powerpc/signal64: Remove TM ifdefery in middle of if/else block
Both rt_sigreturn() and handle_rt_signal_64() contain TM-related ifdefs
which break-up an if/else block. Provide stubs for the ifdef-guarded TM
functions and remove the need for an ifdef in rt_sigreturn().
Rework the remaining TM ifdef in handle_rt_signal64() similar to
commit f1cf4f93de
("powerpc/signal32: Remove ifdefery in middle of if/else").
Unlike in the commit for ppc32, the ifdef can't be removed entirely
since uc_transact in sigframe depends on CONFIG_PPC_TRANSACTIONAL_MEM.
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-6-cmr@codefail.de
This commit is contained in:
parent
1a130b67c6
commit
2d19630e20
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@ -1117,9 +1117,10 @@ void restore_tm_state(struct pt_regs *regs)
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regs->msr |= msr_diff;
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}
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#else
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#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
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#define tm_recheckpoint_new_task(new)
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#define __switch_to_tm(prev, new)
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void tm_reclaim_current(uint8_t cause) {}
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#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
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static inline void save_sprs(struct thread_struct *t)
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@ -594,6 +594,12 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
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return err;
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}
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#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
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static long restore_tm_sigcontexts(struct task_struct *tsk, struct sigcontext __user *sc,
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struct sigcontext __user *tm_sc)
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{
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return -EINVAL;
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}
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#endif
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/*
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@ -710,9 +716,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
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struct pt_regs *regs = current_pt_regs();
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struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
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sigset_t set;
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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unsigned long msr;
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#endif
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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@ -724,48 +728,50 @@ SYSCALL_DEFINE0(rt_sigreturn)
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goto badframe;
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set_current_blocked(&set);
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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/*
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* If there is a transactional state then throw it away.
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* The purpose of a sigreturn is to destroy all traces of the
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* signal frame, this includes any transactional state created
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* within in. We only check for suspended as we can never be
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* active in the kernel, we are active, there is nothing better to
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* do than go ahead and Bad Thing later.
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* The cause is not important as there will never be a
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* recheckpoint so it's not user visible.
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*/
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if (MSR_TM_SUSPENDED(mfmsr()))
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tm_reclaim_current(0);
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if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM)) {
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/*
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* If there is a transactional state then throw it away.
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* The purpose of a sigreturn is to destroy all traces of the
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* signal frame, this includes any transactional state created
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* within in. We only check for suspended as we can never be
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* active in the kernel, we are active, there is nothing better to
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* do than go ahead and Bad Thing later.
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* The cause is not important as there will never be a
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* recheckpoint so it's not user visible.
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*/
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if (MSR_TM_SUSPENDED(mfmsr()))
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tm_reclaim_current(0);
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/*
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* Disable MSR[TS] bit also, so, if there is an exception in the
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* code below (as a page fault in copy_ckvsx_to_user()), it does
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* not recheckpoint this task if there was a context switch inside
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* the exception.
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*
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* A major page fault can indirectly call schedule(). A reschedule
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* process in the middle of an exception can have a side effect
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* (Changing the CPU MSR[TS] state), since schedule() is called
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* with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
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* (switch_to() calls tm_recheckpoint() for the 'new' process). In
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* this case, the process continues to be the same in the CPU, but
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* the CPU state just changed.
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*
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* This can cause a TM Bad Thing, since the MSR in the stack will
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* have the MSR[TS]=0, and this is what will be used to RFID.
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*
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* Clearing MSR[TS] state here will avoid a recheckpoint if there
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* is any process reschedule in kernel space. The MSR[TS] state
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* does not need to be saved also, since it will be replaced with
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* the MSR[TS] that came from user context later, at
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* restore_tm_sigcontexts.
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*/
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regs->msr &= ~MSR_TS_MASK;
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/*
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* Disable MSR[TS] bit also, so, if there is an exception in the
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* code below (as a page fault in copy_ckvsx_to_user()), it does
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* not recheckpoint this task if there was a context switch inside
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* the exception.
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*
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* A major page fault can indirectly call schedule(). A reschedule
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* process in the middle of an exception can have a side effect
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* (Changing the CPU MSR[TS] state), since schedule() is called
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* with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
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* (switch_to() calls tm_recheckpoint() for the 'new' process). In
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* this case, the process continues to be the same in the CPU, but
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* the CPU state just changed.
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*
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* This can cause a TM Bad Thing, since the MSR in the stack will
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* have the MSR[TS]=0, and this is what will be used to RFID.
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*
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* Clearing MSR[TS] state here will avoid a recheckpoint if there
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* is any process reschedule in kernel space. The MSR[TS] state
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* does not need to be saved also, since it will be replaced with
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* the MSR[TS] that came from user context later, at
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* restore_tm_sigcontexts.
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*/
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regs->msr &= ~MSR_TS_MASK;
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if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
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goto badframe;
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if (MSR_TM_ACTIVE(msr)) {
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if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
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goto badframe;
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}
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if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && MSR_TM_ACTIVE(msr)) {
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/* We recheckpoint on return. */
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struct ucontext __user *uc_transact;
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@ -778,9 +784,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
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if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
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&uc_transact->uc_mcontext))
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goto badframe;
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} else
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#endif
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{
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} else {
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/*
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* Fall through, for non-TM restore
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*
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@ -818,10 +822,8 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
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unsigned long newsp = 0;
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long err = 0;
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struct pt_regs *regs = tsk->thread.regs;
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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/* Save the thread's msr before get_tm_stackpointer() changes it */
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unsigned long msr = regs->msr;
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#endif
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frame = get_sigframe(ksig, tsk, sizeof(*frame), 0);
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if (!access_ok(frame, sizeof(*frame)))
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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if (MSR_TM_ACTIVE(msr)) {
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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/* The ucontext_t passed to userland points to the second
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* ucontext_t (for transactional state) with its uc_link ptr.
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*/
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tsk, ksig->sig, NULL,
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(unsigned long)ksig->ka.sa.sa_handler,
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msr);
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} else
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#endif
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{
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} else {
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err |= __put_user(0, &frame->uc.uc_link);
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prepare_setup_sigcontext(tsk);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
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