On 01/05, Mark Rutland wrote: > On APQ8060, the kernel crashes in arch_hw_breakpoint_init, taking an > undefined instruction trap within write_wb_reg. This is because Scorpion > CPUs erroneously appear to set DBGPRSR.SPD when WFI is issued, even if > the core is not powered down. When DBGPRSR.SPD is set, breakpoint and > watchpoint registers are treated as undefined. > > It's possible to trigger similar crashes later on from userspace, by > requesting the kernel to install a breakpoint or watchpoint, as we can > go idle at any point between the reset of the debug registers and their > later use. This has always been the case. > > Given that this has always been broken, no-one has complained until now, > and there is no clear workaround, disable hardware breakpoints and > watchpoints on Scorpion to avoid these issues. I believe the workaround is to read DBGPRSR after exit from WFI? I'm fine with the blacklisting approach though. > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > Reported-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > Cc: Russell King <linux@xxxxxxxxxxxxxxx> > Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- Reviewed-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html