[GIT pull] scheduler updates for 4.18

From: Thomas Gleixner
Date: Sun Jun 24 2018 - 07:57:05 EST

Linus,

please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

A pile of rseq related fixups:

- Prevent infinite recursion when delivering SIGSEGV

- Remove the abort of rseq critical section on fork() as syscalls inside
rseq critical sections are explicitely forbidden. So no point in doing
the abort on the child.

- Align the rseq structure on 32 bytes in the ARM selftest code.

- Fix file permissions of the test script

Thanks,

tglx

------------------>
Mathieu Desnoyers (3):
rseq/selftests: Make run_param_test.sh executable
rseq/selftests/arm: Align 'struct rseq_cs' on 32 bytes
rseq/cleanup: Do not abort rseq c.s. in child on fork()

Will Deacon (1):
rseq: Avoid infinite recursion when delivering SIGSEGV


arch/arm/kernel/signal.c | 4 ++--
arch/powerpc/kernel/signal.c | 4 ++--
arch/x86/entry/common.c | 2 +-
arch/x86/kernel/signal.c | 2 +-
include/linux/sched.h | 23 ++++++++++++-----------
kernel/rseq.c | 7 ++++---
tools/testing/selftests/rseq/rseq-arm.h | 1 +
tools/testing/selftests/rseq/run_param_test.sh | 0
8 files changed, 23 insertions(+), 20 deletions(-)
mode change 100644 => 100755 tools/testing/selftests/rseq/run_param_test.sh

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index f09e9d66d605..dec130e7078c 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -544,7 +544,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
* Increment event counter and perform fixup for the pre-signal
* frame.
*/
- rseq_signal_deliver(regs);
+ rseq_signal_deliver(ksig, regs);

/*
* Set up the stack frame
@@ -666,7 +666,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
- rseq_handle_notify_resume(regs);
+ rseq_handle_notify_resume(NULL, regs);
}
}
local_irq_disable();
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 17fe4339ba59..b3e8db376ecd 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -134,7 +134,7 @@ static void do_signal(struct task_struct *tsk)
/* Re-enable the breakpoints for the signal stack */
thread_change_pc(tsk, tsk->thread.regs);

- rseq_signal_deliver(tsk->thread.regs);
+ rseq_signal_deliver(&ksig, tsk->thread.regs);

if (is32) {
if (ksig.ka.sa.sa_flags & SA_SIGINFO)
@@ -170,7 +170,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
- rseq_handle_notify_resume(regs);
+ rseq_handle_notify_resume(NULL, regs);
}

user_enter();
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 92190879b228..3b2490b81918 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -164,7 +164,7 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
if (cached_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
- rseq_handle_notify_resume(regs);
+ rseq_handle_notify_resume(NULL, regs);
}

if (cached_flags & _TIF_USER_RETURN_NOTIFY)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 445ca11ff863..92a3b312a53c 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -692,7 +692,7 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
* Increment event counter and perform fixup for the pre-signal
* frame.
*/
- rseq_signal_deliver(regs);
+ rseq_signal_deliver(ksig, regs);

/* Set up the stack frame */
if (is_ia32_frame(ksig)) {
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 87bf02d93a27..9256118bd40c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1799,20 +1799,22 @@ static inline void rseq_set_notify_resume(struct task_struct *t)
set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
}

-void __rseq_handle_notify_resume(struct pt_regs *regs);
+void __rseq_handle_notify_resume(struct ksignal *sig, struct pt_regs *regs);

-static inline void rseq_handle_notify_resume(struct pt_regs *regs)
+static inline void rseq_handle_notify_resume(struct ksignal *ksig,
+ struct pt_regs *regs)
{
if (current->rseq)
- __rseq_handle_notify_resume(regs);
+ __rseq_handle_notify_resume(ksig, regs);
}

-static inline void rseq_signal_deliver(struct pt_regs *regs)
+static inline void rseq_signal_deliver(struct ksignal *ksig,
+ struct pt_regs *regs)
{
preempt_disable();
__set_bit(RSEQ_EVENT_SIGNAL_BIT, &current->rseq_event_mask);
preempt_enable();
- rseq_handle_notify_resume(regs);
+ rseq_handle_notify_resume(ksig, regs);
}

/* rseq_preempt() requires preemption to be disabled. */
@@ -1831,9 +1833,7 @@ static inline void rseq_migrate(struct task_struct *t)

/*
* If parent process has a registered restartable sequences area, the
- * child inherits. Only applies when forking a process, not a thread. In
- * case a parent fork() in the middle of a restartable sequence, set the
- * resume notifier to force the child to retry.
+ * child inherits. Only applies when forking a process, not a thread.
*/
static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
{
@@ -1847,7 +1847,6 @@ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
t->rseq_len = current->rseq_len;
t->rseq_sig = current->rseq_sig;
t->rseq_event_mask = current->rseq_event_mask;
- rseq_preempt(t);
}
}

@@ -1864,10 +1863,12 @@ static inline void rseq_execve(struct task_struct *t)
static inline void rseq_set_notify_resume(struct task_struct *t)
{
}
-static inline void rseq_handle_notify_resume(struct pt_regs *regs)
+static inline void rseq_handle_notify_resume(struct ksignal *ksig,
+ struct pt_regs *regs)
{
}
-static inline void rseq_signal_deliver(struct pt_regs *regs)
+static inline void rseq_signal_deliver(struct ksignal *ksig,
+ struct pt_regs *regs)
{
}
static inline void rseq_preempt(struct task_struct *t)
diff --git a/kernel/rseq.c b/kernel/rseq.c
index ae306f90c514..22b6acf1ad63 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -251,10 +251,10 @@ static int rseq_ip_fixup(struct pt_regs *regs)
* respect to other threads scheduled on the same CPU, and with respect
* to signal handlers.
*/
-void __rseq_handle_notify_resume(struct pt_regs *regs)
+void __rseq_handle_notify_resume(struct ksignal *ksig, struct pt_regs *regs)
{
struct task_struct *t = current;
- int ret;
+ int ret, sig;

if (unlikely(t->flags & PF_EXITING))
return;
@@ -268,7 +268,8 @@ void __rseq_handle_notify_resume(struct pt_regs *regs)
return;

error:
- force_sig(SIGSEGV, t);
+ sig = ksig ? ksig->sig : 0;
+ force_sigsegv(sig, t);
}

#ifdef CONFIG_DEBUG_RSEQ
diff --git a/tools/testing/selftests/rseq/rseq-arm.h b/tools/testing/selftests/rseq/rseq-arm.h
index 3b055f9aeaab..3cea19877227 100644
--- a/tools/testing/selftests/rseq/rseq-arm.h
+++ b/tools/testing/selftests/rseq/rseq-arm.h
@@ -57,6 +57,7 @@ do { \
#define __RSEQ_ASM_DEFINE_ABORT(table_label, label, teardown, \
abort_label, version, flags, \
start_ip, post_commit_offset, abort_ip) \
+ ".balign 32\n\t" \
__rseq_str(table_label) ":\n\t" \
".word " __rseq_str(version) ", " __rseq_str(flags) "\n\t" \
".word " __rseq_str(start_ip) ", 0x0, " __rseq_str(post_commit_offset) ", 0x0, " __rseq_str(abort_ip) ", 0x0\n\t" \
diff --git a/tools/testing/selftests/rseq/run_param_test.sh b/tools/testing/selftests/rseq/run_param_test.sh
old mode 100644
new mode 100755