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s390: remove unused s390_base_ext_handler 

s390_base_ext_handler_fn haven't been used since its introduction in
commit ab14de6c37 ("[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: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2020-09-24 17:12:08 +02:00 committed by Heiko Carstens
parent 85cde0192a
commit f38b0a7439
3 changed files with 2 additions and 30 deletions
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6
arch/s390/include/asm/processor.h
View File

@ -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

22
arch/s390/kernel/base.S
View File

@ -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

4
arch/s390/kernel/early.c
View File

@ -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;