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Date: Mon, 2 May 2011 14:50:06 -0400
From: Chris Metcalf <cmetcalf@...era.com>
To: linux-kernel@...r.kernel.org, James Morris <jmorris@...ei.org>
Subject: [PATCH] arch/tile: support TIF_NOTIFY_RESUME
This support is required for CONFIG_KEYS, NFSv4 kernel DNS, etc.
The change is slightly more complex than the minimal thing, since
I took advantage of having to go into the assembly code to just
move a bunch of stuff into C code: specifically, the schedule(),
do_async_page_fault(), do_signal(), and single_step_once() support,
in addition to the TIF_NOTIFY_RESUME support.
Signed-off-by: Chris Metcalf <cmetcalf@...era.com>
---
arch/tile/include/asm/processor.h | 2 +
arch/tile/include/asm/thread_info.h | 5 +-
arch/tile/include/asm/traps.h | 4 +
arch/tile/kernel/intvec_32.S | 114 +++++-----------------------------
arch/tile/kernel/process.c | 48 +++++++++++++++
arch/tile/kernel/single_step.c | 8 +++
arch/tile/mm/fault.c | 6 +-
7 files changed, 87 insertions(+), 100 deletions(-)
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index e688947..d6b43dd 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -215,6 +215,8 @@ static inline void release_thread(struct task_struct *dead_task)
extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern int do_work_pending(struct pt_regs *regs, u32 flags);
+
/*
* Return saved (kernel) PC of a blocked thread.
diff --git a/arch/tile/include/asm/thread_info.h b/arch/tile/include/asm/thread_info.h
index 3405b52..bc4f562 100644
--- a/arch/tile/include/asm/thread_info.h
+++ b/arch/tile/include/asm/thread_info.h
@@ -125,6 +125,7 @@ extern void cpu_idle_on_new_stack(struct thread_info *old_ti,
#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
#define TIF_SECCOMP 6 /* secure computing */
#define TIF_MEMDIE 7 /* OOM killer at work */
+#define TIF_NOTIFY_RESUME 8 /* callback before returning to user */
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
@@ -134,10 +135,12 @@ extern void cpu_idle_on_new_stack(struct thread_info *old_ti,
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_MEMDIE (1<<TIF_MEMDIE)
+#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
/* Work to do on any return to user space. */
#define _TIF_ALLWORK_MASK \
- (_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_SINGLESTEP|_TIF_ASYNC_TLB)
+ (_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_SINGLESTEP|\
+ _TIF_ASYNC_TLB|_TIF_NOTIFY_RESUME)
/*
* Thread-synchronous status.
diff --git a/arch/tile/include/asm/traps.h b/arch/tile/include/asm/traps.h
index d06e35f..5f20f92 100644
--- a/arch/tile/include/asm/traps.h
+++ b/arch/tile/include/asm/traps.h
@@ -15,10 +15,14 @@
#ifndef _ASM_TILE_TRAPS_H
#define _ASM_TILE_TRAPS_H
+#include <arch/chip.h>
+
/* mm/fault.c */
void do_page_fault(struct pt_regs *, int fault_num,
unsigned long address, unsigned long write);
+#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
void do_async_page_fault(struct pt_regs *);
+#endif
#ifndef __tilegx__
/*
diff --git a/arch/tile/kernel/intvec_32.S b/arch/tile/kernel/intvec_32.S
index fffcfa6..f35c312 100644
--- a/arch/tile/kernel/intvec_32.S
+++ b/arch/tile/kernel/intvec_32.S
@@ -851,14 +851,27 @@ STD_ENTRY(interrupt_return)
/* Check to see if there is any work to do before returning to user. */
{
addi r29, r32, THREAD_INFO_FLAGS_OFFSET
- moveli r28, lo16(_TIF_ALLWORK_MASK)
+ moveli r1, lo16(_TIF_ALLWORK_MASK)
}
{
lw r29, r29
- auli r28, r28, ha16(_TIF_ALLWORK_MASK)
+ auli r1, r1, ha16(_TIF_ALLWORK_MASK)
}
- and r28, r29, r28
- bnz r28, .Lwork_pending
+ and r1, r29, r1
+ bzt r1, .Lrestore_all
+
+ /*
+ * Make sure we have all the registers saved for signal
+ * handling or single-step. Call out to C code to figure out
+ * exactly what we need to do for each flag bit, then if
+ * necessary, reload the flags and recheck.
+ */
+ push_extra_callee_saves r0
+ {
+ PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
+ jal do_work_pending
+ }
+ bnz r0, .Lresume_userspace
/*
* In the NMI case we
@@ -1099,99 +1112,6 @@ STD_ENTRY(interrupt_return)
pop_reg r50
pop_reg r51, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(51)
j .Lcontinue_restore_regs
-
-.Lwork_pending:
- /* Mask the reschedule flag */
- andi r28, r29, _TIF_NEED_RESCHED
-
- {
- /*
- * If the NEED_RESCHED flag is called, we call schedule(), which
- * may drop this context right here and go do something else.
- * On return, jump back to .Lresume_userspace and recheck.
- */
- bz r28, .Lasync_tlb
-
- /* Mask the async-tlb flag */
- andi r28, r29, _TIF_ASYNC_TLB
- }
-
- jal schedule
- FEEDBACK_REENTER(interrupt_return)
-
- /* Reload the flags and check again */
- j .Lresume_userspace
-
-.Lasync_tlb:
- {
- bz r28, .Lneed_sigpending
-
- /* Mask the sigpending flag */
- andi r28, r29, _TIF_SIGPENDING
- }
-
- PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
- jal do_async_page_fault
- FEEDBACK_REENTER(interrupt_return)
-
- /*
- * Go restart the "resume userspace" process. We may have
- * fired a signal, and we need to disable interrupts again.
- */
- j .Lresume_userspace
-
-.Lneed_sigpending:
- /*
- * At this point we are either doing signal handling or single-step,
- * so either way make sure we have all the registers saved.
- */
- push_extra_callee_saves r0
-
- {
- /* If no signal pending, skip to singlestep check */
- bz r28, .Lneed_singlestep
-
- /* Mask the singlestep flag */
- andi r28, r29, _TIF_SINGLESTEP
- }
-
- jal do_signal
- FEEDBACK_REENTER(interrupt_return)
-
- /* Reload the flags and check again */
- j .Lresume_userspace
-
-.Lneed_singlestep:
- {
- /* Get a pointer to the EX1 field */
- PTREGS_PTR(r29, PTREGS_OFFSET_EX1)
-
- /* If we get here, our bit must be set. */
- bz r28, .Lwork_confusion
- }
- /* If we are in priv mode, don't single step */
- lw r28, r29
- andi r28, r28, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
- bnz r28, .Lrestore_all
-
- /* Allow interrupts within the single step code */
- TRACE_IRQS_ON /* Note: clobbers registers r0-r29 */
- IRQ_ENABLE(r20, r21)
-
- /* try to single-step the current instruction */
- PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
- jal single_step_once
- FEEDBACK_REENTER(interrupt_return)
-
- /* Re-disable interrupts. TRACE_IRQS_OFF in .Lrestore_all. */
- IRQ_DISABLE(r20,r21)
-
- j .Lrestore_all
-
-.Lwork_confusion:
- move r0, r28
- panic "thread_info allwork flags unhandled on userspace resume: %#x"
-
STD_ENDPROC(interrupt_return)
/*
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index d006510..8e86334 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -25,10 +25,13 @@
#include <linux/hardirq.h>
#include <linux/syscalls.h>
#include <linux/kernel.h>
+#include <linux/tracehook.h>
+#include <linux/signal.h>
#include <asm/system.h>
#include <asm/stack.h>
#include <asm/homecache.h>
#include <asm/syscalls.h>
+#include <asm/traps.h>
#ifdef CONFIG_HARDWALL
#include <asm/hardwall.h>
#endif
@@ -546,6 +549,51 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
return __switch_to(prev, next, next_current_ksp0(next));
}
+/*
+ * This routine is called on return from interrupt if any of the
+ * TIF_WORK_MASK flags are set in thread_info->flags. It is
+ * entered with interrupts disabled so we don't miss an event
+ * that modified the thread_info flags. If any flag is set, we
+ * handle it and return, and the calling assembly code will
+ * re-disable interrupts, reload the thread flags, and call back
+ * if more flags need to be handled.
+ *
+ * We return whether we need to check the thread_info flags again
+ * or not. Note that we don't clear TIF_SINGLESTEP here, so it's
+ * important that it be tested last, and then claim that we don't
+ * need to recheck the flags.
+ */
+int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
+{
+ if (thread_info_flags & _TIF_NEED_RESCHED) {
+ schedule();
+ return 1;
+ }
+#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
+ if (thread_info_flags & _TIF_ASYNC_TLB) {
+ do_async_page_fault(regs);
+ return 1;
+ }
+#endif
+ if (thread_info_flags & _TIF_SIGPENDING) {
+ do_signal(regs);
+ return 1;
+ }
+ if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(regs);
+ if (current->replacement_session_keyring)
+ key_replace_session_keyring();
+ return 1;
+ }
+ if (thread_info_flags & _TIF_SINGLESTEP) {
+ if ((regs->ex1 & SPR_EX_CONTEXT_1_1__PL_MASK) == 0)
+ single_step_once(regs);
+ return 0;
+ }
+ panic("work_pending: bad flags %#x\n", thread_info_flags);
+}
+
/* Note there is an implicit fifth argument if (clone_flags & CLONE_SETTLS). */
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
void __user *, parent_tidptr, void __user *, child_tidptr,
diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c
index 84a729e..86df5a2 100644
--- a/arch/tile/kernel/single_step.c
+++ b/arch/tile/kernel/single_step.c
@@ -318,6 +318,14 @@ void single_step_once(struct pt_regs *regs)
" .popsection\n"
);
+ /*
+ * Enable interrupts here to allow touching userspace and the like.
+ * The callers expect this: do_trap() already has interrupts
+ * enabled, and do_work_pending() handles functions that enable
+ * interrupts internally.
+ */
+ local_irq_enable();
+
if (state == NULL) {
/* allocate a page of writable, executable memory */
state = kmalloc(sizeof(struct single_step_state), GFP_KERNEL);
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 51f8663..24ca54a 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -732,6 +732,7 @@ void do_page_fault(struct pt_regs *regs, int fault_num,
panic("Bad fault number %d in do_page_fault", fault_num);
}
+#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
if (EX1_PL(regs->ex1) != USER_PL) {
struct async_tlb *async;
switch (fault_num) {
@@ -775,6 +776,7 @@ void do_page_fault(struct pt_regs *regs, int fault_num,
return;
}
}
+#endif
handle_page_fault(regs, fault_num, is_page_fault, address, write);
}
@@ -801,8 +803,6 @@ static void handle_async_page_fault(struct pt_regs *regs,
async->address, async->is_write);
}
}
-#endif /* CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC() */
-
/*
* This routine effectively re-issues asynchronous page faults
@@ -824,6 +824,8 @@ void do_async_page_fault(struct pt_regs *regs)
handle_async_page_fault(regs, ¤t->thread.sn_async_tlb);
#endif
}
+#endif /* CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC() */
+
void vmalloc_sync_all(void)
{
--
1.6.5.2
--
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