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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0038-arch-arm64-Add-lazy-preempt-support.patch | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/debian/patches-rt/0038-arch-arm64-Add-lazy-preempt-support.patch b/debian/patches-rt/0038-arch-arm64-Add-lazy-preempt-support.patch new file mode 100644 index 000000000..4df0c8a40 --- /dev/null +++ b/debian/patches-rt/0038-arch-arm64-Add-lazy-preempt-support.patch @@ -0,0 +1,146 @@ +From 12a36ad989490f5ae3ed6a50d764385e8e27e024 Mon Sep 17 00:00:00 2001 +From: Anders Roxell <anders.roxell@linaro.org> +Date: Thu, 14 May 2015 17:52:17 +0200 +Subject: [PATCH 38/62] arch/arm64: Add lazy preempt support +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz + +arm64 is missing support for PREEMPT_RT. The main feature which is +lacking is support for lazy preemption. The arch-specific entry code, +thread information structure definitions, and associated data tables +have to be extended to provide this support. Then the Kconfig file has +to be extended to indicate the support is available, and also to +indicate that support for full RT preemption is now available. + +Signed-off-by: Anders Roxell <anders.roxell@linaro.org> +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + arch/arm64/Kconfig | 1 + + arch/arm64/include/asm/preempt.h | 25 ++++++++++++++++++++++++- + arch/arm64/include/asm/thread_info.h | 8 +++++++- + arch/arm64/kernel/asm-offsets.c | 1 + + arch/arm64/kernel/signal.c | 2 +- + 5 files changed, 34 insertions(+), 3 deletions(-) + +diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig +index ea70eb960565..6e16670a7f43 100644 +--- a/arch/arm64/Kconfig ++++ b/arch/arm64/Kconfig +@@ -199,6 +199,7 @@ config ARM64 + select HAVE_PERF_USER_STACK_DUMP + select HAVE_PREEMPT_DYNAMIC_KEY + select HAVE_REGS_AND_STACK_ACCESS_API ++ select HAVE_PREEMPT_LAZY + select HAVE_POSIX_CPU_TIMERS_TASK_WORK + select HAVE_FUNCTION_ARG_ACCESS_API + select MMU_GATHER_RCU_TABLE_FREE +diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h +index 0159b625cc7f..a5486918e5ee 100644 +--- a/arch/arm64/include/asm/preempt.h ++++ b/arch/arm64/include/asm/preempt.h +@@ -71,13 +71,36 @@ static inline bool __preempt_count_dec_and_test(void) + * interrupt occurring between the non-atomic READ_ONCE/WRITE_ONCE + * pair. + */ +- return !pc || !READ_ONCE(ti->preempt_count); ++ if (!pc || !READ_ONCE(ti->preempt_count)) ++ return true; ++#ifdef CONFIG_PREEMPT_LAZY ++ if ((pc & ~PREEMPT_NEED_RESCHED)) ++ return false; ++ if (current_thread_info()->preempt_lazy_count) ++ return false; ++ return test_thread_flag(TIF_NEED_RESCHED_LAZY); ++#else ++ return false; ++#endif + } + + static inline bool should_resched(int preempt_offset) + { ++#ifdef CONFIG_PREEMPT_LAZY ++ u64 pc = READ_ONCE(current_thread_info()->preempt_count); ++ if (pc == preempt_offset) ++ return true; ++ ++ if ((pc & ~PREEMPT_NEED_RESCHED) != preempt_offset) ++ return false; ++ ++ if (current_thread_info()->preempt_lazy_count) ++ return false; ++ return test_thread_flag(TIF_NEED_RESCHED_LAZY); ++#else + u64 pc = READ_ONCE(current_thread_info()->preempt_count); + return pc == preempt_offset; ++#endif + } + + #ifdef CONFIG_PREEMPTION +diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h +index 848739c15de8..4b7148fd5551 100644 +--- a/arch/arm64/include/asm/thread_info.h ++++ b/arch/arm64/include/asm/thread_info.h +@@ -26,6 +26,7 @@ struct thread_info { + #ifdef CONFIG_ARM64_SW_TTBR0_PAN + u64 ttbr0; /* saved TTBR0_EL1 */ + #endif ++ int preempt_lazy_count; /* 0 => preemptable, <0 => bug */ + union { + u64 preempt_count; /* 0 => preemptible, <0 => bug */ + struct { +@@ -68,6 +69,7 @@ int arch_dup_task_struct(struct task_struct *dst, + #define TIF_UPROBE 4 /* uprobe breakpoint or singlestep */ + #define TIF_MTE_ASYNC_FAULT 5 /* MTE Asynchronous Tag Check Fault */ + #define TIF_NOTIFY_SIGNAL 6 /* signal notifications exist */ ++#define TIF_NEED_RESCHED_LAZY 7 + #define TIF_SYSCALL_TRACE 8 /* syscall trace active */ + #define TIF_SYSCALL_AUDIT 9 /* syscall auditing */ + #define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ +@@ -100,8 +102,10 @@ int arch_dup_task_struct(struct task_struct *dst, + #define _TIF_SVE (1 << TIF_SVE) + #define _TIF_MTE_ASYNC_FAULT (1 << TIF_MTE_ASYNC_FAULT) + #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) ++#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) + +-#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ ++#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \ ++ _TIF_SIGPENDING | \ + _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ + _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \ + _TIF_NOTIFY_SIGNAL) +@@ -110,6 +114,8 @@ int arch_dup_task_struct(struct task_struct *dst, + _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ + _TIF_SYSCALL_EMU) + ++#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY) ++ + #ifdef CONFIG_SHADOW_CALL_STACK + #define INIT_SCS \ + .scs_base = init_shadow_call_stack, \ +diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c +index 1197e7679882..e74c0415f67e 100644 +--- a/arch/arm64/kernel/asm-offsets.c ++++ b/arch/arm64/kernel/asm-offsets.c +@@ -32,6 +32,7 @@ int main(void) + DEFINE(TSK_TI_CPU, offsetof(struct task_struct, thread_info.cpu)); + DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags)); + DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count)); ++ DEFINE(TSK_TI_PREEMPT_LAZY, offsetof(struct task_struct, thread_info.preempt_lazy_count)); + #ifdef CONFIG_ARM64_SW_TTBR0_PAN + DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0)); + #endif +diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c +index 82f4572c8ddf..2a606c7bf025 100644 +--- a/arch/arm64/kernel/signal.c ++++ b/arch/arm64/kernel/signal.c +@@ -1108,7 +1108,7 @@ static void do_signal(struct pt_regs *regs) + void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) + { + do { +- if (thread_flags & _TIF_NEED_RESCHED) { ++ if (thread_flags & _TIF_NEED_RESCHED_MASK) { + /* Unmask Debug and SError for the next task */ + local_daif_restore(DAIF_PROCCTX_NOIRQ); + +-- +2.43.0 + |