leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

s390: convert to generic entry

Browse Source 
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>
This commit is contained in:
Sven Schnelle
2020-11-21 11:14:56 +01:00
committed by Vasily Gorbik
parent ac94a2911e
commit 56e62a7370
39 changed files with 652 additions and 920 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
arch/s390/lib/uaccess.c
View File

@@ -16,8 +16,8 @@
#include <asm/mmu_context.h>
#include <asm/facility.h>
#ifdef CONFIG_DEBUG_USER_ASCE
void debug_user_asce(void)
#ifdef CONFIG_DEBUG_ENTRY
void debug_user_asce(int exit)
{
unsigned long cr1, cr7;
@@ -25,12 +25,14 @@ void debug_user_asce(void)
__ctl_store(cr7, 7, 7);
if (cr1 == S390_lowcore.kernel_asce && cr7 == S390_lowcore.user_asce)
return;
panic("incorrect ASCE on kernel exit\n"
panic("incorrect ASCE on kernel %s\n"
"cr1: %016lx cr7: %016lx\n"
"kernel: %016llx user: %016llx\n",
cr1, cr7, S390_lowcore.kernel_asce, S390_lowcore.user_asce);
exit ? "exit" : "entry", cr1, cr7,
S390_lowcore.kernel_asce, S390_lowcore.user_asce);
}
#endif /*CONFIG_DEBUG_USER_ASCE */
#endif /*CONFIG_DEBUG_ENTRY */
#ifndef CONFIG_HAVE_MARCH_Z10_FEATURES
static DEFINE_STATIC_KEY_FALSE(have_mvcos);