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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2014-02-03 17:37:15 +0100
committerWilly Tarreau <w@1wt.eu>2014-05-19 07:54:37 +0200
commit0e37e30a8f55140dc1702b2d2008d41155bb3360 (patch)
tree5c4007ca42b6df8ce823afa7289568fa692ff1de
parentefe55430442061cb01177c88b891a678935a6eae (diff)
downloadlinux-linaro-stable-0e37e30a8f55140dc1702b2d2008d41155bb3360.tar.gz
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> [dannf: backported to Debian's 2.6.32] Signed-off-by: Willy Tarreau <w@1wt.eu>
-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 d984a2a380c3..5b27ed023392 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -124,7 +124,7 @@ 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
@@ -139,12 +139,15 @@ 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
.org 0x12000
.globl _ehead