[PATCH v2 5.10.y/5.15.y 3/3] ARM: ensure interrupts are enabled in __do_user_fault()
From: Xie Yuanbin <hidden>
Date: 2026-09-17 02:31:45
Also in:
linux-patches, linux-rt-devel, lkml, stable
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
From: "Russell King (Oracle)" <redacted> [ Upstream commit 59e4f3b45b96a24fc9b7a89e5f8a2168b30f95af ] __do_user_fault() may be called from fault handling paths where the interrupts are enabled or disabled. E.g. do_page_fault() calls this with interrupts enabled, whereas do_sect_fault()->do_bad_area() will call this with interrupts disabled. Since this is a userspace fault, we know that interrupts were enabled in the parent context, so call local_irq_enable() here to give a consistent interrupt state. This is necessary for force_sig_info() when PREEMPT_RT is enabled. Reported-by: Yadi.hu <redacted> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Russell King (Oracle) <redacted> Signed-off-by: Xie Yuanbin <redacted> --- arch/arm/mm/fault.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 4afb076383a8..8b31d7704626 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c@@ -137,7 +137,8 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, /* * Something tried to access memory that isn't in our memory map.. - * User mode accesses just cause a SIGSEGV + * User mode accesses just cause a SIGSEGV. Ensure interrupts are enabled + * for preempt RT. */ static void __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
@@ -145,6 +146,8 @@ __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig, { struct task_struct *tsk = current; + local_irq_enable(); + #ifdef CONFIG_DEBUG_USER if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) || ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
@@ -254,6 +257,7 @@ do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr, * should not be faulting in kernel space, which includes the * vector/khelper page. Handle the branch predictor hardening * while interrupts are still disabled, then send a SIGSEGV. + * Note that __do_user_fault() will enable interrupts. */ harden_branch_predictor(); __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
--
2.55.0