diff options
Diffstat (limited to 'debian/patches-rt/0034-x86-Support-for-lazy-preemption.patch')
| -rw-r--r-- | debian/patches-rt/0034-x86-Support-for-lazy-preemption.patch | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/debian/patches-rt/0034-x86-Support-for-lazy-preemption.patch b/debian/patches-rt/0034-x86-Support-for-lazy-preemption.patch new file mode 100644 index 000000000..511fe0a01 --- /dev/null +++ b/debian/patches-rt/0034-x86-Support-for-lazy-preemption.patch @@ -0,0 +1,158 @@ +From 65ce5ba8ccb26e6de364e76228e645b2c02b921d Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 1 Nov 2012 11:03:47 +0100 +Subject: [PATCH 34/62] x86: Support for lazy preemption +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz + +Implement the x86 pieces for lazy preempt. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + arch/x86/Kconfig | 1 + + arch/x86/include/asm/preempt.h | 33 +++++++++++++++++++++++++++++- + arch/x86/include/asm/thread_info.h | 7 +++++++ + include/linux/entry-common.h | 2 +- + kernel/entry/common.c | 2 +- + 5 files changed, 42 insertions(+), 3 deletions(-) + +diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig +index c9bed9c69423..f38bd8a5061e 100644 +--- a/arch/x86/Kconfig ++++ b/arch/x86/Kconfig +@@ -251,6 +251,7 @@ config X86 + select HAVE_PCI + select HAVE_PERF_REGS + select HAVE_PERF_USER_STACK_DUMP ++ select HAVE_PREEMPT_LAZY + select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT + select MMU_GATHER_MERGE_VMAS + select HAVE_POSIX_CPU_TIMERS_TASK_WORK +diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h +index 5f6daea1ee24..cd20b4a5719a 100644 +--- a/arch/x86/include/asm/preempt.h ++++ b/arch/x86/include/asm/preempt.h +@@ -90,17 +90,48 @@ static __always_inline void __preempt_count_sub(int val) + * a decrement which hits zero means we have no preempt_count and should + * reschedule. + */ +-static __always_inline bool __preempt_count_dec_and_test(void) ++static __always_inline bool ____preempt_count_dec_and_test(void) + { + return GEN_UNARY_RMWcc("decl", __preempt_count, e, __percpu_arg([var])); + } + ++static __always_inline bool __preempt_count_dec_and_test(void) ++{ ++ if (____preempt_count_dec_and_test()) ++ return true; ++#ifdef CONFIG_PREEMPT_LAZY ++ if (preempt_count()) ++ return false; ++ if (current_thread_info()->preempt_lazy_count) ++ return false; ++ return test_thread_flag(TIF_NEED_RESCHED_LAZY); ++#else ++ return false; ++#endif ++} ++ + /* + * Returns true when we need to resched and can (barring IRQ state). + */ + static __always_inline bool should_resched(int preempt_offset) + { ++#ifdef CONFIG_PREEMPT_LAZY ++ u32 tmp; ++ tmp = raw_cpu_read_4(__preempt_count); ++ if (tmp == preempt_offset) ++ return true; ++ ++ /* preempt count == 0 ? */ ++ tmp &= ~PREEMPT_NEED_RESCHED; ++ if (tmp != preempt_offset) ++ return false; ++ /* XXX PREEMPT_LOCK_OFFSET */ ++ if (current_thread_info()->preempt_lazy_count) ++ return false; ++ return test_thread_flag(TIF_NEED_RESCHED_LAZY); ++#else + return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset); ++#endif + } + + #ifdef CONFIG_PREEMPTION +diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h +index f0cb881c1d69..0da06a9b5f72 100644 +--- a/arch/x86/include/asm/thread_info.h ++++ b/arch/x86/include/asm/thread_info.h +@@ -57,6 +57,8 @@ struct thread_info { + unsigned long flags; /* low level flags */ + unsigned long syscall_work; /* SYSCALL_WORK_ flags */ + u32 status; /* thread synchronous flags */ ++ int preempt_lazy_count; /* 0 => lazy preemptable ++ <0 => BUG */ + #ifdef CONFIG_SMP + u32 cpu; /* current CPU */ + #endif +@@ -65,6 +67,7 @@ struct thread_info { + #define INIT_THREAD_INFO(tsk) \ + { \ + .flags = 0, \ ++ .preempt_lazy_count = 0, \ + } + + #else /* !__ASSEMBLY__ */ +@@ -92,6 +95,7 @@ struct thread_info { + #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */ + #define TIF_NOTSC 16 /* TSC is not accessible in userland */ + #define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */ ++#define TIF_NEED_RESCHED_LAZY 19 /* lazy rescheduling necessary */ + #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ + #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ + #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ +@@ -115,6 +119,7 @@ struct thread_info { + #define _TIF_NOCPUID (1 << TIF_NOCPUID) + #define _TIF_NOTSC (1 << TIF_NOTSC) + #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) ++#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) + #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) + #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) + #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) +@@ -146,6 +151,8 @@ struct thread_info { + + #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) + ++#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY) ++ + #define STACK_WARN (THREAD_SIZE/8) + + /* +diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h +index d95ab85f96ba..93cc1ae12125 100644 +--- a/include/linux/entry-common.h ++++ b/include/linux/entry-common.h +@@ -59,7 +59,7 @@ + + #define EXIT_TO_USER_MODE_WORK \ + (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ +- _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ ++ _TIF_NEED_RESCHED_MASK | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ + ARCH_EXIT_TO_USER_MODE_WORK) + + /** +diff --git a/kernel/entry/common.c b/kernel/entry/common.c +index 97ff5faad4fb..c6301e520d47 100644 +--- a/kernel/entry/common.c ++++ b/kernel/entry/common.c +@@ -155,7 +155,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, + + local_irq_enable_exit_to_user(ti_work); + +- if (ti_work & _TIF_NEED_RESCHED) ++ if (ti_work & _TIF_NEED_RESCHED_MASK) + schedule(); + + if (ti_work & _TIF_UPROBE) +-- +2.43.0 + |