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entry: move the exit path to header files
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In order to allow inlining the generic entry C functions,
move them to include/linux/entry-common.h.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
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@svens-s390 @intel-lab-lkp
svens-s390 authored and intel-lab-lkp committed May 16, 2023
1 parent 8c8fa60 commit 30656e2
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Showing 2 changed files with 179 additions and 171 deletions.
182 changes: 179 additions & 3 deletions include/linux/entry-common.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,13 @@
#include <linux/syscalls.h>
#include <linux/seccomp.h>
#include <linux/sched.h>

#include <linux/livepatch.h>
#include <asm/entry-common.h>
#include <linux/context_tracking.h>
#include <linux/resume_user_mode.h>
#include <linux/tick.h>

#include <trace/events/syscalls.h>

/*
* Define dummy _TIF work flags if not defined by the architecture or for
Expand Down Expand Up @@ -291,7 +296,7 @@ void exit_to_user_mode(void);
* make the final state transitions. Interrupts must stay disabled between
* return from this function and the invocation of exit_to_user_mode().
*/
void syscall_exit_to_user_mode_work(struct pt_regs *regs);
static void syscall_exit_to_user_mode_work(struct pt_regs *regs);

/**
* syscall_exit_to_user_mode - Handle work before returning to user mode
Expand Down Expand Up @@ -350,7 +355,7 @@ void irqentry_enter_from_user_mode(struct pt_regs *regs);
* Interrupt exit is not invoking #1 which is the syscall specific one time
* work.
*/
void irqentry_exit_to_user_mode(struct pt_regs *regs);
static void irqentry_exit_to_user_mode(struct pt_regs *regs);

#ifndef irqentry_state
/**
Expand Down Expand Up @@ -465,4 +470,175 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
*/
void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);

static 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
* items have been completed.
*/
while (ti_work & EXIT_TO_USER_MODE_WORK) {

local_irq_enable_exit_to_user(ti_work);

if (ti_work & _TIF_NEED_RESCHED)
schedule();

if (ti_work & _TIF_UPROBE)
uprobe_notify_resume(regs);

if (ti_work & _TIF_PATCH_PENDING)
klp_update_patch_state(current);

if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
arch_do_signal_or_restart(regs);

if (ti_work & _TIF_NOTIFY_RESUME)
resume_user_mode_work(regs);

/* Architecture specific TIF work */
arch_exit_to_user_mode_work(regs, ti_work);

/*
* Disable interrupts and reevaluate the work flags as they
* might have changed while interrupts and preemption was
* enabled above.
*/
local_irq_disable_exit_to_user();

/* Check if any of the above work has queued a deferred wakeup */
tick_nohz_user_enter_prepare();

ti_work = read_thread_flags();
}

/* Return the latest work state for arch_exit_to_user_mode() */
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 the address limit is intact and no locks are held */
addr_limit_user_check();
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
* instruction has been already reported in syscall_enter_from_user_mode().
*/
static inline bool report_single_step(unsigned long work)
{
if (work & SYSCALL_WORK_SYSCALL_EMU)
return false;

return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
}

static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
{
bool step;

/*
* If the syscall was rolled back due to syscall user dispatching,
* then the tracers below are not invoked for the same reason as
* the entry side was not invoked in syscall_trace_enter(): The ABI
* of these syscalls is unknown.
*/
if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
if (unlikely(current->syscall_dispatch.on_dispatch)) {
current->syscall_dispatch.on_dispatch = false;
return;
}
}

audit_syscall_exit(regs);

if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
trace_sys_exit(regs, syscall_get_return_value(current, regs));

step = report_single_step(work);
if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
ptrace_report_syscall_exit(regs, step);
}

/*
* Syscall specific exit to user mode preparation. Runs with interrupts
* enabled.
*/
static __always_inline void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
unsigned long nr = syscall_get_nr(current, regs);

CT_WARN_ON(ct_state() != CONTEXT_KERNEL);

if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
local_irq_enable();
}

rseq_syscall(regs);

/*
* Do one-time syscall specific work. If these work items are
* enabled, we want to run them exactly once per syscall exit with
* interrupts enabled.
*/
if (unlikely(work & SYSCALL_WORK_EXIT))
syscall_exit_work(regs, work);
}

static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs)
{
syscall_exit_to_user_mode_prepare(regs);
local_irq_disable_exit_to_user();
exit_to_user_mode_prepare(regs);
}

static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
{
__syscall_exit_to_user_mode_work(regs);
}

/* 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);
}


static __always_inline void irqentry_exit_to_user_mode(struct pt_regs *regs)
{
instrumentation_begin();
exit_to_user_mode_prepare(regs);
instrumentation_end();
__exit_to_user_mode();
}


#endif
168 changes: 0 additions & 168 deletions kernel/entry/common.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -123,19 +123,6 @@ noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
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();
Expand All @@ -144,153 +131,6 @@ void noinstr exit_to_user_mode(void)
/* 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)
{
/*
* Before returning to user space ensure that all pending work
* items have been completed.
*/
while (ti_work & EXIT_TO_USER_MODE_WORK) {

local_irq_enable_exit_to_user(ti_work);

if (ti_work & _TIF_NEED_RESCHED)
schedule();

if (ti_work & _TIF_UPROBE)
uprobe_notify_resume(regs);

if (ti_work & _TIF_PATCH_PENDING)
klp_update_patch_state(current);

if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
arch_do_signal_or_restart(regs);

if (ti_work & _TIF_NOTIFY_RESUME)
resume_user_mode_work(regs);

/* Architecture specific TIF work */
arch_exit_to_user_mode_work(regs, ti_work);

/*
* Disable interrupts and reevaluate the work flags as they
* might have changed while interrupts and preemption was
* enabled above.
*/
local_irq_disable_exit_to_user();

/* Check if any of the above work has queued a deferred wakeup */
tick_nohz_user_enter_prepare();

ti_work = read_thread_flags();
}

/* Return the latest work state for arch_exit_to_user_mode() */
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 the address limit is intact and no locks are held */
addr_limit_user_check();
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
* instruction has been already reported in syscall_enter_from_user_mode().
*/
static inline bool report_single_step(unsigned long work)
{
if (work & SYSCALL_WORK_SYSCALL_EMU)
return false;

return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
}

static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
{
bool step;

/*
* If the syscall was rolled back due to syscall user dispatching,
* then the tracers below are not invoked for the same reason as
* the entry side was not invoked in syscall_trace_enter(): The ABI
* of these syscalls is unknown.
*/
if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
if (unlikely(current->syscall_dispatch.on_dispatch)) {
current->syscall_dispatch.on_dispatch = false;
return;
}
}

audit_syscall_exit(regs);

if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
trace_sys_exit(regs, syscall_get_return_value(current, regs));

step = report_single_step(work);
if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
ptrace_report_syscall_exit(regs, step);
}

/*
* Syscall specific exit to user mode preparation. Runs with interrupts
* enabled.
*/
static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
unsigned long nr = syscall_get_nr(current, regs);

CT_WARN_ON(ct_state() != CONTEXT_KERNEL);

if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
local_irq_enable();
}

rseq_syscall(regs);

/*
* Do one-time syscall specific work. If these work items are
* enabled, we want to run them exactly once per syscall exit with
* interrupts enabled.
*/
if (unlikely(work & SYSCALL_WORK_EXIT))
syscall_exit_work(regs, work);
}

static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs)
{
syscall_exit_to_user_mode_prepare(regs);
local_irq_disable_exit_to_user();
exit_to_user_mode_prepare(regs);
}

void syscall_exit_to_user_mode_work(struct pt_regs *regs)
{
__syscall_exit_to_user_mode_work(regs);
}

__visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
{
instrumentation_begin();
Expand All @@ -304,14 +144,6 @@ noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
__enter_from_user_mode(regs);
}

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();
}

noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
{
irqentry_state_t ret = {
Expand Down

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