diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0263-arch-arm64-Add-lazy-preempt-support.patch | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/debian/patches-rt/0263-arch-arm64-Add-lazy-preempt-support.patch b/debian/patches-rt/0263-arch-arm64-Add-lazy-preempt-support.patch new file mode 100644 index 000000000..bf46cf898 --- /dev/null +++ b/debian/patches-rt/0263-arch-arm64-Add-lazy-preempt-support.patch @@ -0,0 +1,168 @@ +From 7499fc472caecd0270f69d5857ca8a53cc6dad83 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 263/323] arch/arm64: Add lazy preempt support +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.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: Luis Claudio R. Goncalves <lgoncalv@redhat.com> +--- + arch/arm64/Kconfig | 1 + + arch/arm64/include/asm/preempt.h | 25 ++++++++++++++++++++++++- + arch/arm64/include/asm/thread_info.h | 6 +++++- + arch/arm64/kernel/asm-offsets.c | 1 + + arch/arm64/kernel/entry.S | 13 +++++++++++-- + arch/arm64/kernel/signal.c | 2 +- + 6 files changed, 43 insertions(+), 5 deletions(-) + +diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig +index 13cf137da999..7681d7b65c7d 100644 +--- a/arch/arm64/Kconfig ++++ b/arch/arm64/Kconfig +@@ -173,6 +173,7 @@ config ARM64 + select HAVE_PERF_EVENTS + select HAVE_PERF_REGS + select HAVE_PERF_USER_STACK_DUMP ++ select HAVE_PREEMPT_LAZY + select HAVE_REGS_AND_STACK_ACCESS_API + select HAVE_FUNCTION_ARG_ACCESS_API + select HAVE_FUTEX_CMPXCHG if FUTEX +diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h +index f1486b32502c..7a5770d825b9 100644 +--- a/arch/arm64/include/asm/preempt.h ++++ b/arch/arm64/include/asm/preempt.h +@@ -70,13 +70,36 @@ 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 cdcf307764aa..6eb36a2126e8 100644 +--- a/arch/arm64/include/asm/thread_info.h ++++ b/arch/arm64/include/asm/thread_info.h +@@ -29,6 +29,7 @@ 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 { +@@ -74,6 +75,7 @@ void arch_release_task_struct(struct task_struct *tsk); + #define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ + #define TIF_SECCOMP 11 /* syscall secure computing */ + #define TIF_SYSCALL_EMU 12 /* syscall emulation active */ ++#define TIF_NEED_RESCHED_LAZY 13 + #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ + #define TIF_FREEZE 19 + #define TIF_RESTORE_SIGMASK 20 +@@ -99,13 +101,15 @@ void arch_release_task_struct(struct task_struct *tsk); + #define _TIF_32BIT (1 << TIF_32BIT) + #define _TIF_SVE (1 << TIF_SVE) + #define _TIF_MTE_ASYNC_FAULT (1 << TIF_MTE_ASYNC_FAULT) ++#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) + #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) + + #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ + _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ + _TIF_UPROBE | _TIF_FSCHECK | _TIF_MTE_ASYNC_FAULT | \ +- _TIF_NOTIFY_SIGNAL) ++ _TIF_NEED_RESCHED_LAZY | _TIF_NOTIFY_SIGNAL) + ++#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY) + #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ + _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ + _TIF_SYSCALL_EMU) +diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c +index 7d32fc959b1a..b2f29bd2ae87 100644 +--- a/arch/arm64/kernel/asm-offsets.c ++++ b/arch/arm64/kernel/asm-offsets.c +@@ -30,6 +30,7 @@ int main(void) + BLANK(); + 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)); + DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit)); + #ifdef CONFIG_ARM64_SW_TTBR0_PAN + DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0)); +diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S +index a94acea770c7..0bfa079043f8 100644 +--- a/arch/arm64/kernel/entry.S ++++ b/arch/arm64/kernel/entry.S +@@ -523,9 +523,18 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING + mrs x0, daif + orr x24, x24, x0 + alternative_else_nop_endif +- cbnz x24, 1f // preempt count != 0 || NMI return path +- bl arm64_preempt_schedule_irq // irq en/disable is done inside ++ ++ cbz x24, 1f // (need_resched + count) == 0 ++ cbnz w24, 2f // count != 0 ++ ++ ldr w24, [tsk, #TSK_TI_PREEMPT_LAZY] // get preempt lazy count ++ cbnz w24, 2f // preempt lazy count != 0 ++ ++ ldr x0, [tsk, #TSK_TI_FLAGS] // get flags ++ tbz x0, #TIF_NEED_RESCHED_LAZY, 2f // needs rescheduling? + 1: ++ bl arm64_preempt_schedule_irq // irq en/disable is done inside ++2: + #endif + + mov x0, sp +diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c +index b6fbbd527dd7..94eed0dc3afc 100644 +--- a/arch/arm64/kernel/signal.c ++++ b/arch/arm64/kernel/signal.c +@@ -921,7 +921,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, + /* Check valid user FS if needed */ + addr_limit_user_check(); + +- 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 + |