Merge tag 'v3.10.107' into update

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / arm / kernel / hw_breakpoint.c

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 1b803117ed91c212a6f4077d6c87b58c0e219f44..e0c98b47eb9cb70843d934b1e0e1261a2203e3ea 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -1067,6 +1067,22 @@ static int __init arch_hw_breakpoint_init(void)
                return 0;
        }
 
+       /*
+        * Scorpion CPUs (at least those in APQ8060) seem to set DBGPRSR.SPD
+        * whenever a WFI is issued, even if the core is not powered down, in
+        * violation of the architecture.  When DBGPRSR.SPD is set, accesses to
+        * breakpoint and watchpoint registers are treated as undefined, so
+        * this results in boot time and runtime failures when these are
+        * accessed and we unexpectedly take a trap.
+        *
+        * It's not clear if/how this can be worked around, so we blacklist
+        * Scorpion CPUs to avoid these issues.
+       */
+       if ((read_cpuid_id() & 0xff00fff0) == ARM_CPU_PART_SCORPION) {
+               pr_info("Scorpion CPU detected. Hardware breakpoints and watchpoints disabled\n");
+               return 0;
+       }
+
        has_ossr = core_has_os_save_restore();
 
        /* Determine how many BRPs/WRPs are available. */