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Commit 742dc577 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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s390/sclp: make early sclp irq handler more robust 



Make the early sclp interrupt handler more robust:

- disable all interrupt sub classes except for the service signal subclass
- extend ctlreg0 union so it is easily possible to set the service signal
  subclass mask bit without using a magic number
- disable lowcore protection before writing to it
- make sure that all write accesses are done before the original content
  of control register 0 is restored, which could enable lowcore protection

Reviewed-by: default avatarPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 68cc795d

arch/s390/include/asm/ctl_reg.h

+3 −1
Original line number Original line Diff line number Diff line
@@ -62,7 +62,9 @@ union ctlreg0 { 
		unsigned long	   : 4;

		unsigned long	   : 4;

		unsigned long afp  : 1; /* AFP-register control */

		unsigned long afp  : 1; /* AFP-register control */

		unsigned long vx   : 1; /* Vector enablement control */

		unsigned long vx   : 1; /* Vector enablement control */

		unsigned long	   : 17;

		unsigned long	   : 7;

		unsigned long sssm : 1; /* Service signal subclass mask */

		unsigned long	   : 9;

	};

	};

};

};

arch/s390/kernel/sclp.c

+10 −5
Original line number Original line Diff line number Diff line
@@ -18,12 +18,16 @@ static bool have_linemode __section(data); 




static void _sclp_wait_int(void)

static void _sclp_wait_int(void)

{

{

	unsigned long cr0, cr0_new, psw_mask, addr;

	unsigned long psw_mask, addr, flags;

	psw_t psw_ext_save, psw_wait;

	psw_t psw_ext_save, psw_wait;

	union ctlreg0 cr0, cr0_new;





	__ctl_store(cr0, 0, 0);

	raw_local_irq_save(flags);

	cr0_new = cr0 | 0x200;

	__ctl_store(cr0.val, 0, 0);

	__ctl_load(cr0_new, 0, 0);

	cr0_new.val = cr0.val & ~CR0_IRQ_SUBCLASS_MASK;

	cr0_new.lap = 0;

	cr0_new.sssm = 1;

	__ctl_load(cr0_new.val, 0, 0);





	psw_ext_save = S390_lowcore.external_new_psw;

	psw_ext_save = S390_lowcore.external_new_psw;

	psw_mask = __extract_psw();

	psw_mask = __extract_psw();
@@ -45,8 +49,9 @@ static void _sclp_wait_int(void) 
			: "cc", "memory");

			: "cc", "memory");

	} while (S390_lowcore.ext_int_code != EXT_IRQ_SERVICE_SIG);

	} while (S390_lowcore.ext_int_code != EXT_IRQ_SERVICE_SIG);





	__ctl_load(cr0, 0, 0);

	S390_lowcore.external_new_psw = psw_ext_save;

	S390_lowcore.external_new_psw = psw_ext_save;

	__ctl_load(cr0.val, 0, 0);

	raw_local_irq_restore(flags);

}

}





static int _sclp_servc(unsigned int cmd, char *sccb)

static int _sclp_servc(unsigned int cmd, char *sccb)