET(__LC_PER_ATMID, lowcore, per_atmid);
OFFSET(__LC_PER_ADDRESS, lowcore, per_address);
OFFSET(__LC_EXC_ACCESS_ID, lowcore, exc_access_id);
OFFSET(__LC_PER_ACCESS_ID, lowcore, per_access_id);
OFFSET(__LC_OP_ACCESS_ID, lowcore, op_access_id);
OFFSET(__LC_AR_MODE_ID, lowcore, ar_mode_id);
OFFSET(__LC_TRANS_EXC_CODE, lowcore, trans_exc_code);
OFFSET(__LC_MON_CODE, lowcore, monitor_code);
OFFSET(__LC_SUBCHANNEL_ID, lowcore, subchannel_id);
OFFSET(__LC_SUBCHANNEL_NR, lowcore, subchannel_nr);
OFFSET(__LC_IO_INT_PARM, lowcore, io_int_parm);
OFFSET(__LC_IO_INT_WORD, lowcore, io_int_word);
OFFSET(__LC_STFL_FAC_LIST, lowcore, stfl_fac_list);
OFFSET(__LC_STFLE_FAC_LIST, lowcore, stfle_fac_list);
OFFSET(__LC_MCCK_CODE, lowcore, mcck_interruption_code);
OFFSET(__LC_EXT_DAMAGE_CODE, lowcore, external_damage_code);
OFFSET(__LC_MCCK_FAIL_STOR_ADDR, lowcore, failing_storage_address);
OFFSET(__LC_LAST_BREAK, lowcore, breaking_event_addr);
OFFSET(__LC_RETURN_LPSWE, lowcore, return_lpswe);
OFFSET(__LC_RETURN_MCCK_LPSWE, lowcore, return_mcck_lpswe);
OFFSET(__LC_RST_OLD_PSW, lowcore, restart_old_psw);
OFFSET(__LC_EXT_OLD_PSW, lowcore, external_old_psw);
OFFSET(__LC_SVC_OLD_PSW, lowcore, svc_old_psw);
OFFSET(__LC_PGM_OLD_PSW, lowcore, program_old_psw);
OFFSET(__LC_MCK_OLD_PSW, lowcore, mcck_old_psw);
OFFSET(__LC_IO_OLD_PSW, lowcore, io_old_psw);
OFFSET(__LC_RST_NEW_PSW, lowcore, restart_psw);
OFFSET(__LC_EXT_NEW_PSW, lowcore, external_new_psw);
OFFSET(__LC_SVC_NEW_PSW, lowcore, svc_new_psw);
OFFSET(__LC_PGM_NEW_PSW, lowcore, program_new_psw);
OFFSET(__LC_MCK_NEW_PSW, lowcore, mcck_new_psw);
OFFSET(__LC_IO_NEW_PSW, lowcore, io_new_psw);
/* software defined lowcore locations 0x200 - 0xdff*/
OFFSET(__LC_SAVE_AREA_SYNC, lowcore, save_area_sync);
OFFSET(__LC_SAVE_AREA_ASYNC, lowcore, save_area_async);
OFFSET(__LC_SAVE_AREA_RESTART, lowcore, save_area_restart);
OFFSET(__LC_CPU_FLAGS, lowcore, cpu_flags);
OFFSET(__LC_RETURN_PSW, lowcore, return_psw);
OFFSET(__LC_RETURN_MCCK_PSW, lowcore, return_mcck_psw);
OFFSET(__LC_SYS_ENTER_TIMER, lowcore, sys_enter_timer);
OFFSET(__LC_MCCK_ENTER_TIMER, lowcore, mcck_enter_timer);
OFFSET(__LC_EXIT_TIMER, lowcore, exit_timer);
OFFSET(__LC_LAST_UPDATE_TIMER, lowcore, last_update_timer);
OFFSET(__LC_LAST_UPDATE_CLOCK, lowcore, last_update_clock);
OFFSET(__LC_INT_CLOCK, lowcore, int_clock);
OFFSET(__LC_MCCK_CLOCK, lowcore, mcck_clock);
OFFSET(__LC_CLOCK_COMPARATOR, lowcore, clock_comparator);
OFFSET(__LC_BOOT_CLOCK, lowcore, boot_clock);
OFFSET(__LC_CURRENT, lowcore, current_task);
OFFSET(__LC_KERNEL_STACK, lowcore, kernel_stack);
OFFSET(__LC_ASYNC_STACK, lowcore, async_stack);
OFFSET(__LC_NODAT_STACK, lowcore, nodat_stack);
OFFSET(__LC_RESTART_STACK, lowcore, restart_stack);
OFFSET(__LC_MCCK_STACK, lowcore, mcck_stack);
OFFSET(__LC_RESTART_FN, lowcore, restart_fn);
OFFSET(__LC_RESTART_DATA, lowcore, restart_data);
OFFSET(__LC_RESTART_SOURCE, lowcore, restart_source);
OFFSET(__LC_KERNEL_ASCE, lowcore, kernel_asce);
OFFSET(__LC_USER_ASCE, lowcore, user_asce);
OFFSET(__LC_LPP, lowcore, lpp);
OFFSET(__LC_CURRENT_PID, lowcore, current_pid);
OFFSET(__LC_PERCPU_OFFSET, lowcore, percpu_offset);
OFFSET(__LC_MACHINE_FLAGS, lowcore, machine_flags);
OFFSET(__LC_PREEMPT_COUNT, lowcore, preempt_count);
OFFSET(__LC_GMAP, lowcore, gmap);
OFFSET(__LC_BR_R1, lowcore, br_r1_trampoline);
/* software defined ABI-relevant lowcore locations 0xe00 - 0xe20 */
OFFSET(__LC_DUMP_REIPL, lowcore, ipib);
/* hardware defined lowcore locations 0x1000 - 0x18ff */
OFFSET(__LC_MCESAD, lowcore, mcesad);
OFFSET(__LC_EXT_PARAMS2, lowcore, ext_params2);
OFFSET(__LC_FPREGS_SAVE_AREA, lowcore, floating_pt_save_area);
OFFSET(__LC_GPREGS_SAVE_AREA, lowcore, gpregs_save_area);
OFFSET(__LC_PSW_SAVE_AREA, lowcore, psw_save_area);
OFFSET(__LC_PREFIX_SAVE_AREA, lowcore, prefixreg_save_area);
OFFSET(__LC_FP_CREG_SAVE_AREA, lowcore, fpt_creg_save_area);
OFFSET(__LC_TOD_PROGREG_SAVE_AREA, lowcore, tod_progreg_save_area);
OFFSET(__LC_CPU_TIMER_SAVE_AREA, lowcore, cpu_timer_save_area);
OFFSET(__LC_CLOCK_COMP_SAVE_AREA, lowcore, clock_comp_save_area);
OFFSET(__LC_AREGS_SAVE_AREA, lowcore, access_regs_save_area);
OFFSET(__LC_CREGS_SAVE_AREA, lowcore, cregs_save_area);
OFFSET(__LC_PGM_TDB, lowcore, pgm_tdb);
BLANK();
/* extended machine check save area */
OFFSET(__MCESA_GS_SAVE_AREA, mcesa, guarded_storage_save_area);
BLANK();
/* gmap/sie offsets */
OFFSET(__GMAP_ASCE, gmap, asce);
OFFSET(__SIE_PROG0C, kvm_s390_sie_block, prog0c);
OFFSET(__SIE_PROG20, kvm_s390_sie_block, prog20);
/* kexec_sha_region */
OFFSET(__KEXEC_SHA_REGION_START, kexec_sha_region, start);
OFFSET(__KEXEC_SHA_REGION_LEN, kexec_sha_region, len);
DEFINE(__KEXEC_SHA_REGION_SIZE, sizeof(struct kexec_sha_region));
return 0;
}
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