arm64: errata: add workaround for cortex-a53 erratum #845719

[linux-2.6-block.git] / arch / arm64 / kernel / entry.S

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index cf21bb3bf7524c5907463119a20832467b181745..959fe8733560971e4a8d9d222f943dac192c6057 100644 (file)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -21,8 +21,10 @@
 #include <linux/init.h>
 #include <linux/linkage.h>
 
+#include <asm/alternative-asm.h>
 #include <asm/assembler.h>
 #include <asm/asm-offsets.h>
+#include <asm/cpufeature.h>
 #include <asm/errno.h>
 #include <asm/esr.h>
 #include <asm/thread_info.h>
@@ -120,6 +122,24 @@
        ct_user_enter
        ldr     x23, [sp, #S_SP]                // load return stack pointer
        msr     sp_el0, x23
+
+#ifdef CONFIG_ARM64_ERRATUM_845719
+       alternative_insn                                                \
+       "nop",                                                          \
+       "tbz x22, #4, 1f",                                              \
+       ARM64_WORKAROUND_845719
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+       alternative_insn                                                \
+       "nop; nop",                                                     \
+       "mrs x29, contextidr_el1; msr contextidr_el1, x29; 1:",         \
+       ARM64_WORKAROUND_845719
+#else
+       alternative_insn                                                \
+       "nop",                                                          \
+       "msr contextidr_el1, xzr; 1:",                                  \
+       ARM64_WORKAROUND_845719
+#endif
+#endif
        .endif
        msr     elr_el1, x21                    // set up the return data
        msr     spsr_el1, x22