Commit 0cd9b723 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390: add separate program check exit path 



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 ce9dfafe ("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: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 6c816038

arch/s390/kernel/entry.S

+11 −3
Original line number Diff line number Diff line
@@ -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