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Commit cc7786d3 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Benjamin Herrenschmidt
Browse files

powerpc/tm: do not use r13 for tabort_syscall 



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: b4b56f9e (powerpc/tm: Abort syscalls in active transactions)
Cc: stable@vger.kernel.org
Signed-off-by: default avatarNick Piggin <npiggin@gmail.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 7c379526

arch/powerpc/kernel/entry_64.S

+6 −6
Original line number Diff line number Diff line
@@ -368,13 +368,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) 
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,
@@ -382,8 +382,8 @@ 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