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From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 1 Nov 2012 10:14:11 +0100
Subject: powerpc: Add support for lazy preemption
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.10-rt8.tar.xz
Implement the powerpc pieces for lazy preempt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/thread_info.h | 9 +++++++--
arch/powerpc/kernel/asm-offsets.c | 1 +
arch/powerpc/kernel/entry_32.S | 17 ++++++++++++-----
arch/powerpc/kernel/entry_64.S | 16 ++++++++++++----
5 files changed, 33 insertions(+), 11 deletions(-)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -216,6 +216,7 @@ config PPC
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
+ select HAVE_PREEMPT_LAZY
select HAVE_RCU_TABLE_FREE if SMP
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if PPC64 && CPU_LITTLE_ENDIAN
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -37,6 +37,8 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int preempt_lazy_count; /* 0 => preemptable,
+ <0 => BUG */
unsigned long local_flags; /* private flags for thread */
#ifdef CONFIG_LIVEPATCH
unsigned long *livepatch_sp;
@@ -81,7 +83,7 @@ extern int arch_dup_task_struct(struct t
#define TIF_SIGPENDING 1 /* signal pending */
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_FSCHECK 3 /* Check FS is USER_DS on return */
-#define TIF_32BIT 4 /* 32 bit binary */
+#define TIF_NEED_RESCHED_LAZY 4 /* lazy rescheduling necessary */
#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
#define TIF_PATCH_PENDING 6 /* pending live patching update */
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
@@ -100,6 +102,7 @@ extern int arch_dup_task_struct(struct t
#define TIF_ELF2ABI 18 /* function descriptors must die! */
#endif
#define TIF_POLLING_NRFLAG 19 /* true if poll_idle() is polling TIF_NEED_RESCHED */
+#define TIF_32BIT 20 /* 32 bit binary */
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -119,6 +122,7 @@ extern int arch_dup_task_struct(struct t
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
#define _TIF_NOHZ (1<<TIF_NOHZ)
+#define _TIF_NEED_RESCHED_LAZY (1<<TIF_NEED_RESCHED_LAZY)
#define _TIF_FSCHECK (1<<TIF_FSCHECK)
#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
@@ -127,8 +131,9 @@ extern int arch_dup_task_struct(struct t
#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
_TIF_RESTORE_TM | _TIF_PATCH_PENDING | \
- _TIF_FSCHECK)
+ _TIF_FSCHECK | _TIF_NEED_RESCHED_LAZY)
#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
+#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
/* Bits in local_flags */
/* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -156,6 +156,7 @@ int main(void)
OFFSET(TI_FLAGS, thread_info, flags);
OFFSET(TI_LOCAL_FLAGS, thread_info, local_flags);
OFFSET(TI_PREEMPT, thread_info, preempt_count);
+ OFFSET(TI_PREEMPT_LAZY, thread_info, preempt_lazy_count);
OFFSET(TI_TASK, thread_info, task);
OFFSET(TI_CPU, thread_info, cpu);
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -885,7 +885,14 @@ user_exc_return: /* r10 contains MSR_KE
cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
bne restore
andi. r8,r8,_TIF_NEED_RESCHED
+ bne+ 1f
+ lwz r0,TI_PREEMPT_LAZY(r9)
+ cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
+ bne restore
+ lwz r0,TI_FLAGS(r9)
+ andi. r0,r0,_TIF_NEED_RESCHED_LAZY
beq+ restore
+1:
lwz r3,_MSR(r1)
andi. r0,r3,MSR_EE /* interrupts off? */
beq restore /* don't schedule if so */
@@ -896,11 +903,11 @@ user_exc_return: /* r10 contains MSR_KE
*/
bl trace_hardirqs_off
#endif
-1: bl preempt_schedule_irq
+2: bl preempt_schedule_irq
CURRENT_THREAD_INFO(r9, r1)
lwz r3,TI_FLAGS(r9)
- andi. r0,r3,_TIF_NEED_RESCHED
- bne- 1b
+ andi. r0,r3,_TIF_NEED_RESCHED_MASK
+ bne- 2b
#ifdef CONFIG_TRACE_IRQFLAGS
/* And now, to properly rebalance the above, we tell lockdep they
* are being turned back on, which will happen when we return
@@ -1223,7 +1230,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRE
#endif /* !(CONFIG_4xx || CONFIG_BOOKE) */
do_work: /* r10 contains MSR_KERNEL here */
- andi. r0,r9,_TIF_NEED_RESCHED
+ andi. r0,r9,_TIF_NEED_RESCHED_MASK
beq do_user_signal
do_resched: /* r10 contains MSR_KERNEL here */
@@ -1244,7 +1251,7 @@ do_resched: /* r10 contains MSR_KERNEL
MTMSRD(r10) /* disable interrupts */
CURRENT_THREAD_INFO(r9, r1)
lwz r9,TI_FLAGS(r9)
- andi. r0,r9,_TIF_NEED_RESCHED
+ andi. r0,r9,_TIF_NEED_RESCHED_MASK
bne- do_resched
andi. r0,r9,_TIF_USER_WORK_MASK
beq restore_user
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -171,7 +171,7 @@ system_call: /* label this so stack tr
* based on caller's run-mode / personality.
*/
ld r11,SYS_CALL_TABLE@toc(2)
- andi. r10,r10,_TIF_32BIT
+ andis. r10,r10,_TIF_32BIT@h
beq 15f
addi r11,r11,8 /* use 32-bit syscall entries */
clrldi r3,r3,32
@@ -763,7 +763,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
bl restore_math
b restore
#endif
-1: andi. r0,r4,_TIF_NEED_RESCHED
+1: andi. r0,r4,_TIF_NEED_RESCHED_MASK
beq 2f
bl restore_interrupts
SCHEDULE_USER
@@ -825,10 +825,18 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
#ifdef CONFIG_PREEMPT
/* Check if we need to preempt */
+ lwz r8,TI_PREEMPT(r9)
+ cmpwi 0,r8,0 /* if non-zero, just restore regs and return */
+ bne restore
andi. r0,r4,_TIF_NEED_RESCHED
+ bne+ check_count
+
+ andi. r0,r4,_TIF_NEED_RESCHED_LAZY
beq+ restore
+ lwz r8,TI_PREEMPT_LAZY(r9)
+
/* Check that preempt_count() == 0 and interrupts are enabled */
- lwz r8,TI_PREEMPT(r9)
+check_count:
cmpwi cr0,r8,0
bne restore
ld r0,SOFTE(r1)
@@ -845,7 +853,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
/* Re-test flags and eventually loop */
CURRENT_THREAD_INFO(r9, r1)
ld r4,TI_FLAGS(r9)
- andi. r0,r4,_TIF_NEED_RESCHED
+ andi. r0,r4,_TIF_NEED_RESCHED_MASK
bne 1b
/*
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