• Mark Rutland's avatar
    ARM: 8634/1: hw_breakpoint: blacklist Scorpion CPUs · ddc37832
    Mark Rutland authored
    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.
    Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
    Reported-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
    Acked-by: default avatarWill Deacon <will.deacon@arm.com>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    ddc37832
hw_breakpoint.c 27.1 KB