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s390: add separate program check exit path

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System call and program check handler both use the system call exit
path when returning to previous context. However the program check
handler jumps right to the end of the system call exit path if the
previous context is kernel context.

This lead to the quite odd double disabling of interrupts in the
system call exit path introduced with commit ce9dfafe29 ("s390:
fix system call exit path").

To avoid that have a separate program check handler exit path if the
previous context is kernel context.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2020-11-11 18:46:26 +01:00
parent 6c81603801
commit 0cd9b7230c
1 changed files with 11 additions and 3 deletions
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14
arch/s390/kernel/entry.S
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@ -430,8 +430,6 @@ ENTRY(system_call)
TSTMSK __LC_CPU_FLAGS,(_CIF_WORK-_CIF_FPU)
jnz .Lsysc_work
BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
.Lsysc_restore:
DISABLE_INTS
TSTMSK __LC_CPU_FLAGS, _CIF_FPU
jz .Lsysc_skip_fpu
brasl %r14,load_fpu_regs
@ -709,10 +707,20 @@ ENTRY(pgm_check_handler)
.Lpgm_return:
LOCKDEP_SYS_EXIT
tm __PT_PSW+1(%r11),0x01 # returning to user ?
jno .Lsysc_restore
jno .Lpgm_restore
TSTMSK __PT_FLAGS(%r11),_PIF_SYSCALL
jo .Lsysc_do_syscall
j .Lsysc_tif
.Lpgm_restore:
DISABLE_INTS
TSTMSK __LC_CPU_FLAGS, _CIF_FPU
jz .Lpgm_skip_fpu
brasl %r14,load_fpu_regs
.Lpgm_skip_fpu:
mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
stpt __LC_EXIT_TIMER
lmg %r0,%r15,__PT_R0(%r11)
b __LC_RETURN_LPSWE
#
# PER event in supervisor state, must be kprobes