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s390: add 3f program exception handler

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Program exception 3f (secure storage violation) can only be detected
when the CPU is running in SIE with a format 4 state description,
e.g. running a protected guest. Because of this and because user
space partly controls the guest memory mapping and can trigger this
exception, we want to send a SIGSEGV to the process running the guest
and not panic the kernel.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Cc: <stable@vger.kernel.org> # 5.7
Fixes: 084ea4d611 ("s390/mm: add (non)secure page access exceptions handlers")
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Janosch Frank 2020-09-08 09:05:04 -04:00 committed by Vasily Gorbik
parent 73ac74c7d4
commit cd4d3d5f21
3 changed files with 22 additions and 1 deletions
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1
arch/s390/kernel/entry.h
View File

@ -26,6 +26,7 @@ void do_protection_exception(struct pt_regs *regs);
void do_dat_exception(struct pt_regs *regs);
void do_secure_storage_access(struct pt_regs *regs);
void do_non_secure_storage_access(struct pt_regs *regs);
void do_secure_storage_violation(struct pt_regs *regs);
void addressing_exception(struct pt_regs *regs);
void data_exception(struct pt_regs *regs);

2
arch/s390/kernel/pgm_check.S
View File

@ -80,7 +80,7 @@ PGM_CHECK(do_dat_exception) /* 3b */
PGM_CHECK_DEFAULT /* 3c */
PGM_CHECK(do_secure_storage_access) /* 3d */
PGM_CHECK(do_non_secure_storage_access) /* 3e */
PGM_CHECK_DEFAULT /* 3f */
PGM_CHECK(do_secure_storage_violation) /* 3f */
PGM_CHECK(monitor_event_exception) /* 40 */
PGM_CHECK_DEFAULT /* 41 */
PGM_CHECK_DEFAULT /* 42 */

20
arch/s390/mm/fault.c
View File

@ -859,6 +859,21 @@ void do_non_secure_storage_access(struct pt_regs *regs)
}
NOKPROBE_SYMBOL(do_non_secure_storage_access);
void do_secure_storage_violation(struct pt_regs *regs)
{
/*
* Either KVM messed up the secure guest mapping or the same
* page is mapped into multiple secure guests.
*
* This exception is only triggered when a guest 2 is running
* and can therefore never occur in kernel context.
*/
printk_ratelimited(KERN_WARNING
"Secure storage violation in task: %s, pid %d\n",
current->comm, current->pid);
send_sig(SIGSEGV, current, 0);
}
#else
void do_secure_storage_access(struct pt_regs *regs)
{
@ -869,4 +884,9 @@ void do_non_secure_storage_access(struct pt_regs *regs)
{
default_trap_handler(regs);
}
void do_secure_storage_violation(struct pt_regs *regs)
{
default_trap_handler(regs);
}
#endif