[PATCH Dovetail v2 1/6] arm: irq_pipeline: Fix fault_{entry,exit} bypass in do_kernel_address_page_fault

In case do_kernel_address_page_fault() was entered over supervisor mode
the fault_{entry,exit} machinery was bypassed. As a result the inband
IRQ mask might have been touched from the oob stage.

There is another problem with interrupts_enabled() in the supervisor
mode code path. That one will be addressed in a separate patch.

Signed-off-by: Florian Bezdeka <[email protected]>
---
 arch/arm/mm/fault.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 49f5d628c4c9a91a3e879af0d541fd76665d78fe..7a5c0a5a825df5f76eec6aa341d910c3efa63f88 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -382,6 +382,8 @@ do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr,
 {
 	unsigned long irqflags;
 
+	irqflags = fault_entry(ARM_TRAP_ACCESS, regs);
+
 	if (user_mode(regs)) {
 		/*
 		 * Fault from user mode for a kernel space address. User mode
@@ -391,9 +393,7 @@ do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr,
 		 * Note that __do_user_fault() will enable interrupts.
 		 */
 		harden_branch_predictor();
-		irqflags = fault_entry(ARM_TRAP_ACCESS, regs);
 		__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
-		fault_exit(ARM_TRAP_ACCESS, regs, irqflags);
 	} else {
 		/*
 		 * Fault from kernel mode. Enable interrupts if they were
@@ -409,6 +409,8 @@ do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr,
 		__do_kernel_fault(mm, addr, fsr, regs);
 	}
 
+	fault_exit(ARM_TRAP_ACCESS, regs, irqflags);
+
 	return 0;
 }
 

-- 
2.54.0