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KVM: PPC: Book3S HV: Allow negative offsets to real-mode hcall handlers

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The table of offsets to real-mode hcall handlers in book3s_hv_rmhandlers.S
can contain negative values, if some of the handlers end up before the
table in the vmlinux binary.  Thus we need to use a sign-extending load
to read the values in the table rather than a zero-extending load.
Without this, the host crashes when the guest does one of the hcalls
with negative offsets, due to jumping to a bogus address.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Paul Mackerras 2013-07-08 20:09:53 +10:00 committed by Alexander Graf
parent 5448050124
commit 4baa1d871c
1 changed files with 1 additions and 1 deletions
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arch/powerpc/kvm/book3s_hv_rmhandlers.S
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@ -1381,7 +1381,7 @@ hcall_try_real_mode:
cmpldi r3,hcall_real_table_end - hcall_real_table
bge guest_exit_cont
LOAD_REG_ADDR(r4, hcall_real_table)
lwzx r3,r3,r4
lwax r3,r3,r4
cmpwi r3,0
beq guest_exit_cont
add r3,r3,r4