The scheduler now knows enough about these braindead systems to place
32-bit tasks accordingly, so throw out the safety checks and allow the
ret-to-user path to avoid do_notify_resume() if there is nothing to do.
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/kernel/process.c | 14 +-------------
arch/arm64/kernel/signal.c | 26 --------------------------
2 files changed, 1 insertion(+), 39 deletions(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index da313b738c7c..3b08938c7d9d 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -541,15 +541,6 @@ static void erratum_1418040_thread_switch(struct task_struct *prev,
write_sysreg(val, cntkctl_el1);
}
-static void compat_thread_switch(struct task_struct *next)
-{
- if (!is_compat_thread(task_thread_info(next)))
- return;
-
- if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
- set_tsk_thread_flag(next, TIF_NOTIFY_RESUME);
-}
-
/*
* Thread switching.
*/
@@ -566,7 +557,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
uao_thread_switch(next);
ssbs_thread_switch(next);
erratum_1418040_thread_switch(prev, next);
- compat_thread_switch(next);
/*
* Complete any pending TLB or cache maintenance on this CPU in case
@@ -643,10 +633,8 @@ void arch_setup_new_exec(void)
* at the point of execve(), although we try a bit harder to
* honour the cpuset hierarchy.
*/
- if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) {
+ if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
force_compatible_cpus_allowed_ptr(current);
- set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
- }
}
current->mm->context.flags = mmflags;
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index bcb6ca2d9a7c..a8184cad8890 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -911,19 +911,6 @@ static void do_signal(struct pt_regs *regs)
restore_saved_sigmask();
}
-static bool cpu_affinity_invalid(struct pt_regs *regs)
-{
- if (!compat_user_mode(regs))
- return false;
-
- /*
- * We're preemptible, but a reschedule will cause us to check the
- * affinity again.
- */
- return !cpumask_test_cpu(raw_smp_processor_id(),
- system_32bit_el0_cpumask());
-}
-
asmlinkage void do_notify_resume(struct pt_regs *regs,
unsigned long thread_flags)
{
@@ -961,19 +948,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
if (thread_flags & _TIF_NOTIFY_RESUME) {
tracehook_notify_resume(regs);
rseq_handle_notify_resume(NULL, regs);
-
- /*
- * If we reschedule after checking the affinity
- * then we must ensure that TIF_NOTIFY_RESUME
- * is set so that we check the affinity again.
- * Since tracehook_notify_resume() clears the
- * flag, ensure that the compiler doesn't move
- * it after the affinity check.
- */
- barrier();
-
- if (cpu_affinity_invalid(regs))
- force_sig(SIGKILL);
}
if (thread_flags & _TIF_FOREIGN_FPSTATE)
--
2.29.2.576.ga3fc446d84-goog
