@@ -61,12 +61,7 @@ ENTRY(ret_to_user)
enable_irq_notrace @ enable interrupts
mov r0, sp @ 'regs'
bl syscall_exit_to_user_mode
- ldr r1, [tsk, #TI_FLAGS]
- movs r1, r1, lsl #16
- beq 1f
- mov r0, sp @ 'regs'
- bl do_work_pending
-1:
+
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
bl stackleak_erase_on_task_stack
#endif
@@ -74,12 +69,6 @@ ENTRY(ret_to_user)
ENDPROC(ret_to_user)
ENTRY(ret_to_user_from_irq)
- ldr r1, [tsk, #TI_FLAGS]
- movs r1, r1, lsl #16
- beq no_work_pending
- mov r0, sp @ 'regs'
- bl do_work_pending
-no_work_pending:
asm_irqentry_exit_to_user_mode
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
@@ -6,11 +6,6 @@
#include <linux/irqflags.h>
#include <linux/rseq.h>
-static inline bool has_syscall_work(unsigned long flags)
-{
- return unlikely(flags & _TIF_SYSCALL_WORK);
-}
-
long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
{
trace_hardirqs_on();
@@ -28,7 +23,11 @@ void syscall_exit_to_user_mode(struct pt_regs *regs)
rseq_syscall(regs);
local_irq_disable();
- if (has_syscall_work(flags))
+ /*
+ * It really matters that we check for flags != 0 and not
+ * just for pending work here!
+ */
+ if (flags)
do_work_pending(regs, flags);
trace_hardirqs_on();
@@ -45,6 +44,14 @@ noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
{
+ unsigned long flags = read_thread_flags();
+
+ /*
+ * It really matters that we check for flags != 0 and not
+ * just for pending work here!
+ */
+ if (flags)
+ do_work_pending(regs, flags);
trace_hardirqs_on();
/* This context tracking call has inverse naming */
user_enter_callable();
@@ -598,8 +598,7 @@ static void arch_do_signal_or_restart(struct pt_regs *regs)
return;
}
-asmlinkage void
-do_work_pending(struct pt_regs *regs, unsigned int thread_flags)
+void do_work_pending(struct pt_regs *regs, unsigned int thread_flags)
{
/*
* The assembly code enters us with IRQs off, but it hasn't
This moves over the last few lines of assembly to C. The subtle change is that in return to userspace from syscall (SWI) or interrupt, we need to call do_work_pending() as soon as the thread flags are != 0, just checking for work with _TIF_SYSCALL_WORK is not enough (the machine will freeze if we do that). This is because do_work_pending() does not just handle work: it handles _TIF_NEED_RESCHED, _TIF_SIGPENDING, _TIF_NOTIFY_SIGNAL and _TIF_UPROBE as well. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- arch/arm/kernel/entry-common.S | 13 +------------ arch/arm/kernel/entry.c | 19 +++++++++++++------ arch/arm/kernel/signal.c | 3 +-- 3 files changed, 15 insertions(+), 20 deletions(-)