[PATCH 07/18] powerpc/64: context tracking remove _TIF_NOHZ
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2020-11-05 14:57:08
Subsystem:
linux for powerpc (32-bit and 64-bit), ptrace support, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Oleg Nesterov, Linus Torvalds
Add context tracking to the system call handler explicitly, and remove _TIF_NOHZ. This saves 35 cycles on gettid system call cost on POWER9 with a CONFIG_NOHZ_FULL kernel. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/Kconfig | 6 ------ arch/powerpc/Kconfig | 1 - arch/powerpc/include/asm/thread_info.h | 4 +--- arch/powerpc/kernel/ptrace/ptrace.c | 4 ---- arch/powerpc/kernel/signal.c | 4 ---- arch/powerpc/kernel/syscall_64.c | 10 ++++++++++ 6 files changed, 11 insertions(+), 18 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 56b6ccc0e32d..a0b6213f7820 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig@@ -618,12 +618,6 @@ config HAVE_CONTEXT_TRACKING protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on irq exit still need to be protected. -config HAVE_TIF_NOHZ - bool - help - Arch relies on TIF_NOHZ and syscall slow path to implement context - tracking calls to user_enter()/user_exit(). - config HAVE_VIRT_CPU_ACCOUNTING bool
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e9f13fe08492..6eaf12a504f8 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig@@ -193,7 +193,6 @@ config PPC select HAVE_STACKPROTECTOR if PPC64 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r13) select HAVE_STACKPROTECTOR if PPC32 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r2) select HAVE_CONTEXT_TRACKING if PPC64 - select HAVE_TIF_NOHZ if PPC64 select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_STACKOVERFLOW select HAVE_DYNAMIC_FTRACE
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 46a210b03d2b..c9443c16e5fb 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h@@ -95,7 +95,6 @@ void arch_setup_new_exec(void); #define TIF_PATCH_PENDING 6 /* pending live patching update */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SINGLESTEP 8 /* singlestepping active */ -#define TIF_NOHZ 9 /* in adaptive nohz mode */ #define TIF_SECCOMP 10 /* secure computing */ #define TIF_RESTOREALL 11 /* Restore all regs (implies NOERROR) */ #define TIF_NOERROR 12 /* Force successful syscall return */
@@ -128,11 +127,10 @@ void arch_setup_new_exec(void); #define _TIF_UPROBE (1<<TIF_UPROBE) #define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT) #define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE) -#define _TIF_NOHZ (1<<TIF_NOHZ) #define _TIF_SYSCALL_EMU (1<<TIF_SYSCALL_EMU) #define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ - _TIF_NOHZ | _TIF_SYSCALL_EMU) + _TIF_SYSCALL_EMU) #define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \ _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index f6e51be47c6e..8970400e521c 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c@@ -290,8 +290,6 @@ long do_syscall_trace_enter(struct pt_regs *regs) { u32 flags; - user_exit(); - flags = READ_ONCE(current_thread_info()->flags) & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
@@ -368,8 +366,6 @@ void do_syscall_trace_leave(struct pt_regs *regs) step = test_thread_flag(TIF_SINGLESTEP); if (step || test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall_exit(regs, step); - - user_enter(); } void __init pt_regs_check(void);
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index d2c356f37077..44ec7b34b27e 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c@@ -310,8 +310,6 @@ static void do_signal(struct task_struct *tsk) void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) { - user_exit(); - if (thread_info_flags & _TIF_UPROBE) uprobe_notify_resume(regs);
@@ -327,8 +325,6 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); } - - user_enter(); } unsigned long get_tm_stackpointer(struct task_struct *tsk)
diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index 15b628ae25fb..d9df6d14533e 100644
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c@@ -1,9 +1,11 @@ // SPDX-License-Identifier: GPL-2.0-or-later +#include <linux/context_tracking.h> #include <linux/err.h> #include <asm/asm-prototypes.h> #include <asm/book3s/64/kup-radix.h> #include <asm/cputime.h> +#include <asm/interrupt.h> #include <asm/hw_irq.h> #include <asm/interrupt.h> #include <asm/kprobes.h>
@@ -28,6 +30,9 @@ notrace long system_call_exception(long r3, long r4, long r5, if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED); + CT_WARN_ON(ct_state() == CONTEXT_KERNEL); + user_exit_irqoff(); + trace_hardirqs_off(); /* finish reconciling */ if (IS_ENABLED(CONFIG_PPC_BOOK3S))
@@ -158,6 +163,8 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3, unsigned long ti_flags; unsigned long ret = 0; + CT_WARN_ON(ct_state() == CONTEXT_USER); + kuap_check_amr(); regs->result = r3;
@@ -234,8 +241,11 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3, } } + user_enter_irqoff(); + /* scv need not set RI=0 because SRRs are not used */ if (unlikely(!prep_irq_for_enabled_exit(!scv))) { + user_exit_irqoff(); local_irq_enable(); goto again; }
--
2.23.0