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alistair23-linux/arch/s390/lib
Sven Schnelle 56e62a7370 s390: convert to generic entry
This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't
  know about our PIF flags in exit_to_user_mode_loop().

- The old code had several ways to restart syscalls:

  a) PIF_SYSCALL_RESTART, which was only set during execve to force a
     restart after upgrading a process (usually qemu-kvm) to pgste page
     table extensions.

  b) PIF_SYSCALL, which is set by do_signal() to indicate that the
     current syscall should be restarted. This is changed so that
     do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use
     PIF_SYSCALL doesn't work with the generic code, and changing it
     to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART
     more unique.

- On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by
executing a svc instruction on the process stack which causes a fault.
While handling that fault the fault code sets PIF_SYSCALL to hand over
processing to the syscall code on exit to usermode.

The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets
a return value for a syscall. The s390x ptrace ABI uses r2 both for the
syscall number and return value, so ptrace cannot set the syscall number +
return value at the same time. The flag makes handling that a bit easier.
do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET
is set.

CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY.
CR1/7/13 will be checked both on kernel entry and exit to contain the
correct asces.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2021-01-19 12:29:26 +01:00
..
Makefile s390: enable HAVE_FUNCTION_ERROR_INJECTION 2020-07-27 10:33:28 +02:00
delay.c s390/delay: remove udelay_simple() 2020-12-16 14:55:49 +01:00
error-inject.c s390: enable HAVE_FUNCTION_ERROR_INJECTION 2020-07-27 10:33:28 +02:00
find.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mem.S s390: add missing ENDPROC statements to assembler functions 2019-05-02 13:54:11 +02:00
probes.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
spinlock.c s390/spinlock: remove confusing comment in arch_spin_lock_wait 2019-12-11 19:53:23 +01:00
string.c s390/lib: fix kernel doc for memcmp() 2020-10-07 21:50:01 +02:00
test_unwind.c s390/test_unwind: use timer instead of udelay 2020-12-16 14:55:49 +01:00
uaccess.c s390: convert to generic entry 2021-01-19 12:29:26 +01:00
xor.c s390/lib: add missing include 2019-07-29 18:05:02 +02:00