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Move various entry functions from kernel/entry/common.c to <linux/entry-common.h>,

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and always-inline them, to improve syscall entry performance on s390 by ~11%.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-entry-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull generic syscall updates from Ingo Molnar:
 "Move various entry functions from kernel/entry/common.c to a header
  file, and always-inline them, to improve syscall entry performance
  on s390 by ~11%"

* tag 'core-entry-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  entry: Move syscall_enter_from_user_mode() to header file
  entry: Move enter_from_user_mode() to header file
  entry: Move exit to usermode functions to header file
This commit is contained in:
Linus Torvalds 2024-01-08 18:37:13 -08:00
commit cdc202281a
2 changed files with 103 additions and 100 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
include/linux/entry-common.h
View File

@ -7,6 +7,11 @@
#include <linux/syscalls.h>
#include <linux/seccomp.h>
#include <linux/sched.h>
#include <linux/context_tracking.h>
#include <linux/livepatch.h>
#include <linux/resume_user_mode.h>
#include <linux/tick.h>
#include <linux/kmsan.h>
#include <asm/entry-common.h>
@ -98,7 +103,19 @@ static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {}
* done between establishing state and enabling interrupts. The caller must
* enable interrupts before invoking syscall_enter_from_user_mode_work().
*/
void enter_from_user_mode(struct pt_regs *regs);
static __always_inline void enter_from_user_mode(struct pt_regs *regs)
{
arch_enter_from_user_mode(regs);
lockdep_hardirqs_off(CALLER_ADDR0);
CT_WARN_ON(__ct_state() != CONTEXT_USER);
user_exit_irqoff();
instrumentation_begin();
kmsan_unpoison_entry_regs(regs);
trace_hardirqs_off_finish();
instrumentation_end();
}
/**
* syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
@ -117,6 +134,9 @@ void enter_from_user_mode(struct pt_regs *regs);
*/
void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
long syscall_trace_enter(struct pt_regs *regs, long syscall,
unsigned long work);
/**
* syscall_enter_from_user_mode_work - Check and handle work before invoking
* a syscall
@ -140,7 +160,15 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
* ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter()
* 2) Invocation of audit_syscall_entry()
*/
long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
if (work & SYSCALL_WORK_ENTER)
syscall = syscall_trace_enter(regs, syscall, work);
return syscall;
}
/**
* syscall_enter_from_user_mode - Establish state and check and handle work
@ -159,7 +187,19 @@ long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
* Returns: The original or a modified syscall number. See
* syscall_enter_from_user_mode_work() for further explanation.
*/
long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
{
long ret;
enter_from_user_mode(regs);
instrumentation_begin();
local_irq_enable();
ret = syscall_enter_from_user_mode_work(regs, syscall);
instrumentation_end();
return ret;
}
/**
* local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
@ -258,6 +298,43 @@ static __always_inline void arch_exit_to_user_mode(void) { }
*/
void arch_do_signal_or_restart(struct pt_regs *regs);
/**
* exit_to_user_mode_loop - do any pending work before leaving to user space
*/
unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
unsigned long ti_work);
/**
* exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required
* @regs: Pointer to pt_regs on entry stack
*
* 1) check that interrupts are disabled
* 2) call tick_nohz_user_enter_prepare()
* 3) call exit_to_user_mode_loop() if any flags from
* EXIT_TO_USER_MODE_WORK are set
* 4) check that interrupts are still disabled
*/
static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs)
{
unsigned long ti_work;
lockdep_assert_irqs_disabled();
/* Flush pending rcuog wakeup before the last need_resched() check */
tick_nohz_user_enter_prepare();
ti_work = read_thread_flags();
if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
ti_work = exit_to_user_mode_loop(regs, ti_work);
arch_exit_to_user_mode_prepare(regs, ti_work);
/* Ensure that kernel state is sane for a return to userspace */
kmap_assert_nomap();
lockdep_assert_irqs_disabled();
lockdep_sys_exit();
}
/**
* exit_to_user_mode - Fixup state when exiting to user mode
*
@ -276,7 +353,17 @@ void arch_do_signal_or_restart(struct pt_regs *regs);
* non-instrumentable.
* The caller has to invoke syscall_exit_to_user_mode_work() before this.
*/
void exit_to_user_mode(void);
static __always_inline void exit_to_user_mode(void)
{
instrumentation_begin();
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
instrumentation_end();
user_enter_irqoff();
arch_exit_to_user_mode();
lockdep_hardirqs_on(CALLER_ADDR0);
}
/**
* syscall_exit_to_user_mode_work - Handle work before returning to user mode

108
kernel/entry/common.c
View File

@ -15,26 +15,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
/* See comment for enter_from_user_mode() in entry-common.h */
static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
{
arch_enter_from_user_mode(regs);
lockdep_hardirqs_off(CALLER_ADDR0);
CT_WARN_ON(__ct_state() != CONTEXT_USER);
user_exit_irqoff();
instrumentation_begin();
kmsan_unpoison_entry_regs(regs);
trace_hardirqs_off_finish();
instrumentation_end();
}
void noinstr enter_from_user_mode(struct pt_regs *regs)
{
__enter_from_user_mode(regs);
}
static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
{
if (unlikely(audit_context())) {
@ -45,7 +25,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
}
}
static long syscall_trace_enter(struct pt_regs *regs, long syscall,
long syscall_trace_enter(struct pt_regs *regs, long syscall,
unsigned long work)
{
long ret = 0;
@ -85,67 +65,24 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
return ret ? : syscall;
}
static __always_inline long
__syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
if (work & SYSCALL_WORK_ENTER)
syscall = syscall_trace_enter(regs, syscall, work);
return syscall;
}
long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
{
return __syscall_enter_from_user_work(regs, syscall);
}
noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
{
long ret;
__enter_from_user_mode(regs);
instrumentation_begin();
local_irq_enable();
ret = __syscall_enter_from_user_work(regs, syscall);
instrumentation_end();
return ret;
}
noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
{
__enter_from_user_mode(regs);
enter_from_user_mode(regs);
instrumentation_begin();
local_irq_enable();
instrumentation_end();
}
/* See comment for exit_to_user_mode() in entry-common.h */
static __always_inline void __exit_to_user_mode(void)
{
instrumentation_begin();
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
instrumentation_end();
user_enter_irqoff();
arch_exit_to_user_mode();
lockdep_hardirqs_on(CALLER_ADDR0);
}
void noinstr exit_to_user_mode(void)
{
__exit_to_user_mode();
}
/* Workaround to allow gradual conversion of architecture code */
void __weak arch_do_signal_or_restart(struct pt_regs *regs) { }
static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
unsigned long ti_work)
/**
* exit_to_user_mode_loop - do any pending work before leaving to user space
* @regs: Pointer to pt_regs on entry stack
* @ti_work: TIF work flags as read by the caller
*/
__always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
unsigned long ti_work)
{
/*
* Before returning to user space ensure that all pending work
@ -190,27 +127,6 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
return ti_work;
}
static void exit_to_user_mode_prepare(struct pt_regs *regs)
{
unsigned long ti_work;
lockdep_assert_irqs_disabled();
/* Flush pending rcuog wakeup before the last need_resched() check */
tick_nohz_user_enter_prepare();
ti_work = read_thread_flags();
if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
ti_work = exit_to_user_mode_loop(regs, ti_work);
arch_exit_to_user_mode_prepare(regs, ti_work);
/* Ensure that kernel state is sane for a return to userspace */
kmap_assert_nomap();
lockdep_assert_irqs_disabled();
lockdep_sys_exit();
}
/*
* If SYSCALL_EMU is set, then the only reason to report is when
* SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
@ -295,12 +211,12 @@ __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
instrumentation_begin();
__syscall_exit_to_user_mode_work(regs);
instrumentation_end();
__exit_to_user_mode();
exit_to_user_mode();
}
noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
{
__enter_from_user_mode(regs);
enter_from_user_mode(regs);
}
noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
@ -308,7 +224,7 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
instrumentation_begin();
exit_to_user_mode_prepare(regs);
instrumentation_end();
__exit_to_user_mode();
exit_to_user_mode();
}
noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)