diff options
Diffstat (limited to 'debian/patches-rt/0260-x86-Support-for-lazy-preemption.patch')
| -rw-r--r-- | debian/patches-rt/0260-x86-Support-for-lazy-preemption.patch | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/debian/patches-rt/0260-x86-Support-for-lazy-preemption.patch b/debian/patches-rt/0260-x86-Support-for-lazy-preemption.patch new file mode 100644 index 000000000..1b4da37ab --- /dev/null +++ b/debian/patches-rt/0260-x86-Support-for-lazy-preemption.patch @@ -0,0 +1,171 @@ +From 3e75dc5bbc430b2a1db27fe101ed508b067af7b0 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 1 Nov 2012 11:03:47 +0100 +Subject: [PATCH 260/323] x86: Support for lazy preemption +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz + +Implement the x86 pieces for lazy preempt. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com> +--- + arch/x86/Kconfig | 1 + + arch/x86/include/asm/preempt.h | 33 +++++++++++++++++++++++++++++- + arch/x86/include/asm/thread_info.h | 11 ++++++++++ + include/linux/entry-common.h | 6 +++--- + kernel/entry/common.c | 2 +- + 5 files changed, 48 insertions(+), 5 deletions(-) + +diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig +index c72d66a0e840..b9f68b01a8c8 100644 +--- a/arch/x86/Kconfig ++++ b/arch/x86/Kconfig +@@ -213,6 +213,7 @@ 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 HAVE_POSIX_CPU_TIMERS_TASK_WORK + select HAVE_REGS_AND_STACK_ACCESS_API +diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h +index 50e0c0ab7b97..afe37a8c6c24 100644 +--- a/arch/x86/include/asm/preempt.h ++++ b/arch/x86/include/asm/preempt.h +@@ -89,17 +89,48 @@ 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 012c8ee93b67..d77e99ba7610 100644 +--- a/arch/x86/include/asm/thread_info.h ++++ b/arch/x86/include/asm/thread_info.h +@@ -56,17 +56,24 @@ struct task_struct; + struct thread_info { + unsigned long flags; /* low level flags */ + u32 status; /* thread synchronous flags */ ++ int preempt_lazy_count; /* 0 => lazy preemptable ++ <0 => BUG */ + }; + + #define INIT_THREAD_INFO(tsk) \ + { \ + .flags = 0, \ ++ .preempt_lazy_count = 0, \ + } + + #else /* !__ASSEMBLY__ */ + + #include <asm/asm-offsets.h> + ++#define GET_THREAD_INFO(reg) \ ++ _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \ ++ _ASM_SUB $(THREAD_SIZE),reg ; ++ + #endif + + /* +@@ -103,6 +110,7 @@ struct thread_info { + #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ + #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ + #define TIF_X32 30 /* 32-bit native x86-64 binary */ ++#define TIF_NEED_RESCHED_LAZY 31 /* lazy rescheduling necessary */ + + #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) + #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) +@@ -124,6 +132,7 @@ struct thread_info { + #define _TIF_IA32 (1 << TIF_IA32) + #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) + #define _TIF_SLD (1 << TIF_SLD) ++#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_FORCED_TF (1 << TIF_FORCED_TF) +@@ -156,6 +165,8 @@ 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 46c42479f950..b902af13d05f 100644 +--- a/include/linux/entry-common.h ++++ b/include/linux/entry-common.h +@@ -67,9 +67,9 @@ + # define ARCH_EXIT_TO_USER_MODE_WORK (0) + #endif + +-#define EXIT_TO_USER_MODE_WORK \ +- (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ +- _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ ++#define EXIT_TO_USER_MODE_WORK \ ++ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ ++ _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 f32250adb681..cdf97ea30b4c 100644 +--- a/kernel/entry/common.c ++++ b/kernel/entry/common.c +@@ -157,7 +157,7 @@ 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(); + + #ifdef ARCH_RT_DELAYS_SIGNAL_SEND +-- +2.43.0 + |