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When in an active transaction that takes a signal, we need to be careful with the stack. It's possible that the stack has moved back up after the tbegin. The obvious case here is when the tbegin is called inside a function that returns before a tend. In this case, the stack is part of the checkpointed transactional memory state. If we write over this non transactionally or in suspend, we are in trouble because if we get a tm abort, the program counter and stack pointer will be back at the tbegin but our in memory stack won't be valid anymore. To avoid this, when taking a signal in an active transaction, we need to use the stack pointer from the checkpointed state, rather than the speculated state. This ensures that the signal context (written tm suspended) will be written below the stack required for the rollback. The transaction is aborted becuase of the treclaim, so any memory written between the tbegin and the signal will be rolled back anyway. For signals taken in non-TM or suspended mode, we use the normal/non-checkpointed stack pointer. Tested with 64 and 32 bit signals Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> # v3.9 Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
11 lines
251 B
C
11 lines
251 B
C
#ifndef _ASM_POWERPC_SIGNAL_H
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#define _ASM_POWERPC_SIGNAL_H
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#define __ARCH_HAS_SA_RESTORER
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#include <uapi/asm/signal.h>
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#include <uapi/asm/ptrace.h>
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extern unsigned long get_tm_stackpointer(struct pt_regs *regs);
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#endif /* _ASM_POWERPC_SIGNAL_H */
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