Add context tracking to the system call handler explicitly, and remove
_TIF_NOHZ.
This improves system call performance when nohz_full is enabled. On a
POWER9, gettid scv system call cost on a nohz_full CPU improves from
1129 cycles to 1004 cycles and on a housekeeping CPU from 550 cycles
to 430 cycles.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
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 ++++++++++
5 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 107bb4319e0e..28d5a1b1510f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -196,7 +196,6 @@ 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 3d8a47af7a25..386d576673a1 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -94,7 +94,6 @@ 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 3d44b73adb83..4f3d4ff3728c 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c
@@ -262,8 +262,6 @@ 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);
@@ -340,8 +338,6 @@ 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 53782aa60ade..9ded046edb0e 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -282,8 +282,6 @@ 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);
@@ -299,8 +297,6 @@ 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();
}
static 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 dd87b2118620..d7d256a7a41f 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/kup.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))
@@ -182,6 +187,8 @@ 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;
@@ -258,8 +265,11 @@ 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
