Florian Fainelli <f.faine...@gmail.com> writes: > 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.
Can't someone trigger this segv deliberately and spam the kerne log? Doesn't this need something like printk_ratelimit or something to ensure this message only gets printed once? Eric > 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;
