Commit f38b0a74 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Heiko Carstens
Browse files

s390: remove unused s390_base_ext_handler 



s390_base_ext_handler_fn haven't been used since its introduction in
commit ab14de6c ("[S390] Convert memory detection into C code.").

s390_base_ext_handler itself is currently falsely storing 16 registers
at __LC_SAVE_AREA_ASYNC rewriting several following lowcore values:
cpu_flags, return_psw, return_mcck_psw, sync_enter_timer and
async_enter_timer.

Besides that s390_base_ext_handler itself is only potentially hiding
EXT interrupts which should not have happen in the first place. Any
piece of code which requires EXT interrupts before fully functional
ext_int_handler is enabled has to do it on its own, like this is done
by sclp_early_cmd() which is doing EXT interrupts handling synchronously
in sclp_early_wait_irq().

With s390_base_ext_handler removed unexpected EXT interrupt leads
to disabled wait with the address 0x1b0 (__LC_EXT_NEW_PSW), which is
currently setup in the decompressor.

Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 85cde019

arch/s390/include/asm/processor.h

+1 −5
Original line number Diff line number Diff line
@@ -318,14 +318,10 @@ static __always_inline void __noreturn disabled_wait(void) 
}



/*

 * Basic Machine Check/Program Check Handler.

 * Basic Program Check Handler.

 */



extern void s390_base_pgm_handler(void);

extern void s390_base_ext_handler(void);



extern void (*s390_base_pgm_handler_fn)(void);

extern void (*s390_base_ext_handler_fn)(void);



#define ARCH_LOW_ADDRESS_LIMIT	0x7fffffffUL

arch/s390/kernel/base.S

+0 −22
Original line number Diff line number Diff line
@@ -11,32 +11,10 @@ 
#include <asm/asm-offsets.h>

#include <asm/nospec-insn.h>

#include <asm/ptrace.h>

#include <asm/sigp.h>



	GEN_BR_THUNK %r9

	GEN_BR_THUNK %r14



ENTRY(s390_base_ext_handler)

	stmg	%r0,%r15,__LC_SAVE_AREA_ASYNC

	basr	%r13,0

0:	aghi	%r15,-STACK_FRAME_OVERHEAD

	larl	%r1,s390_base_ext_handler_fn

	lg	%r9,0(%r1)

	ltgr	%r9,%r9

	jz	1f

	BASR_EX	%r14,%r9

1:	lmg	%r0,%r15,__LC_SAVE_AREA_ASYNC

	ni	__LC_EXT_OLD_PSW+1,0xfd	# clear wait state bit

	lpswe	__LC_EXT_OLD_PSW

ENDPROC(s390_base_ext_handler)



	.section .bss

	.align 8

	.globl s390_base_ext_handler_fn

s390_base_ext_handler_fn:

	.quad	0

	.previous



ENTRY(s390_base_pgm_handler)

	stmg	%r0,%r15,__LC_SAVE_AREA_SYNC

	basr	%r13,0

arch/s390/kernel/early.c

+1 −3
Original line number Diff line number Diff line
@@ -169,12 +169,10 @@ static noinline __init void setup_lowcore_early(void) 
{

	psw_t psw;



	psw.addr = (unsigned long)s390_base_pgm_handler;

	psw.mask = PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA;

	if (IS_ENABLED(CONFIG_KASAN))

		psw.mask |= PSW_MASK_DAT;

	psw.addr = (unsigned long) s390_base_ext_handler;

	S390_lowcore.external_new_psw = psw;

	psw.addr = (unsigned long) s390_base_pgm_handler;

	S390_lowcore.program_new_psw = psw;

	s390_base_pgm_handler_fn = early_pgm_check_handler;

	S390_lowcore.preempt_count = INIT_PREEMPT_COUNT;