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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2014-02-03 17:37:15 +0100
committerBen Hutchings <ben@decadent.org.uk>2014-04-09 02:20:46 +0100
commit1664028240024d96721a5328c93ff206661cd9e1 (patch)
tree1706582342592e3c724e315fbd5da7068cb2afb8
parentb1a292f3ccbbfe864cb4931e8fed4baea6b17eb8 (diff)
s390: fix kernel crash due to linkage stack instructions
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: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--arch/s390/kernel/head64.S7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 99348c0eaa41..78be2459c9a1 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -61,7 +61,7 @@ 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
@@ -69,12 +69,15 @@ 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)