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powerpc/tm: do not use r13 for tabort_syscall

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commit cc7786d3ee7e3c979799db834b528db2c0834c2e upstream.

tabort_syscall runs with RI=1, so a nested recoverable machine
check will load the paca into r13 and overwrite what we loaded
it with, because exceptions returning to privileged mode do not
restore r13.

Fixes: b4b56f9ecab4 (powerpc/tm: Abort syscalls in active transactions)
Signed-off-by: Nick Piggin <npiggin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicholas Piggin 2016-07-25 14:26:51 +10:00 committed by Greg Kroah-Hartman
parent e70bb22b8f
commit 53545131ec
1 changed files with 6 additions and 6 deletions
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12
arch/powerpc/kernel/entry_64.S
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@ -334,13 +334,13 @@ syscall_exit_work:
tabort_syscall:
/* Firstly we need to enable TM in the kernel */
mfmsr r10
li r13, 1
rldimi r10, r13, MSR_TM_LG, 63-MSR_TM_LG
li r9, 1
rldimi r10, r9, MSR_TM_LG, 63-MSR_TM_LG
mtmsrd r10, 0
/* tabort, this dooms the transaction, nothing else */
li r13, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
TABORT(R13)
li r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
TABORT(R9)
/*
* Return directly to userspace. We have corrupted user register state,
@ -348,8 +348,8 @@ tabort_syscall:
* resume after the tbegin of the aborted transaction with the
* checkpointed register state.
*/
li r13, MSR_RI
andc r10, r10, r13
li r9, MSR_RI
andc r10, r10, r9
mtmsrd r10, 1
mtspr SPRN_SRR0, r11
mtspr SPRN_SRR1, r12