Hi,
Well, looks like we need to resurect TIF_NOTIFY_RESUME now
that we do have some actual need for it. This implies that
I need to rework my perfmon new code base to take this into
account. I don't want to use pfm_needs_checking. So maybe
it is okay to use a higher order TIF bit for perfmon on IA-64
combined with TIF_NOTIFY_RESUME.
For the RSE part, I am not sure I understand the logic behind this
change. I think more explanantions maybe needed to calrify this
a bit more.
On Wed, Aug 08, 2007 at 10:30:37AM +0800, Shaohua Li wrote:
> On Tue, 2007-08-07 at 15:13 +0800, Roland McGrath wrote:
> > That looks reasonable to me, not being expert on the ia64 details.
> > I rolled that into utrace-regset-ia64.patch in the 2.6.22 backport
> > version.
> >
> > > patch is against latest utrace source (2.6.22 base + utrace patches)
> >
> > The latest utrace source is based on 2.6.23-rc2, and your patch does
> > not
> > apply there. TIF_NOTIFY_RESUME has been renamed to TIF_PERFMON_WORK.
> > So you need to rename it back (or to something else) to overload it.
> >
> > If the gist of your patch here seems right to ia64 folks, then I'd
> > suggest
> > you do a patch adding ia64_sync_krbs to the upstream kernel. That
> > would be
> > the necessary prelude to doing the arch_ptrace_stop plan, which I can
> > help
> > ia64 folks with later.
> Ok, this is the patch against 2.6.23-rc2
>
>
> In ptrace case, user space RSE might be newer than kernel RSE. To avoid
> stale RSE is used when return to userspace, this patch synchronize user
> space RSE to kernel RSE.
> Also, as TIF_ALLWORK_MASK bits are limited, TIF_NOTIFY_RESUME is
> overrided.
>
> Signed-off-by: Bibo Mao<bibo.mao@xxxxxxxxx>
> Signed-off-by: Shaohua Li<shaohua.li@xxxxxxxxx>
>
> ==============================================================
> arch/ia64/kernel/perfmon.c | 21 ++--------------
> arch/ia64/kernel/process.c | 14 +++++++++++
> arch/ia64/kernel/ptrace.c | 52 +++++++++++++++++++++++++++++++++++++++++
> include/asm-ia64/ptrace.h | 1
> include/asm-ia64/thread_info.h | 11 ++++++--
> 5 files changed, 78 insertions(+), 21 deletions(-)
>
> Index: 2.6.23-rc2/arch/ia64/kernel/process.c
> ===================================================================
> --- 2.6.23-rc2.orig/arch/ia64/kernel/process.c 2007-08-04 10:49:55.000000000 +0800
> +++ 2.6.23-rc2/arch/ia64/kernel/process.c 2007-08-08 09:27:18.000000000 +0800
> @@ -154,6 +154,17 @@ show_regs (struct pt_regs *regs)
> show_stack(NULL, NULL);
> }
>
> +void tsk_clear_notify_resume(struct task_struct *tsk)
> +{
> +#ifdef CONFIG_PERFMON
> + if (tsk->thread.pfm_needs_checking)
> + return;
> +#endif
> + if (test_ti_thread_flag(task_thread_info(tsk), TIF_RESTORE_RSE))
> + return;
> + clear_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME);
> +}
> +
> void
> do_notify_resume_user (sigset_t *unused, struct sigscratch *scr, long in_syscall)
> {
> @@ -172,6 +183,9 @@ do_notify_resume_user (sigset_t *unused,
> /* deal with pending signal delivery */
> if (test_thread_flag(TIF_SIGPENDING)||test_thread_flag(TIF_RESTORE_SIGMASK))
> ia64_do_signal(scr, in_syscall);
> + /* copy user rbs to kernel rbs */
> + if (unlikely(test_thread_flag(TIF_RESTORE_RSE)))
> + ia64_sync_krbs(current);
> }
>
> static int pal_halt = 1;
> Index: 2.6.23-rc2/arch/ia64/kernel/ptrace.c
> ===================================================================
> --- 2.6.23-rc2.orig/arch/ia64/kernel/ptrace.c 2007-08-08 09:00:28.000000000 +0800
> +++ 2.6.23-rc2/arch/ia64/kernel/ptrace.c 2007-08-08 09:27:18.000000000 +0800
> @@ -554,6 +554,25 @@ ia64_sync_user_rbs (struct task_struct *
> return 0;
> }
>
> +long
> +ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
> + unsigned long user_rbs_start, unsigned long user_rbs_end)
> +{
> + unsigned long addr, val;
> + long ret;
> +
> + /* now copy word for word from user rbs to kernel rbs: */
> + for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
> + if (access_process_vm(child, addr, &val, sizeof(val), 0)
> + != sizeof(val))
> + return -EIO;
> + ret = ia64_poke(child, sw, user_rbs_end, addr, val);
> + if (ret < 0)
> + return ret;
> + }
> + return 0;
> +}
> +
> /*
> * Write f32-f127 back to task->thread.fph if it has been modified.
> */
> @@ -728,6 +747,10 @@ syscall_trace_enter (long arg0, long arg
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> tracehook_report_syscall(®s, 0);
>
> + /* copy user rbs to kernel rbs */
> + if (test_thread_flag(TIF_RESTORE_RSE))
> + ia64_sync_krbs(current);
> +
> if (unlikely(current->audit_context)) {
> long syscall;
> int arch;
> @@ -764,6 +787,10 @@ syscall_trace_leave (long arg0, long arg
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> tracehook_report_syscall(®s, 1);
>
> + /* copy user rbs to kernel rbs */
> + if (test_thread_flag(TIF_RESTORE_RSE))
> + ia64_sync_krbs(current);
> +
> if (test_thread_flag(TIF_SINGLESTEP)) {
> force_sig(SIGTRAP, current); /* XXX */
> tracehook_report_syscall_step(®s);
> @@ -1416,9 +1443,34 @@ gpregs_writeback(struct task_struct *tar
> const struct utrace_regset *regset,
> int now)
> {
> + if (test_and_set_tsk_thread_flag(target, TIF_RESTORE_RSE))
> + return 0;
> + tsk_set_notify_resume(target);
> return do_regset_call(do_gpregs_writeback, target, regset, 0, 0, NULL, NULL);
> }
>
> +static void do_gpregs_readback(struct unw_frame_info *info, void *arg)
> +{
> + struct pt_regs *pt;
> + utrace_getset_t *dst = arg;
> + unsigned long urbs_end;
> +
> + if (unw_unwind_to_user(info) < 0)
> + return;
> + pt = task_pt_regs(dst->target);
> + urbs_end = ia64_get_user_rbs_end(dst->target, pt, NULL);
> + dst->ret = ia64_sync_kernel_rbs(dst->target, info->sw, pt->ar_bspstore, urbs_end);
> +}
> +/*
> + * This is called to read back the register backing store.
> + */
> +long ia64_sync_krbs(struct task_struct *target)
> +{
> + clear_tsk_thread_flag(target, TIF_RESTORE_RSE);
> + tsk_clear_notify_resume(target);
> + return do_regset_call(do_gpregs_readback, target, NULL, 0, 0, NULL, NULL);
> +}
> +
> static int
> fpregs_active(struct task_struct *target, const struct utrace_regset *regset)
> {
> Index: 2.6.23-rc2/include/asm-ia64/ptrace.h
> ===================================================================
> --- 2.6.23-rc2.orig/include/asm-ia64/ptrace.h 2007-08-04 10:49:55.000000000 +0800
> +++ 2.6.23-rc2/include/asm-ia64/ptrace.h 2007-08-08 09:27:18.000000000 +0800
> @@ -292,6 +292,7 @@ struct switch_stack {
> unsigned long, long);
> extern void ia64_flush_fph (struct task_struct *);
> extern void ia64_sync_fph (struct task_struct *);
> + extern long ia64_sync_krbs(struct task_struct *);
> extern long ia64_sync_user_rbs (struct task_struct *, struct switch_stack *,
> unsigned long, unsigned long);
>
> Index: 2.6.23-rc2/include/asm-ia64/thread_info.h
> ===================================================================
> --- 2.6.23-rc2.orig/include/asm-ia64/thread_info.h 2007-08-04 10:49:55.000000000 +0800
> +++ 2.6.23-rc2/include/asm-ia64/thread_info.h 2007-08-08 09:35:08.000000000 +0800
> @@ -71,6 +71,9 @@ struct thread_info {
> #define alloc_task_struct() ((struct task_struct *)__get_free_pages(GFP_KERNEL | __GFP_COMP, KERNEL_STACK_SIZE_ORDER))
> #define free_task_struct(tsk) free_pages((unsigned long) (tsk), KERNEL_STACK_SIZE_ORDER)
>
> +#define tsk_set_notify_resume(tsk) \
> + set_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME)
> +extern void tsk_clear_notify_resume(struct task_struct *tsk);
> #endif /* !__ASSEMBLY */
>
> /*
> @@ -85,28 +88,30 @@ struct thread_info {
> #define TIF_SYSCALL_AUDIT 3 /* syscall auditing active */
> #define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
> #define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
> -#define TIF_PERFMON_WORK 6 /* work for pfm_handle_work() */
> +#define TIF_NOTIFY_RESUME 6 /* resumption notification requested */
> #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
> #define TIF_MEMDIE 17
> #define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
> #define TIF_DB_DISABLED 19 /* debug trap disabled for fsyscall */
> #define TIF_FREEZE 20 /* is freezing for suspend */
> +#define TIF_RESTORE_RSE 21 /* task need RSE synchronization */
>
> #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
> #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
> #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
> #define _TIF_SYSCALL_TRACEAUDIT (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)
> #define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
> -#define _TIF_PERFMON_WORK (1 << TIF_PERFMON_WORK)
> +#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
> #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
> #define _TIF_MCA_INIT (1 << TIF_MCA_INIT)
> #define _TIF_DB_DISABLED (1 << TIF_DB_DISABLED)
> #define _TIF_FREEZE (1 << TIF_FREEZE)
> +#define _TIF_RESTORE_RSE (1 << TIF_RESTORE_RSE)
>
> /* "work to do on user-return" bits */
> -#define TIF_ALLWORK_MASK (_TIF_SIGPENDING|_TIF_PERFMON_WORK|_TIF_SYSCALL_AUDIT|\
> +#define TIF_ALLWORK_MASK (_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SYSCALL_AUDIT|\
> _TIF_NEED_RESCHED| _TIF_SYSCALL_TRACE|\
> _TIF_RESTORE_SIGMASK)
> /* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */
> Index: 2.6.23-rc2/arch/ia64/kernel/perfmon.c
> ===================================================================
> --- 2.6.23-rc2.orig/arch/ia64/kernel/perfmon.c 2007-08-04 10:49:55.000000000 +0800
> +++ 2.6.23-rc2/arch/ia64/kernel/perfmon.c 2007-08-08 09:32:41.000000000 +0800
> @@ -586,21 +586,6 @@ pfm_put_task(struct task_struct *task)
> }
>
> static inline void
> -pfm_set_task_notify(struct task_struct *task)
> -{
> - struct thread_info *info;
> -
> - info = (struct thread_info *) ((char *) task + IA64_TASK_SIZE);
> - set_bit(TIF_PERFMON_WORK, &info->flags);
> -}
> -
> -static inline void
> -pfm_clear_task_notify(void)
> -{
> - clear_thread_flag(TIF_PERFMON_WORK);
> -}
> -
> -static inline void
> pfm_reserve_page(unsigned long a)
> {
> SetPageReserved(vmalloc_to_page((void *)a));
> @@ -3730,7 +3715,7 @@ pfm_restart(pfm_context_t *ctx, void *ar
>
> PFM_SET_WORK_PENDING(task, 1);
>
> - pfm_set_task_notify(task);
> + tsk_set_notify_resume(task);
>
> /*
> * XXX: send reschedule if task runs on another CPU
> @@ -5087,7 +5072,7 @@ pfm_handle_work(void)
>
> PFM_SET_WORK_PENDING(current, 0);
>
> - pfm_clear_task_notify();
> + tsk_clear_notify_resume(current);
>
> regs = task_pt_regs(current);
>
> @@ -5455,7 +5440,7 @@ pfm_overflow_handler(struct task_struct
> * when coming from ctxsw, current still points to the
> * previous task, therefore we must work with task and not current.
> */
> - pfm_set_task_notify(task);
> + tsk_set_notify_resume(task);
> }
> /*
> * defer until state is changed (shorten spin window). the context is locked
> -
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--
-Stephane
