| From 8d7f6690cedb83456edd41c9bd583783f0703bf0 Mon Sep 17 00:00:00 2001 |
| From: Martin Schwidefsky <schwidefsky@de.ibm.com> |
| Date: Mon, 3 Feb 2014 17:37:15 +0100 |
| Subject: s390: fix kernel crash due to linkage stack instructions |
| |
| From: Martin Schwidefsky <schwidefsky@de.ibm.com> |
| |
| commit 8d7f6690cedb83456edd41c9bd583783f0703bf0 upstream. |
| |
| The kernel currently crashes with a low-address-protection exception |
| if a user space process executes an instruction that tries to use the |
| linkage stack. Set the base-ASTE origin and the subspace-ASTE origin |
| of the dispatchable-unit-control-table to point to a dummy ASTE. |
| Set up control register 15 to point to an empty linkage stack with no |
| room left. |
| |
| A user space process with a linkage stack instruction will still crash |
| but with a different exception which is correctly translated to a |
| segmentation fault instead of a kernel oops. |
| |
| Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/s390/kernel/head64.S | 7 +++++-- |
| 1 file changed, 5 insertions(+), 2 deletions(-) |
| |
| --- a/arch/s390/kernel/head64.S |
| +++ b/arch/s390/kernel/head64.S |
| @@ -59,7 +59,7 @@ ENTRY(startup_continue) |
| .quad 0 # cr12: tracing off |
| .quad 0 # cr13: home space segment table |
| .quad 0xc0000000 # cr14: machine check handling off |
| - .quad 0 # cr15: linkage stack operations |
| + .quad .Llinkage_stack # cr15: linkage stack operations |
| .Lpcmsk:.quad 0x0000000180000000 |
| .L4malign:.quad 0xffffffffffc00000 |
| .Lscan2g:.quad 0x80000000 + 0x20000 - 8 # 2GB + 128K - 8 |
| @@ -67,12 +67,15 @@ ENTRY(startup_continue) |
| .Lparmaddr: |
| .quad PARMAREA |
| .align 64 |
| -.Lduct: .long 0,0,0,0,.Lduald,0,0,0 |
| +.Lduct: .long 0,.Laste,.Laste,0,.Lduald,0,0,0 |
| .long 0,0,0,0,0,0,0,0 |
| +.Laste: .quad 0,0xffffffffffffffff,0,0,0,0,0,0 |
| .align 128 |
| .Lduald:.rept 8 |
| .long 0x80000000,0,0,0 # invalid access-list entries |
| .endr |
| +.Llinkage_stack: |
| + .long 0,0,0x89000000,0,0,0,0x8a000000,0 |
| |
| ENTRY(_ehead) |
| |
