Some software such as perf makes unconditional use of the special [vectors] page which is only provided when CONFIG_KUSER_HELPERS is enabled in the kernel.
Facilitate the debugging of such situations by printing a debug message to the kernel log showing the task name and the faulting address. Suggested-by: Russell King <rmk+ker...@armlinux.org.uk> Signed-off-by: Florian Fainelli <f.faine...@gmail.com> --- arch/arm/mm/fault.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index f4ea4c62c613..f17471fbc1c4 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -173,6 +173,11 @@ __do_user_fault(struct task_struct *tsk, unsigned long addr, show_regs(regs); } #endif +#ifndef CONFIG_KUSER_HELPERS + if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000)) + printk(KERN_DEBUG "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n", + tsk->comm, addr); +#endif tsk->thread.address = addr; tsk->thread.error_code = fsr; -- 2.17.1