Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-29 07:31:29 +00:00
Code Issues Packages Projects Releases Wiki Activity

powerpc/signal64: Remove TM ifdefery in middle of if/else block

Browse Source 
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:
Christopher M. Riedl 2021-02-26 19:12:54 -06:00 committed by Michael Ellerman
parent 1a130b67c6
commit 2d19630e20
2 changed files with 54 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/powerpc/kernel/process.c
View File

@ -1117,9 +1117,10 @@ void restore_tm_state(struct pt_regs *regs)
regs->msr |= msr_diff;
}
#else
#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
#define tm_recheckpoint_new_task(new)
#define __switch_to_tm(prev, new)
void tm_reclaim_current(uint8_t cause) {}
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
static inline void save_sprs(struct thread_struct *t)

102
arch/powerpc/kernel/signal_64.c
View File

@ -594,6 +594,12 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
return err;
}
#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
static long restore_tm_sigcontexts(struct task_struct *tsk, struct sigcontext __user *sc,
struct sigcontext __user *tm_sc)
{
return -EINVAL;
}
#endif
/*
@ -710,9 +716,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
struct pt_regs *regs = current_pt_regs();
struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
sigset_t set;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
unsigned long msr;
#endif
/* Always make any pending restarted system calls return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
@ -724,48 +728,50 @@ SYSCALL_DEFINE0(rt_sigreturn)
goto badframe;
set_current_blocked(&set);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* If there is a transactional state then throw it away.
* The purpose of a sigreturn is to destroy all traces of the
* signal frame, this includes any transactional state created
* within in. We only check for suspended as we can never be
* active in the kernel, we are active, there is nothing better to
* do than go ahead and Bad Thing later.
* The cause is not important as there will never be a
* recheckpoint so it's not user visible.
*/
if (MSR_TM_SUSPENDED(mfmsr()))
tm_reclaim_current(0);
if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM)) {
/*
* If there is a transactional state then throw it away.
* The purpose of a sigreturn is to destroy all traces of the
* signal frame, this includes any transactional state created
* within in. We only check for suspended as we can never be
* active in the kernel, we are active, there is nothing better to
* do than go ahead and Bad Thing later.
* The cause is not important as there will never be a
* recheckpoint so it's not user visible.
*/
if (MSR_TM_SUSPENDED(mfmsr()))
tm_reclaim_current(0);
/*
* Disable MSR[TS] bit also, so, if there is an exception in the
* code below (as a page fault in copy_ckvsx_to_user()), it does
* not recheckpoint this task if there was a context switch inside
* the exception.
*
* A major page fault can indirectly call schedule(). A reschedule
* process in the middle of an exception can have a side effect
* (Changing the CPU MSR[TS] state), since schedule() is called
* with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
* (switch_to() calls tm_recheckpoint() for the 'new' process). In
* this case, the process continues to be the same in the CPU, but
* the CPU state just changed.
*
* This can cause a TM Bad Thing, since the MSR in the stack will
* have the MSR[TS]=0, and this is what will be used to RFID.
*
* Clearing MSR[TS] state here will avoid a recheckpoint if there
* is any process reschedule in kernel space. The MSR[TS] state
* does not need to be saved also, since it will be replaced with
* the MSR[TS] that came from user context later, at
* restore_tm_sigcontexts.
*/
regs->msr &= ~MSR_TS_MASK;
/*
* Disable MSR[TS] bit also, so, if there is an exception in the
* code below (as a page fault in copy_ckvsx_to_user()), it does
* not recheckpoint this task if there was a context switch inside
* the exception.
*
* A major page fault can indirectly call schedule(). A reschedule
* process in the middle of an exception can have a side effect
* (Changing the CPU MSR[TS] state), since schedule() is called
* with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
* (switch_to() calls tm_recheckpoint() for the 'new' process). In
* this case, the process continues to be the same in the CPU, but
* the CPU state just changed.
*
* This can cause a TM Bad Thing, since the MSR in the stack will
* have the MSR[TS]=0, and this is what will be used to RFID.
*
* Clearing MSR[TS] state here will avoid a recheckpoint if there
* is any process reschedule in kernel space. The MSR[TS] state
* does not need to be saved also, since it will be replaced with
* the MSR[TS] that came from user context later, at
* restore_tm_sigcontexts.
*/
regs->msr &= ~MSR_TS_MASK;
if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
goto badframe;
if (MSR_TM_ACTIVE(msr)) {
if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
goto badframe;
}
if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && MSR_TM_ACTIVE(msr)) {
/* We recheckpoint on return. */
struct ucontext __user *uc_transact;
@ -778,9 +784,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
&uc_transact->uc_mcontext))
goto badframe;
} else
#endif
{
} else {
/*
* Fall through, for non-TM restore
*
@ -818,10 +822,8 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
unsigned long newsp = 0;
long err = 0;
struct pt_regs *regs = tsk->thread.regs;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/* Save the thread's msr before get_tm_stackpointer() changes it */
unsigned long msr = regs->msr;
#endif
frame = get_sigframe(ksig, tsk, sizeof(*frame), 0);
if (!access_ok(frame, sizeof(*frame)))
@ -836,8 +838,9 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (MSR_TM_ACTIVE(msr)) {
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/* The ucontext_t passed to userland points to the second
* ucontext_t (for transactional state) with its uc_link ptr.
*/
@ -847,9 +850,8 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
tsk, ksig->sig, NULL,
(unsigned long)ksig->ka.sa.sa_handler,
msr);
} else
#endif
{
} else {
err |= __put_user(0, &frame->uc.uc_link);
prepare_setup_sigcontext(tsk);
err |= setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,