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linux/arch/s390/kernel/asm-offsets.c
Heiko Carstens 8b72f5a97b s390/mm: Reimplement lazy ASCE handling 
Reduce system call overhead time (round trip time for invoking a
non-existent system call) by 25%.

With the removal of set_fs() [1] lazy control register handling was removed
in order to keep kernel entry and exit simple. However this made system
calls slower.

With the conversion to generic entry [2] and numerous follow up changes
which simplified the entry code significantly, adding support for lazy asce
handling doesn't add much complexity to the entry code anymore.

In particular this means:

- On kernel entry the primary asce is not modified and contains the user
  asce

- Kernel accesses which require secondary-space mode (for example futex
  operations) are surrounded by enable_sacf_uaccess() and
  disable_sacf_uaccess() calls. enable_sacf_uaccess() sets the primary asce
  to kernel asce so that the sacf instruction can be used to switch to
  secondary-space mode. The primary asce is changed back to user asce with
  disable_sacf_uaccess().

The state of the control register which contains the primary asce is
reflected with a new TIF_ASCE_PRIMARY bit. This is required on context
switch so that the correct asce is restored for the scheduled in process.

In result address spaces are now setup like this:

CPU running in               | %cr1 ASCE | %cr7 ASCE | %cr13 ASCE
-----------------------------|-----------|-----------|-----------
user space                   |  user     |  user     |  kernel
kernel (no sacf)             |  user     |  user     |  kernel
kernel (during sacf uaccess) |  kernel   |  user     |  kernel
kernel (kvm guest execution) |  guest    |  user     |  kernel

In result cr1 control register content is not changed except for:
- futex system calls
- legacy s390 PCI system calls
- the kvm specific cmpxchg_user_key() uaccess helper

This leads to faster system call execution.

[1] 87d5986345 ("s390/mm: remove set_fs / rework address space handling")
[2] 56e62a7370 ("s390: convert to generic entry")

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-14 11:23:21 +02:00

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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.
*/
#include <linux/kbuild.h>
#include <linux/sched.h>
#include <linux/purgatory.h>
#include <linux/pgtable.h>
#include <linux/ftrace_regs.h>
#include <asm/kvm_host_types.h>
#include <asm/stacktrace.h>
#include <asm/ptrace.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);
OFFSET(__TI_sie, task_struct, thread_info.sie);
BLANK();
/* pt_regs offsets */
OFFSET(__PT_PSW, pt_regs, psw);
OFFSET(__PT_GPRS, pt_regs, gprs);
OFFSET(__PT_R0, pt_regs, gprs[0]);
OFFSET(__PT_R1, pt_regs, gprs[1]);
OFFSET(__PT_R2, pt_regs, gprs[2]);
OFFSET(__PT_R3, pt_regs, gprs[3]);
OFFSET(__PT_R4, pt_regs, gprs[4]);
OFFSET(__PT_R5, pt_regs, gprs[5]);
OFFSET(__PT_R6, pt_regs, gprs[6]);
OFFSET(__PT_R7, pt_regs, gprs[7]);
OFFSET(__PT_R8, pt_regs, gprs[8]);
OFFSET(__PT_R9, pt_regs, gprs[9]);
OFFSET(__PT_R10, pt_regs, gprs[10]);
OFFSET(__PT_R11, pt_regs, gprs[11]);
OFFSET(__PT_R12, pt_regs, gprs[12]);
OFFSET(__PT_R13, pt_regs, gprs[13]);
OFFSET(__PT_R14, pt_regs, gprs[14]);
OFFSET(__PT_R15, pt_regs, gprs[15]);
OFFSET(__PT_ORIG_GPR2, pt_regs, orig_gpr2);
OFFSET(__PT_INT_CODE, pt_regs, int_code);
OFFSET(__PT_FLAGS, pt_regs, flags);
OFFSET(__PT_LAST_BREAK, pt_regs, last_break);
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, empty[0]);
OFFSET(__SF_SIE_CONTROL, stack_frame, sie_control_block);
OFFSET(__SF_SIE_SAVEAREA, stack_frame, sie_savearea);
OFFSET(__SF_SIE_REASON, stack_frame, sie_reason);
OFFSET(__SF_SIE_FLAGS, stack_frame, sie_flags);
OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
OFFSET(__SF_SIE_GUEST_ASCE, stack_frame, sie_guest_asce);
DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
BLANK();
OFFSET(__SFUSER_BACKCHAIN, stack_frame_user, back_chain);
DEFINE(STACK_FRAME_USER_OVERHEAD, sizeof(struct stack_frame_user));
OFFSET(__SFVDSO_RETURN_ADDRESS, stack_frame_vdso_wrapper, return_address);
DEFINE(STACK_FRAME_VDSO_OVERHEAD, sizeof(struct stack_frame_vdso_wrapper));
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_PGM_ILC, lowcore, pgm_ilc);
OFFSET(__LC_PGM_CODE, lowcore, pgm_code);
OFFSET(__LC_PGM_INT_CODE, lowcore, pgm_int_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_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_PGM_LAST_BREAK, lowcore, pgm_last_break);
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, lowcore, save_area);
OFFSET(__LC_SAVE_AREA_RESTART, lowcore, save_area_restart);
OFFSET(__LC_PCPU, lowcore, pcpu);
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_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_RESTART_FLAGS, lowcore, restart_flags);
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_LAST_BREAK, lowcore, last_break);
/* software defined ABI-relevant lowcore locations 0xe00 - 0xe20 */
OFFSET(__LC_DUMP_REIPL, lowcore, ipib);
OFFSET(__LC_VMCORE_INFO, lowcore, vmcore_info);
OFFSET(__LC_OS_INFO, lowcore, os_info);
/* 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_LAST_BREAK_SAVE_AREA, lowcore, last_break_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();
/* gmap/sie offsets */
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));
/* sizeof kernel parameter area */
DEFINE(__PARMAREA_SIZE, sizeof(struct parmarea));
/* kernel parameter area offsets */
DEFINE(IPL_DEVICE, PARMAREA + offsetof(struct parmarea, ipl_device));
DEFINE(INITRD_START, PARMAREA + offsetof(struct parmarea, initrd_start));
DEFINE(INITRD_SIZE, PARMAREA + offsetof(struct parmarea, initrd_size));
DEFINE(OLDMEM_BASE, PARMAREA + offsetof(struct parmarea, oldmem_base));
DEFINE(OLDMEM_SIZE, PARMAREA + offsetof(struct parmarea, oldmem_size));
DEFINE(COMMAND_LINE, PARMAREA + offsetof(struct parmarea, command_line));
DEFINE(MAX_COMMAND_LINE_SIZE, PARMAREA + offsetof(struct parmarea, max_command_line_size));
OFFSET(__FTRACE_REGS_PT_REGS, __arch_ftrace_regs, regs);
DEFINE(__FTRACE_REGS_SIZE, sizeof(struct __arch_ftrace_regs));
OFFSET(__PCPU_FLAGS, pcpu, flags);
return 0;
}
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