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133 lines
5.2 KiB
Diff
133 lines
5.2 KiB
Diff
From 24b4d4f5deeb374106d6864e3f213f4efbeda8e7 Mon Sep 17 00:00:00 2001
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From: Anders Roxell <anders.roxell@linaro.org>
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Date: Thu, 14 May 2015 17:52:17 +0200
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Subject: [PATCH 392/414] arch/arm64: Add lazy preempt support
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arm64 is missing support for PREEMPT_RT. The main feature which is
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lacking is support for lazy preemption. The arch-specific entry code,
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thread information structure definitions, and associated data tables
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have to be extended to provide this support. Then the Kconfig file has
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to be extended to indicate the support is available, and also to
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indicate that support for full RT preemption is now available.
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Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
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---
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arch/arm64/Kconfig | 1 +
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arch/arm64/include/asm/thread_info.h | 6 +++++-
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arch/arm64/kernel/asm-offsets.c | 1 +
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arch/arm64/kernel/entry.S | 12 +++++++++---
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arch/arm64/kernel/signal.c | 2 +-
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5 files changed, 17 insertions(+), 5 deletions(-)
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diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
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index c8bcd6e41192..7e08c4fd1ae0 100644
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--- a/arch/arm64/Kconfig
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+++ b/arch/arm64/Kconfig
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@@ -103,6 +103,7 @@ config ARM64
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select HAVE_PERF_EVENTS
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select HAVE_PERF_REGS
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select HAVE_PERF_USER_STACK_DUMP
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+ select HAVE_PREEMPT_LAZY
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select HAVE_REGS_AND_STACK_ACCESS_API
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select HAVE_RCU_TABLE_FREE
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select HAVE_SYSCALL_TRACEPOINTS
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diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
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index ddded6497a8a..935271f5914d 100644
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--- a/arch/arm64/include/asm/thread_info.h
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+++ b/arch/arm64/include/asm/thread_info.h
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@@ -43,6 +43,7 @@ struct thread_info {
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u64 ttbr0; /* saved TTBR0_EL1 */
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#endif
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int preempt_count; /* 0 => preemptable, <0 => bug */
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+ int preempt_lazy_count; /* 0 => preemptable, <0 => bug */
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};
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#define INIT_THREAD_INFO(tsk) \
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@@ -82,6 +83,7 @@ void arch_setup_new_exec(void);
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#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */
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#define TIF_UPROBE 4 /* uprobe breakpoint or singlestep */
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#define TIF_FSCHECK 5 /* Check FS is USER_DS on return */
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+#define TIF_NEED_RESCHED_LAZY 6
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#define TIF_NOHZ 7
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#define TIF_SYSCALL_TRACE 8
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#define TIF_SYSCALL_AUDIT 9
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@@ -97,6 +99,7 @@ void arch_setup_new_exec(void);
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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#define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE)
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+#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY)
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#define _TIF_NOHZ (1 << TIF_NOHZ)
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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@@ -108,8 +111,9 @@ void arch_setup_new_exec(void);
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#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
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_TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
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- _TIF_UPROBE | _TIF_FSCHECK)
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+ _TIF_UPROBE | _TIF_FSCHECK | _TIF_NEED_RESCHED_LAZY)
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+#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
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#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
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_TIF_NOHZ)
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diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
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index af247d10252f..215a48154042 100644
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--- a/arch/arm64/kernel/asm-offsets.c
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+++ b/arch/arm64/kernel/asm-offsets.c
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@@ -39,6 +39,7 @@ int main(void)
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BLANK();
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DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags));
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DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count));
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+ DEFINE(TSK_TI_PREEMPT_LAZY, offsetof(struct task_struct, thread_info.preempt_lazy_count));
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DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit));
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#ifdef CONFIG_ARM64_SW_TTBR0_PAN
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DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0));
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diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
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index 93958d1341bb..ed6959beb5a4 100644
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--- a/arch/arm64/kernel/entry.S
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+++ b/arch/arm64/kernel/entry.S
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@@ -607,11 +607,16 @@ el1_irq:
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#ifdef CONFIG_PREEMPT
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ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count
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- cbnz w24, 1f // preempt count != 0
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+ cbnz w24, 2f // preempt count != 0
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ldr x0, [tsk, #TSK_TI_FLAGS] // get flags
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- tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
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- bl el1_preempt
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+ tbnz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
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+
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+ ldr w24, [tsk, #TSK_TI_PREEMPT_LAZY] // get preempt lazy count
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+ cbnz w24, 2f // preempt lazy count != 0
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+ tbz x0, #TIF_NEED_RESCHED_LAZY, 2f // needs rescheduling?
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1:
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+ bl el1_preempt
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+2:
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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bl trace_hardirqs_on
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@@ -625,6 +630,7 @@ el1_preempt:
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1: bl preempt_schedule_irq // irq en/disable is done inside
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ldr x0, [tsk, #TSK_TI_FLAGS] // get new tasks TI_FLAGS
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tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling?
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+ tbnz x0, #TIF_NEED_RESCHED_LAZY, 1b // needs rescheduling?
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ret x24
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#endif
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diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
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index 0bdc96c61bc0..5393eb231209 100644
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--- a/arch/arm64/kernel/signal.c
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+++ b/arch/arm64/kernel/signal.c
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@@ -755,7 +755,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
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/* Check valid user FS if needed */
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addr_limit_user_check();
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- if (thread_flags & _TIF_NEED_RESCHED) {
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+ if (thread_flags & _TIF_NEED_RESCHED_MASK) {
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schedule();
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} else {
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local_irq_enable();
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--
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2.17.0
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